Parallel Sympatric Divergence Driven by Disruptive Selection Acting on a Magic Temporal Isolation Trait in a Wild...

Area of Science:

• Evolutionary Biology
• Genetics
• Speciation Research

Background:

• Sympatric speciation, where new species arise without geographic isolation, is a key evolutionary question.
• Understanding the genetic basis of ecological divergence in sympatry is crucial.
• Reproductive timing is a critical 'magic trait' influencing assortative mating and ecological adaptation.

Purpose of the Study:

• Investigate the genetic architecture of adaptive divergence in reproductive season for Neosalanx brevirostris.
• Identify evolutionary forces driving sympatric speciation in this species.
• Examine the role of standing genetic variation in rapid ecological divergence.

Main Methods:

• Population genomic approaches were used to compare ecotypes and ancestral populations.
• Analysis of genome-wide single nucleotide polymorphisms (SNPs) to detect adaptive divergence.
• Comparison of genetic structure and allele frequency changes across lakes.

Main Results:

• Sympatric ecological divergence in reproductive season evolved independently in two lakes.
• A set of adaptive SNPs, present as standing variation in the ancestral population, was identified.
• Disruptive natural selection, driven by resource competition, was implicated in reproductive timing divergence.

Conclusions:

• Neosalanx brevirostris provides a model for studying repeated, independent sympatric speciation.
• Complex genetic architectures involving photosensory, circadian, and hormonal pathways underlie reproductive seasonality.
• Findings offer insights into early-stage sympatric ecological divergence and speciation mechanisms.