Microhabitat Preferences (microhabitat + preference)

Distribution by Scientific Domains


Selected Abstracts


Vertical distribution of Hymenophyllaceae species among host tree microhabitats in a temperate rain forest in Southern Chile

JOURNAL OF VEGETATION SCIENCE, Issue 4 2009
Maria J. Parra
Abstract Question: Are differences in microhabitat preferences of co-occurring epiphytic Hymenophyllaceae species (filmy ferns) correlated with differences in ecophysiological responses to light availability and humidity in the host tree? Location: The Andean foothills in south-central Chile. Methods: We evaluated the distribution pattern of nine filmy fern species in microhabitats that differ in light availability and humidity in four host tree species. A DCA was developed to assess Hymenophyllaceae species microhabitat preference in terms of canopy openness (CO) and relative humidity. We assessed whether differences in chlorophyll content, maximum photochemical efficiency (Fv/Fm), photosynthetic capacity (Amax), evapotranspiration (E) and instantaneous water use efficiency (WUE) are consistent with any pattern. Results: CO and relative humidity differed significantly with height in the host trees. While CO increased with height in a host tree, relative humidity decreased. DCA analysis showed that filmy fern species distribution within and among trees was mainly explained by the relative humidity of the microhabitat. Chlorophyll content, chlorophyll a/b ratio, Amax and E differed significantly among filmy fern species. Amax and E were correlated with axis 1 scores from the DCA analysis. Conclusions: The vertical distribution and abundance of filmy fern species in Chilean temperate rain forest seems to be closely related to the different microhabitats offered by host trees. This pattern may reflect interspecific differences in ecophysiological traits related both to light availability and humidity. Our results suggest that humidity is the main environmental factor driving functional responses and habitat preferences of these filmy fern species. [source]


Ontogenetic Microhabitat Shifts in the Bullhead, Cottus gobio L.,in a Fast Flowing Stream

INTERNATIONAL REVIEW OF HYDROBIOLOGY, Issue 3 2005
Milène Legalle
Abstract We investigated differences in microhabitat preference curves for bullheads, Cottus gobio L., of different size-classes during low flow periods, and evaluated the influence of such differences on habitat use through Weighted Usable Area (WUA) predictions in relation to river flow in a piedmont stream in Southwest France. Water depth, current velocity, and substratum composition were used to calculate proportional use values for each size-class (SC), and to quantify size-specific microhabitat preferences. Bullhead used non-cohesive and coarse mineral particles (pebbles, cobbles, boulders), but there was a spatial segregation of individuals from different size classes (SC1,SC4). Smaller bullhead (SC1, total length <60 mm) took refuge under cobbles, significantly preferred shallower areas, and were less prone to select high current velocities than larger bullhead (SC 2 to 4, >60 mm), the latter occurring below (or under) the largest particles, where current velocity is weakened and sand accumulates. SC1 bullhead had a more restricted range for each habitat descriptors, and were thus likely to require a more specific habitat type than other bullhead. The maximum WUA values and the related preferred discharges (0.15,0.75 m3 s,1) depended on the considered size-class. Our results suggest that ontogenetic niche shifts may play a role in the structure and dynamics of populations, by adjusting species' requirements to the spatial and temporal dynamics of environmental conditions, including abiotic and biotic conditions. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]


Spatial and ontogenetic variability in the microhabitat use of stream-dwelling spined loach (Cobitis taenia) and stone loach (Barbatula barbatula)

JOURNAL OF APPLIED ICHTHYOLOGY, Issue 6 2004
G. H. Copp
Summary Ontogenetic and spatial variability in microhabitat use of spined loach Cobitis taenia (Linnaeus), considered as one species for the purposes of this study, and stone loach Barbatula barbatula (Linnaeus) were examined in the River Great Ouse basin, England, using multivariate and habitat suitability methods, including a technique for handling spatial variation in collections of preference curves. Distinct ordinations of spined age classes and stone loach developmental stages, respectively, in canonical correspondence analysis of species × variables × samples relationships suggest that the two species occupy completely different microhabitats; however, young-of-the-year spined loach occurred more often than expected with all developmental stages of stone loach except young larvae. Water velocity and filamentous algae were the most influential microhabitat variables, the latter decreasing in importance with increasing age of both fish species. Preferred water velocities generally decreased with age in spined loach and increased in stone loach, with substratum size generally increasing with fish age in both species. Spatial variation in microhabitat preferences was great in both species but less so in the spined loach, suggesting that limited plasticity in habitat use could account, at least in part, for the latter species' limited distribution and abundance in the catchment. Preference curves for a species, if generated and verified for all life intervals and all seasons, could be used as a management tool for a given stream or sector of river basin. But preference curves should be generated for each location to ensure that river management decisions with regard habitat and species conservation consider local-level species requirements. Thus, a multi-(eco)species and multi-scale approach is required in habitat suitability assessments. [source]


Diet and food partitioning between juveniles of mutton Lutjanus analis, dog Lutjanus jocu and lane Lutjanus synagris snappers (Perciformes: Lutjanidae) in a mangrove-fringed estuarine environment

JOURNAL OF FISH BIOLOGY, Issue 10 2010
C. R. Pimentel
Diet of juvenile mutton Lutjanus analis, dog Lutjanus jocu and lane Lutjanus synagris snappers were studied in the tropical Brazilian estuarine system of the Piraquê-açú and Piraquê-mirim Rivers to determine how these species share the resources in this restricted space. The three species prey principally upon Peracarida (L. synagris: relative importance index IRIc = 29%), Natantia (L. analis and L. synagris: IRIc = 39 and 38%, respectively), Reptantia (L. analis and L. jocu: IRIc = 28 and 43%, respectively) and Teleostei (L. jocu: IRIc = 24%). The three species use estuaries as nursery habitats but food overlap was not biologically significant due to a combination of interspecific differences in size, spatial distribution, microhabitat preferences and seasonal patterns of abundance and prey choice. Large marine protected areas incorporating essential habitats for all life stages are suggested to be the best tool for the management of these economically important species. [source]


Behavioural interactions between native smokey dace and introduced yellowfin shiner: implications from habitat selection theory for an ongoing invasion

JOURNAL OF FISH BIOLOGY, Issue 2003
C. M. Wagner
The occupation of adjacent, non-overlapping positions along environmental gradients by closely related and ecologically similar species has drawn considerable attention from ecologists over the past decades. Condition-specific competition, wherein competitive superiority varies with the abiotic environmental gradient, has been proposed as the major structuring force behind such distributions. These concepts, however, are generally applied to explain the contemporary distribution of organisms that share an evolutionary history. Our aim was to apply these concepts to the naive interactions between native and introduced fishes. In 1990 yellowfin shiner (Notropis lutipinnis) were introduced into the headwaters of the Little Tennessee River of western North Carolina, U.S.A. where it exhibits microhabitat preferences that overlap significantly with those of a threatened native minnow, the smokey dace (Clinostomus funduloides raneyi). Previous research has established that these drift-feeding minnows: (1) differ in their average ability to intercept drifting prey as a function of water velocity; (2) generally occupy focal-point velocities that maximize the rate of prey capture; and, (3) occasionally defend the forward positions in foraging aggregations that form in high quality patches. We present the results of a series of experiments designed to: (1) evaluate the role of aggression in the establishment and maintenance of preferred foraging positions in drift-feeding minnows; (2) test the effects of prey availability, group size, and velocity on dominance rank, spatial position in groups, and feeding rates of individuals; and, (3) evaluate the potential for condition-specific competition to establish competitive refugia for the native within the natural heterogeneity of mountain streams. [source]


Spatial patterns of association at local and regional scales in coastal sand dune communities

JOURNAL OF VEGETATION SCIENCE, Issue 5 2009
Estelle Forey
Abstract Questions: Are positive understorey-dominant associations important in physically severe dune communities and does the strength of positive associations vary with disturbance at the local scale and with stress at the regional scale? Do associational patterns observed at the neighbourhood scale predict diversity at higher scales? Location: Coastal sand dunes, Aquitaine (France). Methods: Associational patterns with five dominant species were recorded along a local gradient of disturbance and a 240-km long regional gradient. Density, richness, cover and variance ratio of understorey species were recorded in quadrats located in dominant and in open areas. Spatial pattern of dominant plant species was recorded using a distance-based method. Results: Positive understorey-dominant associations were most frequent at both regional and local scale, although negative associations with understorey species were observed for one of the five dominants. At the regional scale, there was a shift in the magnitude of spatial associations, with higher positive associations in the most stressful sites, whereas spatial associations where not affected by the local disturbance gradient. Positive associations were not related to the size of the dominants but rather influenced by the identity of the dominant species. Conclusions: Our study highlights the potential crucial role of facilitation together with the importance of turnover of the dominants in explaining large-scale variation in diversity. However, because positive associations may also be attributed to environmental heterogeneity or co-occurrence of microhabitat preferences of species, experiments are needed to fully assess the relative importance of facilitation versus other drivers of community diversity. [source]


Vertical distribution of Hymenophyllaceae species among host tree microhabitats in a temperate rain forest in Southern Chile

JOURNAL OF VEGETATION SCIENCE, Issue 4 2009
Maria J. Parra
Abstract Question: Are differences in microhabitat preferences of co-occurring epiphytic Hymenophyllaceae species (filmy ferns) correlated with differences in ecophysiological responses to light availability and humidity in the host tree? Location: The Andean foothills in south-central Chile. Methods: We evaluated the distribution pattern of nine filmy fern species in microhabitats that differ in light availability and humidity in four host tree species. A DCA was developed to assess Hymenophyllaceae species microhabitat preference in terms of canopy openness (CO) and relative humidity. We assessed whether differences in chlorophyll content, maximum photochemical efficiency (Fv/Fm), photosynthetic capacity (Amax), evapotranspiration (E) and instantaneous water use efficiency (WUE) are consistent with any pattern. Results: CO and relative humidity differed significantly with height in the host trees. While CO increased with height in a host tree, relative humidity decreased. DCA analysis showed that filmy fern species distribution within and among trees was mainly explained by the relative humidity of the microhabitat. Chlorophyll content, chlorophyll a/b ratio, Amax and E differed significantly among filmy fern species. Amax and E were correlated with axis 1 scores from the DCA analysis. Conclusions: The vertical distribution and abundance of filmy fern species in Chilean temperate rain forest seems to be closely related to the different microhabitats offered by host trees. This pattern may reflect interspecific differences in ecophysiological traits related both to light availability and humidity. Our results suggest that humidity is the main environmental factor driving functional responses and habitat preferences of these filmy fern species. [source]


Reproductive interference in two ground-hopper species: testing hypotheses of coexistence in the field

OIKOS, Issue 9 2007
Julia Gröning
Similar to resource competition, reproductive interference may hamper the coexistence of closely related species. Species that utilize similar signal channels during mate finding may face substantial fitness costs when they come into contact and demographic displacement of the inferior species (sexual exclusion) is a likely outcome of such interactions. The two ground-hopper species Tetrix ceperoi and Tetrix subulata broadly overlap in their ranges and general habitat requirements, but rarely co-occur on a local scale. Results from laboratory and field experiments suggest that this mosaic pattern of sympatry might be influenced by reproductive interference. Here, we examine the significance of sexual interactions for these species in the field and test hypotheses on mechanisms of coexistence. Our results show that heterospecific sexual interactions also occur under field conditions, but in contrast to the experiments T. ceperoi was not the inferior species. The number of male mating attempts of both species was strongly correlated with encounter frequencies. Males discriminated between the sexes but not between the species, suggesting an incomplete mate recognition system in both species. The analysis of microhabitat preferences and spatial distribution revealed that habitat partitioning is not a suitable mechanism of coexistence in this system. Instead, the costs of reproductive interference are substantially mitigated by different niche breadths leading to different degrees of aggregation. Despite a considerable niche overlap T. ceperoi displayed a stronger preference for bare ground and occurred more aggregated than T. subulata, which had a broader niche. These differences may reduce the frequencies of heterospecific encounters and interactions in the field. Our results demonstrate that coexistence in the presence of reproductive interference is comparable to resource competition, being strongly influenced by ecological traits of the involved species, such as niche breadth and dispersion pattern. [source]