Will sympatric speciation fail due to stochastic competitive exclusion?

Area of Science:

• Evolutionary biology
• Ecological dynamics
• Population genetics

Background:

• Sympatric speciation, the evolution of new species from a single ancestral species while inhabiting the same geographic region, necessitates the coexistence of diverging populations.
• Initial stages of divergence, particularly with small mutational steps, often involve minimal niche differentiation, leading to resource overlap and potential competitive exclusion.

Purpose of the Study:

• To investigate the ecological factors influencing sympatric speciation in fluctuating environments.
• To model the population dynamics of a diverging asexual population under environmental variability and assess the role of trait space correlation.

Main Methods:

• Theoretical modeling of population dynamics.
• Analysis of asexual population divergence in stochastic environments.
• Examination of the relationship between environmental fluctuation correlation and speciation success.

Main Results:

• Rapidly declining correlation between species' responses to environmental fluctuations, coupled with high environmental variability, can impede or prevent full speciation.
• Stochastic extinctions are more likely when environmental correlation decays faster than interspecific competition, particularly with strong demographic stochasticity or lack of niche separation.
• Speciation driven solely by sexual selection may be susceptible to these extinction dynamics.

Conclusions:

• Short-term ecological dynamics, specifically population fluctuations and competition, are intricately linked to long-term evolutionary outcomes in sympatric speciation.
• Environmental variability and the rate of niche differentiation are critical factors determining the feasibility of sympatric speciation.
• The study highlights the importance of ecological interactions in shaping macroevolutionary patterns.