Question

2. (22 points) A critically endangered salamander species (abbreviated Rs) is now confined to two isolated populations after replacement of much of its pine forest habitat by commercial pine plantations, and other factors like habitat fragmentation, fire suppression, introduced fish, and roads reduced the quality of remaining habitat. Patterns of genetic variation were compared to several more common closely related species (Rc and Ra) with similar life history and ecological traits. Review the provided data to describe and explain the genetic consequences of the challenges that the Rs species has faced. Include an explanation of how the data reveal information about the demographic history of Rs in contrast to that of the other species. You should specifically note the significance of values of allelic richness, M ratio, heterozygosity, and Fis from Table 1 and the reasons that the histograms in Fig. 1 show different patterns. Note the general trends that can be inferred from Table 2.

Answer 1

• Human induced evolutions like urbanization, pollution ,climatic change, habitat fragmentation cause ecological consequences and greater effects on evolutionary diversification.

• These evolutionary changes might have the strongest effect on the population variations of the evolving species, the structure of their communities and the functions of those species ecosystems.

• Human activities also affect the food chain in an ecosystem thereby the food web. This disturbance in one population may affect a few species.

• Allele Richness or Allelic Diversity (average number of alleles per locus) and heterozygosity are the measures of Genetic diversity.

• The Table 2 shows the Observed Heterozygosity (Ho- The frequency of Heterozygous individuals in a population) or the Expected Heterozygosity (HE ) and the Histogram shows the allele richness of the species Rs, Rc and Ra respectively.

• From these observations it is clear that, the factors, Ho, HE and Allele Richness for the species Rs is very low as compared to other species Rc and Ra.

• The decrease in the observed heterozygosity can induce a decrease in the average fitness of the species. At the same time, the decrease in the Allele richness of a species could lead o a reduction in the population potential to adapt to future environmental changes.