07 - Lion Family Reunion: Conservation Biology Genetics
In order to predict what events created the observed genetic patterns, scientists next reconstruct the evolutionary history of all the different haplotypes using phylogenies – the “phylo” part of phylogeogra - phy. Phylogenies describe patterns of ancestry. Often phylogenies are displayed as trees or networks where whatever is being compared – family members, species, or in this case unique haplotypes – are on the tips of each branch (Figure 3). Common ancestors are represented by the intersection between two branches, which are known as a node. Haplotypes that are several nodes away from one another are more distantly related than those that are only separated by a single node. Similarly, haplotypes that are connected by short branches are more closely related than those connected by longer branches. The tip of each branch is labeled with the haplotype’s name and in some cases an additional pie chart showing all the populations where the haplotype can be found.
By combining data from phylogenies and population genetics scientists can reveal key events in the history of a species. More spe- cifically phylogeographical studies can help scientists determine when/where members colonized new areas (expansion events), when/ where populations went through a sudden decline in size (bottleneck events), when/where populations divided and be - came isolated from each other (vicariance events), and when/where members from two different populations met (admixture events). In addition, once a species’ phylo- geography has been created, the genetic information can be organized and shared in a database called a GRDB (Genotype Refer- ence Database) that can be used to predict the geographic origins of an individual. APPLICATIONS - PAST HISTORIES, FUTURE CHALLENGES, CURRENT DECISIONS Phylogeography studies are helping conser- vation biologists preserve current diversity. By knowing the geography of a species’ genetics, scientists can identify hot spots (areas of high or unique genetic diversity)
Figure 3: An example genetic tree - human mtDNA haplotypes.
that should be protected. Scientists tasked with helping threatened species also use these studies to subdivide these species into biologically based management units (mu) or evolutionarily significant units (esu). Finally, phylogeography is being used to decide where best to reintroduce individuals that were removed from their habitat, either because of illegal wildlife selling or habitat destruction (Box 2).
Box 2: You Want Me To Live Where? Introducing animals back to their native habitats has clear advantages – it’s an enriching environment for the animal, helps maintain the diversity of the species, and minimizes animal care costs. However, it’s also very difficult especially for more complex animals (primates, large cats, elephants, dolphins, etc.). These animals don’t have necessary survival skills, are too trusting of humans, and are suscep- tible to local disease. To overcome these challenges, reintroduction is now being carried out in two stages. First, captured animals are introduced to a semi-wild preserve where they are encouraged to relearn key skills. Then, offspring from these ‘rehabilitated’ animals are released as a group back into the wild where they help each other adapt to the harder conditions. In addition, scientists identify the likely geographic origin of captured animals and release them nearby to maximize the chance that the reintroduced animals will be genetically adapted to the environment.
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