Conservation genetics of the endangered Pampas deer (Ozotoceros bezoarticus)

Abstract

The Pampas deer (Ozotoceros bezoarticus L. 1758) is the most endangered neotropical cervid, and in the past occupied a wide range of open habitats including grassland, pampas, savanna, and cerrado (Brazil) from 5 degrees to 41 degrees S. To better understand the effect of habitat fragmentation on gene flow and genetic variation, and to uncover genetic units for conservation, we examined DNA sequences from the mitochondrial control region of 54 individuals from six localities distributed throughout the present geographical range of the Pampas deer. Our results suggest that the control region of the Pampas deer is one of the most polymorphic of any mammal. This remarkably high variability probably reflects large historic population sizes of millions of individuals in contrast to numbers of fewer than 80,000 today. Gene flow between populations is generally close to one migrant per generation and, with the exception of two populations from Argentina, all populations are significantly differentiated. The degree of gene flow was correlated with geographical distance between populations, a result consistent with limited dispersal being the primary determinant of genetic differentiation between populations. The molecular genetic results provide a mandate for habitat restoration and reintroduction of Pampas deer so that levels of genetic variation can be preserved and historic patterns of abundance can be reconstructed. However, the source of individuals for reintroduction generally should be from populations geographically closest to those now in danger of extinction.

Genetic diversity of two Brazilian populations of the Pampas deer (Ozotoceros bezoarticus, Linnaeus 1758)

“…These results are quite distinct from those obtained by González et al (1998) for mtDNA. This can be a consequence of the differences in the genetic characteristics of the markers used in each study, since different classes of markers can give rise to very distinct results.…”

“…These results are concordant with González et al (1998) that found a remarkably high variability in the control region of the mitochondrial DNA. This high genetic variability at nuclear (RAPD) and mtDNA at both populations can reflect the historically large population sizes and their recent decline.…”

“…As a general rule, males are the dispersal sex in the mammal species (Greenwood, 1980;Handley and Perrin, 2007), and differences in geographic structure of mitochondrial and nuclear polymorphisms caused by this biased dispersal pattern have been widely reported (Ishibashi et al, 1997;Mesa et al, 2000;Escorza-Trevino and Dizon, 2000;Prugnolle and Meeus, 2002). Unfortunately, dispersal patterns in the pampas deer are poorly known, but the hypothesis that in this species the dispersion is done mainly by males can explain the differences on the data found in our study from those obtained by González et al (1998).…”

“…This classification, primarily based on morphological characters (Cabrera, 1943), was reinforced by the remarkable mtDNA sequence divergence between them (González et al, 1998). Aside this, the habitats occupied by these two populations present diverse climate conditions.…”

“…Based on morphological data, Cabrera (1943Cabrera ( , 1960 Until now, only one genetic study was done in this species. In this work, González et al (1998) found a remarkable high level of genetic diversity within Pampas deer populations when analyzing the control region of the mitochondrial DNA (mtDNA). A high sequence divergence correlated with geographic distance was found between populations, suggesting that genetic differentiation in this species is largely explained by the limited dispersal abilities of individuals rather than the presence of long-standing ecological or geographical barriers.…”