Biology subjects

Smallegange, I.

Publications and source records attributed to Smallegange, I..

5 recordsLinked to original sources

bioRxiv2025

Local resource heterogeneity drives density-dependent dispersal expression in a phoretic mite

O_LIDispersal is favoured in highly heterogenous and ephemeral environments where it can increase fitness. However, whilst we generally assume that unfavourable local conditions cue dispersal to elsewhere, little is known about how heterogeneity in local conditions influences dispersal expression. This is an important element of dispersal, since dispersal characteristics rely on such local cues to signal their development. C_LIO_LIWe assessed the role of local environmental heterogeneity on the expression of a plastic dispersal phenotype in experimental populations of the bulb mite Rhizoglyphus robini through a multigenerational, 18-week experiment. Populations were kept under either heterogenous, homogenous, or intermediate food distribution treatments, and at low or high population density, via culling. This allowed us to test for the effect of local environmental heterogeneity and competition on dispersal expression, but also on population size and growth. C_LIO_LIWe found that heterogenous environments induce greater expression of dispersal in high density environments, but not in low-density ones. Additionally, whilst culled treatments have on average larger population sizes than non-culled treatments, non-culled and heterogenous environments have similar sizes to culled treatments. Treatments did not impact population growth rate. C_LIO_LIOur findings that heterogenous treatments only induce greater dispersal expression under non-culled treatments suggests that heterogeneity may exacerbate competition around feeding patches, causing infrequent access to food. We also infer that culled populations become larger than non-culled, at least in the short term, due to rapid compensatory growth causing an overrepresentation of juveniles in the population. It is unclear why unculled heterogenous environments exhibit a similarly large population size to culled environment but could be due to food being hard to access but easy to locate. C_LIO_LIOverall, we find an ecologically significant impact of local heterogeneity on population size and dispersal expression, much of which may arise due to the influences of heterogeneity on competition around foraging spaces. Such findings highlight the need to distinguish between local and regional heterogeneity when modelling the evolution of dispersal, since these two alternate levels may perform significantly different roles in influencing the expression or adaptive value of dispersal. C_LI

evolutionary biology↗

bioRxiv2023

DEBBIES to compare life history strategies across ectotherms

Demographic models are used to explore how life history traits structure life history strategies across species. This study presents the DEBBIES dataset that contains estimates of eight life history traits (length at birth, puberty and maximum length, maximum reproduction rate, fraction energy allocated to respiration versus reproduction, von Bertalanffy growth rate, mortality rates) for 185 ectotherm species. The dataset can be used to parameterise dynamic energy budget integral projection models (DEB-IPMs) to calculate key demographic quantities like population growth rate and demographic resilience, but also link to conservation status or biogeographical characteristics. Our technical validation shows a satisfactory agreement between observed and predicted longevity, generation time, age at maturity across all species. Compared to existing datasets, DEBBIES accommodates (i) easy cross-taxonomical comparisons, (ii) many data-deficient species, and (iii) population forecasts to novel conditions because DEB-IPMs include a mechanistic description of the trade-off between growth and reproduction. This dataset has the potential for biologists to unlock general predictions on ectotherm population responses from only a few key life history traits.

ecology↗

bioRxiv2023

Community phylogenetic structure shapes pathogen outbreak potential in an epidemiological multi-host model

Biodiversity loss and anthropogenic modifications to species communities are impacting the frequency and magnitude of disease emergence events. These changes may be related through mechanisms in which biodiversity either increases (amplifies) or decreases (dilutes) disease prevalence. Biodiversity effects can be direct, when contacts among competent hosts are substituted by contacts with sink hosts, or indirect through regulation of host abundances. Whether a disease is diluted or amplified depends on the competence of the host species in the community. Here, we introduce a multi-host compartmental disease model in which we assume that host competence is determined by evolutionary relatedness. By simulating communities of varying phylogenetic structure, and estimating community disease outbreak potential (R0), we show how differences in host phylogenetic relatedness can switch host communities from diluting to amplifying a disease, even when species richness is unchanged. We additionally show that phylogenetic dilution can occur simultaneously with amplification through species richness, highlighting the multidimensionality of the disease-diversity relationship. We illustrate our model using empirical data describing the relationship between phylogenetic distances separating hosts and their likelihood of disease sharing. Our study demonstrates how a phylogenetic dilution effect can emerge when we allow transmission to depend on host evolutionary histories.

ecology↗

bioRxiv2019

The role of genetic diversity in the evolution and maintenance of environmentally-cued, male alternative reproductive tactics

BackgroundAlternative reproductive tactics (ARTs) are taxonomically pervasive strategies adopted by individuals to maximize reproductive success within populations. Even for conditionally-dependent traits, consensus postulates most ARTs involve both genetic and environmental interactions (GEIs), but to date, quantifying genetic variation underlying the threshold disposing an individual to switch phenotypes in response to an environmental cue has been a difficult undertaking. Our study aims to investigate the origins and maintenance of ARTs within environmentally disparate populations of the microscopic bulb mite, Rhizoglyphus robini, that express fighter and scrambler male morphs mediated by a complex combination of environmental and genetic factors. ResultsUsing never-before-published individual genetic profiling, we found all individuals across populations are highly inbred with the exception of scrambler males in stressed environments. In fact within the poor environment, scrambler males and females showed no significant difference in genetic differentiation (Fst) compared to all other comparisons, and although fighters were highly divergent from the rest of the population in both poor or rich environments (e.g., Fst, STRUCTURE), fighters demonstrated approximately three times less genetic divergence from the population in poor environments. AMOVA analyses further corroborated significant genetic differentiation across subpopulations, between morphs and sexes, and among subpopulations within each environment. ConclusionOur study provides new insights into the origin of ARTs in the bulb mite, highlighting the importance of GEIs: genetic correlations, epistatic interactions, and sex-specific inbreeding depression across environmental stressors. Asymmetric reproductive output, coupled with the purging of highly inbred individuals during environmental oscillations, also facilitates genetic variation within populations, despite evidence for strong directional selection. This cryptic genetic variation also conceivably facilitates stable population persistence even in the face of spatially or temporally unstable environmental challenges. Ultimately, understanding the genetic context that maintains thresholds, even for conditionally-dependent ARTs, will enhance our understanding of within population variation and our ability to predict responses to selection.

evolutionary biology↗

bioRxiv2018

A Modelling Exercise to Show Why Population Models Should Incorporate Distinct Life-Histories of Dispersers

Dispersal is an important form of movement influencing population dynamics, species distribution, and gene flow between populations. In population models, dispersal is often included in a simplified manner by removing a random proportion of the population. Many ecologists now argue that models should be formulated at the level of individuals instead of the population-level. To fully understand the effects of dispersal on natural systems, it is therefore necessary to incorporate individual-level differences in dispersal behaviour in population models. Here we parameterised an integral projection model (IPM), which allows for studying how individual life histories determine population-level processes, using bulb mites, Rhizoglyphus robini, to assess to what extent dispersal expression (frequency of individuals in the dispersal stage) and dispersal probability affect the proportion of dispersers and natal population growth rate. We find that allowing for life-history differences between resident phenotypes and disperser phenotypes shows that multiple combinations of dispersal probability and dispersal expression can produce the same proportion of leaving individuals. Additionally, a given proportion of dispersing individuals results in different natal population growth rates. The results highlight that dispersal life histories, and the frequency with which disperser phenotypes occur in the natal population, significantly affect population-level processes. Thus, biological realism of dispersal population models can be increased by incorporating the typically observed life history differences between resident phenotypes and disperser phenotypes, and we here present a methodology to do so.

ecology↗