Читать книгу Fundamentals of Conservation Biology - Malcolm L. Hunter Jr. - Страница 97

Genotypic diversity is the number of different allele combinations in a population. It can be an important consideration in itself because different alleles in combination generate different interactions and phenotypes. Returning to the bison example, consider the three genotypes: X/X, X/Y (same as Y/X) and Y/Y. Genotypic diversity refers to the number and distribution of individuals across these genotypes. If most individuals in the population were X/X (or X/Y or Y/Y), then the bison population would have low genotypic diversity. If individuals were well distributed across the three genotypes then genotypic diversity would be high (these are very similar concepts for measuring species diversity and evenness discussed in Chapter 3). In the context of more loci and more alleles associated with each, you can imagine that many unique combinations among them and hence genotypes will be manifested.

Why is genotypic diversity relevant? Genetic variability imparts adaptability. Consider seagrass, an important plant of tidal environments, as an example. Replicated plots in the Baltic Sea were planted with one, three, or six genotypes. An unprecedented heat wave occurred during the experiment. Recovery following the heat wave was much better in the plots with seagrass of multiple genotypes (Reusch et al. 2005). Genotypic diversity is also important for economic and cultural reasons. The columnar cactus is used in Central Mexico for its edible fruits. Consumers prefer some cactus genotypes more than others based on the flavor, shape, and color of fruits associated with each. The process of bringing cacti from the wild into cultivated populations has created new genotypes and, interestingly, also enhanced genotypic diversity in the wild when cultivated forms (and the new genotypes they represent) are replanted back in the wild (Casas et al. 2006).