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Different Habitats (different + habitat)
Terms modified by Different Habitats Selected AbstractsDUSKY DOLPHIN (LAGENORHYNCHUS OBSCURUS) FORAGING IN TWO DIFFERENT HABITATS: ACTIVE ACOUSTIC DETECTION OF DOLPHINS AND THEIR PREYMARINE MAMMAL SCIENCE, Issue 2 2004Kelly J. Benoit-Bird Abstract Active-acoustic surveys were used to determine the distribution of dusky dolphins and potential prey in two different New Zealand locations. During seven survey days off Kaikoura Canyon, dusky dolphins were found within the DeepScattering Layer (DSL) at 2000 when it rose to within 125 m of the surface. As the DSL rose to 30 m at 0100, the observed depth of dolphins decreased, presumably as the dolphins followed the vertical migration of their prey. Acoustically identified subgroups of coordinated animals ranged from one to five dolphins. Time, depth of layer, and layer variance contributed significantly to predicting foraging dusky dolphin subgroup size. In the much shallower and more enclosed Admiralty Bay, dolphins noted at the surface as foraging were always detected with the sonar, but were never observed in coordinated subgroups during the brief (two-day) study there. In Admiralty Bay dolphin abundance was correlated with mean volume scattering from potential prey in the water column; and when volume scattering, an index of prey density, was low, dolphins were rarely present. Ecological differences between the deep waters of Kaikoura Canyon and the shallow nearshore waters of Admiralty Bay may result in differences in how, when, and in what social groupings dusky dolphins forage. [source] Detecting local adaptation in widespread grassland species , the importance of scale and local plant communityJOURNAL OF ECOLOGY, Issue 6 2006ARMIN BISCHOFF Summary 1Adaptation of plant populations to local environments has been shown in many species but local adaptation is not always apparent and spatial scales of differentiation are not well known. In a reciprocal transplant experiment we tested whether: (i) three widespread grassland species are locally adapted at a European scale; (ii) detection of local adaptation depends on competition with the local plant community; and (iii) local differentiation between neighbouring populations from contrasting habitats can be stronger than differentiation at a European scale. 2Seeds of Holcus lanatus, Lotus corniculatus and Plantago lanceolata from a Swiss, Czech and UK population were sown in a reciprocal transplant experiment at fields that exhibit environmental conditions similar to the source sites. Seedling emergence, survival, growth and reproduction were recorded for two consecutive years. 3The effect of competition was tested by comparing individuals in weeded monocultures with plants sown together with species from the local grassland community. To compare large-scale vs. small-scale differentiation, a neighbouring population from a contrasting habitat (wet-dry contrast) was compared with the ,home' and ,foreign' populations. 4In P. lanceolata and H. lanatus, a significant home-site advantage was detected in fitness-related traits, thus indicating local adaptation. In L. corniculatus, an overall superiority of one provenance was found. 5The detection of local adaptation depended on competition with the local plant community. In the absence of competition the home-site advantage was underestimated in P. lanceolata and overestimated in H. lanatus. 6A significant population differentiation between contrasting local habitats was found. In some traits, this small-scale was greater than large-scale differentiation between countries. 7Our results indicate that local adaptation in real plant communities cannot necessarily be predicted from plants grown in weeded monocultures and that tests on the relationship between fitness and geographical distance have to account for habitat-dependent small-scale differentiation. Considering the strong small-scale differentiation, a local provenance from a different habitat may not be the best choice in ecological restoration if distant populations from a more similar habitat are available. [source] The distribution and prevalence of sponges in relation to environmental gradients within a temperate sea lough: vertical cliff surfacesDIVERSITY AND DISTRIBUTIONS, Issue 6 2000James J. Bell Abstract. The prevalence and distribution of sponges was surveyed on vertical cliff surfaces at Lough Hyne Marine Nature Reserve, Co. Cork, Ireland. The number of sponge species was recorded at 6-metre depth intervals at four sites within Lough Hyne, and at one site on the adjacent Atlantic coastline to examine differences in abundance and zonation patterns. Sites ranged from an exposed turbulent regime to sheltered, sedimented environments. Individual species showed different distributions and prevalence between sites and with increasing depth. Greatest differences were observed between the most- and least-disturbed sites. Distinct sponge zonation patterns were evident at all sites sampled. Twenty-five species were considered dominant at all five sites with the remaining 48 species considered rare. Only four of the 25 most-dominant species occurred at the site experiencing the most turbulent flow conditions, whereas 12 species were found at the site of unidirectional fast flow. At sites of moderate to slight water movement and high sedimentation, between 18 and 24 of the most dominant species were present. Encrusting forms constituted high proportions of sponge communities at all five sites sampled (although consisting of different species). At sites of turbulent and unidirectional fast flow massive forms also dominated whereas at the least turbulent sites, where sedimentation was high, arborescent sponges were abundant. Few species showed exclusive distribution to a single depth and site, but there was some degree of correlation between species distributions and abiotic factors such as sedimentation rate and flow regimes. Sponge distributions and densities are discussed with respect to the suitability of species' morphologies to particular environments, intra-specific and inter-specific competition and physiological adaptations that enable them to survive in different habitats. [source] Habitat size and number in multi-habitat landscapes: a model approach based on species-area curvesECOGRAPHY, Issue 1 2002Even Tjørve This paper discusses species diversity in simple multi-habitat environments. Its main purpose is to present simple mathematical and graphical models on how landscape patterns affect species numbers. The idea is to build models of species diversity in multi-habitat landscapes by combining species-area curves for different habitats. Predictions are made about how variables such as species richness and species overlap between habitats influence the proportion of the total landscape each habitat should constitute, and how many habitats it should be divided into in order to be able to sustain the maximal number of species. Habitat size and numbers are the only factors discussed here, not habitat spatial patterns. Among the predictions are: 1) where there are differences in species diversity between habitats, optimal landscape patterns contain larger proportions of species rich habitats. 2) Species overlap between habitats shifts the optimum further towards larger proportions of species rich habitat types. 3) Species overlap also shifts the optimum towards fewer habitat types. 4) Species diversity in landscapes with large species overlap is more resistant to changes in landscape (or reserve) size. This type of model approach can produce theories useful to nature and landscape management in general, and the design of nature reserves and national parks in particular. [source] Population dynamics of insects associated with Rumex obtusifolius in different habitatsENTOMOLOGICAL RESEARCH, Issue 2 2006Ohseok KWON Abstract The effect of different habitats on insect communities associated with Rumex obtusifolius was studied in detail. Study sites were selected for their variety of environmental characteristics (vegetation and habitat): shaded woodland, disturbed wasteland and pasture. The results of this study were that insect populations associated with R. obtusifolius responded differently to the different habitats. The observed differences in population dynamics among the insects showed quite clearly their responses to different habitats. There was also a pattern of time partitioning in the exploitation of the host-plant among the insect species observed. Philaenus spumarius at nymphal stage had a peak density on approximately 20 June, Apion frumentarium and Apion spp. (Apion species other than A. frumentarium) had a peak density on approximately 30 June and Aphis rumicis had a peak density on approximately 28 July. This pattern of shift in time for peak population density (time-shift) among the insects sharing a common host-plant may guarantee each insect the opportunity to exploit the plant to a maximum. [source] Diversity of bacteriorhodopsins in different hypersaline waters from a single Spanish salternENVIRONMENTAL MICROBIOLOGY, Issue 11 2003R. Thane Papke Summary Haloarchaeal rhodopsins are a diverse group of transmembrane proteins that use light energy to drive several different cellular processes. Two rhodopsins, bacteriorhodopsin and halorhodopsins, are H+ and Cl, ion pumps, respectively, and two rhodopsins, sensory rhodopsin I and II, regulate phototaxis. Bacteriorhodopsin is of special interest as it is a non-chlorophyll-based type of phototrophy (i.e. generation of chemical energy from light energy). However, very little is known about the diversity and distribution of rhodopsin genes in hypersaline environments. Here, we have used environmental PCR and cloning techniques to directly retrieve rhodopsin genes from three different salinity ponds located in a sea salt manufacturing facility near Alicante, Spain. Our survey resulted in the discovery of previously concealed variation including what is hypothesized to be bacteriorhodopsin genes from the uncultivated square morphotype that dominates these environments. In some instances, identical genes were discovered in seemingly different habitats suggesting that some haloarchaea are present over widely varying concentrations of salt. [source] THE BIOLOGY OF SPECIATIONEVOLUTION, Issue 2 2010James M. Sobel Since Darwin published the "Origin," great progress has been made in our understanding of speciation mechanisms. The early investigations by Mayr and Dobzhansky linked Darwin's view of speciation by adaptive divergence to the evolution of reproductive isolation, and thus provided a framework for studying the origin of species. However, major controversies and questions remain, including: When is speciation nonecological? Under what conditions does geographic isolation constitute a reproductive isolating barrier? and How do we estimate the "importance" of different isolating barriers? Here, we address these questions, providing historical background and offering some new perspectives. A topic of great recent interest is the role of ecology in speciation. "Ecological speciation" is defined as the case in which divergent selection leads to reproductive isolation, with speciation under uniform selection, polyploid speciation, and speciation by genetic drift defined as "nonecological." We review these proposed cases of nonecological speciation and conclude that speciation by uniform selection and polyploidy normally involve ecological processes. Furthermore, because selection can impart reproductive isolation both directly through traits under selection and indirectly through pleiotropy and linkage, it is much more effective in producing isolation than genetic drift. We thus argue that natural selection is a ubiquitous part of speciation, and given the many ways in which stochastic and deterministic factors may interact during divergence, we question whether the ecological speciation concept is useful. We also suggest that geographic isolation caused by adaptation to different habitats plays a major, and largely neglected, role in speciation. We thus provide a framework for incorporating geographic isolation into the biological species concept (BSC) by separating ecological from historical processes that govern species distributions, allowing for an estimate of geographic isolation based upon genetic differences between taxa. Finally, we suggest that the individual and relative contributions of all potential barriers be estimated for species pairs that have recently achieved species status under the criteria of the BSC. Only in this way will it be possible to distinguish those barriers that have actually contributed to speciation from those that have accumulated after speciation is complete. We conclude that ecological adaptation is the major driver of reproductive isolation, and that the term "biology of speciation," as proposed by Mayr, remains an accurate and useful characterization of the diversity of speciation mechanisms. [source] FEMALE SOLDIER BEETLES DISPLAY A FLEXIBLE PREFERENCE FOR SELECTIVELY FAVORED MALE PHENOTYPESEVOLUTION, Issue 5 2005Denson Kelly Mclain Abstract In Georgia (USA) the soldier beetle, Chauliognathus pennsylvanicus (Coleoptera; Cantharidae), exhibits clinal variation in the length of the spot on its elytron. This suggests that the viability of phenotypes varies by habitat. Evidence of viability selection comes from within-site changes in the spot length distribution across a breeding season. When males with spots of intermediate length became less frequent, they became disproportionately less likely to mate, consistent with either a loss of vigor among remaining males or female rejection of disfavored phenotypes. Persistent, daily courtship by males provides females with the opportunity to track changes in male phenotype frequency and to exercise choice for phenotypes favored under natural selection. A laboratory experiment in which the frequency of one spot morph (long) or the other (short) was increased from 25% to 75% over a period of 30 days revealed that females possess a flexible preference that leads them to prefer whichever spot type has become more common over time. A haploid genetic model demonstrates that a flexible female preference for the locally favored male phenotype can be selected for when different viability alleles, genetically correlated with the male trait, are favored in different habitats that are linked by gene flow. Thus, migration between different kinds of habitat patches of a metapopulation could maintain the variation in male quality. This variation favors female choice for any trait that is directly or indirectly favored by natural selection. Such choice imparts positive frequency-dependent selection that could rapidly fix traits pleiotropically linked to viability. Rapid fixation would cause differentiation between populations of colonizing species as females exercise choice for mates favored under new ecological conditions. [source] N2 -fixation and complementary chromatic adaptation in non-heterocystous cyanobacteria from Lake ConstanceFEMS MICROBIOLOGY ECOLOGY, Issue 2 2001Christine Postius Abstract Non-heterocystous, mostly filamentous cyanobacteria were isolated from the crust of stones, from the periphyton of two macrophytes from the littoral zone and from the pelagic environment of Lake Constance. All isolates were cultivated as unialgal strains. DNA analysis by restriction fragment length polymorphism with the psbA gene probe revealed high genetic diversity among the strains from the littoral zone. For all genotypes, the occurrence of the nifH gene encoding a nitrogenase subunit and of genes encoding subunits of phycoerythrin and phycocyanin were tested by Southern blot hybridization. In addition, the isolates were investigated for their ability for complementary chromatic adaptation (CCA) and for anaerobic N2 -fixation. With respect to these characteristics, all cyanobacteria included in this study were assigned to four different types: (1) strains without the capability to fix N2 or to perform CCA of the group III type (CCA III); (2) strains which show both features; (3) strains with the ability to fix nitrogen, but that do not show any CCA III; and (4) strains that produce phycoerythrin, but without the capacity for CCA III or N2 -fixation. By examining the frequency distribution of isolates, these types were shown to prefer different habitats. While cyanobacterial strains capable of N2 -fixation, but without CCA III, were mainly obtained from stone crusts in the supralittoral zone, those with the potential for N2 -fixation as well as for CCA III were largely isolated from submersed macrophytes. Cyanobacteria that produce phycoerythrin, but do not perform CCA III or N2 -fixation, were found in the pelagic zone only. [source] The enhancement of cod stocksFISH AND FISHERIES, Issue 2 2000T. Svåsand Atlantic cod have been a primary target for marine stock enhancement since the 1880s. In the early part of this period, hatched larvae were released in Norway, the USA and Canada. The last larval releases were conducted in Norway in 1971, and a century of cod larvae releases were halted without any clear evidence of benefit. Since the early 1980s, the focus has been on production of larger, more viable juvenile cod. Emphasis has been given to the design of tag,release programmes involving large-scale releases and ecosystem analysis in selected ecosystems. Most of this research has been carried out in Norway, where more than one million tagged juvenile cod have been released. Smaller stocking experiments have also been performed in Denmark, Sweden, the Faroe Islands and the USA. This paper reviews the major findings from these programmes. We include summaries and evaluations of rearing techniques for juvenile cod, methods of tagging and recapture, experimental fishing, migration, mortality and growth rates in the different habitats, genetic analysis, and ecosystem studies that have tried to describe the variation in the cod carrying capacity of selected release areas. Despite relatively large variation in environmental conditions, in cod production and in fishing mortality along the Norwegian coast, results indicate that, under the conditions experienced during the 1980s and 1990s, releases of juvenile cod did not significantly increase cod production and catches. The biological limitations and future prospects of Atlantic cod stock enhancement are addressed. [source] Determinants of within- and among-clutch variation in levels of maternal hormones in Black-Headed Gull eggsFUNCTIONAL ECOLOGY, Issue 3 2002Groothuis T. G. Summary 1.,Females of egg-laying vertebrates may adjust the development of their offspring to prevailing environmental conditions by regulating the deposition of hormones into their eggs. Within- and amng-clutch variation in levels of steroid hormones were studied in the egg yolks of the Black-Headed Gull (Larus ridibundus, Linnaeus) in relation to environmental conditions at the nest site. This species breeds in colonies of different densities and in different habitats, and the chicks hatch asynchronously. 2.,Egg yolks contained very high levels of androstenedione, substantial levels of testosterone and moderate levels of 5,-dihydrotestosterone. Oestrogen (17,-oestradiol) was not detected. 3.,Androgen levels increased strongly with laying order, irrespective of egg or yolk mass. This may compensate for the disadvantages of the later hatching chicks. These results have implications for adaptive hypotheses that were proposed for asynchronous incubation. 4.,Eggs of lighter clutches contained more androgens, perhaps to compensate for a lower nutritional quality of these eggs. 5.,Birds breeding in the periphery of a colony, being relatively more aggressive and having relatively large territories, laid eggs that contained more androgens than those of birds breeding in the centre. These high yolk androgen levels may facilitate growth and motor development of the chicks, which may be especially important for chicks developing at the periphery of a colony. Reduced levels may be adaptive for birds breeding in the centre, where risk of infectious diseases is high, since steroids may be immunosuppressive. 6.,Corrected for nest distance, clutches of birds in high vegetation, where predation risk is less severe and therefore competition for nest sites perhaps high, contained relatively high levels of androgens. It is suggested that the level of yolk androgens reflects the hormonal condition of the female, that in turn is influenced by her characteristics such as her age and aggressiveness, and the level of social stimulation. [source] Exploration correlates with settlement: red squirrel dispersal in contrasting habitatsJOURNAL OF ANIMAL ECOLOGY, Issue 6 2004DIANE L. HAUGHLAND Summary 1Dispersers in heterogeneous habitat theoretically should target the habitat(s) where reproduction and survival (i.e. fitness) will be highest. However, the cues that dispersing animals respond to are not well understood: differences in habitat quality ultimately may be important, but whether animals respond to these differences may be influenced by their own familiarity with different habitats. 2To determine if dispersers reacted to differences in habitat, we documented the exploratory movements, dispersal, and settlement patterns of juvenile North American red squirrels (Tamiasciurus hudsonicus) originating in adjacent patches of different habitats. 3Dispersers originating in mature, closed-canopy forest (linked to higher female reproductive success and smaller territories) did not explore contrasting open forest with lower tree densities, and the magnitude of the dispersers' explorations was relatively similar. In contrast, dispersers from the open forest habitat made explorations that carried them into contrasting, mature forest habitat, and their explorations were more variable across individuals. 4When settlement occurred, it was strongly philopatric in all groups of dispersers, although the distances and directions favoured during the exploratory phase of dispersal remained strong predictors of where settlement occurred. Overall, processes favouring philopatry (i.e. maternal influences, competitive advantages, etc.) appeared to dominate the dispersal of our study animals, even those that were exposed to higher quality habitat during their explorations. 5Secondarily, annual stochasticity (or some correlate) affected the scale of exploration and timing of settlement more than the relative quality of habitat in which dispersers were born. 6Studies such as this that seek to understand the relative importance of individual experience, habitat familiarity, and habitat quality are important to ultimately understanding how individual animals and populations react to habitat heterogeneity. [source] Parental behaviour of a precocial species: implications for juvenile survivalJOURNAL OF APPLIED ECOLOGY, Issue 4 2009Victoria J. Dreitz Summary 1., Parents determine habitat selection for precocial young by leading their young to foraging areas until the chicks attain full independence. There are potential benefits and costs to reproductive success associated with changing habitats while caring for young. This study investigated the relationship between different types of habitats and their quality on chick survival and brood movements of a declining upland shorebird, the mountain plover Charadrius montanus. 2., From 2004 to 2006, a total of 153 mountain plover broods were monitored on the primary breeding habitats in eastern Colorado, USA; two shortgrass prairie habitats that were either occupied or unoccupied by black-tailed prairie dogs Cynomys ludovicianus and agricultural lands. Habitat quality hypotheses were tested using newly developed statistical applications to estimate survival of chicks and brood movement patterns. 3., Chick survival and brood movements were influenced by habitat. Chick survival over the 30-day brood-rearing period was substantially higher on nesting habitat of shortgrass occupied by prairie dogs compared with agricultural land and shortgrass unoccupied by prairie dogs. The rate of brood movement away from shortgrass with prairie dogs was lower than shortgrass without prairie dogs, but higher than agricultural lands for each year of the study. 4., This study suggests that complex processes influence how different habitats affect brood-rearing activity of mountain plovers. Even though broods moved off nesting habitat of shortgrass occupied by prairie dogs, this habitat had the highest survival rate and is highly important to mountain plover reproductive success. 5.,Synthesis and applications. In order to develop effective conservation strategies, the provision of adequate breeding habitat should include information on patterns of habitat selection for all stages of the breeding cycle, including the nesting and dependent young periods. From a conservation perspective, understanding the habitat use of young birds is critical when population dynamics show great sensitivity to survival of young. Previous studies on mountain plovers have suggested that nest success is similar among shortgrass prairie habitats and agricultural lands. Thus, conservation measures that increase nest success may be ineffective for mountain plovers unless they are accompanied by measures promoting chick survival. [source] Are urban bird communities influenced by the bird diversity of adjacent landscapes?JOURNAL OF APPLIED ECOLOGY, Issue 5 2001Philippe Clergeau Summary 1The species diversity of adjacent landscapes influences the conservation or restoration of several animal groups in urban areas, but the effect on birds is unclear. To address this question, we compared bird species richness (BSR) and community composition between periurban (area surrounding the town) and urban (suburban and centre areas) landscapes across three spatial scales. 2At a large biogeographical scale (temperate and boreal climatic zone), relationships between the BSR of urban areas and their surrounding landscapes were examined in a meta-analysis of 18 published studies. In general, BSR was negatively correlated with latitude and urbanization. The BSR of suburban and centre landscapes correlated positively with the BSR of periurban landscapes. However, latitudinal effects were also involved, as BSR in urban and periurban landscapes declined as town latitude increased. Similarity indices were low (50%) between periurban and centre bird communities. 3At a regional scale, we assessed winter bird data from several towns within three regions of temperate and boreal countries (western France, northern Finland and eastern Canada). The type of periurban landscape, number of inhabitants and town diameter did not affect BSR. BSR was similar between the cities of a given biogeographical area. Bird communities were more similar between similar habitat types of different cities than between different habitats of the same city. 4At a local scale, we tested the influence of proximity to the periurban landscape on BSR in parks of western French towns of different size. Neither BSR nor community similarity changed in relation to the distance of the park from the periurban landscape. 5Guild composition according to diet and feeding habitat did not vary between urban and periurban locations at regional or local scales. 6We conclude that, at regional and local scales, urban bird communities are independent of the bird diversity of adjacent landscapes, and that local features are more important than surrounding landscapes in determining BSR. Whatever the biodiversity quality of the periurban landscape, site-specific actions such as shrub and tree planting, water restoration and increasing vegetation diversity can change bird diversity in towns and improve the quality of human,wildlife contacts. [source] Genetic analysis of ratmouth barbell (Ptychidio jordani Myers) from different geographic sub-populations in the Pearl River Basin using microsatellite markersJOURNAL OF APPLIED ICHTHYOLOGY, Issue 2 2009X.-P. Zhu Summary Thirteen polymorphic microsatellite markers were used to study the genetic variation of Ptychidio jordani sampled from the three sites of Liuzhou, Guiping and Yunan in the Pearl River Basin with the help of local fishers. Allele numbers ranged from 2 to 19 and fragment sizes ranged from 108 to 288. Average polymorphism information content (PIC), average observed heterozygosity (Ho) and average expected heterozygosity (He) were 0.439917, 0.4147 and 0.4986, respectively, which indicate a comparatively high level of genetic diversity. The coefficient of genetic differentiation (Gst) between the two sub-populations ranged from 0.0074 to 0.0156, which shows little differentiation between sub-populations. amova analysis also offered evidence of weak differentiation with 0.53% variation between sub-populations, 99.47% variation within sub-populations and the Fst = 0.00531. The morphological variation among geographic sub-populations might result from different habitats. The correlation between genotype and morphological characters was analyzed and a significant correlation found between the genotype of microsatellite locus Hlj038 and the ratio of body depth and body length. The results suggest a possible linkage between this locus and these morphological characters. [source] Direct detection of Kitasatospora species with a chaperone oligonucleotide microarray method lacking PCR amplificationJOURNAL OF BASIC MICROBIOLOGY, Issue 4 2008Sebastian Guenther Abstract Identification of members of the genus Kitasatospora from soil samples has been introduced to evaluate occurrence of potential natural compound producers in different habitats. The microarray hybridization usually involves PCR amplification of the target DNA. Since PCR might lead to biased amplification, a diagnostic Kitasatospora microarray technique was improved by a protocol lacking PCR amplification prior to hybridization. The described advanced hybridization method used chaperone oligonucleotides for direct co-hybridization with genomic DNA on an oligonuclotide microarray with optical readout. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Patterns of population genetic diversity in riparian and aquatic plant species along riversJOURNAL OF BIOGEOGRAPHY, Issue 9 2010Olivier Honnay Abstract Aim, The downstream hydrochoric spread of seeds of aquatic and riparian plant species, without upstream compensation, can be expected to result in downstream accumulation of population genetic diversity. This idea has been termed the ,unidirectional dispersal hypothesis' and is the genetic equivalent of the more generally known ,drift paradox'. Our aim was to test this unidirectional diversity hypothesis, and to present a general synthesis of the patterns of population genetic variation across different riparian and aquatic plant species along rivers. Location, The Meuse River (Belgium) and rivers world-wide. Methods, First, we used amplified fragment length polymorphism markers to compare patterns of within- and between-population genetic diversity among three riparian plant species (Sisymbrium austriacum, Erysimum cheiranthoides and Rorippa sylvestris), typically occurring in different habitats along a gradient perpendicular to the Meuse River. Second, we performed a meta-analysis on studies reporting on the population genetic structure of riparian and aquatic plant species along rivers. Results, Along the Meuse River, we found significant genetic differentiation among populations of all three riparian species, and significant isolation by distance for one of them (R. sylvestris). There was no clear association between the typical habitat of a species and its population genetic structure. None of the three species provided evidence for the unidirectional dispersal hypothesis. The meta-analysis, based on 21 data records, did not support the unidirectional dispersal hypothesis either. Average weighted population genetic differentiation across species was significant. Main conclusions, Important mechanisms of upstream seed dispersal, probably through zoochory, together with higher seed recruitment opportunities in upstream habitats due to density dependence of recruitment, may explain the absence of downstream accumulation of genetic diversity. Also, it seems difficult to find consistent patterns in genetic variation in species from aquatic and riparian habitats. We argue that this is due to the recurrent extinctions and colonizations characteristic of these habitats, resulting in complex genetic patterns. Our results strongly support previous suggestions that stream ecology should consistently embrace metapopulation theory to be able to understand patterns of genetic diversity, as well as species diversity. [source] Ecological factors drive differentiation in wolves from British ColumbiaJOURNAL OF BIOGEOGRAPHY, Issue 8 2009Violeta Muñoz-Fuentes Abstract Aim, Limited population structure is predicted for vagile, generalist species, such as the grey wolf (Canis lupus L.). Our aims were to study how genetic variability of grey wolves was distributed in an area comprising different habitats that lay within the potential dispersal range of an individual and to make inferences about the impact of ecology on population structure. Location, British Columbia, Canada , which is characterized by a continuum of biogeoclimatic zones across which grey wolves are distributed , and adjacent areas in both Canada and Alaska, United States. Methods, We obtained mitochondrial DNA control region sequences from grey wolves from across the province and integrated our genetic results with data on phenotype, behaviour and ecology (distance, habitat and prey composition). We also compared the genetic diversity and differentiation of British Columbia grey wolves with those of other North American wolf populations. Results, We found strong genetic differentiation between adjacent populations of grey wolves from coastal and inland British Columbia. We show that the most likely factor explaining this differentiation is habitat discontinuity between the coastal and interior regions of British Columbia, as opposed to geographic distance or physical barriers to dispersal. We hypothesize that dispersing grey wolves select habitats similar to the one in which they were reared, and that this differentiation is maintained largely through behavioural mechanisms. Main conclusions, The identification of strong genetic structure on a scale within the dispersing capabilities of an individual suggests that ecological factors are driving wolf differentiation in British Columbia. Coastal wolves are highly distinct and representative of a unique ecosystem, whereas inland British Columbia grey wolves are more similar to adjacent populations of wolves located in Alaska, Alberta and Northwest Territories. Given their unique ecological, morphological, behavioural and genetic characteristics, grey wolves of coastal British Columbia should be considered an Evolutionary Significant Unit (ESU) and, consequently, warrant special conservation status. If ecology can drive differentiation in a highly mobile generalist such as the grey wolf, ecology probably drives differentiation in many other species as well. [source] Biogeography and conservation of the genus Ficus (Moraceae) in MexicoJOURNAL OF BIOGEOGRAPHY, Issue 3 2004Alejandra Serrato Abstract Aim, The main objective of this study is to document the biogeographical patterns, endemism and degree of conservation of the species of Ficus (Moraceae) in Mexico. There are over 750 species of the genus Ficus distributed worldwide, and Mexico practically represents its northernmost limit in the American continent. Detailed studies at regional scales may help to understand the biogeography of large genera such as Ficus. Location, Mexico. Methods, The biogeographical patterns of Mexican Ficus were obtained from information of fig specimens available in two of the main herbaria of Mexico (2140 vouchers), collecting figs throughout this country, and revising the specialized literature. The presence of each species of Ficus was recorded for every one of Mexico's states and several tropical countries of America. Besides, the Mexican territory was divided into cells of 1° × 1° and the presence or absence of all species of the genus was recorded. Rarity of species was classified based on the width of geographic distribution, habitat specificity and population size. Results, A total of 21 species of Ficus occur in Mexico, including six species (28.6%) that are endemic to this country. Five species are included in subgenus Pharmacosycea and 16 species are documented under subgenus Urostigma. Affinities of Ficus flora with other tropical countries in America generally decreased as geographical distances from Mexico increased. Mexican states and cells with highest values of Ficus species richness (both total and endemic species) were located. Ten species, including three endemics, presented a wide distribution. Five species, including two endemics, possess the three attributes of rarity (narrow geographical distribution, high habitat specificity and scarce local populations). Three species of Ficus, including the endemic and very rare Ficuslapathifolia (Liebm.) Miq., are not recorded in any protected area existing in Mexico. Main conclusions, Most of the Mexican Ficus show a great morphological variation and occupy different habitats along their geographic distribution. The biogeographical patterns described here establish a fundamental scenario for ongoing studies on Ficus,pollinator interactions. However, many local populations are considered to be at risk, as there have been significant reductions in the number and size of local populations. Further studies are needed to understand the process of colonization, maintenance and persistence of fig,pollinator mutualism in species with different patterns of geographic distribution. Mexican Ficus require special policies for conservation due to their complex degree of rarity, particularly their geographic distribution in different types of vegetation, ranging from dry scrublands to tropical rain forests. [source] Invasive Acacia auriculiformis Benth. in different habitats in Unguja, ZanzibarAFRICAN JOURNAL OF ECOLOGY, Issue 1 2009Riitta Kotiluoto Abstract Acacia auriculiformis Benth., Mimosaceae, has been introduced relatively recently as a plantation tree to the island of Unguja, Zanzibar. It has been reported to establish itself outside the plantations, but it is not known if the success of establishment depends on habitat quality. We investigated the occurrence of A. auriculiformis in 5-m-wide sample lines, which started from the edge of acacia plantations and reached farthermost the distance of 1 km. The results of 7.24 ha studied showed that: (1) A. auriculiformis occurred in most of the studied habitats in Unguja and appeared to be more abundant in deep soils than in shallow coral-derived soils. However, statistical analyses suggested that the species has little preference or avoidance towards any of the habitats, even though forests , the least disturbed habitats , seemed to have less acacias than other more disturbed habitats. (2) The number of acacias decreased rapidly with the distance from an acacia plantation, and most of the found acacias were still young, below three metres tall. Our results suggest that the invasion of A. auriculiformis is at its beginning in Unguja. If no preventive measures are taken, A. auriculiformis may have an increasing impact on local ecosystem in the future. Résumé Acacia auriculiformis Benth., une mimosacée, a été introduit assez récemment sous forme de plantation dans l'île d'Unjuga, à Zanzibar. On a rapporté qu'il s'était établi de lui-même en dehors des plantations, mais on ne sait pas si la réussite de cette installation dépend de la qualité de l'habitat. Nous avons étudié la présence d'Acacia auriculiformis sur des bandes échantillons de cinq mètres de large qui commençaient à la lisière des plantations d'acacia et s'éloignaient jusqu'à un kilomètre. Les résultats obtenus sur les 7,24 ha étudiés montrent que 1) Acacia auriculiformis existe dans la plupart des habitats étudiés à Unjuga et semble plus abondant dans des sols profonds que dans des sols peu profonds dérivés des coraux. Cependant, les analyses statistiques suggèrent que l'espèce montre peu de préférences ou de rejet envers aucun des habitats, même si les forêts , les habitats les moins perturbés , semblent contenir moins d'acacias que d'autres habitats plus perturbés et que 2) le nombre d'acacias diminue rapidement quand on s'éloigne des plantations d'acacias, et que la plupart des acacias trouvés sont encore jeunes et mesurent moins de trois mètres de haut. Nos résultats suggèrent que l'invasion d'Acacia auriculiformis en est encore à ses début sur Unjuga. Si l'on ne prend pas de mesures préventives, A. auriculiformis pourrait avoir un impact croissant sur l'écosystème local dans le futur. [source] Soil macrofauna research in ecosystems in UgandaAFRICAN JOURNAL OF ECOLOGY, Issue 2007M. J. N. Okwakol Abstract Soil is a living entity, comprising an inseparable mixture of solid, liquid and gaseous phases, and diverse fauna and flora, the below ground biodiversity. The macrofauna consists of animals longer than 4 mm or wider than 2 mm, which are easily located by the naked eye and include arthropods, molluscs and earthworms. This review is aimed at developing an inventory of the present knowledge about macrofauna in ecosystems in Uganda and identifying future priorities for research, application and capacity building. It is noted that there are a few assessments of soil macrofauna, diversity and abundance made for different habitats. Similarly, studies on their importance in ecosystems, distribution patterns, management, linkage with above ground biodiversity and effects of land use on them are deficient. Further, there is little documentation of farmers' knowledge and practices related to soil macrofauna management and conservation. It is also noted that the current gaps in the soil macrofauna data and information have been caused by lack of capacity and expertise to identify, evaluate and manage this resource. More research and training in the taxonomy, ecology, economic evaluation and management of this fauna are suggested. [source] An investigation into the composition, complexity and functioning of snake communities in the mangroves of south-eastern NigeriaAFRICAN JOURNAL OF ECOLOGY, Issue 3 2002Luca Luiselli Abstract The structure of the snake community was studied between 1996 and 2000 on a transect in the mangrove ecological zone of southern Nigeria, West Africa. In three major habitats, both taxonomical diversity and frequency of observations in relation to sampling effort were investigated. In general terms, the complexity of the snake community appeared less than in other habitats of the same geographic region (i.e. swamp forest and forest,plantation mosaics). In fact, only eighteen species were recorded, whereas 43 species are known to inhabit neighbouring habitats. A Principal Component Analysis allowed arrangement of the various species into two main groups in relation to the habitats of capture: (1) a group of species of rainforest biota (i.e. Toxicodryas blandingii, Thelotornis kirtlandii, Thrasops flavigularis, Rhamnophis aethiopissa, Gastropyxis smaragdina, Grayia smythii, Pseudohaje goldii, Python sebae), and (2) a group of species that, at least in Niger Delta, are typically linked to altered habitats, including derived savannas, plantations and suburbia (i.e. Psammophis cf. phillipsi, Philothamnus cf. nitidus, Hapsidophrys lineatus, Crotaphopeltis hotamboeia, Boaedon lineatus, Naja nigricollis, Python regius). The community structure in terms of food habits and body sizes appeared similar to those of other snake assemblages from different habitats of southern Nigeria. The conservation implications of our results are also discussed. Résumé On a étudié entre 1996 et 2000 la structure de la communauté des serpents dans un transect de la zone écologique de mangroves du sud du Nigeria, en Afrique de l'Ouest. On a étudié, dans trois habitats importants, la diversité taxonomique et la fréquence des observations par rapport à l'importance des échantillonnages. En termes généraux, la communauté des serpents y semblait moins complexe que dans d'autres habitats de la même région géographique (c.-à-d. la forêt marécageuse et une mosaïque de plantations forestières). En fait, on n'a rapporté que 18 espèces, alors qu'on sait que 43 espèces vivent dans les habitats voisins. Une Analyse du Composant Principal a permis de ranger les différentes espèces en deux groupes principaux, liés aux habitats où se sont faites les captures : (1) un groupe avec les espèces des biotes de forêt pluviale (Toxicodryas blandingii, Thelotornis kirtlandii, Thrasops flavigularis, Rhamnophis aethiopissa, Gastropyxis smaragdina, Grayia smythii, Pseudohaje goldii, Python sebae) et (2) un groupe d'espèces qui, au moins dans le delta du Niger, sont typiquement liées à des habitats dégradés, y compris des savanes dérivées, des plantations et des faubourgs urbains (Psammophis phillipsi, Philothamnus cf. nitidus, Hapsidophrys lineatus, Crotaphopeltis hotamboeia, Boaedon lineatus, Naja nigricollis, Python regius). La structure de la communauté, en ce qui concerne les habitudes alimentaires et la taille corporelle, était semblable à celle des autres groupes de serpents dans différents habitats du sud du Nigeria. On discute de l'implication de nos résultats pour la conservation. [source] Facilitation research in marine systems: state of the art, emerging patterns and insights for future developmentsJOURNAL OF ECOLOGY, Issue 6 2009Fabio Bulleri Summary 1. Positive species interactions are increasingly recognized as important drivers of community structure and ecosystem functioning. Although the literature on facilitative interactions in terrestrial environments has been reviewed and emerging patterns have been synthesized, comparable attempts are lacking for the marine realm. 2. By means of a quantitative survey of the literature, I provide a critical summary of current knowledge on positive species interactions in marine environments. In particular, I (i) assess how marine facilitation research compares to that carried out in terrestrial environments in terms of focus and philosophical approach; (ii) illustrate the mechanisms by which facilitation takes place in different habitats; (iii) assess whether benefactor and beneficiary species are more likely to belong to the same or to a different trophic level; and (iv) provide examples of how including facilitation into ecological theory might advance our understanding of the mechanisms that regulate ecosystem functioning. 3. Except for some studies in intertidal habitats, few studies in marine environments have been framed within mainstream facilitation theory (e.g. the Stress Gradient Hypothesis) and research does not seem to be organized in a self-contained theme. Amelioration of physical conditions appears to be the most common mechanism of facilitation in intertidal habitats, whilst associational defence predominates in the subtidal. 4. In contrast to the terrestrial literature, dominated by plant,plant interactions, marine benefactors and beneficiary species often belong to different trophic levels. This might imply little overlapping of resource niches or a differential response to environmental conditions or consumer pressure, with implications for the persistence of facilitative effects at the extreme ends of stress gradients. 5. Recent research shows that facilitation can enhance temporal variability and invasibility of marine communities and emphasizes the central role of positive species interactions in regulating the functioning of natural ecosystems. 6.Synthesis. Studies encompassing a wide variety of life histories and environmental conditions are central to achieving a unified facilitation theory. Research in marine environments can provide new insights into the mechanisms underlying variations in the strength and direction of species interactions, but this will require greater awareness and consideration of facilitation. [source] Spatial patterns of recruitment in Mediterranean plant species: linking the fate of seeds, seedlings and saplings in heterogeneous landscapes at different scalesJOURNAL OF ECOLOGY, Issue 6 2008Lorena Gómez-Aparicio Summary 1Plant recruitment is a multiphase process that takes place in environments that are heterogeneous in space and time. In this work, I analyse how environmental heterogeneity in Mediterranean forests affects dynamics of early recruitment at different scales, using the wind-dispersed tree Acer opalus subsp. granatense as a case study. 2Seed dispersal and viability, post-dispersal predation, seedling emergence and seedling and sapling survival were evaluated in different habitats (regional scale) and microhabitats (local scale). Simultaneously, a review of the literature on spatial dynamics of plant recruitment in Mediterranean systems was conducted to look for general patterns and investigate their fit to the Acer system. Nineteen woody and herbaceous species were included in the review. 3At the regional scale, Acer recruitment dynamics strongly converged among sites of the same habitat. This was mainly due to large seedling emergence and survival differences among habitats. Although most of the studies reviewed analyzed only one site per habitat type, they also support strong regional variation (either site- or habitat-specific) in recruitment patterns. 4At the local scale, Acer recruitment was microhabitat-specific, a result shared by almost all the reviewed species independently of their life form and dispersal syndrome. This was mostly due to spatial differences in seed arrival (higher under conspecifics) and seedling survival (higher under nurse shrubs). 5Spatial discordance among seed rain and recruitment was found in 60% of the reviewed species at the regional scale, and in 67% at the local scale. Acer results supported this predominant lack of concordance. Discordance among seed rain and recruitment suggests that regeneration is largely limited by safe sites than by seed availability. Because seedling survival was the limiting process with a larger impact on the magnitude and spatial pattern of recruitment, safe sites might be defined as those where seedlings have a higher survival probability. 6Synthesis: This study indicates that the influence of seed dispersal on the spatial patterns and demography of plant species could be limited in heterogeneous and stressful environments (as are found in the Mediterranean), where recruitment is restricted to a small fraction of the landscape. If we are to preserve the distribution and abundance of Mediterranean species in the face of environmental changes, we need to explicitly consider the strong patch-specificity that characterizes their recruitment process at all scales. [source] Floral free fall in the Swiss lowlands: environmental determinants of local plant extinction in a peri-urban landscapeJOURNAL OF ECOLOGY, Issue 4 2007IVANA STEHLIK Summary 1Local floras are being depleted by a host of human activities, including habitat destruction and fragmentation, eutrophication, and the intensification of agriculture. Species with particular ecological demands or life-history attributes are more prone to extinction than species with a broader niche. 2We used an old herbarium from the municipality of Küsnacht (Swiss lowlands) as a historical record for comparison with contemporary plant diversity. This comparison revealed that 17% to 28% of all vascular plants that occurred between 1839 and 1915 were extinct by 2003. 3Species of different habitats and life-forms had significantly different rates of extinction: wetlands, disturbed sites and meadows lost most species, whereas forests and rocky habitats were least affected; aquatics and annuals were most prone to extinction, geophytes and hemicryptophytes were intermediate, and phanerophytes and chamaephytes were least affected. 4Species adapted to nutrient-poor soils suffered highest extinction in all habitats, indicating that eutrophication poses an urgent threat to species diversity. Light and soil moisture requirements also had significant effects on extinction, but the direction of the effect varied by habitat. 5When species were grouped into IUCN categories of the red list of Switzerland, the rank order of the observed extinction matched the red list assignment. 6Because many of the remaining species had high estimated extinction probabilities and because extinction is often delayed (extinction debt), a substantial part of the remaining flora of Küsnacht is likely to go extinct in the near future. This will increase the dominance of the common species that already comprise 81% of the local flora. 7The rates and patterns of extinction in Küsnacht are probably representative of surrounding Swiss lowlands and peri-urban landscapes in most developed countries. Studies such as ours can serve as a call for action and form a basis for future monitoring of biodiversity. [source] The effects of neighbouring tree islands on pollinator density and diversity, and on pollination of a wet prairie species, Asclepias lanceolata (Apocynaceae)JOURNAL OF ECOLOGY, Issue 3 2006DEREK R. ARTZ Summary 1The Everglades (Florida, USA) is a mosaic of different habitats. Tropical and temperate trees grow on patches of high ground (tree islands) surrounded by lower elevation wetland communities (marl prairie). 2Tree islands of various sizes provide nesting substrate, larval host plants and floral resources for insect pollinators. Herbaceous plants in the open surrounding wetlands may also depend on these pollinators. 3We investigated pollinator diversity and abundances in both tree island and marl prairie habitats using transect sampling methods and estimated pollination success of the milkweed Asclepias lanceolata, an insect-pollinated marl prairie species, in relation to distance from and size of the closest tree island. 4On a total of 11 bayhead tree islands, we found that insect diversity and abundance were greater on the edge of larger tree islands (20,30 m2) than on smaller tree islands (5,10 m2). Pollinator diversity and abundance in the marl prairie decreased with increasing distance from tree islands. 5Pairs of potted A. lanceolata plants were placed in the marl prairie at distances up to 1000 m from small and large tree islands. Fruit and seed production were highest for plants placed less than 25 m from tree islands and decreased with increasing distance. 6Our results suggest that tree islands are an important source of pollinators for the plants in the tree island and surrounding wetland habitats. 7This landscape-based study illustrates how overall landscape structure affects important biotic interactions, particularly plant,pollinator relationships. Our findings have far-reaching ecological implications for the reproductive success of plants in small, isolated populations that may depend on insect vectors for pollination. [source] Stable genetic polymorphism in heterogeneous environments: balance between asymmetrical dispersal and selection in the acorn barnacleJOURNAL OF EVOLUTIONARY BIOLOGY, Issue 2 2006D. VÉLIZ Abstract Elucidating the processes responsible for maintaining polymorphism at ecologically relevant genes is intimately related to understanding the interplay between selection imposed by habitat heterogeneity and a species' capacity for dispersal in the face of environmental constraints. In this paper, we used a model-based approach to solve equilibria of balanced polymorphism, given values of fitness and larval dispersal among different habitats in the acorn barnacle Semibalanus balanoides from the Gulf of St Lawrence. Our results showed that allele frequencies observed at both MPI* and GPI* loci represented stable equilibria, given empirical estimates of fitness values, and that considerably more larvae dispersed from one region (north) to the other (south) than vice versa. Dispersal conditions were predicted to be similar for the maintenance of polymorphism at both loci. Moreover, the values of asymmetrical dispersal required by the model to reach stable equilibria were compatible with empirical estimates of larval dispersal and oceanic circulation documented in this system. Overall, this study illustrated the usefulness of a modified and computable version of Bulmer's model (1972) in order to test hypotheses of balanced polymorphism resulting from interactions between spatial selection and asymmetrical dispersal. [source] Distribution, abundance, and conservation of Vinaceous Amazons (Amazona vinacea) in Argentina and ParaguayJOURNAL OF FIELD ORNITHOLOGY, Issue 1 2007Kristina Cockle ABSTRACT Vinaceous Amazons (Amazona vinacea) are endemic to the Atlantic forest of southeastern Brazil, eastern Paraguay, and the province of Misiones in Argentina. We searched for Vinaceous Amazons throughout the western part of its range in Argentina and Paraguay during 1639 days of fieldwork from 1997 to 2006. These parrots have disappeared from most areas where they were historically recorded in these countries, and are now limited to a few sites in northeastern Paraguay and central Misiones (Argentina). We estimate the minimum remaining populations at 220 individuals in Paraguay and 203 individuals in Argentina. Important sites for the species are (1) the farming area from San Pedro to Tobuna (Misiones, Argentina) and (2) the Itaipú reserves complex and Reserva Natural Privada Itabó (Paraguay). In our surveys, Vinaceous Amazons were absent from the largest tracts of forest in Misiones, and were most often observed feeding, roosting, and nesting in small forest remnants and in agricultural areas that included forest fragments and isolated trees. Threats to amazons in these areas include nest poaching, forest clearing, and being shot as a crop pest. We confirmed 40 Vinaceous Amazons kept as pets in 35 homes between San Pedro and Tobuna. Environmental education and law enforcement are urgently needed to reduce threats in populated areas, and subsistence farmers need technical and logistical support to slow or stop the conversion of forest into cropland. Finally, additional study is needed to determine this amazon's habitat preferences, nest site requirements, and demography in different habitats. SINOPSIS El loro vinoso (Amazona vinacea) es endémico del bosque Atlántico del sudeste de Brasil, este de Paraguay, y la provincia de Misiones en Argentina. Buscamos esta especie durante 1639 días de trabajo de campo de 1997 a 2006, a lo largo de la porción oeste de su distribución, en Argentina y Paraguay. A. vinacea ha desaparecido de la mayor parte de las áreas donde ha sido registrada históricamente en estos paises, y permanece sólo en algunos pocos sitios del noroeste de Paraguay y del centro de Misiones (Argentina). Estimamos el tamaño mínimo de las poblaciones remanentes en 220 individuos en Paraguay y 203 individuos en Argentina. Los sitios importantes para la especie son: (1) la zona rural de San Pedro a Tobuna (Misiones, Argentina) y (2) el complejo de reservas de Itaipú y la Reserva Natural Privada Itabó (Paraguay). A. vinacea no fue encontrada en los tractos más grandes de bosque durante nuestras prospecciones en Misiones. Mayormente fue observada alimentándose, durmiendo y nidificando en pequeños remanentes boscosos y en hábitats antropogénicos. Las amenazas en estos hábitats incluyen robo de pichones de los nidos, deforestación, y cacería por daño a cultivos. Confirmamos la existencia de 40 ejemplares cautivos como mascotas en 35 hogares de San Pedro y Tobuna. Para reducir las amenazas se requieren urgentemente educación ambiental y fortalecimiento legal en las áreas pobladas. Es necesario proveer de apoyo técnico y logístico a los agricultores de subsistencia para reducir la conversión de bosques a cultivos. Finalmente, estudios futuros deberían tratar la preferencia de hábitat del loro, sus requerimientos de nidificación, y su demografía en distintos hábitats. [source] Influence of selected factors on the dietary compositions of three targeted and co-occurring temperate species of reef fishes: implications for food partitioningJOURNAL OF FISH BIOLOGY, Issue 6 2010M. E. Platell The dietary compositions of three medium to large targeted fish species, which co-occur over reefs in temperate waters of south-western Australia, were determined. These data were then used to ascertain statistically the extent to which body size, season and habitat influence the diets of these species and the degree to which food resources were partitioned among and within those species, and thus reduced the potential of interspecific and intraspecific competition. On the west coast, Bodianus frenchii (Labridae) and Epinephelides armatus (Serranidae) spent their whole life over prominent limestone reefs, as did Glaucosoma hebraicum (Glaucosomatidae) in all but juvenile life, when it lived over low-relief, limestone substrata. The dietary composition of each species changed with increasing body size, which, in G. hebraicum, was particularly pronounced at c. 300 mm total length (LT) and therefore at the size when this species shifts habitat. When the three species co-occurred over the same reefs, their dietary compositions were significantly different, with that of B. frenchii being by far the most discrete, reflecting a far greater contribution by sedentary taxa. Thus, the diet of B. frenchii was distinguished from those of the other two species in containing substantial volumes of bivalve and gastropod molluscs and echinoid echinoderms and essentially no teleosts. Although the diets of G. hebraicum and particularly E. armatus were dominated by teleosts, and especially for larger individuals, the former species ingested greater volumes of cephalopods and small crustaceans. The pointed jaws of B. frenchii, with their forwardly directed and interlocking anterior incisors, are ideally adapted for biting and retaining their invertebrate prey, which are attached to or reside within reef crevices. In contrast, the mouths of G. hebraicum and E. armatus are broader and rounder and contain numerous small, slender and inward-pointing teeth. These teeth, in conjunction with prominent backward-curved canines in E. armatus, facilitate the capture and retention of fish prey. Observations in situ indicate that G. hebraicum is a suction feeder, while E. armatus is predominantly a ram feeder. Although reef environments on the west and south coasts differ, the diet of B. frenchii on these coasts differed only slightly. Interspecific differences in diet, combined with size-related changes in dietary compositions and the occupation of different habitats by juvenile and adult G. hebraicum, reduce the potential for competition for food resources among and within B. frenchii, G. hebraicum and E. armatus and thus helps facilitate the coexistence of these species which historically have been abundant over reefs in south-western Australia. [source] HABITAT DIFFERENCES IN THE TIMING OF REPRODUCTION OF THE INVASIVE ALGA SARGASSUM MUTICUM (PHAEOPHYTA, SARGASSACEAE) OVER TIDAL AND LUNAR CYCLES,JOURNAL OF PHYCOLOGY, Issue 1 2009Carla Monteiro Sargassum muticum (Yendo) Fensholt is an invasive species that is firmly established on intertidal and subtidal rocky shores of Europe and the Pacific coast of North America. Local success and spread of S. muticum is thought to rely on its reproductive potential that seems dependent on exogenous factors like tidal and lunar cycles. This study is the first to compare the reproductive patterns (periodicity of egg expulsion and embryo settlement) of this invader in two different habitats: the middle and low intertidal. The combination of monthly, daily, and tidal samples at triplicate sites within each habitat showed a semilunar periodicity of egg expulsion and embryo settlement coincident with increasing tidal amplitude just before full and new moons. In both habitats, duration of each egg expulsion event was ,1 week, and embryo settlement occurred during the first daily low tide and with the incoming high tide during spring tides. However, both expulsion and settlement started 1,2 d earlier, expulsion saturation was faster, and settlement was higher in the mid- compared to the low intertidal. Our results suggest that the exact timing of gamete expulsion and embryo release of S. muticum responds to local factors, including tidal cues, which result in differences between mid- and low-intertidal habitats. 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