Assessment of demographic bottleneck in Indian horse and endangered pony breeds.

Abstract

Bottleneck study of any continuously decreasing population is important and crucial issue in its conservation strategies including the analysis of simulated and real populations (Williamson-Natesan 2005; Busch et al. 2007). A bottleneck in a population can increase the rate of inbreeding, loss of genetic variation, fixation of deleterious alleles, thereby reducing evolutionary potential of animals to adapt to new selective pressures, such as climatic change or shift in available resources and increasing the probability of population extinction (Frankham 1995). The genetic changes caused by a bottleneck in a population’s effective size can lower the possibility of population’s persistence (Vrijenhoek 1994; Newman and Pilson 1997). Various endangered or threatened populations have been reported to have low levels of genetic variations (Vrijenhoek 1994; Gibbs et al. 1998). However, all the populations that have been reduced in size did not show quantifiable lower levels of genetic diversity (Waldman et al. 1998) which also necessitates the assessment of bottlenecks with molecular marker for their conservation and evolutionary genetics. India is bestowed with a rich biodiversity of equids in the form of two horses (Marwari and Kathiawari) and four endangered pony breeds (Bhutia, Spiti, Manipuri and Zanskari) besides indigenous donkeys and wild asses (Gupta et al. 2012a,b; 2014). Overall population of these breeds, specially endangered pony breeds has declined in most of the pockets in their home tracts (less than 1000) which is due to their decreased utility and increased modernization of transport system even in hilly and difficult terrains (Gupta et al. 2012a, b). It is expected that bottleneck might have taken