Biology subjects

Monro, K.

Publications and source records attributed to Monro, K..

5 recordsLinked to original sources

bioRxiv2023

When is warmer better? Disentangling within- and between-generation effects of thermal history on survival

O_LIUnderstanding the fitness consequences of thermal history is necessary to predict organismal responses to global warming. This is especially challenging for ectotherms with complex life cycles, since distinct life stages can differ in thermal sensitivity, acclimate to different thermal environments, and accrue responses to acclimation within and between generations. C_LIO_LIAlthough acclimation is widely hypothesized to benefit organisms by helping them (or their offspring) to compensate for negative impacts of environmental change, equivocal support for this hypothesis highlights the need to assess alternatives. However, assessments that do so in ways that explicitly dissect responses across life stages and generations remain limited. C_LIO_LIWe assess alternative hypotheses for acclimation responses (none, beneficial, colder-is-better, and warmer-is-better) within and between generations of an externally-fertilizing marine tubeworm whose vulnerability to warming rests on survival at early planktonic stages (gametes, embryos, and larvae). We start by acclimating parents, gametes, and embryos to ambient and projected warmer temperatures (17 {degrees}C and 22 {degrees}C) factorially by life stage. We then rear individuals with differing acclimation histories to the end of larval development at test temperatures from 10 {degrees}C to 28 {degrees}C (upper and lower survival limits) to estimate thermal survival curves for development, and compare curves among acclimation histories. C_LIO_LIWe show that survival curves are most responsive to parental acclimation followed by acclimation at embryogenesis, but are buffered against acclimation at fertilization. Moreover, curves respond independently to acclimation within and between generations, and respond largely as predicted by the warmer-is-better hypothesis, despite the semblance of beneficial acclimation after successive acclimations to warmer temperature. C_LIO_LIOur study demonstrates the varied nature of thermal acclimation, and the importance of considering how acclimation responses aggregate across complex life cycles when predicting vulnerability to warming. C_LI

ecology↗

bioRxiv2023

Temperature and sex shape reproductive barriers in a climate change hotspot

Climate change is shifting species ranges and altering reproductive interactions within those ranges, offering closely-related species new scope to mate and potentially hybridize. Predicting hybridization and its outcomes requires assessing the interplay of biological and climatic factors that mediate reproductive barriers across life stages. However, few studies have done so across the range of environments that parents and offspring potentially encounter in nature, as is crucial to understand the environmental sensitivity of reproductive isolation and its fate under climate change. We set out to assess prezygotic and postzygotic reproductive barriers, and their dependence on temperature and sex, in sister species of a marine tubeworm (Galeolaria) from a sentinel region for climate change impacts in southern Australia. We performed reciprocal crosses within- and between-species using replicate populations, and assessed fertility of crosses, survival of embryos, and survival of larvae, at five temperatures spanning the thermal ranges of populations in nature. We found that barriers were weak and independent of temperature at fertilization, but stronger and more temperature-sensitive at larval development, as species diverged in thermal tolerance. Barriers were asymmetric between reciprocal hybrids, moreover, suggesting a complex interplay between thermal adaptation in parental lineages and maternal inheritance of factors (e.g., mitochondria, endosymbionts) that influence hybrid viability across temperatures. Together, our findings provide new insights into the roles of temperature and sex in reproductive barriers across early life stages, and point to shifting strengths of reproductive isolation in future climates.

ecology↗

bioRxiv2023

Predicting the evolution of adaptation and plasticity from temporal environmental change

Environmental change drives evolutionary adaptation, which determines geographic patterns of biodiversity. At a time of rapid environmental change, however, our ability to predict its evolutionary impacts is far from complete. Temporal environmental change, in particular, often involves joint changes in major components such as mean, trend, cyclic change, and noise. While theoretical predictions exist for adaptation to temporal change in isolated components, knowledge gaps remain. To identify those gaps, we review the relevant theoretical literature, finding that studies rarely assess the relative effects of components changing simultaneously, or attempt to translate theoretical predictions to field conditions. To address those gaps, we draw on classic evolutionary theory to develop a model for the evolution of environmental tolerance, determined by an evolving phenotypically plastic trait, in response to major components of temporal environmental change. We assess the effects of different components on the evolution of tolerance, including rates of adaptation towards new environmental optima, and the evolution of plasticity. We retrieve and synthesize earlier predictions of responses to components changing in isolation, while also generating new predictions of responses to components changing simultaneously. Notably, we show how different forms of environmental predictability emerging from the interplay of cyclic change, stochastic change (noise), and generation time shape predicted outcomes. We then parameterise our model using temperature time series from global marine hotspot in southern Australia, illustrating its utility for predicting testable geographic patterns in evolved thermal tolerance. Our framework provides new insights into the evolution of adaptation and plasticity under temporal environmental change, while offering a path to improving predictions of biological responses to climate change.

evolutionary biology↗

bioRxiv2022

Climate adaptation and vulnerability of foundation species in a global change hotspot

Climate change is altering species ranges, and abundances within ranges, as populations become differentially adapted and vulnerable to the climates they face. Hence, characterising current ranges, whether species harbour and exchange adaptive genetic variants, and how variants are distributed across landscapes undergoing rapid change, is crucial to predicting responses to future climates and informing conservation strategies. Such insights are nonetheless lacking for most species of conservation concern. We characterise genomic patterns of neutral variation, climate adaptation, and climate vulnerability (the amount of genomic change needed to track climate change by adaptation) in sister foundation species, the endemic marine tubeworms Galeolaria caespitosa and Galeolaria gemineoa, across a sentinel region for climate change impacts. First, species are shown to be partly sympatric despite previous support for non-overlapping ranges, and genetically isolated despite known capacity for hybrid crosses to yield viable early offspring. Second, species show signals of polygenic adaptation, but to differing components of temperature and involving mostly different loci. Last, species are predicted to be differentially vulnerable to climate change, with G. gemineoa -- the less genetically diverse species -- needing double the adaptation to track projected changes in temperature compared to its sister species. Together, our findings provide new insights into climate adaptation and its potential disruption by climate change for foundation species that enhance local biodiversity, with implications for evolutionarily-enlightened management of coastal ecosystems.

evolutionary biology↗

bioRxiv2020

Metabolic scaling has diversified among species, despite an evolutionary constraint within species

Metabolic rate scales disproportionally with body mass, such that the energetic cost of living is relatively lower in larger organisms. Theory emphasises the importance of fixed physical constraints on metabolic scaling, yet empirical data are lacking with which to assess how evolutionary processes (e.g. mutation, drift, selection) contribute to the observed variation in metabolic scaling across the tree of life. Using a large-scale quantitative genetic study of growth in cockroaches, we show that ontogenetic metabolic scaling is evolutionarily constrained due to an absence of additive genetic variation in juvenile metabolic rate and mass. Using a phylogenetic analysis, we also show that ontogenetic metabolic scaling is more similar among closely related species than among distant relatives, suggesting that the constraints on metabolic scaling are subject to change during lineage diversification. Our results are consistent with growing evidence that there is strong stabilising selection on combinations of mass and metabolic rate within species.

physiology↗