Biology subjects

Issar, S.

Publications and source records attributed to Issar, S..

4 recordsLinked to original sources

bioRxiv2023

Previous breeding success and carrion substrate together influence subsequent carrion choice by adult Nicrophorus vespilloides

Insects can adjust their behaviour in relation to experience in a wide range of contexts including foraging, mate selection, and choice of oviposition site. Here we investigate whether burying beetles modulate their choice of carrion in relation to the outcome of their past breeding experience. Burying beetles require small vertebrate carrion to reproduce. Beetle parents convert carrion into an edible nursery for their larvae, whom they typically care for throughout larval development. We tested whether a beetles past breeding experience influenced its subsequent choice of carrion, when presented simultaneously with either a dead mouse or a dead chick. We found that both male and female beetles favoured the same carrion as used in their first breeding attempt - but only if they had produced many larvae and only if they had previously bred on a mouse. Beetles that had produced fewer larvae on a dead mouse switched to favouring dead chicks in their second breeding attempt. Those that had bred on a dead chick chose carrion at random subsequently, regardless of their previous breeding success. Our general conclusion is that burying beetles can integrate different sources of information about their past breeding experience with current cues when selecting carrion for reproduction.

evolutionary biology↗

bioRxiv2022

Multilevel selection leads to divergent coadaptation of care-giving parents during pre-hatching parental care

The joint actions of animals in partnerships or social groups evolve under both natural selection, from the wider environment, and social selection, imposed by other members of the pair or group. We used experimental evolution to investigate how jointly expressed actions evolve upon exposure to a new environmental challenge. Our work focused on the evolution of carrion nest preparation by pairs of burying beetles Nicrophorus vespilloides, a joint activity undertaken by the pair but typically led by the male. In previous work, we found that carrion nest preparation evolved to be faster in experimental populations without post-hatching care (No Care lines) than with post-hatching care (Full Care lines). Here we investigate how this joint activity evolved. After 15 generations of experimental evolution, we created heterotypic pairs (No Care females with Full Care males, and No Care males with Full Care females) and compared their carrion nest making with homotypic No Care and Full Care pairs. We found that pairs with No Care males prepared the nest more rapidly than pairs with Full Care males, regardless of the females line of origin. This suggests that males led the way by adapting their nest preparation behaviour to the No Care environment first, with females secondarily co-adapting their behaviour to the males behaviour by reducing their nest preparation behaviour. We discuss how social coadaptations within pairs or groups could act as a post-mating barrier to gene flow.

evolutionary biology↗

bioRxiv2018

The induction of larval resource preference in heterogeneous habitats

Animals often have to evaluate and choose between multiple food sources in their habitat, and these potentially complex decisions can have a large impact on their fitness. Among other factors, previous experience with an alternative resource can significantly increase subsequent preference for the resource (\"induction of preference\"). Such induction of resource preference is particularly relevant in spatially or temporally heterogeneous habitats. Although most mobile species - especially generalists - probably frequently encounter habitat heterogeneity, the impact of preference induction on individual behaviour and fitness in heterogeneous habitats is poorly understood. We analysed larval preference induction in wheat-adapted generalist red flour beetles (Tribolium castaneum) under three types of habitat heterogeneity. We first analysed the induction of larval preference for novel resources (other cereal flours) under temporal heterogeneity, exposing larvae to new resources during development. We found that larvae preferred a new resource if they experienced it recently, but that the magnitude of induction varied across resources. Interestingly, we also observed specific induction for a homogenous mix of wheat and a novel resource, with larvae preferring the mix over either pure resource. To analyse induction under spatial heterogeneity, we placed beetle eggs in one of two alternative resource patches and tested the preference of emerged larvae. Unexpectedly, hatching into a novel resource did not always induce preference. Finally, we found that induction of preference for new resources could be maladaptive for larval development. Together, our work demonstrates that experience-based plasticity of larval resource choice may strongly impact larval preference and fitness in heterogeneous habitats.

ecology↗

bioRxiv2017

FEMALE CHEMICAL WARFARE DRIVES FITNESS EFFECTS OF GROUP SEX RATIO

In animals, skewed sex ratios can affect individual fitness either via sexual interactions (e.g. intersexual conflict or intrasexual mate competition) or non-sexual interactions (e.g. sex-specific resource competition). Because most analyses of sex ratio focus on sexual interactions, the relative importance of these mechanisms remains unclear. We addressed this problem using the flour beetle Tribolium castaneum, where male-biased sex ratios increase female fitness relative to unbiased or female-biased groups. Although flour beetles show both sexual and non-sexual (resource) competition, we found that sexual interactions did not explain female fitness. Instead, female fecundity was dramatically reduced even after a brief exposure to flour conditioned by other females. Earlier studies suggested that quinones (secreted toxins) might mediate density-dependent population growth in flour beetles. We identified ethyl- and methyl-benzoquinone (EBQ and MBQ) as the primary components of adult stink glands that regulate female fecundity. In female-biased groups (i.e. at high female density), females upregulated quinones and suppressed each others reproduction. In male-biased groups, low female density lead to low quinone levels, allowing higher fecundity. Thus, quinones serve both as indicators and mediators of female competition, resulting in the observed fitness decline in female-biased groups. Our results underscore the importance of non-sexual interference competition that may often underlie the fitness consequences of skewed sex ratios.

evolutionary biology↗