Genome size versus geographic range size in birds

Abstract

Why do some species occur in small, restricted areas, while others are distributed globally? Environmental heterogeneity increases with area and so does the number of species. Hence, diverse biotic and abiotic conditions across large ranges may lead to specific adaptations that are often linked to a species’ genome size and chromosome number. Therefore, a positive association between genome size and geographic range is anticipated. Moreover, high cognitive ability in organisms would be favored by natural selection to cope with the dynamic conditions within large geographic ranges. Here, we tested these hypotheses in birds—the most mobile terrestrial vertebrates—and accounted for the effects of various confounding variables, such as body mass, relative brain mass, and geographic latitude. Using phylogenetic generalized least squares and phylogenetic confirmatory path analysis, we demonstrated that range size is positively associated with bird genome size but probably not with chromosome number. Moreover, relative brain mass had no effect on range size, whereas body mass had a possible weak and negative effect, and range size was larger at higher geographic latitudes. However, our models did not fully explain the overall variation in range size. Hence, natural selection may impose larger genomes in birds with larger geographic ranges, although there may be additional explanations for this phenomenon.

A Bird’s-Eye View of Endangered Species Conservation: Avian Genomics and Stem Cell Approaches for Green Peafowl (Pavo muticus)

“…The genome of birds is generally small, staying in the range from 0.91 Gb (blackchinned hummingbird, Archilochus alexandri) to 1.3 Gb (common ostrich, Struthio camelus) [52]. In addition to a generally smaller size, the bird genome is characterized by a lower number of repetitive elements [53,54], a low proportion of non-coding regions in general, and intensive evidence of gene loss [54].…”

Larger genomes show improved buffering of adult fitness against environmental stress in seed beetles

“…[ 8 ] found that GS was indeed related to phenotypic plasticity in thermal sensitivity in several life-history traits across distinct Drosophila melanogaster genotypes. Second, in comparative studies, species with larger genomes have been found to have larger environmental and geographical distributions in bacteria [ 17 ], birds [ 18 ] and caddisflies [ 19 ], consistent with larger genomes being better able to produce viable phenotypes under a wider range of environments.…”