scholarly journals Feeding Strategies of Co-occurring Newt Species across Different Conditions of Syntopy: A Test of the “Within-Population Niche Variation” Hypothesis

Diversity ◽  
2020 ◽  
Vol 12 (5) ◽  
pp. 181
Author(s):  
Jennifer Mirabasso ◽  
Alessandra M. Bissattini ◽  
Marco A. Bologna ◽  
Luca Luiselli ◽  
Luca Stellati ◽  
...  
Keyword(s):  
Central Italy ◽  
Feeding Strategies ◽  
Individual Specialization ◽  
Intraspecific Trait Variation ◽  
Size Dependent ◽  
Niche Variation ◽  
Feeding Specialization ◽  
Dietary Strategy ◽  
Coexisting Species ◽  
Niche Variation Hypothesis

Intraspecific trait variation in generalist animals is widespread in nature, yet its effects on community ecology are not well understood. Newts are considered opportunistic feeders that may co-occur in different syntopic conditions and represent an excellent model for studying the role of individual feeding specialization in shaping the population dietary strategy. Here, we investigated the diet of three newt species from central Italy occurring in artificial habitats in different coexistence conditions to test the predictions of the niche width (NW) variation hypotheses. Population NW did not vary among species and between presence and absence of coexisting species. An overall positive relationship between individual specialization and population NW was observed. However, this pattern was disrupted by the condition of syntopy with newt populations showing an individual NW variation invariant with population NW in presence of coexisting species, whereas it was larger in populations occurring alone. The observed pattern of newt behavior was not consistent with any of the proposed scenarios. We found a consistent pattern with the degree of individual specialization being (1) size-dependent (specialized individuals increasing within larger sized species) and (2) assemblage-complexity-dependent (specialized individuals increasing in syntopic populations in comparison to singly populations).

scholarly journals A test of the Niche Variation Hypothesis in a ruminant herbivore

2020 ◽  
Vol 89 (12) ◽  
pp. 2825-2839
Author(s):  
Brett R. Jesmer ◽  
Matthew J. Kauffman ◽  
Melanie A. Murphy ◽  
Jacob R. Goheen
Keyword(s):  
Niche Variation ◽  
Niche Variation Hypothesis

Grasshopper Mandibles and the Niche Variation Hypothesis

Evolution ◽  
1983 ◽  
Vol 37 (2) ◽  
pp. 375 ◽  
Author(s):  
Bruce D. Patterson
Keyword(s):  
Niche Variation ◽  
Niche Variation Hypothesis

scholarly journals How to Become a Generalist Species? Individual Niche Variation Across Habitat Transformation Gradients

2020 ◽  
Vol 8 ◽  
Author(s):  
Dan Liang ◽  
Shengnan Yang ◽  
Emilio Pagani-Núñez ◽  
Chao He ◽  
Yang Liu ◽  
...  
Keyword(s):  
Habitat Type ◽  
Bird Species ◽  
Niche Width ◽  
Natural Habitats ◽  
Generalist Species ◽  
Niche Expansion ◽  
Habitat Transformation ◽  
Niche Dynamics ◽  
Niche Variation ◽  
Niche Variation Hypothesis

Species in transformed habitats, frequently labeled as environmental generalists, tend to show broader niches than species in natural habitats. However, how population niche expansion translates into changes in the niches of individual organisms remains unclear, particularly in the context of habitat transformation. Niche expansion could be a product of individuals having broader niches, greater distances among individuals’ niches, or a combination of both processes. This would challenge the traditional conceptions on niche dynamics, which emphasize the role played by individual specialization (IS). Here, using stable isotopes, we computed total niche width (TNW), its within- and between-individual components (WIC and BIC), and IS (the ratio WIC/TNW), in 13 populations of 6 bird species and 8 populations of 3 frog species in natural and transformed habitats. We confirmed that species had broader niche width in transformed than in natural habitats, yet population niche expansion across habitats was mainly a product of increased distance between individuals. Within each habitat type, increases in TNW were linked to increases in WIC for all habitat types, while relationships between TNW and BIC were found in transformed but not in natural habitats. Hence, both increased individual niche width and increased distance among individuals were apparent within habitats, particularly in transformed ones, where increases in WIC dominated. Neither across or within habitats was niche expansion associated with increasing IS. Therefore, our results overturn traditional conceptions associated with the niche variation hypothesis and illustrate that niche expansion is not invariably associated with increased IS, because the distance between individual’s niches (BIC) can increase, as well as the breadth of those niches (WIC).

A mixed-feeding Equus species from the middle pleistocene of South Africa

2004 ◽  
Vol 62 (3) ◽  
pp. 316-323 ◽  
Author(s):  
Thomas M. Kaiser ◽  
Tamara A. Franz-Odendaal
Keyword(s):  
South Africa ◽  
Minor Component ◽  
Middle Pleistocene ◽  
Feeding Strategies ◽  
Mixed Feeding ◽  
Dietary Flexibility ◽  
Extant Species ◽  
Dietary Strategy ◽  
Mammalian Herbivore ◽  
A Minor

The dietary regime of Equus capensis from the Middle Pleistocene of South Africa is investigated by mesowear analysis. Results indicate that the mesowear signature of this species resembles that of two extant mixed feeders, the Grant's Gazelle (Gazella granti) and the Thomson's Gazelle (Gazella thomsoni), suggesting a mixed feeding dietary strategy for E. capensis. The mesowear signature of a contemporaneous population of Equus mosbachensis from Europe (Arago, France) is also determined for comparative purposes and has a typical grazing signature. In general, all extant species of Equus are believed to be almost exclusively grazers. However, a considerable degree of dietary flexibility is recently reported. The dietary signal of E. capensis is considered to be the result of feeding on the unique fynbos vegetation, which was beginning to establish itself at this time in southwestern South Africa. Grasses are a minor component of this floral kingdom. Our findings thus provide further evidence for the unexpected flexibility in feeding strategies of Equus, the most widely distributed equid taxon in the Quaternary. They highlight the potential use of the attrition"abrasion wear equilibrium as a habitat indicator, by mirroring the availability of food items in mammalian herbivore ecosystems.

Upscaling the niche variation hypothesis from the intra- to the inter-specific level

Oecologia ◽  
2015 ◽  
Vol 179 (3) ◽  
pp. 835-842 ◽  
Author(s):  
Marjorie Bison ◽  
Sébastien Ibanez ◽  
Claire Redjadj ◽  
Frédéric Boyer ◽  
Eric Coissac ◽  
...  
Keyword(s):  
Specific Level ◽  
Niche Variation ◽  
Niche Variation Hypothesis
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