Change in Recessive Lethal Alleles Frequency in Inbred Populations

TL;DR

This paper develops an analytical model for the change in recessive lethal allele frequencies in inbred populations, showing how different inbreeding practices influence allele loss and population health over generations.

Contribution

It introduces a new analytical formula for RRLA frequency in infinite populations and examines the effects of various inbreeding types in finite populations.

Findings

Severe inbreeding accelerates RRLA loss.

Populations practicing 30% half-sib marriages lose over 95% of RRLA in 100 generations.

Small inbred populations can recover and reduce RRLA with sufficient resources.

Abstract

In a population practicing consanguineous marriage, rare recessive lethal alleles (RRLA) have higher chances of affecting phenotypes. As inbreeding causes more homozygosity and subsequently more deaths, the loss of individuals with RRLA decreases the frequency of these alleles. Although this phenomenon is well studied in general, here some hitherto unstudied cases are presented. An analytical formula for the RRLA frequency is presented for infinite monoecious population practicing several different types of inbreeding. In finite diecious populations, it is found that more severe inbreeding leads to quicker RRLA losses, making the upcoming generations healthier. A population of size 10,000 practicing 30% half-sib marriages loses more than 95% of its RRLA in 100 generations; a population practicing 30% cousin marriages loses about 75% of its RRLA. Our findings also suggest that given enough resources to grow, a small inbred population will be able to rebound while losing the RRLA.