Biology subjects

Peter Andolfatto

Publications and source records attributed to Peter Andolfatto.

3 recordsLinked to original sources

bioRxiv2016

Phylogenetic incongruence and the origins of cardenolide-resistant forms of Na+,K+-ATPase in North American Danaus butterflies

Rapid species radiations can obscure phylogenetic relationships between even distantly related species and lead to incorrect evolutionary inferences. For this reason, we examined evolutionary relationships among the three North American milkweed butterflies, Danaus plexippus, D. gilippus and D. eresimus using >400 orthologous gene sequences assembled from transcriptome data. Contrary to previous phylogenetic assessments, our results indicate that D. plexippus and D. eresimus are the sister taxa among these species. This result explains many previously noted phylogenetic incongruences such as an amino acid substitution in the sodium-potassium pump (Na+,K+-ATPase) of D. eresimus and D. plexippus, which increases resistance to the toxins found in these butterflies host plants. In accordance with a rapid radiation of Danaus butterflies, we also find evidence that both incomplete lineage sorting and post-speciation genetic exchange have contributed significantly to the evolutionary histories of these species. Furthermore, our findings suggest that D. plexippus is highly derived both morphologically and behaviorally.

Evolutionary Biology↗

bioRxiv2015

Genetics of intra-species variation in avoidance behavior induced by a thermal stimulus in C. elegans

Individuals within a species vary in their responses to a wide range of stimuli, partly as a result of differences in their genetic makeup. Relatively little is known about the genetic and neuronal mechanisms contributing to diversity of behavior in natural populations. By studying animal-to-animal variation in innate avoidance behavior to thermal stimuli in the nematode Caenorhabditis elegans, we uncovered genetic principles of how different components of a behavioral response can be altered in nature to generate behavioral diversity. Using a thermal pulse assay, we uncovered heritable variation in responses to a transient temperature increase. Quantitative trait locus mapping revealed that separate components of this response were controlled by distinct genomic loci. The loci we identified contributed to variation in components of thermal pulse avoidance behavior in an additive fashion. Our results show that the escape behavior induced by thermal stimuli is composed of simpler behavioral components that are influenced by at least six distinct genetic loci. The loci that decouple components of the escape behavior reveal a genetic system that allows independent modification of behavioral parameters. Our work sets the foundation for future studies of evolution of innate behaviors at the molecular and neuronal level.

Genetics↗

bioRxiv2014

Reproductive isolation of hybrid populations driven by genetic incompatibilities

Despite its role in homogenizing populations, hybridization has also been proposed as a means to generate new species. The conceptual basis for this idea is that hybridization can result in novel phenotypes through recombination between the parental genomes, allowing a hybrid population to occupy ecological niches unavailable to parental species. A key feature of these models is that these novel phenotypes ecologically isolate hybrid populations from parental populations, precipitating speciation. Here we present an alternative model of the evolution of reproductive isolation in hybrid populations that occurs as a simple consequence of selection against incompatibilities. Unlike previous models, our model does not require small population sizes, the availability of new niches for hybrids or ecological or sexual selection on hybrid traits. We show that reproductive isolation between hybrids and parents evolves frequently and rapidly under this model, even in the presence of substantial ongoing migration with parental species and strong selection against hybrids. Our model predicts that multiple distinct hybrid species can emerge from replicate hybrid populations formed from the same parental species, potentially generating patterns of species diversity and relatedness that resemble an adaptive radiation.

Evolutionary Biology↗