2018/12/07

A typical example of genetic degradation - Galapagos Giant Tortoises

The giant tortoises of Galapagos are endangered due to rapid loss of genetic diversity

https://www.researchgate.net/publication/8602585_Genetic_analysis_of_a_successful_repatriation_programme_Giant_Galpagos_tortoises

Excerpt: "As natural populations of endangered species dwindle to precarious levels, remaining members are sometimes brought into captivity, allowed to breed and their offspring returned to the natural habitat. One goal of such repatriation programmes is to retain as much of the genetic variation of the species as possible. A taxon of giant Galápagos tortoises on the island of Española has been the subject of a captive breeding-repatriation programme for 33 years. Core breeders, consisting of 12 females and three males, have produced more than 1200 offspring that have been released on Española where in situ reproduction has recently been observed. Using microsatellite DNA markers, we have determined the maternity and paternity of 132 repatriated offspring. Contributions of the breeders are highly skewed. This has led to a further loss of genetic variation that is detrimental to the long-term survival of the population. Modifications to the breeding programme could alleviate this problem."
 
My comment: These Darwin's favourite pets show us what is happening in the wild. Organisms are experiencing rapid loss of genetic diversity. Scientists know that the only way to rescue them is to breed them with their predecessors. This has to be done in captivity, because pheromones control mating behaviour and different species of tortoises will not mate in the wild. Genetic diversity can be rejuvenated only by using biological information existing in the same kind. But the total amount of biological information is still only decreasing in the species groups. And this same phenomenon can be observed all over nature. There is no mechanism for evolution. Don't be deceived.