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Phylogenetic Lineages (phylogenetic + lineage)
Selected AbstractsPseudomonas community structure and antagonistic potential in the rhizosphere: insights gained by combining phylogenetic and functional gene-based analysesENVIRONMENTAL MICROBIOLOGY, Issue 9 2007Rodrigo Costa Summary The Pseudomonas community structure and antagonistic potential in the rhizospheres of strawberry and oilseed rape (host plants of the fungal phytopathogen Verticillium dahliae) were assessed. The use of a new PCR-DGGE system, designed to target Pseudomonas -specific gacA gene fragments in environmental DNA, circumvented common biases of 16S rRNA gene-based DGGE analyses and proved to be a reliable tool to unravel the diversity of uncultured Pseudomonas in bulk and rhizosphere soils. Pseudomonas -specific gacA fingerprints of total-community (TC) rhizosphere DNA were surprisingly diverse, plant-specific and differed markedly from those of the corresponding bulk soils. By combining multiple culture-dependent and independent surveys, a group of Pseudomonas isolates antagonistic towards V. dahliae was shown to be genotypically conserved, to carry the phlD biosynthetic locus (involved in the biosynthesis of 2,4-diacetylphloroglucinol , 2,4-DAPG), and to correspond to a dominant and highly frequent Pseudomonas population in the rhizosphere of field-grown strawberries planted at three sites in Germany which have different land use histories. This population belongs to the Pseudomonas fluorescens phylogenetic lineage and showed closest relatedness to P. fluorescens strain F113 (97% gacA gene sequence identity in 492-bp sequences), a biocontrol agent and 2,4-DAPG producer. Partial gacA gene sequences derived from isolates, clones of the strawberry rhizosphere and DGGE bands retrieved in this study represent previously undescribed Pseudomonas gacA gene clusters as revealed by phylogenetic analysis. [source] Microbial diversity of a sulphide spire located in the Edmond deep-sea hydrothermal vent field on the Central Indian RidgeGEOBIOLOGY, Issue 2 2003Joost Hoek ABSTRACT A culture-independent molecular phylogenetic survey was carried out for a bacterial and archaeal community of a mineralized crust coating a sulphide spire, which was collected from the Edmond vent field (23° S, 69° E, 3300 m depth) on the Central Indian Ridge. Small-subunit rRNA genes (16S rDNA) were amplified from environmental DNA by PCR utilizing Bacteria-specific, and Archaea-specific 16S rDNA primers. PCR products were cloned and 26 bacterial and nine archaeal unique sequence types (phylotypes) were identified from 150 clones analysed by restriction fragment length polymorphism, representing eight and four distinct lineages, respectively. The majority (>90%) of the bacterial phylotypes group with the ,-Proteobacteria and confirms the global prevalence of ,-Proteobacteria in deep-sea hydrothermal environments. Among the ,-Proteobacteria, >40% of the phylotypes were closely related to the recently isolated deep-sea vent thermophilic chemolithoautotrophic sulphur-reducer, Nautilia lithotrophica. A single bacterial sequence was nearly identical (99% similarity) to the thermophilic hydrogen-oxidizing Hydrogenobacter thermolithotrophum, and is the first report of Hydrogenobacter at deep-sea hydrothermal vents. A majority (97%) of the archaeal phylotypes grouped with the ,Deep-sea Hydrothermal Vent Euryarchaeotal Group', a phylogenetic lineage of uncultured Archaea that have only been reported from other deep-sea hydrothermal vents on the Mid-Atlantic Ridge, East Pacific Rise, Juan de Fuca Ridge, Isu,Ogasawara Arc, Okinawa Trough and the Manus Basin. A single sequence was closely related to the hyperthermophilic sulphur-reducing Thermococcales frequently found in diverse deep-sea vent environments. Scanning electron micrographs of the mineralized crust reveal abundant filamentous, rod and coccoidal forms encased in sulphur and sulphide mineral precipitate, suggesting that the thermophilic chemolithoautorophs and sulphide-producing heterotrophs may influence the architecture and sulphur cycling of the sulphide spire. [source] Enamel ridge alignment in upper molars of ruminants in relation to their natural dietJOURNAL OF ZOOLOGY, Issue 1 2010T. M. Kaiser Abstract Although it is generally thought that dental design reflects mechanical adaptations to particular diets, concrete concepts of such adaptations beyond the evolution of hypsodonty are largely missing. We investigated the alignment of enamel ridges in the occlusal molar surface of 37 ruminant species and tested for correlations with the percentage of grass in the natural diet. Independent of phylogenetic lineage, species that were either larger and/or included more grass in their natural diet showed a higher proportion of enamel ridges aligned at low angles to the direction of the chewing stroke. Possible explanations for this design are a potential alignment of grass blades in parallel to the molar tooth row, a potential increased proportion of a propalinal (anterior,posterior) chewing movement in grazers as opposed to a strictly transversal chewing stroke in browsers and the general distribution of forces along the occlusal surface during the chewing stroke. The latter will be less heterogenous (with less force peaks) with an increasing proportion of low-angle enamel ridges. While the validity of these explanations will have to be tested in further studies, the enamel ridge alignment represents a clear signal that deviates from an arbitrary distribution and hence most likely represents a functional adaptation. [source] Recognizing diversity in coral symbiotic dinoflagellate communitiesMOLECULAR ECOLOGY, Issue 6 2007AMY M. APPRILL Abstract A detailed understanding of how diversity in endosymbiotic dinoflagellate communities maps onto the physiological range of coral hosts is critical to predicting how coral reef ecosystems will respond to climate change. Species-level taxonomy of the dinoflagellate genus Symbiodinium has been predominantly examined using the internal transcribed spacer (ITS) region of the nuclear ribosomal array (rDNA ITS2) and downstream screening for dominant types using denaturing gradient gel electrophoresis (DGGE). Here, ITS2 diversity in the communities of Symbiodinium harboured by two Hawaiian coral species was explored using direct sequencing of clone libraries. We resolved sixfold to eightfold greater diversity per coral species than previously reported, the majority of which corresponds to a novel and distinct phylogenetic lineage. We evaluated how these sequences migrate in DGGE and demonstrate that this method does not effectively resolve this diversity. We conclude that the Porites spp. examined here harbour diverse assemblages of novel Symbiodinium types and that cloning and sequencing is an effective methodological approach for resolving the complexity of endosymbiotic dinoflagellate communities harboured by reef corals. [source] Hydraulic properties and freezing-induced cavitation in sympatric evergreen and deciduous oaks with contrasting habitatsPLANT CELL & ENVIRONMENT, Issue 12 2001J. Cavender-Bares Abstract We investigated the hydraulic properties in relation to soil moisture, leaf habit, and phylogenetic lineage of 17 species of oaks (Quercus) that occur sympatrically in northern central Florida (USA). Leaf area per shoot increased and Huber values (ratio of sapwood area to leaf area) decreased with increasing soil moisture of species' habitats. As a result, maximum hydraulic conductance and maximum transpiration were positively correlated with mean soil moisture when calculated on a sapwood area basis, but not when calculated on a leaf area basis. This reveals the important role that changes in allometry among closely related species can play in co-ordinating water transport capacity with soil water availability. There were significant differences in specific conductivity between species, but these differences were not explained by leaf habit or by evolutionary lineage. However, white oaks had significantly smaller average vessel diameters than red oaks or live oaks. Due to their lower Huber values, maximum leaf specific conductivity (KL) was higher in evergreen species than in deciduous species and higher in live oaks than in red oaks or white oaks. There were large differences between species and between evolutionary lineages in freeze,thaw-induced embolism. Deciduous species, on average, showed greater vulnerability to freezing than evergreen species. This result is strongly influenced by evolutionary lineage. Specifically, white oaks, which are all deciduous, had significantly higher vulnerability to freezing than live oaks (all evergreen) and red oaks, which include both evergreen and deciduous species. These results highlight the importance of taking evolutionary lineage into account in comparative physiological studies. [source] High local and global diversity of Flavobacteria in marine planktonENVIRONMENTAL MICROBIOLOGY, Issue 5 2007Cecilia Alonso Summary Members of the phylum Bacteroidetes are among the most abundant microbes in coastal marine waters, but it is unclear to which extent the diversity within this phylum is covered by currently available 16S rRNA gene sequence information. We, thus, obtained a comprehensive collection of sequence types affiliated with Bacteroidetes in coastal North Sea surface waters and we compared this local diversity with the available sequences of marine planktonic and other aquatic Bacteroidetes. Approximately 15% of > 600 clones from two libraries (August 2000, June 2001) were related to Bacteroidetes, specifically to the Flavobacteria. Local diversity appeared to be almost exhaustively sampled. However, the diversity of the two libraries virtually did not overlap, indicating a pronounced temporal variability of the planktonic Flavobacteria assemblage. The majority of sequence types represented novel phylogenetic lineages, adding 6,7% to the currently known genera and species of Bacteroidetes in marine waters. Different diversity estimators suggested that so far only approximately half of the global diversity of planktonic marine Bacteroidetes has been described. The data set moreover indicated that cultivation-independent techniques and isolation approaches have recovered almost equally sized and virtually non-overlapping fractions of the currently known diversity within this phylum. Interestingly, only 15% of genera of Bacteroidetes from various aquatic environments appear to occur in more than one habitat type. [source] Maximum growth rates and possible life strategies of different bacterioplankton groups in relation to phosphorus availability in a freshwater reservoirENVIRONMENTAL MICROBIOLOGY, Issue 9 2006Karel, imek Summary We investigated net growth rates of distinct bacterioplankton groups and heterotrophic nanoflagellate (HNF) communities in relation to phosphorus availability by analysing eight in situ manipulation experiments, conducted between 1997 and 2003, in the canyon-shaped ,ímov reservoir (Czech Republic). Water samples were size-fractionated and incubated in dialysis bags at the sampling site or transplanted into an area of the reservoir, which differed in phosphorus limitation (range of soluble reactive phosphorus concentrations , SRP, 0.7,96 µg l,1). Using five different rRNA-targeted oligonucleotide probes, net growth rates of the probe-defined bacterial groups and HNF assemblages were estimated and related to SRP using Monod kinetics, yielding growth rate constants specific for each bacterial group. We found highly significant differences among their maximum growth rates while insignificant differences were detected in the saturation constants. However, the latter constants represent only tentative estimates mainly due to insufficient sensitivity of the method used at low in situ SRP concentrations. Interestingly, in these same experiments HNF assemblages grew significantly faster than any bacterial group studied except for a small, but abundant cluster of Betaproteobacteria (targeted by the R-BT065 probe). Potential ecological implications of different growth capabilities for possible life strategies of different bacterial phylogenetic lineages are discussed. [source] Microbial biodiversity in groundwater ecosystemsFRESHWATER BIOLOGY, Issue 4 2009C. GRIEBLER Summary 1. Groundwater ecosystems offer vast and complex habitats for diverse microbial communities. Here we review the current status of groundwater microbial biodiversity research with a focus on Bacteria and Archaea and on the prospects of modern techniques for enhancing our understanding of microbial biodiversity patterns and their relation to environmental conditions. 2. The enormous volume of the saturated terrestrial underground forms the largest habitat for microorganisms on earth. Up to 40% of prokaryotic biomass on earth is hidden within this terrestrial subsurface. Besides representing a globally important pool of carbon and nutrients in organisms, these communities harbour a degree of microbial diversity only marginally explored to date. 3. Although first observations of groundwater microbiota date back to Antonie van Leeuwenhoek in 1677, the systematic investigation of groundwater microbial biodiversity has gained momentum only within the last few decades. These investigations were initiated by an increasing awareness of the importance of aquifer microbiota for ecosystem services and functioning, including the provision of drinking water and the degradation of contaminants. 4. The development of sampling techniques suitable for microbiological investigations as well as the application of both cultivation-based and molecular methods has yielded substantial insights into microbial communities in contaminated aquifers, whereas knowledge of microbial biodiversity in pristine habitats is still poor at present. 5. Several novel phylogenetic lineages have been described from groundwater habitats, but to date no clearly ,endemic' subsurface microbial phyla have been identified. The future will show if the rather low diversity generally found in pristine oligotrophic aquifers is a fact or just a result of low abundances and insufficient resolution of today's methods. Refined approaches complemented by statistically rigorous applications of biodiversity estimates are urgently needed. 6. Factors identified to control microbial diversity in aquifers include spatial heterogeneity, temporal variability and disturbances such as pollution with chemical anthropogenic contaminants. Although first insights into the importance of individual biogeochemical processes may be obtained from surveys of microbial diversity within functional groups, direct links to groundwater ecosystem functioning have rarely been established so far. [source] Sensory ecology of prey rustling sounds: acoustical features and their classification by wild Grey Mouse LemursFUNCTIONAL ECOLOGY, Issue 1 2007H. R. GOERLITZ Summary 1Predatory mammals and birds from several phylogenetic lineages use prey rustling sounds to detect and locate prey. However, it is not known whether these rustling sounds convey information about the prey, such as its size or profitability, and whether predators use them to classify prey accordingly. 2We recorded rustling sounds of insects in Madagascar walking on natural substrate and show a clear correlation between insect mass and several acoustic parameters. 3In subsequent behavioural experiments in the field, we determined whether nocturnal animals, when foraging for insects, evaluate these parameters to classify their prey. We used field-experienced Grey Mouse Lemurs Microcebus murinus in short-term captivity. Mouse Lemurs are generally regarded as a good model for the most ancestral primate condition. They use multimodal sensorial information to find food (mainly fruit, gum, insect secretions and arthropods) in nightly forest. Acoustic cues play a role in detection of insect prey. 4When presented with two simultaneous playbacks of rustling sounds, lemurs spontaneously chose the one higher above their hearing threshold, i.e. they used the rustling sound's amplitude for classification. We were not able, despite attempts in a reinforced paradigm, to persuade lemurs to use cues other than amplitude, e.g. frequency cues, for prey discrimination. 5Our data suggests that Mouse Lemurs, when foraging for insects, use the mass,amplitude correlation of prey-generated rustling sounds to evaluate the average mass of insects and to guide their foraging decisions. [source] Floristic biogeography of the Hawaiian Islands: influences of area, environment and paleogeographyJOURNAL OF BIOGEOGRAPHY, Issue 3 2004Jonathan P. Price Abstract Aim, A detailed database of distributions and phylogenetic relationships of native Hawaiian flowering plant species is used to weigh the relative influences of environmental and historical factors on species numbers and endemism. Location, The Hawaiian Islands are isolated in the North Pacific Ocean nearly 4000 km from the nearest continent and nearly as distant from the closest high islands, the Marquesas. The range of island sizes, environments, and geological histories within an extremely isolated archipelago make the Hawaiian Islands an ideal system in which to study spatial variation in species distributions and diversity. Because the biota is derived from colonization followed by extensive speciation, the role of evolution in shaping the regional species assemblage can be readily examined. Methods, For whole islands and regions of each major habitat, species,area relationships were assessed. Residuals of species,area relationships were subjected to correlation analysis with measures of endemism, isolation, elevation and island age. Putative groups of descendents of each colonist from outside the Hawaiian Islands were considered phylogenetic lineages whose distributions were included in analyses. Results, The species,area relationship is a prominent pattern among islands and among regions of each given habitat. Species number in each case correlates positively with number of endemics, number of lineages and number of species per lineage. For mesic and wet habitat regions, island age is more influential than area on species numbers, with older islands having more species, more single-island endemics, and higher species : lineage ratios than their areas alone would predict. Main conclusions, Because species numbers and endemism are closely tied to speciation in the Hawaiian flora, particularly in the most species-rich phylogenetic lineages, individual islands' histories are central in shaping their biota. The Maui Nui complex of islands (Maui, Moloka,i, L,na,i and Kaho,olawe), which formed a single large landmass during most of its history, is best viewed in terms of either the age or area of the complex as a whole, rather than the individual islands existing today. [source] Glacial refugia and the phylogeography of Steller's sea lion (Eumatopias jubatus) in the North PacificJOURNAL OF EVOLUTIONARY BIOLOGY, Issue 3 2006A. HARLIN-COGNATO Abstract Mitochondrial DNA sequence data were used to examine the phylogeographic history of Steller's sea lions (Eumetopias jubatus) in relation to the presence of Plio-Pleistocene insular refugia. Cytochrome b and control region sequences from 336 Steller's sea lions reveal phylogenetic lineages associated with continental refugia south of the ice sheets in North America and Eurasia. Phylogenetic analysis suggests the genetic structure of E. jubatus is the result of Pleistocene glacial geology, which caused the elimination and subsequent reappearance of suitable rookery habitat during glacial and interglacial periods. The cyclic nature of geological change produced a series of independent population expansions, contractions and isolations that had analogous results on Steller's sea lions and other marine and terrestrial species. Our data show evidence of four glacial refugia in which populations of Steller's sea lions diverged. These events occurred from approximately 60 000 to 180 000 years BP and thus preceded the last glacial maximum. [source] Defining reproductively isolated units in a cryptic and syntopic species complex using mitochondrial and nuclear markers: the brooding brittle star, Amphipholis squamata (Ophiuroidea)MOLECULAR ECOLOGY, Issue 7 2008E. BOISSIN Abstract At a time when biodiversity is threatened, we are still discovering new species, and particularly in the marine realm. Delimiting species boundaries is the first step to get a precise idea of diversity. For sympatric species which are morphologically undistinguishable, using a combination of independent molecular markers is a necessary step to define separate species. Amphipholis squamata, a cosmopolitan brittle star, includes several very divergent mitochondrial lineages. These lineages appear totally intermixed in the field and studies on morphology and colour polymorphism failed to find any diagnostic character. Therefore, these mitochondrial lineages may be totally interbreeding presently. To test this hypothesis, we characterized the genetic structure of the complex in the French Mediterranean coast using sequences of mitochondrial DNA (16S) and for the first time, several nuclear DNA markers (introns and microsatellites). The data revealed six phylogenetic lineages corresponding to at least four biological species. These sibling species seem to live in syntopy. However, they seem to display contrasted levels of genetic diversity, suggesting they have distinct demographic histories and/or life-history traits. Genetic differentiation and isolation-by-distance within the French Mediterranean coasts are revealed in three lineages, as expected for a species without a free larval phase. Finally, although recombinant nuclear genotypes are common within mitochondrial lineages, the data set displays a total lack of heterozygotes, suggesting a very high selfing rate, a feature likely to have favoured the formation of the species complex. [source] DNA barcode discovers two cryptic species and two geographical radiations in the invasive drosophilid Zaprionus indianusMOLECULAR ECOLOGY RESOURCES, Issue 3 2008AMIR YASSIN Abstract Comparing introduced to ancestral populations within a phylogeographical context is crucial in any study aiming to understand the ecological genetics of an invasive species. Zaprionus indianus is a cosmopolitan drosophilid that has recently succeeded to expand its geographical range upon three continents (Africa, Asia and the Americas). We studied the distribution of mitochondrial DNA (mtDNA) haplotypes for two genes (CO-I and CO-II) among 23 geographical populations. mtDNA revealed the presence of two well-supported phylogenetic lineages (phylads), with bootstrap value of 100%. Phylad I included three African populations, reinforcing the African-origin hypothesis of the species. Within phylad II, a distinct phylogeographical pattern was discovered: Atlantic populations (from the Americas and Madeira) were closer to the ancestral African populations than to Eastern ones (from Madagascar, Middle East and India). This means that during its passage from endemism to cosmopolitanism, Z. indianus exhibited two independent radiations, the older (the Eastern) to the East, and the younger (the Atlantic) to the West. Discriminant function analysis using 13 morphometrical characters was also able to discriminate between the two molecular phylads (93.34 ± 1.67%), although detailed morphological analysis of male genitalia using scanning electron microscopy showed no significant differences. Finally, crossing experiments revealed the presence of reproductive barrier between populations from the two phylads, and further between populations within phylad I. Hence, a bona species status was assigned to two new, cryptic species: Zaprionus africanus and Zaprionus gabonicus, and both were encompassed along with Z. indianus and Zaprionus megalorchis into the indianus complex. The ecology of these two species reveals that they are forest dwellers, which explains their restricted endemic distribution, in contrast to their relative cosmopolitan Z. indianus, known to be a human-commensal. Our results reconfirm the great utility of mtDNA at both inter- and intraspecific analyses within the frame of an integrated taxonomical project. [source] Molecular, ecological and evolutionary approaches to understanding Alternaria diseases of citrusMOLECULAR PLANT PATHOLOGY, Issue 6 2003Kazuya Akimitsu SUMMARY Alternaria fungi cause four different diseases of citrus: Alternaria brown spot of tangerines, Alternaria leaf spot of rough lemon, Alternaria black rot of several citrus fruits and Mancha foliar of Mexican lime. The first three diseases are caused by the small-spored species, Alternaria alternata and the causal agents can only be differentiated using pathogenicity tests, toxin assays or genetic markers. Mancha foliar is caused by the morphologically distinct, large-spored species A. limicola. Substantial progress has been made in understanding the biology, ecology, population biology, systematics, molecular biology and biochemistry of the interactions between these pathogens and citrus. Epidemiological studies have focused on brown spot of tangerines and their hybrids and have contributed to the development of a model of disease development which has improved control and reduced fungicide use. Studies of the population genetics, host specificity and ecology of A. alternata from different ecological niches on citrus have revealed host specific forms of the pathogen which cause disease on different citrus species, the existence of three phylogenetic lineages of the fungus which cause brown spot world-wide, and closely related non-pathogenic isolates which colonize healthy citrus tissue. The role of host-specific toxins in Alternaria diseases of citrus has been extensively studied for over 20 years, and these pathosystems have become model systems for host-pathogen interactions. Recent molecular research has started to unravel the genetic basis of toxin production and the host susceptibility to toxin, and the role of extracellular, degradative enzymes in disease. [source] Haplotype diversity of Tilletiopsis spp. causing white haze in apple orchards in Northern ItalyPLANT PATHOLOGY, Issue 3 2010S. Baric White haze (WH), a manifestation of extensive colonization of anamorphic smut fungi of the genus Tilletiopsis on the surface of apple fruit, has recently been described as a new postharvest disorder of the cultivar Elstar. This study shows that these fungi can also affect apple fruit of different cultivars prior to harvest, and therefore seriously compromise the quality of the produce in Northern Italy. In order to identify the Tilletiopsis taxa involved in the induction of WH in this region, 48 isolates, mainly derived from fruit samples, were analysed by DNA sequencing of the internal transcribed spacer region. Six haplotypes were identified that could be assigned to three different phylogenetic lineages, the T. washingtonensis group, the T. pallescens group and the Entylomataceae. More than 40% of the isolates were classified as T. washingtonensis which had not previously been associated with WH. Furthermore, this is the first study that reports the occurrence of this species on field-grown fruit samples. The extensive overgrowth of apple fruit by Tilletiopsis spp., appearing erratically in the last decade, may be a consequence of moist weather conditions and novel cultural practices, such as the use of hail nets and the intensive application of foliar nutrients. [source] Identification, distribution and current taxonomy of Botryosphaeriaceae species associated with grapevine decline in New South Wales and South AustraliaAUSTRALIAN JOURNAL OF GRAPE AND WINE RESEARCH, Issue 1 2010W.M. PITT Abstract Background and Aims:, Botryosphaeriaceae species are recognised as important pathogens of grapevines both in Australia and overseas. The identity, prevalence and distribution of Botryosphaeriaceae species in vineyards throughout the major winegrowing regions of New South Wales (NSW) and South Australia (SA) was determined to provide a foundation for improved disease prevention and management. Methods and Results:, Field surveys from 91 vineyards across NSW and SA resulted in the collection of 2239 diseased wood samples and subsequent isolation of 1258 Botryosphaeriaceae isolates. Morphological identification along with phylogenetic analysis of ribosomal DNA internal transcribed spacer regions (ITS1-5.8S-ITS2) and partial sequences of the translation elongation factor 1-, gene (EF1-,) showed that eight Botryosphaeriaceae species from four phylogenetic lineages occur on grapevines in eastern Australia, including Diplodia seriata, Diplodia mutila, Lasiodiplodia theobromae, Neofusicoccum parvum, Neofusicoccum australe, Botryosphaeria dothidea, Dothiorella viticola and Dothiorella iberica. Conclusions:, The prevalence of individual species varied according to geography and climate. Species of Diplodia and Dothiorella, characterised by thick-walled, pigmented conidia were the most prevalent and were distributed widely throughout both NSW and SA. Species with hyaline conidia, such as Neofusicoccum and Fusicoccum, were isolated less frequently and displayed more limited geographic ranges, whilst only a single isolate of Lasiodiplodia was recovered, this being from the northern most region of NSW. Significance of the Study:, The identification of eight taxa within the Botryosphaeriaceae, and their distributions throughout south-eastern Australia was established and discussed in context with climate, reported optimum growth temperatures, and more recent taxonomic and nomenclatural revisions. We established a sound base for control strategies based on the prevailing species in Australian viticultural regions. [source] Changes in ventral head width, a discriminating shape factor among African cichlids, can be induced by chronic hypoxiaBIOLOGICAL JOURNAL OF THE LINNEAN SOCIETY, Issue 3 2009HENDRIKUS A. RUTJES A massive enlargement of the gill surface proved to be an important factor in the hypoxia survival of young cichlids. Because the heads of cichlids are densely packed with structures related to both feeding and breathing, we hypothesized that the extra space needed for gill enlargement requires such large structural reorganizations that outer head shape is affected. We used a three-dimensional model to describe changes in the outer head shape of cichlids. Broods of cichlids of different phylogenetic lineages, habitats, and trophic specialization were split and raised at either 10% or 80,90% air saturation. Despite the above-mentioned differences between the species that were used, all hypoxia raised groups showed similar volume enlargements. Volume increases were most prominent in the ventral suspensorial and ventral opercular subcompartments. A relation with the enlarged gills of hypoxia raised fish is likely because the gills are mainly located in these compartments. The differences in ventral width correspond to those found in other studies comprising a wide variety of genotypic and phenotypic variations. The present study shows that such variation in the ventral width is conceivable by phenotypic plasticity alone. © 2009 The Linnean Society of London, Biological Journal of the Linnean Society, 2009, 98, 608,619. [source] | |||||||||||||||||||||||||