What Is The Most Recent Estimate Of The Effective Population Size Of The Ancestral Population Of Modern Dogs (Canis Lupus Familiaris) During The Initial Stages Of Domestication, And How Does This Estimate Inform Our Understanding Of The Selective Pressures That Drove The Fixation Of The AMY2B Gene Duplication, Which Is Associated With Starch Digestion And Is Thought To Be A Key Adaptation For Dog Domestication?

The effective population size (Ne) of the ancestral population of modern dogs during the early stages of domestication is estimated to be approximately 13,000. This moderately sized population allowed for strong selective pressures to act efficiently, facilitating the fixation of advantageous alleles. One such adaptation is the AMY2B gene duplication, which enhances starch digestion—a crucial trait as dogs adapted to a diet rich in human-related starches.

In a population of Ne = 13,000, the selective advantage provided by the AMY2B duplication would be significant enough to drive its spread and fixation. This process was likely accelerated by the relatively small population size, which made genetic drift less influential compared to larger populations. The strong selection pressure for starch digestion, coupled with the population's structure, enabled this duplication to become a key adaptation in dog domestication, highlighting the interplay between population genetics and dietary adaptation.