The ascent of cat breeds: genetic evaluations of breeds and worldwide random-bred populations

Abstract

The diaspora of the modern cat was traced with microsatellite markers from the presumed site of domestication to distant regions of the world. Genetic data were derived from over 1100 individuals, representing 17 random-bred populations from five continents and 22 breeds. The Mediterranean was reconfirmed to be the probable site of domestication. Genetic diversity has remained broad throughout the world, with distinct genetic clustering in the Mediterranean basin, Europe/America, Asia and Africa. However, Asian cats appeared to have separated early and expanded in relative isolation. Most breeds were derived from indigenous cats of their purported regions of origin. However, the Persian and Japanese bobtail were more aligned with European/American than with Mediterranean basin or Asian clusters. Three recently derived breeds were not distinct from their parental breeds of origin. Pure breeding was associated with a loss of genetic diversity; however, this loss did not correlate with breed popularity or age.

Fig. 1. Bayesian analysis of cat breeds and populations

The colors correspond to predicted genetic clusters; Western Europe (red), Mediterranean basin (blue), Asia/Southeast Asia (green), and East Africa (yellow). Each column represents an individual cat. The Y-axis represents the proportion of interactions that an individual is assigned to the given cluster. a, The first three basal separations of random bred cats and wildcats. b, (Top) The first basal separation of all populations (K=2). Asian breeds, the Sokoke, and Asian random bred populations (green) are clearly distinguished from all other cats. (Bottom) Analysis of all populations (K=3). African/Mediterranean/Asian cats (red) separate from Southeast Asian (green) and European (blue) populations. c, Twenty-two cat breeds (K=20). Havana Browns and Siamese, and Persians and Exotics, Burmese and Singapura are not genetically differentiated. Burmese appear to share origins with Siamese and Korat. Korats and Birmans also appear to be strongly related. Persians and Siberians show within breed heterogeneity.

Fig. 2. Neighbor-joining tree of cat breeds and populations

The phylogenetic tree was constructed using Cavalli-Sforza's chord distance. Bootstrap values above 50% are presented on relationship nodes. Asian (green), Western European (red), East African (purple), Mediterranean basin (blue) and wildcat (black) populations form strongly supported monophyletic branches. European and African wildcats are closely related whereas short branches of most all other populations indicate close relationships of these breeds and populations. Random bred populations are indicated in italics, breeds are in standard font.

Fig. 3. Factorial Correspondence Analysis of cat breeds and populations

Squares represent population centers of the following geographic regions: Asian populations (green), Western European (red), Mediterranean basin (blue), East African (purple), and wildcat (black). The affinities of the Sokokes to the Asian populations, the Japanese Bobtails to the Mediterranean and European cats, and the Tunisian cats to the European populations, are apparent and are in agreement with the Structure results. Arabian wildcats (F. s. tristami) associate with East African populations, European (F. s. silvestris) with European populations, and African (F. s. caffra) appear most distinct from all other groups. See Supplementary Figure 1 for alternate views.

Fig. 4. Genetic diversity indices of breeds, random bred populations and wildcats

Light bars represent observed heterozygosity (H_O) and dark bars represent the inbreeding coefficient (F_IS). Populations listed in ascending order of heterozygosity, breeds are on the left, random bred populations in the middle, and wildcat populations to the right. Y-axis represents the proportion of heterozygosity or inbreeding coefficient.