Biology subjects

Paris, C. I.

Publications and source records attributed to Paris, C. I..

3 recordsLinked to original sources

bioRxiv2021

Recurring adaptive introgression of a supergene that determines social organization

Introgression has been proposed as an essential source of adaptive genetic variation. However, a key barrier to adaptive introgression is that recombination can break down combinations of alleles that underpin many traits. This barrier might be overcome in supergene regions, where suppressed recombination leads to joint inheritance across many loci. Here, we study the evolution of a large supergene region that determines a major social and ecological trait in Solenopsis fire ants: whether colonies have one queen or multiple queens. Using coalescent-based phylogenies built from the genomes of 365 haploid fire ant males, we show that the supergene variant responsible for multiple-queen colonies evolved in one species and repeatedly spread to other species through introgressive hybridization. This finding highlights how supergene architecture can enable a complex adaptive phenotype to recurrently permeate species boundaries.

evolutionary biology↗

bioRxiv2020

Genomic architecture and evolutionary conflict drive allele-specific expression in the social supergene of the red fire ant

Supergenes are genomic regions of suppressed recombination that underlie complex polymorphisms. Despite the importance of such regions, our empirical understanding of their early evolution is limited. The young "social" supergene of the fire ant Solenopsis invicta provides a powerful system for disentangling the roles of evolutionary conflict and the implications of suppressed recombination. We used population genomics to identify genetic differences between supergene variants and gene expression analyses across different populations, castes and body parts to characterize allelic expression differences for the hundreds of genes in the supergene. We find that the expression of most genes is independent of social form or supergene variant, in line with the young age of this system. Many of the genes with allelic expression differences, however, show a pattern consistent with gene degeneration due to suppressed recombination. In contrast, a small portion of the genes has the signature of evolutionary conflict between social forms.

molecular biology↗

bioRxiv2018

Degenerative expansion of a young supergene

Suppressed recombination ultimately leads to gene loss, as demonstrated by the depauperate Y chromosomes of long-established XY pairs. To understand the shorter term effects, we used high-resolution optical mapping and k-mer distribution analysis on a young non-recombining region of fire ant social chromosomes. Instead of shrinking, the region has increased in length by more than 30%. This demonstrates that degenerative expansion can occur during the early evolution of non-recombining regions.

evolutionary biology↗