Coevolutionary Interactions between Sexual and Habitat Isolation during Reinforcement

Area of Science:

• Evolutionary biology
• Population genetics

Background:

• Speciation often involves multiple genetic barriers to gene flow, known as "speciation coupling."
• The evolutionary interactions between these barriers, particularly during reinforcement, are crucial for understanding speciation.
• Prezygotic isolation barriers, such as sexual and habitat isolation, can evolve in concert or independently.

Purpose of the Study:

• To investigate the interaction between the evolution of sexual and habitat isolation during speciation.
• To review empirical literature on the coevolution of sexual and habitat isolation.
• To develop a population genetic model to explore these interactions under reinforcement.

Main Methods:

• Literature review of studies examining both sexual and habitat isolation.
• Development of a two-allele population genetic model for reinforcement.
• Analysis of asymmetrical migration rates to assess their impact on barrier evolution.

Main Results:

• Empirical literature, primarily from phytophagous insects, shows coevolution of sexual and habitat isolation in 76% of cases.
• The population genetic model indicates that habitat isolation is often more effective during reinforcement.
• Interactions between barriers depend on hybrid fitness and migration rates, leading to variable evolutionary dynamics.
• Asymmetrical migration rates differentially influence the evolution of sexual and habitat isolation.

Conclusions:

• The coevolution of sexual and habitat isolation is common but not universal, with interactions significantly influenced by ecological and genetic factors.
• Habitat isolation may play a more prominent role in reinforcement compared to sexual isolation under certain conditions.
• Understanding the interplay of different barriers is key to predicting speciation outcomes, highlighting the variability in speciation coupling.