Intercontinental genomic parallelism in multiple three-spined stickleback adaptive radiations

Area of Science:

• Evolutionary biology
• Genomics
• Ecology

Background:

• Parallelism, the evolution of similar traits in similar conditions, offers insights into adaptation by natural selection.
• Previous studies often used predefined environments, potentially overestimating parallelism.
• Understanding genomic parallelism requires analyzing continuous environmental and phenotypic variation.

Purpose of the Study:

• To estimate genomic parallelism across intercontinental freshwater adaptive radiations of three-spined stickleback (Gasterosteus aculeatus).
• To associate genome-wide allele frequencies with continuous environmental and phenotypic variation.
• To determine predictors of genomic parallelism at a large geographic scale.

Main Methods:

• Large-scale biological sampling and phenotyping of 1,380 three-spined sticklebacks from 73 freshwater and 4 marine populations.
• Restriction site associated DNA sequencing (RAD-Seq) to generate genome-wide allele frequency data.
• Statistical association of allele frequencies with continuous environmental and phenotypic data.

Main Results:

• Quantitative variation in phenotypes and environments can predict genomic parallelism.
• Genomic parallelism in early adaptive radiations is based on standing genetic variation.
• Environmental similarity is a stronger predictor of genome-wide parallelism than phenotypic similarity.

Conclusions:

• Environmental and phenotypic factors significantly predict genomic divergence patterns.
• Continuous variation analysis provides a clearer understanding of genomic parallelism than dichotomous approaches.
• This study highlights the predictive power of environmental factors in shaping parallel evolution.