Biology subjects

Rossiter, S.

Publications and source records attributed to Rossiter, S..

6 recordsLinked to original sources

bioRxiv2025

Multi-trophic metacommunity responses to habitatnfragmentation in the Brazilian Atlantic Forest

The structure of ecological communities is profoundly altered by anthropogenic disturbance to landscapes. However, most reported impacts rely on the quantification of diversity estimates for single trophic levels or impacts on key species of interest. In this analysis we integrate measures of community structure, comparisons of interaction networks and measures of {beta}-diversity across four trophic levels: plants, bats, bat ectoparasites and bacteria within the ectoparasites. Our data show that bat, bat fly, and bacterial communities are significantly nested across forest fragments, with specialist consumers in all groups being found in fewer fragments than generalists. We found substantial {beta}-diversity in both species richness and interaction richness across fragments but no decline in interaction redundancy with decreasing fragment size, likely because even intact forest networks had very low redundancy in our dataset. Despite the loss of species and interactions, our data provide support for the conservation value of even the smallest and most disturbed forest fragments where essential seed dispersal services are potentially maintained by Artibeus, Carollia and Sturnira and distinct sets of taxa and interactions are supported. These species may be key in the potential recovery of these habitats, but our data highlight the fragility of these communities which have contracted around these disturbance-tolerant species.

ecology↗

bioRxiv2025

Bat power-metabolic profiling of the Egyptian fruit bat Rousettus aegyptiacus reveals distinctive cardiac adaptations

AimThe present study aimed to elucidate which pathways contribute to cardiometabolic adaptation in Egyptian fruit bats. MethodsUtilising cardiac tissues from Egyptian fruit bats (Rousettus aegyptiacus) and C57BL/6J mice, we combined liquid chromatography-mass spectrometry metabolic profiling, non-targeted 1H NMR spectroscopy, and in silicocomputational modelling using the genome-scale mammalian network CardioNet. Main FindingsOur analyses revealed that bat hearts exhibit a distinct metabolic profile characterised by depleted glycogen reserves and increased reliance on lipid oxidation to meet energy demands. Notably, bat hearts displayed elevated fluxes in oxidative phosphorylation, {beta}-oxidation of long-chain fatty acids, and the Krebs cycle, alongside reduced amino acid catabolism. These findings suggest that bats have evolved unique metabolic strategies to support the high-energy demands of flight, maintaining cardiac function without succumbing to pathological remodelling. ConclusionsThis study provides the first comprehensive insight into the metabolic adaptations in the cardiac tissue of a bat species, contributing to our understanding of how these mammals endure extreme physiological stresses. Integrating metabolomics with computational modelling offers a powerful approach to studying metabolic adaptations in non-model species, potentially informing therapeutic strategies for human cardiac conditions.

systems biology↗

bioRxiv2024

The importance of small island populations for the long term survival of endangered large-bodied insular mammals

Island populations of large vertebrates have experienced higher extinction rates than mainland populations over long timescales due to demographic stochasticity, genetic drift and inbreeding. Conversely, small island populations often experience relatively less anthropogenic habitat degradation than populations on larger islands, making them potential targets for conservation interventions such as genetic rescue to improve their overall genetic diversity. Here we determine the consequences and conservation implications of long-term isolation and recent human activities on genetic diversity of island populations of two forest-dependent mammals endemic to the Wallacea archipelago: the anoa (Bubalus spp.) and babirusa (Babyrousa spp.). Using genomic analyses and habitat suitability models, we show that, compared to closely related species, populations on mainland Sulawesi exhibit low heterozygosity, high inbreeding, and a high proportion of deleterious alleles. In contrast, populations on smaller islands possess fewer deleterious mutations despite exhibiting lower heterozygosity and higher inbreeding. Site frequency spectra indicate that these patterns reflect stronger, long-term purging in smaller island populations. Our results thus suggest that conservation efforts should focus on protecting small island habitats and avoiding translocations from mainland populations. This study highlights the crucial role of small offshore islands for the long-term survival of Wallaceas iconic and indigenous mammals in the face of development on the mainland. Significance statementWithin tropical archipelagos, such as the Wallacea biodiversity hotspot, larger islands experience greater resource exploitation compared to smaller ones, highlighting the potential of smaller islands as refuges for conservation. To investigate the genetic health of populations on small islands, we used genomic, occurrence, and environmental data from a system of replicated populations of anoa and babirusa across islands of varying sizes. In contrast to larger islands like Sulawesi, our results demonstrate that smaller offshore islands not only provide higher-quality habitats but also support populations that have efficiently purged harmful mutations. Thus, despite their known vulnerability over geological time-frames, small island populations can provide long term insurance against human-driven extinction and conservation efforts should prioritise habitat management over translocations.

evolutionary biology↗

bioRxiv2021

Ecological constraints on highly evolvable olfactory receptor genes and morphology

While evolvability of genes and traits may promote specialization during species diversification, how ecology subsequently restricts such variation remains unclear. Chemosensation requires animals to decipher a complex chemical background to locate fitness-related resources, and thus the underlying genomic architecture and morphology must cope with constant exposure to a changing odorant landscape; detecting adaptation amidst extensive chemosensory diversity is an open challenge. Phyllostomid bats, an ecologically diverse clade that evolved plant-visiting from an insectivorous ancestor, suggest the evolution of novel food detection mechanisms is a key innovation: phyllostomids behaviorally rely strongly on olfaction, while echolocation is supplemental. If this is true, exceptional variation in underlying olfactory genes and phenotypes may have preceded dietary diversification. We compared olfactory receptor (OR) genes sequenced from olfactory epithelium transcriptomes and olfactory epithelium surface area of bats with differing diets. Surprisingly, although OR evolution rates were quite variable and generally high, they are largely independent of diet. Olfactory epithelial surface area, however, is relatively larger in plant-visiting bats and there is an inverse relationship between OR evolution rates and surface area. Relatively larger surface areas suggest greater reliance on olfactory detection and stronger constraint on maintaining an already diverse OR repertoire. Instead of the typical case in which specialization and elaboration is coupled with rapid diversification of associated genes, here the relevant genes are already evolving so quickly that increased reliance on smell has led to stabilizing selection, presumably to maintain the ability to consistently discriminate among specific odorants -- a potential ecological constraint on sensory evolution. Significance StatementThe evolutionary relationship between genes and morphology is complex to decipher, and macroevolutionary trends are often measured independently; this is especially challenging to quantify in unstable genomic regions or hypervariable traits. Odorant cues are detected by proteins encoded by the largest and fasted-evolving gene family in the mammalian genome and expressed in epithelia distributed on elaborate bony structures in the nose, posing a challenge to quantification. Yet, the direct interaction of the olfactory system with environmental signals strongly suggest that selection shapes its immense diversity. In neotropical bats, where reliance on plant-visiting evolved from an insectivorous ancestor, we discovered clear dietary differences amongst species, but only after considering morphological and molecular data simultaneously, emphasizing the power of a coupled analysis.

evolutionary biology↗

bioRxiv2020

Population genetic structure in the insular Ryukyu flying fox, Pteropus dasymallus

Small isolated populations are vulnerable to both stochastic events and the negative consequences of genetic drift. For threatened species, the genetic management of such populations has therefore become a crucial aspect of conservation. Flying foxes (Pteropus spp, Chiroptera) are keystone species with essential roles in pollination and seed dispersal in tropical and subtropical ecosystems. Yet many flying fox species are also of conservation concern, having experienced dramatic population declines driven by habitat loss and hunting. The Ryukyu flying fox (Pteropus dasymallus) ranges from Japan and Taiwan to the northern Philippines, and has undergone precipitous population crashes on several islands in recent decades. To assess population genetic structure and diversity in P. dasymallus, and its likely causes, we analyzed mitochondrial and microsatellite DNA. Both markers showed significant genetic differentiation among most island populations with patterns of isolation-by-distance. However, while mitochondrial haplotypes showed some mixing across the region, likely reflecting historical colonization and/or dispersal events, microsatellites markers showed clear subdivisions corresponding to the position of deep ocean trenches. The current distribution of P. dasymallus and its subspecific diversity therefore appears to have arisen through vicariance coupled with a long history of restricted gene flow across oceanic barriers. We conclude that isolated island subgroups should be managed separately, with efforts directed at reducing further declines.

ecology↗

bioRxiv2018

Evidence for multifactorial processes underlying phenotypic variation in bat visual opsins

Studies of opsin genes offer insights into the evolutionary history and molecular basis of vertebrate color vision, but most assume intact open reading frames equate to functional phenotypes. Despite known variation in opsin repertoires and associated visual phenotypes, the genetic basis of such patterns has not been examined at each step of the central dogma. By comparing sequences, gene expression, and protein localization across a hyperdiverse group of mammals, noctilionoid bats, we find evidence that independent losses of S-opsin arose through disruptions at different stages of protein synthesis, while maintenance relates to frugivory. Discordance between DNA, RNA, and protein reveals that the loss of short-wave sensitivity in some lineages resulted from transcriptional and post-transcriptional changes in addition to degradation of open reading frames. These mismatches imply that visual phenotypes cannot reliably be predicted from genotypes alone, and connect ecology to multiple mechanisms behind the loss of color in vertebrates.

genomics↗