Long-term evolution of polygenic traits under frequency-dependent intraspecific competition

Area of Science:

• Evolutionary biology
• Population genetics
• Mathematical biology

Background:

• Quantitative traits are influenced by multiple genes (loci).
• Evolution is shaped by selection (stabilizing and frequency-dependent disruptive) and mutation.
• Intraspecific competition introduces frequency-dependent disruptive selection.

Purpose of the Study:

• To analytically investigate the long-term evolution of quantitative traits under complex selection pressures.
• To determine conditions for the existence and nature of long-term evolutionary equilibria.
• To explore the influence of initial genetic architecture on evolutionary trajectories.

Main Methods:

• Analytical investigation of a multi-locus model for quantitative traits.
• Utilizing existing results on short-term dynamics under linkage equilibrium.
• Numerical examples to illustrate evolutionary outcomes with multiple equilibria.

Main Results:

• Populations consistently reach a long-term equilibrium (LTE) stable against small mutations.
• Multiple, explicitly calculable LTEs can coexist.
• Evolutionary outcomes are contingent on initial genetic makeup and mutation characteristics when multiple LTEs exist.

Conclusions:

• Long-term evolutionary trajectories are not solely predictable from ecological factors.
• A partial order exists among LTEs, with a 'largest' element attainable under specific mutation conditions.
• The interplay between genetics and ecology is crucial for understanding evolutionary endpoints.