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Generalisation within specialization: inter-individual diet variation in the only specialized salamander in the world.

Costa A, Salvidio S, Posillico M, Matteucci G, De Cinti B, Romano A - Sci Rep (2015)

Bottom Line: Our results showed that Salamandrina is highly specialized on Collembola and the more specialized individuals are the better performing ones.Our findings reflects the optimal foraging theory both at population and individual level, since animals in better physiological conditions are able to exploit the most profitable prey, suggesting that the two coexisting strategies are not equivalent.At last this species, feeding on decomposers of litter detritus, could play a key role determining litter retention rate, nutrient cycle and carbon sequestration.

View Article: PubMed Central - PubMed

Affiliation: Consiglio Nazionale delle Ricerche, Istituto di Biologia Agroambientale e Forestale (CNR-IBAF), Area di Ricerca Roma 1, Via Salaria km 29, 300-00015. Monterotondo (RM) (Italy).

ABSTRACT
Specialization is typically inferred at population and species level but in the last decade many authors highlighted this trait at the individual level, finding that generalist populations can be composed by both generalist and specialist individual. Despite hundreds of reported cases of individual specialization there is a complete lack of information on inter-individual diet variation in specialist species. We studied the diet of the Italian endemic Spectacled Salamander (Salamandrina perspicillata), in a temperate forest ecosystem, to disclose the realised trophic niche, prey selection strategy in function of phenotypic variation and inter-individual diet variation. Our results showed that Salamandrina is highly specialized on Collembola and the more specialized individuals are the better performing ones. Analyses of inter-individual diet variation showed that a subset of animals exhibited a broader trophic niche, adopting different foraging strategies. Our findings reflects the optimal foraging theory both at population and individual level, since animals in better physiological conditions are able to exploit the most profitable prey, suggesting that the two coexisting strategies are not equivalent. At last this species, feeding on decomposers of litter detritus, could play a key role determining litter retention rate, nutrient cycle and carbon sequestration.

No MeSH data available.


Related in: MedlinePlus

Costello’s modified graphical interpretation of the foraging strategy (Amundsen et al., 1992).Autumn data are represented by squares, while spring data are represented by triangles. Labels of prey categories with both values of Prey importance and Frequency of occurrence lower than 0.30 are not shown.
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f1: Costello’s modified graphical interpretation of the foraging strategy (Amundsen et al., 1992).Autumn data are represented by squares, while spring data are represented by triangles. Labels of prey categories with both values of Prey importance and Frequency of occurrence lower than 0.30 are not shown.

Mentions: With regard to the trophic niche width of Salamandrina, the diversity in the diet composition was significantly higher (t-test: p < 0.001) in Autumn (Shannon-Weaver index = 1.16 – Evenness = 0.40) than in Spring (S-W index = 0.83 – Evenness = 0.28), and the diversity, for the invertebrate community, significantly differed between seasons (t-test: p < 0.001) and was higher in Autumn (S-W index = 2.23 – Evenness = 0.68) than in Spring (S-W index = 1.86 – Evenness = 0.61). There was no significant evidence of different prey use between sexes (ANOSIM: Autumn; R = −0.06; p = 0.711 – Spring; R = −0.07; p = 0.842). The graphical representation of the feeding strategy (Fig. 1) confirmed that Salamandrina, in both seasons, behaves as a specialist predator on Collembola. Furthermore, the graphical analysis suggests that Salamandrina has a narrow trophic niche, and Collembola were the bulk of the realized trophic niche, along with Araneae and Acarina, while these contributed to a lesser extent. Even if Salamandrina appears to be specialized on Collembola in both seasons, the intensity of specialization is even higher in Spring than in Autumn: indeed all salamanders fed on Collembola in Spring.


Generalisation within specialization: inter-individual diet variation in the only specialized salamander in the world.

Costa A, Salvidio S, Posillico M, Matteucci G, De Cinti B, Romano A - Sci Rep (2015)

Costello’s modified graphical interpretation of the foraging strategy (Amundsen et al., 1992).Autumn data are represented by squares, while spring data are represented by triangles. Labels of prey categories with both values of Prey importance and Frequency of occurrence lower than 0.30 are not shown.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4543951&req=5

f1: Costello’s modified graphical interpretation of the foraging strategy (Amundsen et al., 1992).Autumn data are represented by squares, while spring data are represented by triangles. Labels of prey categories with both values of Prey importance and Frequency of occurrence lower than 0.30 are not shown.
Mentions: With regard to the trophic niche width of Salamandrina, the diversity in the diet composition was significantly higher (t-test: p < 0.001) in Autumn (Shannon-Weaver index = 1.16 – Evenness = 0.40) than in Spring (S-W index = 0.83 – Evenness = 0.28), and the diversity, for the invertebrate community, significantly differed between seasons (t-test: p < 0.001) and was higher in Autumn (S-W index = 2.23 – Evenness = 0.68) than in Spring (S-W index = 1.86 – Evenness = 0.61). There was no significant evidence of different prey use between sexes (ANOSIM: Autumn; R = −0.06; p = 0.711 – Spring; R = −0.07; p = 0.842). The graphical representation of the feeding strategy (Fig. 1) confirmed that Salamandrina, in both seasons, behaves as a specialist predator on Collembola. Furthermore, the graphical analysis suggests that Salamandrina has a narrow trophic niche, and Collembola were the bulk of the realized trophic niche, along with Araneae and Acarina, while these contributed to a lesser extent. Even if Salamandrina appears to be specialized on Collembola in both seasons, the intensity of specialization is even higher in Spring than in Autumn: indeed all salamanders fed on Collembola in Spring.

Bottom Line: Our results showed that Salamandrina is highly specialized on Collembola and the more specialized individuals are the better performing ones.Our findings reflects the optimal foraging theory both at population and individual level, since animals in better physiological conditions are able to exploit the most profitable prey, suggesting that the two coexisting strategies are not equivalent.At last this species, feeding on decomposers of litter detritus, could play a key role determining litter retention rate, nutrient cycle and carbon sequestration.

View Article: PubMed Central - PubMed

Affiliation: Consiglio Nazionale delle Ricerche, Istituto di Biologia Agroambientale e Forestale (CNR-IBAF), Area di Ricerca Roma 1, Via Salaria km 29, 300-00015. Monterotondo (RM) (Italy).

ABSTRACT
Specialization is typically inferred at population and species level but in the last decade many authors highlighted this trait at the individual level, finding that generalist populations can be composed by both generalist and specialist individual. Despite hundreds of reported cases of individual specialization there is a complete lack of information on inter-individual diet variation in specialist species. We studied the diet of the Italian endemic Spectacled Salamander (Salamandrina perspicillata), in a temperate forest ecosystem, to disclose the realised trophic niche, prey selection strategy in function of phenotypic variation and inter-individual diet variation. Our results showed that Salamandrina is highly specialized on Collembola and the more specialized individuals are the better performing ones. Analyses of inter-individual diet variation showed that a subset of animals exhibited a broader trophic niche, adopting different foraging strategies. Our findings reflects the optimal foraging theory both at population and individual level, since animals in better physiological conditions are able to exploit the most profitable prey, suggesting that the two coexisting strategies are not equivalent. At last this species, feeding on decomposers of litter detritus, could play a key role determining litter retention rate, nutrient cycle and carbon sequestration.

No MeSH data available.


Related in: MedlinePlus