[Dogs, wolves and genes].

Area of Science:

• Genetics
• Evolutionary Biology
• Canid Genomics

Background:

• A significant genetic polymorphism linked to dog size is identified in the Insulin-like Growth Factor 1 (IGF1) gene region.
• This polymorphism involves a single base change in a nearby long non-coding RNA (lncRNA).

Discussion:

• The "small" (C) allele of this single nucleotide polymorphism (SNP) is prevalent in small modern dog breeds and other canids like foxes and jackals.
• Conversely, the "large" (T) allele is dominant in wolves and large dog breeds.
• The "small" allele, present at low frequencies in ancient wolves, represents the ancestral canid allele, recently selected during the development of small dog breeds through artificial selection.

Key Insights:

• The IGF1 gene region harbors a critical genetic determinant of canine size variation.
• A specific SNP in a neighboring lncRNA acts as a major regulator of size, with distinct alleles associated with small and large body types.
• The ancestral "small" allele has been recently and strongly selected in domestic dogs, driving the evolution of small breeds.

Outlook:

• Further research into the functional mechanisms of the lncRNA and its interaction with IGF1 could reveal novel insights into growth regulation.
• Understanding the evolutionary trajectory of this polymorphism provides a model for studying recent selection events in domestic animals.
• Comparative genomic studies across a wider range of canid species may illuminate the precise timing and selective pressures involved in the domestication and diversification of dog size.