Tension versus ecological zones in a two-locus system

Area of Science:

• Population Genetics
• Evolutionary Biology
• Quantitative Genetics

Background:

• Previous theories suggest tension and ecological zones are indistinguishable based on gene frequency clines.
• Distinguishing between these zones is crucial for understanding evolutionary processes and speciation.

Purpose of the Study:

• To analytically demonstrate that genetic statistics other than gene frequency can differentiate between tension and ecological zones.
• To identify specific genetic statistics that exhibit distinct spatial distributions in each zone type.

Main Methods:

• Utilized a two-locus cline model with assumptions of random mating, weak selection, no drift, no mutation, and multiplicative viabilities.
• Examined deviations of genotypic frequencies from Hardy-Weinberg equilibrium (HWE) and random association of gametes (RAG).
• Analyzed deviations of additive and dominance variances from HWE values.

Main Results:

• Deviations from HWE and RAG, as well as variances, show discontinuous spatial distributions in ecological zones with sharp boundaries.
• These deviations exhibit continuous spatial distributions within tension zones.
• Linkage disequilibrium amplifies the differences between deviations from HWE and RAG for two-locus genotypic frequencies.

Conclusions:

• Genetic statistics beyond simple gene frequency clines provide a robust method for distinguishing tension and ecological zones.
• The spatial patterns of deviations in genotypic frequencies and variances offer a novel approach to zone identification in evolutionary studies.
• This research contributes to a refined understanding of how genetic variation is structured across hybrid zones.