Quantitative genetic variance in experimental fly populations evolving with or without environmental heterogeneity

Area of Science:

• Evolutionary Biology
• Quantitative Genetics
• Population Genetics

Background:

• Heterogeneous environments are theorized to maintain greater genetic variation in fitness than homogeneous environments.
• The relationship between environmental heterogeneity and genetic variation is complex, influenced by the type of heterogeneity, genetic architecture of traits, and environmental history.

Purpose of the Study:

• To measure quantitative genetic (QG) variance for fitness-related traits in Drosophila melanogaster populations.
• To compare QG variance under constant (salt, cadmium) and heterogeneous (temporal, spatial) selective regimes.

Main Methods:

• Experimental evolution of replicated Drosophila melanogaster populations under four distinct selective regimes.
• Measurement of quantitative genetic variance for three fitness-related traits.
• Comparison of genetic variation patterns across different environmental conditions.

Main Results:

• Spatial heterogeneity led to higher genetic variation compared to temporal heterogeneity and constant environments.
• Salt-enriched environments showed higher genetic variation than cadmium-enriched environments, contrary to expectations.
• Quantitative genetic patterns aligned with genome-wide sequence diversity for some traits (selected SNPs) but not others (neutral SNPs).

Conclusions:

• Spatial environmental variation is a significant driver of increased genetic variation within populations.
• The specific nature of environmental challenges (e.g., salt vs. cadmium) can influence the maintenance of genetic variation.
• The link between quantitative genetic variance and genome-wide diversity depends on the specific traits and selective pressures.