title: Correlated evolution of male and female reproductive traits drive a cascading effect of reinforcement in Drosophila yakuba.
abstract: Selection against maladaptive hybridization can drive the evolution of reproductive isolation in a process called reinforcement. While the importance of reinforcement in evolution has been historically debated, many examples now exist. Despite these examples, we typically lack a detailed understanding of the mechanisms limiting the spread of reinforced phenotypes throughout a species' range. Here we address this issue in the fruit fly Drosophila yakuba, a species that hybridizes with its sister species D. santomea and is undergoing reinforcement in a well-defined hybrid zone on the island of São Tomé. Within this region, female D. yakuba show increased postmating-prezygotic (gametic) isolation towards D. santomea when compared with females from allopatric populations. We use a combination of natural collections, fertility assays, and experimental evolution to understand why reinforced gametic isolation in D. yakuba is confined to this hybrid zone. We show that, among other traits, D. yakuba males from sympatric populations sire fewer progeny than allopatric males when mated to allopatric D. yakuba females. Our results provide a novel example of reinforcement acting on a postmating-prezygotic trait in males, resulting in a cascade of reproductive isolation among conspecific populations.
authors.affiliation: Biology Department, University of North Carolina, 250 Bell Tower Drive, Chapel Hill, NC 27599, USA aacomeault@gmail.com.
authors.forename: Aaron A
authors.initials: AA
authors.lastname: Comeault
authors.affiliation: Department of Human Genetics, The University of Chicago, 920 East 58th Street, Chicago, IL 60637, USA.
authors.forename: Aarti
authors.initials: A
authors.lastname: Venkat
authors.affiliation: Biology Department, University of North Carolina, 250 Bell Tower Drive, Chapel Hill, NC 27599, USA dmatute@email.unc.edu.
authors.forename: Daniel R
authors.initials: DR
authors.lastname: Matute
mesh_terms: D000818:Animals; D004330:Drosophila / Q000235:genetics* / Q000502:physiology; D005260:Female; D006824:Hybridization, Genetic; D008297:Male; D012098:Reproduction; D060047:Reproductive Isolation; D012726:Sexual Behavior, Animal; D061350:Sympatry
keywords: coevolution; cryptic sexual choice; experimental evolution; reinforcement