Maintaining Biodiversity in Reintroduction

Conservation genetics uses genetic pathways to maintaining biodiversity. If genetic biodiversity decreases however then the species present are at risk of extinction such as with the Mexican gray wolf. In order to save the species, strategic interference and manipulation is sometimes required in order to steer the conservation in favor of the species at risk.

In the case of the Mexican gray wolf, the wolves are held captive as a part of the Mexican Wolf Species Survival Plan ("Mexican Gray Wolf Recovery Program"). It is a plan between Mexico and the United States to reestablish the species through captive breeding. The success of the Blue Range Mexican Wolf Reintroduction project is due to the SPP. The SPP has around 50 holding facilities many of which are zoos. Before being released into the wild, the wolves go through a series of pre-release facilities for evaluation and acclimation. Also, as a precaution, the wolves released into the wild are those whose genes are strongly present in captivity in order to preserve those genes in case of a disaster in the wild that wipes out those genes and reduces the diversity ("Mexican Gray Wolf Recovery Program").

Alameda Park Zoo

There are multiple other measures that are taken up to continue promoting genetic diversity in the species. When there are less genetic lineages available to be passed on, the probability of inbreeding is more likely. Inbreeding reduces genetic diversity because there are less genes being circulated to promote diversity. Inbreeding can cause reduced litter size and an increase in pup-mortality which is a step closer to extinction rather conservation (Associated Press). The  SPP encourages genetic exchange during captivity by transferring wolves among facilities therefore expanding the genetic variation ("Mexican Gray Wolf Recovery Program").

A study was conducted testing the relationship of inbreeding with sperm quality and reproductive success in Mexican gray wolves. Semen sample from three distinct lineages were analyzed and compared to samples from subsequent lineage crosses of progeny and from the gray wolf itself (Asa, Miller, Agnew, Rebolledo, Lindsey , Callahan, and Bauman 326-331). 

The table above depicts the relationship between inbreeding a reproductive success; as the inbreeding coefficient increases, the reproductive success decreases. Samples of male progeny from lineage crosses harboring low inbreeding coefficients were similar to the gray wolves in quality unlike the samples from the offspring of back-crosses (Asa, Miller, Agnew, Rebolledo, Lindsey , Callahan, and Bauman 326-331).

The quality of offspring a reproductive success goes hand-in-hand with the quality of sperm. One of the best ways to preserve the Mexican gray wolf is to develop a strong sperm bank. Scientists are on the hunt for prime preservation techniques. One study manipulated temperature to conclude the best preservation temperature procducing the most viable sperm (Zindl, Asa, and Gunzel-Apel 1797-1802). Below are the results of the study. Results show a highly significant decrease in the viability of sperm post-thaw from fresh sperm and cooled sperm. This indicates that there are still many steps to be taken in order to sustain a strong sperm bank for the conservation of the Mexican gray wolf via temperature isolation.

Though still in the works for prime results, there is a huge benefit of freezing sperm for the purpose of genetic diversity. Frozen, preserved sperm can be transferred to breeding facilities and promote genetic variation by injecting the sperm in a female breeder, also known as artificial insemination. For artificial insemination, sperm doesn't always have to be frozen either; sperm can be fresh, fresh and chilled, or frozen-thawed. Even more flexibility is available with artificial insemination as it may be vaginal, intrauterine, or intratubal and the semen injected can be ejaculated or epididymal from the male donor (Thomassen, and Farstad 190-199).