Geographical distribution of sheep breeds in Brazil and their relationship with climatic and environmental factors as risk classification for conservation

Abstract

Background: The aim of this study was to evaluate the distribution of sheep breeds in Brazil, correlate their occurrence with environmental factors and determine their risk for extinction. Methods: The localization of all flocks of purebred sheep (commerical and naturalised, hair and wool) in Brazil was spatialized in ARCGIS along with climatic (Thermal Humidity Index, precipitation, solar radiation, relative humidity) and physical environmental controls (altitude, pasture type). Data were analysed using analysis of variance, logisitic regression and cluster analyses. Distance matrices were constructed using longitude/latitude and those from environmental controls and these were correlated using Mantel test. Results: Santa Ines and Dorper were the most popular breeds with a countrywide distribution. Over 80% of most breeds occurred within 500 km of their midpoint which has implications for their conservation and vulnerability as those breeds with few flocks and restricted geographical distribution are at higher risk. This was especially evident for the naturalised breeds. Spatial distribution of breeds was highly correlated with environmental controls and two distinct clusters were found. Spatial distribution of breeds was highly correlated with environmental controls. Naturalised sheep breeds in Brazil tend to be more localized than commercial breeds which may mean they are at greater risk. Hair and wool sheep tend to occur in specific environments. Conclusions: Flocks in the center west and northeast tend to further away from the midpoint for the breed, making germplasm exchange, and therefore avoidance of inbreeding and their conservation, more difficult.