Estimating gametic introgression rates in a risk assessment context: a case study with Scots pine relicts

Area of Science:

• Evolutionary biology
• Conservation genetics
• Population genetics

Background:

• Accurate estimation of recent gene immigration is vital for evolutionary and conservation studies.
• Existing genetic methods for recent migration rate estimation are often scarce and lack thorough evaluation.
• Gene flow estimation requires methods that are accurate and allow for statistical uncertainty assessment.

Purpose of the Study:

• To develop and evaluate a novel maximum-likelihood method for estimating recent uniparental gametic immigration.
• To assess pollen introgression rates into an endangered population of Pinus sylvestris var. nevadensis.
• To provide a tool for risk assessment in gene flow studies.

Main Methods:

• Development of a straightforward maximum-likelihood method to estimate recent uniparental gametic immigration.
• Application of the method to an endangered population of Pinus sylvestris var. nevadensis.
• Numerical simulations to evaluate the method's accuracy, bias, and confidence interval estimation.

Main Results:

• High pollen introgression (approx. 40%) was detected at the seed-crop level in the relict pine population.
• Substantial male gametic introgression (10-15%) was observed in naturally regenerated recruits.
• The profile-likelihood method demonstrated superior performance for confidence interval estimation compared to bootstrapping.

Conclusions:

• The developed maximum-likelihood method provides accurate and virtually unbiased estimates of uniparental gametic immigration.
• The method facilitates decision-making in gene flow risk assessment contexts.
• Reliable confidence limits for immigration estimates are achievable using the profile-likelihood approach.