Effect of the Seed Bank on Evolutionary Rescue in Small Populations: Univariate and Multivariate Demogenetic Dynamics

Area of Science:

• Ecology and Evolutionary Biology
• Population Genetics
• Conservation Biology

Background:

• Seed banks play an uncertain role in evolutionary rescue under global change.
• They buffer populations from random events but can harbor maladapted genes and slow generational turnover.

Purpose of the Study:

• To predict the effect of seed banks on the persistence of annual plant populations facing directional environmental change.
• To investigate how seed banks influence evolutionary adaptation and genetic dynamics under global change scenarios.

Main Methods:

• Developed analytical and individual-based models to simulate demogenetic dynamics.
• Analyzed univariate and multivariate trait optima changes under abrupt and sustained directional shifts.
• Incorporated factors like optimum fluctuation magnitude, change type, selection strength, and vital rates.

Main Results:

• Seed banks generally increase adaptation lag but enhance population persistence (200-250 years) by absorbing demographic losses.
• Seed banks had minimal impact on genetic skew, though this may depend on the fitness component under selection.
• Multivariate models showed seed banks can reshape the genetic (G) matrix, reducing mutational correlation impacts and potentially accelerating adaptation.

Conclusions:

• Seed banks can be crucial for long-term population persistence under environmental change, despite initial adaptation delays.
• The genetic architecture modification by seed banks can facilitate adaptation, especially under antagonistic pleiotropy.
• Environmental fluctuation magnitude is key; large fluctuations can make past gene pools adaptive stepping stones.