From micro- to macroevolution through quantitative genetic variation: positive evidence from field crickets.

Area of Science:

• Evolutionary biology
• Quantitative genetics
• Ecology and evolutionary biology

Background:

• The additive genetic variance-covariance matrix (G) represents genetic constraints on evolution.
• Understanding the evolutionary rate and pattern of G is crucial for linking microevolution to macroevolution.
• The long-term constraining effect of G on evolutionary trajectories remains uncertain.

Purpose of the Study:

• To investigate the evolutionary rate and pattern of the G matrix in field crickets.
• To test the hypothesis that G constrains species divergence.
• To determine if macroevolutionary patterns can be predicted from quantitative genetic theory.

Main Methods:

• Estimated quantitative genetic parameters for morphological traits in seven species of field crickets (Gryllus and Teleogryllus).
• Utilized a nested full-sibling family design for parameter estimation.
• Employed statistical approaches (T method, Flury hierarchy, Mantel test) to compare G matrices phylogenetically.

Main Results:

• G matrices were generally similar across species, indicating a low rate of G evolution.
• Observed variation in G matrices was partly explained by genotype-by-environment interaction.
• Species divergence patterns (trait values) were predictable from the ancestral G matrix, supporting the constraint hypothesis.

Conclusions:

• The G matrix evolves slowly and influences species divergence.
• Macroevolutionary patterns can be qualitatively predicted from quantitative genetic theory.
• The study provides evidence for the role of genetic constraints in shaping evolutionary trajectories.