Ecomorphological individual variation in a population of <i>Haplochromis nyererei</i> from the Tanzanian part of Lake Victoria

Fermon, Yves; Cibert, Christian

doi:10.1111/j.1095-8649.1998.tb00110.x

Cited by 13 publications

(18 citation statements)

References 43 publications

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“…Many studies focusing on individual specialization have relied on gut contents as a source of diet information (Bryan & Larkin 1972; Roughgarden 1974; Robinson et al. 1993; Schindler 1997; Fermon & Cibert 1998; Warburton, Retif & Hume 1998; Svanbäck & Bolnick 2007). However, gut contents are a ‘snapshot’ of an individual's diet and do not necessarily reflect long‐term preferences (Warburton et al.…”

Section: Methodsmentioning

confidence: 99%

Individual‐level diet variation in four species of Brazilian frogs

Araújo

Bolnick

Martinelli

et al. 2009

Journal of Animal Ecology

105

119

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Summary 1.Many natural populations exploiting a wide range of resources are actually composed of relatively specialized individuals. 2. This interindividual variation is thought to be a consequence of the invasion of 'empty' niches in depauperate communities, generally in temperate regions. If individual niches are constrained by functional trade-offs, the expansion of the population niche is only achieved by an increase in interindividual variation, consistent with the 'niche variation hypothesis'. 3. According to this hypothesis, we should not expect interindividual variation in species belonging to highly diverse, packed communities. 4. In the present study, we measured the degree of interindividual diet variation in four species of frogs of the highly diverse Brazilian Cerrado, using both gut contents and δ 13 C stable isotopes. 5. We found evidence of significant diet variation in the four species, indicating that this phenomenon is not restricted to depauperate communities in temperate regions. 6. The lack of correlations between the frogs' morphology and diet indicate that trade-offs do not depend on the morphological characters measured here and are probably not biomechanical. The nature of the trade-offs remains unknown, but are likely to be cognitive or physiological. 7. Finally, we found a positive correlation between the population niche width and the degree of diet variation, but a null model showed that this correlation can be generated by individuals sampling randomly from a common set of resources. Therefore, albeit consistent with, our results cannot be taken as evidence in favour of the niche variation hypothesis.

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Section: Methodsmentioning

confidence: 99%

Individual‐level diet variation in four species of Brazilian frogs

Araújo

Bolnick

Martinelli

et al. 2009

Journal of Animal Ecology

105

119

View full text Add to dashboard Cite

show abstract

“…The most compelling examples come from studies on fishes, in which researchers repeatedly sampled stomachs of the same individuals and observed high temporal consistency of individual diets (e.g., Bryan and Larkin 1972;Schindler 1997). Other studies showed that morphological variation among consumers explained some of the variation in stomach contents (Fermon and Cibert 1998;Robinson et al 1993;Svanback and Bolnick manuscript). Such morphology-diet correlations are strong evidence that some of the stomach content variation represents consistent diet variation among foragers.…”

Section: Introductionmentioning

confidence: 95%

“…Many studies focusing on individual specialization have relied on gut contents as a source of diet information (Bryan and Larkin 1972;Fermon and Cibert 1998;Robinson et al 1993;Roughgarden 1974;Schindler 1997;Warburton et al 1998;Svanback and Bolnick manuscript). An important underlying assumption in these studies is that the prey found in the stomach actually represents the longterm resource use of individuals.…”

Section: Introductionmentioning

confidence: 97%

Using δ13C stable isotopes to quantify individual-level diet variation

et al. 2007

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Individual-level diet variation can be easily quantified by gut-content analysis. However, because gut contents are a 'snapshot' of individuals' feeding habits, such cross-sectional data can be subject to sampling error and lead one to overestimate levels of diet variation. In contrast, stable isotopes reflect an individual's long-term diet, so isotope variation among individuals can be interpreted as diet variation. Nevertheless, population isotope variances alone cannot be directly compared among populations, because they depend on both the level of diet variation and the variance of prey isotope ratios. We developed a method to convert population isotope variances into a standardized index of individual specialization (WIC/TNW) that can be compared among populations, or to gut-content variation. We applied this method to diet and carbon isotope data of four species of frogs of the Brazilian savannah. Isotopes showed that gut contents provided a reliable measure of diet variation in three populations, but greatly overestimated diet variation in another population. Our method is sensitive to incomplete sampling of the prey and to among-individual variance in fractionation. Therefore, thorough sampling of prey and estimates of fractionation variance are desirable. Otherwise, the method is straightforward and provides a new tool for quantifying individual-level diet variation in natural populations that combines both gut-content and isotope data.

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“…While many of the Lake Victoria haplochromine species have been classified based mainly on coloration of mature males, little effort has been put on establishing the shape differences between the species, so that quantifiable differences in shape are not known to date. This study is one of the first to apply GM on Lake Victoria cichlids (but see, Fermon and Cibert 1998). We selected the relatively simple species community of a satellite of Lake Victoria – Lake Kanyaboli.…”

Section: Introductionmentioning

confidence: 99%

Morphometric differentiation among haplochromine cichlid fish species of a satellite lake of Lake Victoria

Odhiambo

Kerschbaumer

Postl

et al. 2011

Journal of Zoological Systematics and Evolutionary Research

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Lake Victoria holds a young but species‐rich assemblage of cichlid fishes, which form a monophyletic assemblage with additional species from surrounding water bodies, termed the Lake Victoria superflock. Lake Victoria is surrounded by smaller lakes that are somewhat disconnected from the main lake. Lake Kanyaboli is such a small lake, having markedly reduced species diversity, in part comprised of Lake Victoria species and endemics. Here, we studied the modern haplochromine component of the cichlid fauna, represented by Lipochromis maxillaris, Astatotilapia nubila, Xystichromis phytophagus and Astatotilapia sp. ‘Bigeye’, as well as a number of unidentified modern haplochromine specimens. We used landmark‐based geometric morphometrics to study the degree of morphological divergence among those young entities. Twenty landmarks and 14 interlandmark distances were used for shape analysis. Multivariate analysis revealed significant differences between all four species, but principal component analysis and canonical variate analysis did not clearly discriminate between A. nubila and X. phytophagus, demonstrating great overall morphological similarity despite clear dietary differences. Besides coloration there was sexual dimorphism in body proportions, so that only male individuals were analysed further. In all four species, the observed similarities and differences in body shape conform to the type of ecological specialization of the fish. Most unidentified specimens overlapped the range of A. nubila and X. phytophagus, while the assignment test based on the canonical variate analysis suggested 70% of the three overlapping entities as separate units. To test their reproductive distinctness and to demonstrate potential hybridization, nuclear genetic data are needed.

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Ecomorphological individual variation in a population of Haplochromis nyererei from the Tanzanian part of Lake Victoria

Cited by 13 publications

References 43 publications

Individual‐level diet variation in four species of Brazilian frogs

Individual‐level diet variation in four species of Brazilian frogs

Using δ13C stable isotopes to quantify individual-level diet variation

Morphometric differentiation among haplochromine cichlid fish species of a satellite lake of Lake Victoria

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