Recent secondary contact, genome-wide admixture, and limited introgression of neo-sex chromosomes between two Pacific island bird species

bioRxiv (Cold Spring Harbor Laboratory), Journal Year: 2023, Volume and Issue: unknown

Published: Sept. 17, 2023

Abstract Secondary contact between closely related taxa represents a “moment of truth” for speciation. Removal geographic barriers allows us to test the strength reproductive isolation that evolved in allopatry and identify genetic, behavioral, and/or ecological separate species sympatry. Sex chromosomes are known rapidly accumulate differences species, an effect may be exacerbated neo-sex because they regions genome have recently become linked sex transitioning from autosomal sex-specific inheritance. Two bird honeyeater family — Myzomela cardinalis tristrami carry come into recent secondary Solomon Islands after being isolated ∼3 my. Hybrids these two been observed sympatry at least 100 years. To determine genetic consequences hybridization, we use population genomic analyses individuals sampled characterize gene flow zone. Using genome-wide estimates diversity, differentiation, divergence, find degree direction introgression varies dramatically across genome. Autosomal is bidirectional, with phenotypic hybrids parentals both showing admixed ancestry. On chromosomes, story different. Introgression Z limited neo-Z sequence shows no evidence introgression, whereas W neo-W strong but highly asymmetric, moving only invasive M. resident . Thus, incomplete, chromosome prevented one (W/neo-W) or (Z/neo-Z) directions. The previously indicates hybridization permit some regions, divergence can maintained by associated evolving sex-linked Author Summary When new colonizes island interacts native provided rare opportunity factors keep distinct interbreeding. Regions evolve influence mate choice especially likely act as flow. red cardinalis, birds family, arrived Makira Islands, joining endemic, all black tristrami. We used isolation, well those other understand history their range overlap on Makira. found ( i.e., chromosomes) were either ability move moved direction, invading This work highlights how certain important defining boundaries generation maintenance biodiversity.

Language: Английский

Falling shoulders ahead: adaptive alien genes are maintained amid vanishing introgression footprint in sea squirts

bioRxiv (Cold Spring Harbor Laboratory), Journal Year: 2023, Volume and Issue: unknown

Published: Sept. 23, 2023

Abstract Human transport of species across oceans disrupts natural dispersal barriers and facilitates hybridisation between previously allopatric species. The recent introduction the North Pacific sea squirt, Ciona robusta , into native range Atlantic C. intestinalis is a good example this outcome. Recent studies have revealed an adaptive introgression, in single chromosomal region, from introduced Here, we monitored introgression over time, examining both frequency alien genes at core hitchhiking footprint shoulders island, by studying thousand spp. individuals collected 22 ports contact zone, 14 which were sampled 20 generations apart. For that purpose, developed KASP multiplex genotyping approach, proved effective identifying native, non-indigenous hybrid detecting introgressed haplotypes. Adaptive detected where they had been found ago, as well some newly ports. region alleles highest locally must be, remains stable space time. In contrast, observed erosion ancestry tracts flanking on edges core, consistent with second phase local sweep purge incompatible alleles. Our study reveals how island fall time after initial sweep.

Language: Английский