Testicular biometry and hierarchy of dominance of the white-lipped peccary (Mammalia, Tayassuidae)

Abstract The objective of this study was to obtain data on the testicular biometry of the white-lipped peccary (Tayassu pecari) and to verify if there is a correlation between the individual’s biometric data with their dominance rank. Data were collected from 16 adult males, aged between two and seven years, who made up the same group. By the agonistic interactions analyses we calculated the linearity indexes (h') of the dominance hierarchy and dominance rank. At the end of the behavioral observations, males were captured to collect biometric data from the testis. White-lipped peccaries showed testicles located in a perineal position, inclined cranio-ventrally with oval shape, flattened laterally and with tenso-elastic consistency (2.54±0.07). There was variance in the means (± standard deviation) of testis length (5.88±1.05cm), width (4.24 ± 0.98cm), height (4.44±0.86cm), and total scrotal width (8.78±17.05). The linear dominance hierarchy described the social structure of the males of this group (h'>0.9), with probability of linearity in the hierarchy greater than chance (P = 0.02). There was a correlation between dominance rank with the body mass, length and volume of the testicles. As in general the dimensions of the testicles are directly correlated with sperm production and also testosterone, this characteristic favors the reproductive performance of dominant white-lips males. Therefore, the characteristics of testicular biometry of white-lips should be considered for the selection of individuals more likely to reproduce in captivity favoring the conservation of this vulnerable species. Resumo O objetivo neste estudo foi obter dados sobre a biometria testicular do queixada (Tayassu pecari) e verificar se há correlação entre os dados biométricos do indivíduo com seu posto de dominância. Os dados foram coletados de 16 queixadas adultos, com idades entre dois e sete anos, que compunham o mesmo grupo. Por meio de análises das interações agonísticas foram calculados os índices de linearidade (h') da hierarquia de dominância e determinado o rank dos indivíduos. Ao final das observações comportamentais, os machos foram capturados para coleta de dados biométricos do testículo. Os queixadas apresentaram testículos localizados em posição perineal, inclinados cranioventralmente com formato oval, achatados láterolateralmente e com consistência tensoelástica (2,54±0,07). Houve variação nas médias (± desvio padrão) do comprimento testicular (5,88±1,05cm), largura