Genomic Patterns of Parallel Divergence Across Demographically Heterogeneous Stickleback Populations in Eastern...

Area of Science:

• Evolutionary genetics
• Population genomics
• Speciation research

Background:

• Threespine stickleback (Gasterosteus aculeatus) is a crucial model organism for evolutionary genetics.
• Most genomic studies focus on North American west coast and European populations.
• Limited genomic data exists for Atlantic Canadian stickleback populations.

Purpose of the Study:

• To investigate genomic differentiation between marine and freshwater stickleback in Atlantic Canada.
• To understand the demographic contexts and genetic basis of adaptation to freshwater environments.
• To identify specific genes and pathways involved in freshwater adaptation.

Main Methods:

• Restriction site-associated DNA sequencing (RAD-seq) of pooled samples.
• Analysis of genomic differentiation patterns across marine and freshwater populations.
• Gene ontology analysis to identify enriched functions in candidate regions.

Main Results:

• Significant heterogeneity in marine-freshwater genomic differentiation was observed.
• Some populations showed strong divergence (isolation and drift), others gene flow and admixture.
• Genomic regions near dopamine receptor genes (Drd4a, Drd2l) were repeatedly differentiated.
• Candidate regions were enriched for nervous system development and dopamine receptor activity functions.

Conclusions:

• Freshwater adaptation in Atlantic Canadian stickleback occurs under diverse demographic scenarios.
• Repeatedly differentiated genomic regions suggest a role for neurological and behavioral adaptations.
• Dopamine receptor pathways may be key targets in adaptation to freshwater environments.