Biology subjects

Spadavecchia, G.

Publications and source records attributed to Spadavecchia, G..

3 recordsLinked to original sources

bioRxiv2022

Spatial differentiation of background matching strategies along a Late Pleistocene range expansion route

Late Pleistocene climate changes have deeply impacted the range dynamics of temperate species. While the genetic legacy of these dynamics has been widely investigated, little is known about their phenotypic consequences. Anti-predatory strategies offer intriguing opportunities to study phenotypic evolution in response to dispersal dynamics since the ability to avoid predation can be pivotal for populations colonizing new environments. Here we investigated the spatial differentiation of background colour matching strategies along a Late Pleistocene range expansion route of a temperate species, the Tyrrhenian tree frog Hyla sarda. Using common-garden experiments, we investigated whether individuals sampled in the source area (Sardinia) and individuals sampled in the newly founded area (Corsica) differ in two components of the camouflage strategy: colour change abilities and background choice behaviour. We found a remarkable spatial structure in both colour change abilities and background choice behaviour, across the expansion range. Tree frogs from the source area displayed higher colour change abilities and a more pronounced preference for a greener background, with respect to tree frogs from the newly colonized area. We discuss these results in the context of the spatial and demographic components of the expansion dynamics. Our results support the intriguing hypothesis that Late Pleistocene biogeographic history might be an overlooked major player in shaping current spatial patterns of phenotypic traits variation across animal populations.

evolutionary biology↗

bioRxiv2022

First brain de-novo transcriptome of Tyrrenhian tree frog, Hyla sarda, for the study of dispersal-related behavioral variation

Dispersal is a key process in ecology and evolution as it contributes to shaping the spatial patterns of biological diversity at all its levels of organization. Growing evidence is unveiling the role of phenotypic trait variation in affecting dispersal dynamics of populations, and that substantial, rapid, and directional changes in the phenotypic makeup of populations would occur during range expansions by spatial sorting of dispersal-related traits. Accordingly, selective pressures at the front of a range expansion wave would actively promote individuals with higher dispersal abilities. Although many studies have been focusing on phenotypic trait evolution during range expansion, its genomic underpinnings are almost unexplored, hampering a thorough understanding of the evolutionary processes involved during dispersal. The Tyrrhenian tree frog Hyla sarda is a small amphibian endemic to the Tyrrhenian islands. According to previous phylogeographic studies, H. sarda underwent a northward range expansion from the north of Sardinia (western Mediterranean sea) during the last glacial phase. The colonization of the Corsica island was allowed by the temporary formation of a wide land bridge connecting Sardinia and Corsica, induced by the marine regression occurred during the last glacial maximum. The postglacial loss of this land bridge prevented any subsequent gene flow between Corsican and Sardinian populations. As a consequence, the genetic and phenotypic legacies of this range expansion event can still be detected in current populations, which makes H. sarda an interesting candidate species for the study of the genetic underpinnings of phenotypic trait evolution during range expansions. Here, we contribute to the investigation of the genetic underpinning phenotypic trait evolution during range expansion, by generating the first brain de-novo transcriptome of H. sarda. We focused on the brain transcriptome as behavioural variation at personality traits has been identified as a key component of the dispersal syndromes, substantial personality traits variation has been observed within H. sarda populations, and brain gene expression patterns have been linked to a vast number of behavioural responses to environmental stimuli.

evolutionary biology↗

bioRxiv2020

Paso doble: A two-step Late Pleistocene range expansion in the Tyrrhenian tree frog Hyla sarda

The Tyrrhenian tree frog, Hyla sarda, is an amphibian endemic to the Tyrrhenian islands (Western Mediterranean). Previous investigations of its Pleistocene evolutionary history suggested that it colonised the northern portion of its current range, through a spatial diffusion process from the Sardinia island, during the last glaciation. However, southern and northern portions of the species range experienced markedly different climatic conditions during the Late Pleistocene, suggesting the possibility of an unusual two-step process of demographic expansion. Here, we use Bayesian phylogeographic approaches to locate the ancestral area in Sardinia and to characterise better the demographic component of this expansion event. These analyses located the ancestral area for H. sarda populations along the central-eastern coast of the Sardinia island, within an area previously shown to host suitable bioclimatic conditions for H. sarda populations throughout the Late Pleistocene. Historical demographic reconstructions clearly showed that a two-step process of demographic growth fits well the data, with northern populations expanding later than Sardinia populations. The harsher climatic conditions occurred in northern islands during the glacial epoch, as compared to Sardinia, likely delayed tree frog colonisation of northern territories, and the associated demographic growth.

evolutionary biology↗