Biology subjects

Palomar, G.

Publications and source records attributed to Palomar, G..

3 recordsLinked to original sources

bioRxiv2024

The Amphibian Genomics Consortium: advancing genomic and genetic resources for amphibian research and conservation

Amphibians represent a diverse group of tetrapods, marked by deep divergence times between their three systematic orders and families. Studying amphibian biology through the genomics lens increases our understanding of the features of this animal class and that of other terrestrial vertebrates. The need for amphibian genomic resources is more urgent than ever due to the increasing threats to this group. Amphibians are one of the most imperiled taxonomic groups, with approximately 41% of species threatened with extinction due to habitat loss, changes in land use patterns, disease, climate change, and their synergistic effects. Amphibian genomic resources have provided a better understanding of ontogenetic diversity, tissue regeneration, diverse life history and reproductive modes, anti-predator strategies, and resilience and adaptive responses. They also serve as essential models for studying broad genomic traits, such as evolutionary genome expansions and contractions, as they exhibit the widest range of genome sizes among all animal taxa and possess multiple mechanisms of genetic sex determination. Despite these features, genome sequencing of amphibians has significantly lagged behind that of other vertebrates, primarily due to the challenges of assembling their large, repeat-rich genomes and the relative lack of societal support. The emergence of long-read sequencing technologies, combined with advanced molecular and computational techniques that improve scaffolding and reduce computational workloads, is now making it possible to address some of these challenges. To promote and accelerate the production and use of amphibian genomics research through international coordination and collaboration, we launched the Amphibian Genomics Consortium (AGC, https://mvs.unimelb.edu.au/amphibian-genomics-consortium) in early 2023. This burgeoning community already has more than 282 members from 41 countries. The AGC aims to leverage the diverse capabilities of its members to advance genomic resources for amphibians and bridge the implementation gap between biologists, bioinformaticians, and conservation practitioners. Here we evaluate the state of the field of amphibian genomics, highlight previous studies, present challenges to overcome, and call on the research and conservation communities to unite as part of the AGC to enable amphibian genomics research to "leap" to the next level.

genomics↗

bioRxiv2023

The Major Histocompatibility Complex modulates Batrachochytrium dendrobatidis and Ranavirus infections in three amphibian species

Genetic variation of immune genes is an important component of genetic diversity. Major histocompatibility complex (MHC) genes have been put forward as a model for studying how genetic diversity is maintained and geographically distributed in wild populations. Pathogen-mediated selection processes (i.e., heterozygosity advantage, rare-allele advantage or fluctuating selection) and demography are believed to generate and maintain the extreme diversity of MHC genes observed. However, establishing the relative importance of the different proposed mechanisms has proved extremely difficult, but heterozygote advantage is expected to be more detectable when multiple pathogens are considered simultaneously. Here, we test whether MHC diversity in three amphibian species (Ichthyosaura alpestris, Pleurodeles waltl, and Pelophylax perezi) is driven by pathogen-mediated selection. We examined the relationship between the individual MHC class II exon variability with individual infection status (infected or not), infection intensity, and co-infection of two main amphibian pathogens: Batrachochytrium dendrobatidis (Bd) and Ranavirus sp. (Rv). We found higher MHC class II exon 2 allelic diversity in I.alpestris and P. perezi than in P.waltl but no significant differences in allele frequencies between infection groups. We also observed significant differences in Bd infection intensity between Bd infected individuals and co-infected individuals depending on the number of MHC loci that an individual carries. For I. alpestris, we show stronger evidence for MHC associations with infection intensity and status when individuals carry specific alleles and supertypes. Our results suggest that studying the association between MHC genes and single and co-infected individuals might provide new insights into host-parasite evolution and a better understanding of evolutionary mechanisms driven by MHC diversity.

evolutionary biology↗

bioRxiv2023

Latitude-specific urbanization effects on life history traits in the damselfly Ischnura elegans

O_LIMany species are currently adapting to cities at different latitudes. Adaptation to urbanization may require eco-evolutionary changes in response to temperature and invasive species that may differ between latitudes. C_LIO_LIHere, we studied single and combined effects of increased temperatures and invasive alien predator presence on the phenotypic response of replicated urban and rural populations of the damselfly Ischnura elegans and contrasted these between central and high latitudes. C_LIO_LILarvae were exposed to temperature treatments (current [20 {o}C], mild warming [24 {o}C], and heat wave [28 {o}C; for high latitude only]) crossed with the presence or absence of chemical cues released by the spiny-cheek crayfish (Faxonius limosus), only present at the central latitude. We measured treatment effects on larval development time, mass, and growth rate. C_LIO_LIUrbanization type affected all life history traits, yet these responses were often dependent on latitude, temperature, and sex. Mild warming decreased mass in rural and increased growth rate in urban populations. The effects of urbanization on mass were latitude-dependent, with central-latitude populations having a greater phenotypic difference. Urbanization effects were sex-specific with urban males being lighter and having a lower growth rate than rural males. At the current temperature and mild warming, the predator cue reduced the growth rate, and this independently of urbanization level and latitude of origin. This pattern was reversed during a heat wave in high-latitude damselflies. C_LIO_LIOur results highlight the context-dependency of evolutionary and plastic responses to urbanisation, and caution for generalizing how populations respond to cities based on populations at a single latitude. C_LI

evolutionary biology↗