Data from: Assortative mating in animals

Assortative mating occurs when there is a correlation (positive or
negative) between male and female phenotypes or genotypes across mated
pairs. To determine the typical strength and direction of assortative
mating in animals, we carried out a meta-analysis of published measures of
assortative mating for a variety of phenotypic and genotypic traits in a
diverse set of animal taxa. We focused on the strength of assortment
within populations, excluding reproductively isolated populations and
species. We collected 1,116 published correlations between mated pairs
from 254 species (360 unique species-trait combinations) in five phyla.
The mean correlation between mates was 0.28, showing an overall tendency
toward positive assortative mating within populations. Although 19% of the
correlations were negative, simulations suggest that these could represent
type I error and that negative assortative mating may be rare. We also
find significant differences in the strength of assortment among major
taxonomic groups and among trait categories. We discuss various possible
reasons for the evolution of assortative mating and its implications for
speciation.