We determined mtDNA sequence variation in four populations of Afghan Pika from Northern Khorasan Province, North-eastern Iran, focusing on differentiation and genetic diversity. The result of cytochrome b region of mitochondrial gene variation indicated high levels of haplotype diversity (0.834±0.059) among all individuals of O.rufescens and low nucleotide diversity (0.0024±0.0008). In comparison with other Pikas, afghan pika showed low haplotype diversity but nucleotide diversity was high in Afghan Pika than other species of Pikas except collard pika (Table 7).
Totally, our result showed low nucleotide diversity and high haplotype diversity, which may represent a signal of rapid demographic expansion from a small effective population size (Avise 2000, Lanier 2013). To test the hypothesis on past population growth, we used Fu’s Fs neutral test (Lin et al. 2010). Our results showed this common view with significant negative value of Fs (-4.5) ...view middle of the document...
The all haplotypes or specimens from the four populations were mixed with one another and were clustered into one big group and just two small groups separated from this.
Differences in habitat selection related to environmental changes adaptation (Morris, 2011), that could be a major factor in evolutionary processes in pikas. Pikas usually show more intraspecific diversity than interspecific diversity (Lanier and Olson, 2009).result of AMOVA analysis supported this hypothesis. Analysis of molecular variance (AMOVA) showed significant partitioning of variance (P <0.05) among (18.6%) and within (81.4%) populations. Fixation index was low (0.18) and significant (P < 0.05) in cytochrome b mitochondrial sequences and revealed low genetic differentiation among populations. This may result from the high gene flow among these populations (table 4).
Considering the formula Nm ≈ (1/FST -1)/4, when Nm>0.5 or Fst<0.33, gene flow could be the main factor and conversely (He et al. 2006). Our result showed that gene flow between populations was high. We suggest that the high level of gene flow or low-level of genetic differentiation between populations have obtained from the close habitat connectivity between local populations.
Our result showed a high and negative value of gene flow between GH and GL. Negative values of gene flow showed that gene flow was extremely high and differentiation within population was higher than differentiation among populations. In the other hands these populations have little genetic variation and are panmictic by nature (Goodman, 1997)
The results of this paper can create a framework for planning effective management strategies for populations of Afghan Pika in this region. It seems that, agricultural development and natural barriers among isolated habitats did not decrease gene flow of the Afghan Pika populations in Northern Khorasan province. It must be mentioned that our results were obtained using the single-locus data of mtDNA. To confirm this information, other analysis based on nuclear locus markers or even other mitochondrial markers with high number of individuals is needed for planning further investigation on Afghan Pika populations.