Digest: Multivariate genetic variation constrains adaptation to environmental changes during range expansion.

Area of Science:

• Evolutionary biology
• Population genetics
• Ecology

Background:

• Understanding how populations diverge and adapt across landscapes is crucial for predicting species' responses to environmental change.
• Selection and standing genetic variation are key factors influencing evolutionary trajectories and population divergence.

Purpose of the Study:

• To investigate the relationship between selection gradients, genetic covariance (G-matrix), and population divergence in the ivy-leaved morning glory (Ipomoea hederacea).
• To assess potential genetic constraints on population divergence and range expansion at the species' range edge.

Main Methods:

• Field-based estimation of selection gradients on plant traits.
• Comparison of selection gradients with the G-matrix and measures of population divergence.
• Analysis of four North American populations of Ipomoea hederacea.

Main Results:

• Population divergence and genetic covariances were largely unaligned with the estimated selection gradient at the species' range edge.
• This misalignment suggests potential limitations in the evolutionary response of populations at range edges.

Conclusions:

• Limited evolvability or multivariate genetic variation may restrict species' range expansion.
• Genetic constraints play a significant role in population divergence and local adaptation, particularly under changing climate conditions.