TY - JOUR T1 - Darwin’s finches - an adaptive radiation constructed from ancestral genetic modules JF - bioRxiv DO - 10.1101/2021.09.17.460815 SP - 2021.09.17.460815 AU - Carl-Johan Rubin AU - Erik D. Enbody AU - Mariya P. Dobreva AU - Arhat Abzhanov AU - Brian W. Davis AU - Sangeet Lamichhaney AU - Mats Pettersson AU - C. Grace Sprehn AU - Carlos A. Valle AU - Karla Vasco AU - Ola Wallerman AU - B. Rosemary Grant AU - Peter R. Grant AU - Leif Andersson Y1 - 2021/01/01 UR - http://biorxiv.org/content/early/2021/09/18/2021.09.17.460815.abstract N2 - Recent adaptive radiations are models for investigating mechanisms contributing to the evolution of biodiversity. An unresolved question is the relative importance of new mutations, ancestral variants, and introgressive hybridization for phenotypic evolution and speciation. Here we address this issue using Darwin’s finches, which vary in size from an 8g warbler finch with a pointed beak to a 40g large ground finch with a massive blunt beak. We present a highly contiguous genome assembly for one of the species and investigate the genomic architecture underlying phenotypic diversity in the entire radiation. Admixture mapping for beak and body size in the small, medium and large ground finches revealed 28 loci showing strong genetic differentiation. These loci represent ancestral haplotype blocks with origins as old as the Darwin’s finch phylogeny (1-2 million years). Genes expressed in the developing beak are overrepresented in these genomic regions. Frequencies of allelic variants at the 28 loci covary with phenotypic similarities in body and beak size across the Darwin’s finch phylogeny. These ancestral haplotypes constitute genetic modules for selection, and act as key determinants of the exceptional phenotypic diversity of Darwin’s finches. Such ancestral haplotype blocks can be critical for how species adapt to environmental variability and change.Competing Interest StatementThe authors have declared no competing interest. ER -