Microhabitat and prey size among three species of Rana (Anura: Ranidae) sympatric in eastern Canada

1989 ◽  
Vol 67 (9) ◽  
pp. 2244-2252 ◽  
Author(s):  
Donald F. McAlpine ◽  
Timothy G. Dilworth
Keyword(s):  
Prey Size ◽  
Interspecific Interactions ◽  
Stomach Contents ◽  
Size Analysis ◽  
Eastern Canada ◽  
Leopard Frogs ◽  
Species Pairs ◽  
Prey Length ◽  
A Site ◽  
Structural Aspects

Microhabitat, prey size, and body morphology were examined in sympatric leopard frogs (Rana pipiens), green frogs (R. clamitans), and bullfrogs (R. catesbeiana) at a site in central New Brunswick. Ratios of head widths among species pairs were 1.23 (leopard and green frogs) and 1.51 (bullfrogs and green frogs), suggesting that leopard and green frogs may take prey of similar size. Analysis of stomach contents showed no significant differences in the mean prey sizes selected by leopard and green frogs. Rana sp. figured prominently in the diet of bullfrogs at the study site. Overlap among the species for prey length indicates the potential for competition between green and leopard frogs (Pij = 0.40 versus Pij = 1.41 for green frogs and bullfrogs). Structural aspects of habitat associated with vegetation were most important in discriminating microhabitat. Leopard frogs selected microhabitats that were much more densely vegetated than those of either bullfrogs or green frogs. In water, green frogs occupied sites that were closer to shore, were of lower water temperature, and had a higher vegetation canopy than sites occupied by bullfrogs. On land, green frogs selected microhabitats that were closer to water and less densely vegetated than those of leopard frogs. There was much greater microhabitat separation between leopard and green frogs than between green frogs and bullfrogs. There is some evidence that predation (bullfrogs preying on green frogs) and perhaps past competition (between green frogs and leopard frogs) have contributed to the patterns of resource use described. A number of other potential mechanisms (i.e., species phylogenies, inherent physiological or behavioural constraints acquired independently of interspecific interactions) remain unevaluated.

scholarly journals Multi-modal signal evolution in birds: re-examining a standard proxy for sexual selection

2018 ◽  
Vol 285 (1889) ◽  
pp. 20181557 ◽  
Author(s):  
Christopher R. Cooney ◽  
Hannah E. A. MacGregor ◽  
Nathalie Seddon ◽  
Joseph A. Tobias
Keyword(s):  
Sexual Selection ◽  
Interspecific Interactions ◽  
Habitat Type ◽  
Negative Relationship ◽  
Key Factors ◽  
Phenotypic Data ◽  
Species Pairs ◽  
Multiple Alternative ◽  
Mating Signal ◽  
Diversification Hypothesis

Sexual selection is proposed to be an important driver of speciation and phenotypic diversification in animal systems. However, previous phylogenetic tests have produced conflicting results, perhaps because they have focused on a single signalling modality (visual ornaments), whereas sexual selection may act on alternative signalling modalities (e.g. acoustic ornaments). Here, we compile phenotypic data from 259 avian sister species pairs to assess the relationship between visible plumage dichromatism—a standard index of sexual selection in birds—and macroevolutionary divergence in the other major avian signalling modality: song. We find evidence for a strong negative relationship between the degree of plumage dichromatism and divergence in song traits, which remains significant even when accounting for other key factors, including habitat type, ecological divergence and interspecific interactions. This negative relationship is opposite to the pattern expected by a straightforward interpretation of the sexual selection–diversification hypothesis, whereby higher levels of dichromatism indicating strong sexual selection should be related to greater levels of mating signal divergence regardless of signalling modality. Our findings imply a ‘trade-off’ between the elaboration of visual ornaments and the diversification of acoustic mating signals, and suggest that the effects of sexual selection on diversification can only be determined by considering multiple alternative signalling modalities.

scholarly journals Variations of Salminus hilarii diet (Ostariophysi, Characidae): seasonal and ontogenetic effects

2015 ◽  
Vol 75 (3) ◽  
pp. 574-580
Author(s):  
GA Villares Junior ◽  
R Goitein
Keyword(s):  
Prey Size ◽  
Pearson Correlation ◽  
Feeding Activity ◽  
Stomach Contents ◽  
Food Composition ◽  
Spearman Correlation ◽  
Statistical Comparison ◽  
Significant Difference ◽  
Ontogenetic Effects ◽  
Size And Morphology

AbstractThis study described the variations seasonal and ontogenetic of Salminus hilarii diet. Samples were collected in the Sorocaba River, São Paulo, Brazil, one of the few rivers where individuals of the species still occur in a higher frequency. The preys consumed were analyzed by Importance Alimentary Index (AIi). To determine similarities between year seasons, the AIi data were analyzed by the Morisita-Horn index and reduced in cluster analysis, along with a statistical comparison made by one-way ANOSIM test (5%). The feeding activity was analyzed according to the stomach repletion index and compared among the year seasons using non parametric variance analysis Kruskal-Wallis test (5%). Comparison of prey consumed between immature and adult individuals was made by Spearman correlation (5%). A Pearson correlation (5%) was applied between the standard length of the fish and prey consumed, as well as between the mouth and prey heights. The analyzes of stomach contents showed that the diet of this species was exclusively piscivorous, with significant difference of prey consumption during the period, the same happening among adult and immature individuals. It was observed that these fishes use to swallow their prey whole and that significant correlations between size of predator and prey size can be observed. There is also correlation between the mouth height and the maximum prey depth. Salminus hilarii feeds on the available prey, and the species food composition and feeding activity depends on prey`s abundance, their size and morphology, as do the water temperatures.

Feeding habits of the velvet belly lanternshark Etmopterus spinax (Chondrichthyes: Etmopteridae) off the Algarve, southern Portugal

2006 ◽  
Vol 86 (4) ◽  
pp. 835-841 ◽  
Author(s):  
João Neiva ◽  
Rui Coelho ◽  
Karim Erzini
Keyword(s):  
Deep Water ◽  
Foraging Behaviour ◽  
Prey Size ◽  
Feeding Habits ◽  
Feeding Strategy ◽  
Stomach Contents ◽  
Prey Composition ◽  
Southern Portugal ◽  
Meganyctiphanes Norvegica ◽  
Diet Shifts

Etmopterus spinax is one of the most abundant predators of the upper continental slope off the Algarve (southern Portugal), where it is captured in large quantities in deep-water fisheries. The feeding habits of E. spinax off the Algarve were investigated through the analysis of stomach contents of 376 individuals. Prey composition was described and maturity, sex and size related variations in the diet analysed. The overall diet of E. spinax suggested a fairly generalized benthopelagic foraging behaviour primarily tuned to pelagic macroplankton/microneckton, teleost fish and cephalopods. Sex and maturity related differences in the diet were not significant. Two main ontogenic diet shifts were observed at about 17 and 28 cm total length. Small and medium sized immature sharks had a diet dominated by eurybathic crustaceans, chiefly Meganyctiphanes norvegica and Pasiphaea sivado. Larger individuals consumed more teleosts and cephalopods, in part associated with scavenging as a new feeding strategy. With increasing shark size the diet diversified both in terms of resources exploited and prey size.

Pollination in alpine Norway: flowering phenology, insect visitors, and visitation rates in two plant communities

1993 ◽  
Vol 71 (8) ◽  
pp. 1072-1079 ◽  
Author(s):  
Ørjan Totland
Keyword(s):  
Plant Communities ◽  
Interspecific Interactions ◽  
Flowering Phenology ◽  
Alpine Plant ◽  
Visitation Rates ◽  
Species Pairs ◽  
Alpine Plant Communities ◽  
Selection For ◽  
Insect Visitors ◽  
Key Words Alpine

Pollination studies in European alpine communities are few. The objective of this study was to describe the pollination ecology in two alpine plant communities at Finse, southwestern Norway. Because of late snowmelt and early winter at Finse, the time available for flowering and seed maturation is restricted. Flowering was concentrated at the beginning of the season in both communities, and large overlaps in flowering time were found for most species. In one of the communities, flowering peaks were significantly clumped, whereas in the other they were randomly distributed through the season. However, in this community, five insect-pollinated species flowered simultaneously early in the season. Diptera almost exclusively dominated the visitor assemblage. Most plant species pairs had high overlaps in flower visitor species. Species flowering simultaneously attracted the same visitor species. In one community, eight species pairs flowered sequentially and shared visitors. Visitation rates were highest at the lowest elevated site. The results are compared with those obtained in other alpine areas. It is argued that selection for an early flowering is probably stronger than selection pressures resulting from interspecific interactions. Key words: alpine, Diptera, flowering phenology, flower visitors, season length, visitation rate.

scholarly journals A Virtual and Comparative Study on Soil Features and its Managing Ability

2021 ◽  
Vol 9 (1) ◽  
pp. 159-163
Author(s):  
Anuja Narayanan
Keyword(s):  
Empirical Models ◽  
Geotechnical Properties ◽  
Grain Size Analysis ◽  
Size Analysis ◽  
Structural Factors ◽  
Simple Method ◽  
Angle Of Internal Friction ◽  
Soil Features ◽  
Different Types ◽  
A Site

The study is related to the comparison of soil characteristics in some areas from a depth of 1m, 1.2m, and 1.5m; physical and geotechnical properties of the soil samples are studied in the laboratory to develop a simple method to determine the type of soil on a site. The tests conducted are grain size analysis, specific gravity, and field density. Moreover, the research intends to validate the behavior of sieving systems for different types of soils and at various loading conditions. From work, a decision support system to facilitate a sieving system that integrates geological, geotechnical, and structural factors is developed. The study reveals that an increase in the plasticity index decreases the angle of internal friction. The empirical models developed with the help of regression analysis for the benefit of field engineers for predicting the geotechnical properties.

scholarly journals Diet of invasive pikeperch Sander lucioperca: developing non-destructive tissue sampling for stable isotope analysis with comparisons to stomach contents analysis

2018 ◽  
pp. 49 ◽  
Author(s):  
Emma T. Nolan ◽  
J. Robert Britton
Keyword(s):  
Stable Isotope ◽  
Stable Isotope Analysis ◽  
Prey Size ◽  
Isotope Analysis ◽  
Stomach Contents ◽  
Sander Lucioperca ◽  
Destructive Sampling ◽  
Stomach Contents Analysis ◽  
Non Destructive ◽  
Dietary Analyses

Impact assessments of invasive piscivorous fishes usually rely on dietary analyses to quantify their predation pressure on prey communities. Stomach contents analysis (SCA), typically a destructive sampling method, is frequently used for this. However, many invasive piscivores are exploited by catch-and-release sport angling, with destructive sampling often not feasible. Stable isotope analysis (SIA) provides an alternative dietary analysis tool to SCA, with use of fin tissue, scales and/or epidermal mucus potentially enabling its non-destructive application. Here, the diet of a population of pikeperch Sander lucioperca, an invasive sport fish to Great Britain, was investigated by applying SIA to a range of tissues. Testing SI data of dorsal muscle (destructive sampling) versus fin, scale and mucus (non-destructive sampling) revealed highly significant relationships, indicating that the tissues collected non-destructively can be reliably applied to pikeperch diet assessments. Application of these SI data to Bayesian mixing models predicted that as S. lucioperca length increased, their diet shifted from macro-invertebrates to fish. Although similar ontogenetic patterns were evident in SCA, this was inhibited by 54% of fish having empty stomachs. Nevertheless, SCA revealed that as S. lucioperca length increased, their prey size significantly increased. However, the prey:predator length ratios ranged between 0.08 and 0.38, indicating most prey were relatively small. These results suggest that when non-destructive sampling is required for dietary analyses of sport fishes, SIA can be applied using fin, scales and/ or mucus. However, where destructive sampling has been completed, SCA provides complementary dietary insights, especially in relation to prey size.

Swordfish Xiphias gladius diet in the Florida Straits

2020 ◽  
Vol 96 (4) ◽  
pp. 695-706
Author(s):  
Amy M Heemsoth ◽  
Amy C Hirons ◽  
Caroline M Collatos ◽  
David W Kerstetter
Keyword(s):  
Diet Composition ◽  
Stomach Contents ◽  
Relative Importance ◽  
Crustacean Species ◽  
Index Of Relative Importance ◽  
Xiphias Gladius ◽  
Florida Straits ◽  
Prey Length ◽  
Positive Significant Correlation

Swordfish Xiphias gladius inhabit the Florida Straits year-round and provide a significant role in the food web as top-level predators. However, little is known about the diet composition and thus ecological role of swordfish in Florida. This study investigated swordfish diet by analyzing stomach contents of 131 swordfish in the Florida Straits from April 2007 to December 2008. Identifiable species included 13 teleost species, 3 cephalopod species, and 1 crustacean species. Cephalopods dominated the swordfish diet by weight (72.4%) and number (69.9%), and ranked highest in importance in the diet by the index of relative importance (IRI; 81.5%). Teleosts occurred the most (99.1%) but represented the second highest importance in diet by weight (25.2%), number (26.3%), and IRI (17.6%). Illex sp. was the prey with the greatest dietary importance, followed by unidentifiable ommastrephid squids. Stomach fullness index values ranged from 0 (empty) to 8.98 (mean = 0.37). A positive significant correlation between swordfish length and prey length was found (r2 = 0.104, P = 0.037), and no significant correlations were found between swordfish weight and prey weight (r2 = –0.075, P = 0.065). This is the first study to report a comprehensive diet of swordfish inhabiting waters in the Florida Straits region and suggests swordfish may be opportunistic feeders, altering their diet when abundance or presence of prey changes.

Variation in anti-predator behaviors of white-tailed deer (Odocoileus virginianus) in a multi-predator system

2019 ◽  
Vol 97 (11) ◽  
pp. 1030-1041
Author(s):  
E.R. Olson ◽  
T.R. Van Deelen ◽  
S.J. Ventura
Keyword(s):  
Odocoileus Virginianus ◽  
Interspecific Interactions ◽  
Food Resource ◽  
Risky Behaviors ◽  
Behavioral Observation ◽  
Relative Effect ◽  
Habitat Characteristics ◽  
Intraspecific Interactions ◽  
Intraspecific Interaction ◽  
A Site

Anti-predator responses to perceived predation risk can influence population demography. Understanding the relative effect of predator exposure and intraspecific interactions across a variety of anti-predator behaviors provides important insight into inter- and intra-specific drivers of species-specific behaviors. We merged classical behavioral observation methods with camera trapping techniques to examine anti-predator behaviors of white-tailed deer (Odocoileus virginianus (Zimmermann, 1780)) relative to variation in predator exposure and interspecific interactions. We coded 772 behavioral observations from >180 000 images spanning 605 trap-nights. Seasonal differences in behavioral responses to diminishing returns on foraging effort indicated that deer are risk-averse foragers and are more likely to exhibit risky behaviors in the presence of a concentrated food resource when the nutritional value of food resources are high. However, deer tended to spend less time at a site as resources diminished, supporting marginal value theories of habitat use. Intraspecific interaction predicted vigilance and the amount of time spent at a site. Similar to many other species, deer tended to be less vigilant and spend more time at a site as group size increased. Our research suggests that white-tailed deer in Wisconsin make foraging decisions based on factors associated with individual fitness, presence of conspecifics, and habitat characteristics.

The Diets of Two Coexisting Species of Antechinus (Marsupialia: Dasyuridae).

1980 ◽  
Vol 7 (3) ◽  
pp. 365 ◽  
Author(s):  
S Hall
Keyword(s):  
Size Range ◽  
Prey Size ◽  
Diversity Index ◽  
Large Population ◽  
Stomach Contents ◽  
Trophic Diversity ◽  
Individual Variations ◽  
Faecal Samples ◽  
Antechinus Stuartii ◽  
Coexisting Species

An analysis of faecal samples and stomach contents of Antechinus stuartii and A. swainsonii inhabiting forest in southern Victoria revealed a large overlap in the type and size of prey items taken by these dasyurids. The frequencies of 23 prey types and 15 prey sizes in the diets of these predators were both positively correlated. Weevils (Coleoptera, Curculionidae) represented the only difference in prey types not attributed to individual variations. A. stuartii took more, and a wider size range of, weevils than did A. swainsonii; the trophic diversity index of prey types was greater for A. stuartii. The larger A. swainsonii took more prey greater than 20 mm; it took prey on the average 23% longer and 75% heavier than did A. stuartii; the trophic diversity index of prey size was greater for A. swainsonii. It is concluded that these morphologically distinct predators are exploiting the same large population of prey. They are both generalists and appear to be opportunistic feeders.

What goes in does not come out: different non-lethal dietary methods give contradictory interpretation of prey selectivity in amphibians

2014 ◽  
Vol 35 (2) ◽  
pp. 255-262 ◽  
Author(s):  
Andrea Costa ◽  
Sebastiano Salvidio ◽  
Mario Posillico ◽  
Tiziana Altea ◽  
Giorgio Matteucci ◽  
...  
Keyword(s):  
Prey Selection ◽  
Central Italy ◽  
Stomach Contents ◽  
Stomach Content Analysis ◽  
Selection Strategy ◽  
Prey Selectivity ◽  
Faecal Analysis ◽  
Trophic Strategy ◽  
A Site ◽  
Significant Positive Selection

To date the most commonly used non-lethal methods in amphibian dietary studies are stomach flushing and faecal analysis. In this study, we compared the outcome of these two methods in interpreting prey selectivity when the available prey community in the environment is known. Stomach flushed contents and faeces were obtained from the same 27 individuals of the spectacled salamander (Salamandrina perspicillata) from a site in Central Italy. The interpretation of the population prey selection strategy varied in relation to the method used. Stomach content analysis suggested that salamanders were highly specialized on springtails, while faecal contents indicated a generalist trophic strategy. Prey selectivity indexes were also highly divergent: the analysis of stomach contents indicated a significant positive selection upon springtails, while exactly the opposite conclusion was obtained when faecal contents were analyzed. The results confirm that in amphibians, stomach analysis provides more reliable dietary data in comparison to faecal analysis. This is related to the fact that soft-bodied prey items tend to be more fully digested, disappearing in faeces while highly chitinized and less digestible prey taxa tend to increase their relative abundances in faeces.

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