We get by with a little help from our friends: shared adaptive variation provides a bridge to novel ecological specialists during adaptive radiation
Year: 2022
Type: article
Abstract: Adaptive radiations involve astounding bursts of phenotypic, ecological and species diversity. However, the microevolutionary processes that underlie the origins of these bursts are still poorly understood. We report the discovery of an intermediate C. sp. ‘wide-mouth’ scale-eating ecomorph in a sympatric radiation of Cyprinodon pupfishes, illuminating the transition from a widespread algae-eating generalist to a novel microendemic scale-eating specialist. We first show that this ecomorph occurs in sympatry with generalist C. variegatus and scale-eating specialist C. desquamator on San Salvador Island, Bahamas, but is genetically differentiated, morphologically distinct and often consumes scales. We then compared the timing of selective sweeps on shared and unique adaptive variants in trophic specialists to characterize their adaptive walk. Shared adaptive regions swept first in both the specialist desquamator and the intermediate ‘wide-mouth’ ecomorph, followed by unique sweeps of introgressed variation in ‘wide-mouth’ and de novo variation in desquamator . The two scale-eating populations additionally shared 9% of their hard selective sweeps with the molluscivore C. brontotheroides , despite no single common ancestor among specialists. Our work provides a new microevolutionary framework for investigating how major ecological transitions occur and illustrates how both shared and unique genetic variation can provide a bridge for multiple species to access novel ecological niches.
Authors: Emilie J. Richards, Christopher H. Martin
Language: English
Subfield: Genetics
Domain: Life Sciences
Open Access status: hybrid
Awards: QLCI-CI: NSF Quantum Leap Challenge Institute for Hybrid Quantum Architectures and Networks, G641215329, G6671297155, CAREER: Cryptic origins of evolutionary novelty in Caribbean pupfishes: genomic, functional, and ecological conditions for crossing fitness valleys and colonizing adaptive peaks, Discovery and functional analysis of novel candidate genes and variants underlying craniofacial diversification in Cyprinodon pupfishes
OpenAlex ID: W4281482489