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Bauld JT, Abernethy KA, Newton J, Lehmann D, Jones IL, Bussière LF. Can diet niche partitioning enhance sexual dimorphism? Ecol Evol 2022; 12:e9599. [PMID: 36545364 PMCID: PMC9760898 DOI: 10.1002/ece3.9599] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2022] [Revised: 11/01/2022] [Accepted: 11/20/2022] [Indexed: 12/23/2022] Open
Abstract
Classic evolutionary theory suggests that sexual dimorphism evolves primarily via sexual and fecundity selection. However, theory and evidence are beginning to accumulate suggesting that resource competition can drive the evolution of sexual dimorphism, via ecological character displacement between sexes. A key prediction of this hypothesis is that the extent of ecological divergence between sexes will be associated with the extent of sexual dimorphism. As the stable isotope ratios of animal tissues provide a quantitative measure of various aspects of ecology, we carried out a meta-analysis examining associations between the extent of isotopic divergence between sexes and the extent of body size dimorphism. Our models demonstrate that large amounts of between-study variation in isotopic (ecological) divergence between sexes is nonrandom and may be associated with the traits of study subjects. We, therefore, completed meta-regressions to examine whether the extent of isotopic divergence between sexes is associated with the extent of sexual size dimorphism. We found modest but significantly positive associations across species between size dimorphism and ecological differences between sexes, that increased in strength when the ecological opportunity for dietary divergence between sexes was greatest. Our results, therefore, provide further evidence that ecologically mediated selection, not directly related to reproduction, can contribute to the evolution of sexual dimorphism.
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Affiliation(s)
- Joshua T. Bauld
- Biological and Environmental SciencesUniversity of StirlingStirlingUK
| | - Katharine A. Abernethy
- Biological and Environmental SciencesUniversity of StirlingStirlingUK
- Institut de Recherche en Ecologie TropicaleCENARESTLibrevilleGabon
| | - Jason Newton
- National Environmental Isotope FacilityScottish Universities Environmental Research CentreEast KilbrideUK
| | - David Lehmann
- Agence Nationale des Parcs Nationaux (ANPN)LibrevilleGabon
| | - Isabel L. Jones
- Biological and Environmental SciencesUniversity of StirlingStirlingUK
| | - Luc F. Bussière
- Biology and Environmental Sciences and Gothenburg Global Biodiversity CentreUniversity of GothenburgGothenburgSweden
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Thomas H, Cameron SF, Campbell HA, Micheli-Campbell MA, Kirke EC, Wheatley R, Wilson RS. Rocky escarpment versus savanna woodlands: comparing diet and body condition as indicators of habitat quality for the endangered northern quoll (Dasyurus hallucatus). WILDLIFE RESEARCH 2021. [DOI: 10.1071/wr20032] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Abstract
ContextUnderstanding what constitutes high-quality habitat for threatened species is critical for conservation management planning. The endangered northern quoll (Dasyurus hallucatus) has experienced an uneven range contraction among habitat types. Once common across multiple habitats of northern mainland Australia, declining populations have now contracted to rocky escarpments.
AimThe island refuge of Groote Eylandt, Northern Territory, Australia, has not experienced the declines as seen on mainland Australia. Here, northern quolls persist in both rocky escarpment and savanna woodland, which provides a rare opportunity to investigate the habitat quality of rocky escarpments and savanna woodland for the northern quoll.
MethodsNorthern quolls (n=111) were trapped in both rocky escarpment (n=61) and savanna woodland (n=50) habitats before the breeding season (May). We conducted body condition assessment, scat analysis, and measured trophic niche breadth of individuals occupying each habitat type.
Key resultsFemale quolls occupying rocky escarpments exhibited a lower body condition than did quolls occupying savanna woodland. Quolls from rocky escarpments consumed a significantly higher proportion of mammals and fed within a narrower dietary niche than did those occupying savanna woodland.
ConclusionsQuolls had adapted to the dietary resources available within each habitat type, suggesting that the lack of quolls in savanna woodland on the mainland is due to factors other than availability of dietary resources.
ImplicationsGroote Eylandt is of critical conservation significance, where high numbers of northern quolls exist in both rocky escarpment and savanna woodland habitats. For population viability on the mainland, managing threats such as feral predators and inappropriate fire regimes in savanna woodland, particularly those surrounding rocky escarpment, should be prioritised.
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Musseau C, Vincenzi S, Santoul F, Boulêtreau S, Jesenšek D, Crivelli AJ. Within-individual trophic variability drives short-term intraspecific trait variation in natural populations. J Anim Ecol 2020; 89:921-932. [PMID: 31758696 DOI: 10.1111/1365-2656.13149] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2019] [Accepted: 10/20/2019] [Indexed: 11/29/2022]
Abstract
Intraspecific trait variability (ITV) maintains functional diversity in populations and communities, and plays a crucial role in ecological and evolutionary processes such as trophic cascades or speciation. Furthermore, functional variation within a species and its populations can help buffer against harmful environmental changes. Trait variability within species can be observed from differences among populations, and between- and within individuals. In animals, ITV can be driven by ontogeny, the environment in which populations live and by within-individual specialization or variation unrelated to growth. However, we still know little about the relative strength of these drivers in determining ITV variation in natural populations. Here, we aimed to (a) measure the relative strength of between- and within-individual effects of body size on ITV over time, and (b) disentangle the trophic changes due to ontogeny from other sources of variability, such as the environment experienced by populations and individual preferences at varying temporal and spatial scales. We used as a model system the endangered marble trout Salmo marmoratus, a freshwater fish living in a restricted geographical area (<900 km2 ) that shows marked changes in diet through ontogeny. We investigated two trophic traits, trophic position and resource use, with stable isotopes (δ15 N and δ13 C), and followed over time 238 individually tagged marble trout from six populations to estimate the trophic changes between and within individuals through ontogeny at three different time-scales (short term: 3 months, medium term: 1 year and long term: 2 years). We found that the relative strength of between- and within-individual effects of body size on trophic position and resource use change strongly over time. Both effects played a similar role in ITV over medium- and long-term time-scales, but within-individual effects were significantly driving trophic variability over short-term scales. Apart from ontogenetic shifts, individuals showed variability in trophic traits as big as the variability estimated between populations. Overall, our results show how the relative strengths of ITV drivers change over time. This study evidences the crucial importance of considering effects of time-scales on functional variability at individual, population and species levels.
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Affiliation(s)
- Camille Musseau
- Department of Biology, Chemistry, Pharmacy, Institute of Biology, Freie Universität Berlin, Berlin, Germany.,Berlin-Brandenburg Institute of Advanced Biodiversity Research, Berlin, Germany.,Leibniz-Institute of Freshwater Ecology and Inland Fisheries (IGB), Berlin, Germany.,EcoLab, Université de Toulouse, CNRS, Toulouse, France
| | - Simone Vincenzi
- Center for Stock Assessment Research, Department of Applied Mathematics and Statistics, University of California, Santa Cruz, CA, USA
| | | | | | | | - Alain J Crivelli
- Research Institute for the Conservation of Mediterranean Wetlands, Tour du Valat, Arles, France
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Foraging strategies of individual silky pocket mice over a boom-bust cycle in a stochastic dryland ecosystem. Oecologia 2019; 190:569-578. [PMID: 31190119 DOI: 10.1007/s00442-019-04432-x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2018] [Accepted: 06/07/2019] [Indexed: 01/19/2023]
Abstract
Small mammals use multiple foraging strategies to compensate for fluctuating resource quality in stochastic environments. These strategies may lead to increased dietary overlap when competition for resources is strong. To quantify temporal contributions of high (C3) versus low quality (C4) resources in diets of silky pocket mice (Perognathus flavus), we used stable carbon isotope (δ13C) analysis of 1391 plasma samples collected over 2 years. Of these, 695 samples were from 170 individuals sampled ≥ 3 times across seasons or years, allowing us to assess changes in dietary breadth at the population and individual levels across a boom-bust population cycle. In 2014, the P. flavus population increased to 412 captures compared to 8 captures in prior and subsequent years, while populations of co-occurring small mammals remained stable. As intraspecific competition increased, the population-wide dietary niche of P. flavus did not change, but individual specialization increased significantly. During this period, ~ 27% (41/151) of individuals sampled specialized on C3 resources, which were abundant during the spring and previous fall seasons. Most of the remaining individuals were C3-C4 generalists (64%) (96/151), and only 9% (14/151) specialized on C4 resources. In 2015, P. flavus population density and resource availability declined, individual dietary breadth expanded (84% generalists), no C3 specialists were found, and specialization on C4 resources increased (16%). Our results demonstrate a high degree of inter-individual plasticity in P. flavus foraging strategies, which has implications for how this species will respond to environmental change that is predicted to decrease C3 resources in the future.
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Isotope ecology detects fine-scale variation in Svalbard reindeer diet: implications for monitoring herbivory in the changing Arctic. Polar Biol 2019. [DOI: 10.1007/s00300-019-02474-8] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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Voigt CC, Krofel M, Menges V, Wachter B, Melzheimer J. Sex‐specific dietary specialization in a terrestrial apex predator, the leopard, revealed by stable isotope analysis. J Zool (1987) 2018. [DOI: 10.1111/jzo.12566] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- C. C. Voigt
- Department of Evolutionary Ecology Leibniz Institute for Zoo and Wildlife Research Berlin Germany
- Department of Animal Behavior Institute of Biology Berlin Germany
| | - M. Krofel
- Department of Forestry and Renewable Forest Resources Biotechnical Faculty University of Ljubljana Ljubljana Slovenia
| | - V. Menges
- Department of Evolutionary Ecology Leibniz Institute for Zoo and Wildlife Research Berlin Germany
| | - B. Wachter
- Department of Evolutionary Ecology Leibniz Institute for Zoo and Wildlife Research Berlin Germany
| | - J. Melzheimer
- Department of Evolutionary Ecology Leibniz Institute for Zoo and Wildlife Research Berlin Germany
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Burnik Šturm M, Ganbaatar O, Voigt CC, Kaczensky P. Sequential stable isotope analysis reveals differences in multi-year dietary history of three sympatric equid species in SW Mongolia. J Appl Ecol 2017; 54:1110-1119. [PMID: 28717255 PMCID: PMC5510718 DOI: 10.1111/1365-2664.12825] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2016] [Accepted: 10/20/2016] [Indexed: 11/29/2022]
Abstract
1. Competition among sympatric wild herbivores is reduced by different physiological, morphological, and behavioral traits resulting in different dietary niches. Wild equids are a rather uniform group of large herbivores which have dramatically declined in numbers and range. Correlative evidence suggests that pasture competition with livestock is one of the key factors for this decline, and the situation may be aggravated in areas where different equid species overlap. 2. The Dzungarian Gobi is currently the only place where two wild equid species coexist and share the range with the domesticated form of a third equid species. In the arid and winter cold Gobi, pasture productivity is low, highly seasonal, and wild equids additionally face increasing livestock densities. 3. We used stable isotope chronologies of tail hairs to draw inferences about multi-year diet seasonality, isotopic dietary niches, and physiological adaptations in the Asiatic wild ass (khulan), reintroduced Przewalski's horse, and domestic horse in the Mongolian part of the Dzungarian Gobi. 4. Our results showed that even in the arid Gobi, both horse species are predominantly grazers, whereas khulan are highly seasonal, switching from being grazers in summer to mixed feeders in winter. The isotopic dietary niches of the two horse species were almost identical, did not vary with season as in khulan, and were narrower than in the latter. Higher δ15N values point towards higher water use efficiency in khulan, which may be one reason why they can exploit pastures further away from water. 5. Synthesis and applications: The high degree of isotopic dietary niche overlap in the two horses points towards a high potential for pasture competition during the critical nutritional bottleneck in winter and highlights the need to severely restrict grazing of domestic horses on the range of the Przewalski's horses. Khulan are less constrained by water and seem more flexible in their choice of diet or less successful in exploiting grass dominated habitats in winter due to human presence. Providing additional water sources could increase the competition between khulan and livestock, and should therefore be only done following careful consideration.
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Affiliation(s)
- Martina Burnik Šturm
- Research Institute of Wildlife EcologyUniversity of Veterinary MedicineViennaAustria
| | - Oyunsaikhan Ganbaatar
- Great Gobi B Strictly Protected Area AdministrationTakhin TalGobi Altai ProvinceMongolia
- Department of ZoologySchool of Biology and BiotechnologyNational University of MongoliaUlan BatorMongolia
| | | | - Petra Kaczensky
- Research Institute of Wildlife EcologyUniversity of Veterinary MedicineViennaAustria
- Present address:
Norwegian Institute for Nature Research – NINATrondheimNorway
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Codron D, Codron J, Sponheimer M, Clauss M. Within-Population Isotopic Niche Variability in Savanna Mammals: Disparity between Carnivores and Herbivores. Front Ecol Evol 2016. [DOI: 10.3389/fevo.2016.00015] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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Yeakel JD, Bhat U, Elliott Smith EA, Newsome SD. Exploring the Isotopic Niche: Isotopic Variance, Physiological Incorporation, and the Temporal Dynamics of Foraging. Front Ecol Evol 2016. [DOI: 10.3389/fevo.2016.00001] [Citation(s) in RCA: 52] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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