title: Inbreeding and Offspring Sex Ratio in the Pygmy Hippopotamus (Cheoropsis liberiensis) Population Kept in Zoological Gardens.
abstract: The aim of this study was to estimate the inbreeding level and its impact on offspring sex ratio in the pygmy hippopotamus population kept in zoological gardens. Records of pygmy hippopotamus born between 1873-2013 were extracted from the international studbook. Totally, 1357 individuals originating from 148 breeding units were included (individuals with unknown sex were omitted). The offspring sex ratio is defined as the number of sons to the total number of progeny of each dam and sire. Spearman's rank correlation was employed to examine the relationships between the inbreeding level and offspring sex ratio. Inbreeding coefficients and individual increase in inbreeding coefficients (included as a linear co-variable) were examined as well as the geographic region and birth period using general linear models. The average inbreeding coefficient was 5.39%. The following sex proportion was observed for the inbred population: 57% and 43% for females and males, respectively. A significant relationship between inbreeding level of parents and their offspring sex ratio were estimated for European zoological gardens, whereas in others geographic regions the dependencies were insignificant.
authors.forename: Magdalena
authors.initials: M
authors.lastname: Graczyk
authors.forename: Piotr
authors.initials: P
authors.lastname: Cwiertnia
authors.forename: Alicja
authors.initials: A
authors.lastname: Borowska
authors.forename: Elżbieta
authors.initials: E
authors.lastname: Barczak
authors.forename: Tomasz
authors.initials: T
authors.lastname: Szwaczkowski
mesh_terms: D000818:Animals; D000836:Animals, Zoo; D001188:Artiodactyla / Q000235:genetics*; D005260:Female; D007178:Inbreeding; D008297:Male; D010375:Pedigree; D012744:Sex Ratio; D013997:Time Factors