Can diet niche partitioning enhance sexual dimorphism?

Bauld, Joshua T.; Abernethy, Katharine; Newton, Jason; Lehmann, David; Jones, Isabel L.; Bussière, Luc F.

doi:10.1002/ece3.9599

Cited by 6 publications

(2 citation statements)

References 199 publications

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“…For example, a study on lynx in Norway ( Lynx lynx ) showed that females with kittens had higher roe deer ( Capreolus capreolus ) kill rates compared to solitary females, likely linked to increased energetic demands (Nilsen et al., 2009 ). However, dietary differences between male and female carnivores are typically attributed to sexual size dimorphism (Bauld et al., 2022 ), where larger males are able to kill larger prey (Magnusdottir et al., 2012 ; Voigt et al., 2018 ). Yet we found that male and female coyote diets were quite similar across seasons, perhaps because males in our population are only ~2 kg heavier than females (on average).…”

Section: Discussionmentioning

confidence: 99%

Resource pulses shape seasonal and individual variation in the diet of an omnivorous carnivore

Jensen,

Muthersbaugh,

Ruth

et al. 2024

Ecology and Evolution

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Resource pulses are ecologically important phenomenon that occur in most ecosystems globally. Following optimal foraging theory, many consumers switch to pulsatile foods when available, examples of which include fruit mast and vulnerable young prey. Yet how the availability of resource pulses shapes the ecology of predators is still an emerging area of research; and how much individual variation there is in response to pulses is not well understood. We hypothesized that resource pulses would lead to dietary convergence in our population, which we tested by tracking both population‐level and individual coyote diets for 3 years in South Carolina, USA. We (1) described seasonal dietary shifts in relation to resource pulses; (2) compared male and female diets across seasons; and (3) tested this dietary convergence hypothesis by quantifying individual dietary variation both across and within periods when resource pulses were available. We found that pulses of white‐tailed deer fawns and blackberries composed over half of coyote diet in summer, and persimmon fruits were an important component in fall. Male and female coyotes generally had similar diets, but males consumed more deer in fall, perhaps driven by scavenging more. We found support for our dietary convergence hypothesis, where individuals had more similar diets during resource pulses compared to a non‐pulse period. We also found that this convergence happened before peak availability, suggesting a non‐symmetric response to pulse availability. We show that nearly all coyotes eat fawns, suggesting that targeted efforts to remove “fawn killers” would be in vain. Instead, given how quickly coyotes collectively converge on resource pulses, our findings show that resource pulses could potentially be used by managers to alter the behavior of apex predators. More broadly, we open a new line of inquiry into how variation in individual foraging decisions scales up to shape the effects of resource pulses on ecological communities.

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Section: Discussionmentioning

confidence: 99%

Resource pulses shape seasonal and individual variation in the diet of an omnivorous carnivore

Jensen,

Muthersbaugh,

Ruth

et al. 2024

Ecology and Evolution

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“…Historically the direction of SSD has been attributed to the balance of sexual selection for increased male size and fecundity selection for increased female size ( Fairbairn et al. 2007 ), although the role of ecological selection in generating SSD is increasingly being recognized ( Shine 1989 ; Mysterud 2000 ; Bauld et al. 2022 ; Bravo et al.…”

Section: Introductionmentioning

confidence: 99%

Sharks Violate Rensch's Rule for Sexual Size Dimorphism

Gayford,

Sternes

2024

Integrative Organismal Biology

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Systematic trends in body size variation exist in a multitude of vertebrate radiations, however their underlying ecological and evolutionary causes remain poorly understood. Rensch's rule describes one such trend – in which the scaling of sexual size dimorphism (SSD) depends on which sex is larger. Where SSD is male-biased, SSD should scale hyperallometrically, as opposed to hypoallometrically where SSD is female-biased. The evidence for Rensch's rule is mixed, and comes from a small subset of total vertebrate diversity. We conducted the first empirical test of Rensch's rule in sharks, seeking to confirm or refute a long-hypothesied trend. We find that sharks violate Rensch's rule, as the magnitude of SSD increases with body size despite sharks predominantly exhibiting female-biased SSD. This adds to a growing literature of vertebrate clades that appear not to follow Rensch's rule, suggesting the absence of a single, conserved scaling trend for SSD amongst vertebrates. It is likely that selection associated with fecundity results in the ‘inverse Rensch's rule’ observed in sharks, although additional studies will be required to fully reveal the factors underlying SSD variation in this clade.

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