Biology subjects

Beaman, J. E.

Publications and source records attributed to Beaman, J. E..

5 recordsLinked to original sources

bioRxiv2025

Nesting behaviour drives the evolution of heat tolerance and climate vulnerability in bees

Species vulnerability to climate change depends in part on their capacity to evolve in response to increasing heat1. Within terrestrial ectotherms, heat tolerance generally corresponds weakly to current climates, which has led many to conclude that this trait is evolutionarily constrained2-4. However, most studies have not accounted for the role of microclimates, potentially obscuring signals of local adaptation. We examined heat tolerance in 95 species of wild bees that varied in nesting behaviour across the latitudinal extent of Australia. Species nest (ground, wooden cavities, or plant stems) micro-climate temperatures predicted heat tolerance evolution, where stem nesters evolved the highest heat tolerances, and ground nesters evolved the lowest heat tolerances due to their ability to evade extreme heat. A moderate level of phylogenetic inertia in heat tolerance was explained by patterns of related species sharing nesting behaviours. This indicated repeated adaptive evolution of similar heat tolerances, rather than strong evolutionary constraints on heat tolerance. Finally, incorporating nesting behaviour into assessments of climate change vulnerability changed the rank order of which species were most at risk. This underscores the need to understand what drives the evolution of heat tolerance across species to better identify the taxa most at risk to climate change.

ecology↗

bioRxiv2024

Species richness patterns in Fijian bees are explained by constraints in physiological traits

Determining the ecological and evolutionary mechanisms that underpin patterns of species richness across elevational gradients is a key question in evolutionary ecology, and can help to understand species extinction risk under changing climates. In the tropical montane islands of Fiji, there are 28 species of endemic bee in the subgenus Lasioglossum (Homalictus), where species richness increases with elevation despite decreasing land surface (habitat) areas. We used a combination of spatially explicit phylogenetic diversity analyses and phylogenetic trait analyses to examine the factors shaping species distributions in these bees. We found that species at higher elevations had lower heat tolerance and desiccation resistance than those at lower elevations, consistent with these traits constraining species elevational ranges. We also found high species phylogenetic diversity within mountains, and high phylogenetic signal in species heat tolerance and minimum elevational ranges, consistent with these traits being evolutionarily conserved among mountain-top taxa following vicariant (allopatric) speciation. We found no evidence to suggest that interspecific competition is shaping species elevational ranges. In all, our findings indicate that phylogenetic conservatism in physiological traits related to climatic niche, such as heat tolerance, can explain why species richness is highest at mountain tops in this system, with species having tracked their climatic niches over time towards ever higher (cooler and wetter) elevations. Because high elevations in this archipelago are extremely limited ([~]2.3% of total land area), only miniscule elevational islands in the sky remain into which this diverse, but climate-restricted fauna, can retreat as climates warm.

evolutionary biology↗

bioRxiv2022

Physiological traits and their relationships vary along an aridity gradient within and among Fijian bee species

O_LITemperature and water availability are hypothesised to be important abiotic drivers of the evolution of metabolic rates and gas exchange patterns, respectively. Specifically, the metabolic cold adaptation hypothesis (MCA) predicts that cold environments select for faster metabolic rates to counter the thermodynamics of biochemical reactions while the hygric hypothesis predicts that dry environments select for discontinuous gas exchange to reduce water loss. C_LIO_LIAlthough these two hypotheses consider different physiological traits and how they vary along different abiotic gradients, metabolic rate drives frequency of gas exchange patterns in insects meaning these two traits are inherently linked. Despite this link, the MCA and hygric hypotheses are rarely considered together and the extent to which metabolic rates and frequency of gas exchange vary and co-vary across climatic gradients remains unclear. C_LIO_LIWe tested the MCA and hygric hypotheses within a species of endemic Fijian bee, Homalictus fijiensis, across an altitudinal gradient of 1100 m, and among four Fijian bee species, including H. fijiensis, that inhabit different altitudinal bands. In Fiji, environmental temperature is [~]5{degrees}C lower in the central highlands than in the coastal lowlands with the highlands receiving [~]100 mm of additional precipitation than the lowlands each month. C_LIO_LIWe found an MCA-like pattern within H. fijiensis and among Fijian bee species, where metabolic rate decreased with increasing temperature, but precipitation also explained variation in metabolic rate. However, we did not find support for the hygric hypothesis within H. fijiensis or among species (frequency of gas exchange was not negatively correlated with precipitation). C_LIO_LIThe relationship between metabolic rate and frequency of gas exchange was steeper for species that occupied lower elevations on average, suggesting it is possible that these two traits can evolve independently of each other despite being positively correlated. C_LI

evolutionary biology↗

bioRxiv2022

Linking physiology to ecosystem function: how vulnerable are different functional groups to climate change?

O_LIThe resilience of ecosystem function under global climate change is governed by individual species vulnerabilities and the functional groups they contribute to (e.g. decomposition, primary production, pollination, primary, secondary and tertiary consumption). Yet it remains unclear whether species that contribute to different functional groups, which underpin ecosystem function, differ in their vulnerability to climate change. C_LIO_LIIt is important to examine if functional group vulnerability differs across space (e.g. tropical vs temperate latitudes) to determine if some regions will be more vulnerable to loss of ecosystem function than others, and to examine whether localized effects of particular community compositions override global patterns of functional group vulnerability. C_LIO_LIWe used existing upper thermal limit data across a range of terrestrial species (N = 1,743) to calculate species warming margins (degrees distance between a species upper thermal limit and the maximum environmental temperature they inhabit), as a metric of climate change vulnerability, to determine whether species that comprise different functional groups exhibit differential vulnerability to climate change, and if vulnerability trends change across geographic space. C_LIO_LIWe found that primary producers had the broadest warming margins across the globe ( = 21.85 {degrees}C) and that tertiary consumers had the narrowest warming margins ( = 4.37 {degrees}C), where vulnerability tended to increase with trophic level. C_LIO_LISpecies that contribute towards primary production were more vulnerable in low-latitude than mid-latitude regions, but warming margins across all other functional groups did not differ across regions when evolutionary history was considered. However, when evolutionary history was excluded from the analyses (as closely related species often play similar functional roles within ecosystems demonstrating true variation in functional group warming margins) we found that pollinators are more vulnerable in mid-latitude regions and that primary producers are more vulnerable in low-latitude environments. C_LIO_LIThis study provides a critical first step in linking individual species vulnerabilities with whole ecosystem responses to climate change. C_LI

ecology↗

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↗