Hybrids Cause Conservation Conundrum

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Hybrids cause conservation conundrum, according to a report in ScienceNOW, 17 September 2007 and ScienceDaily 2 Oct 2007. The California tiger salamander is a “threatened species that lives in the Salinas Valley in California. For the last 50 years it has been breeding with banded salamanders introduced from Texas. Biologists have studied the native and introduced species and the hybrid of the two species and found the hybrids were “significantly more likely to survive than either parental species”. The researchers suggest that this is example of “hybrid vigour”.

These observations have caused problems for conservationists, “for example, should any populations of foreign or hybrid salamanders be eradicated to preserve the genetic purity of the Californian natives?” The work may also challenge conservationists’ criteria for deciding which populations get protection under the US Endangered Species Act. Benjamin Fitzpatrick of University of Tennessee, Knoxville who took part in the study commented: “We will have to decide what it takes to qualify as Native.”

ScienceDaily

Editorial Comment: Have you noticed the hypocrisy of most Conservationists – they usually believe in evolution, but do anything they can to stop it.

“Hybrid vigour” is the reason mixed breed dogs are more robust than pure breed dogs, but it is really a misnomer. All breeds of dogs are the one species, so the offspring produced by cross breeding are not really hybrids. The reason for the vigour is that pure bred animals are the result of inbreeding, so any genetic defects tend to accumulate. Cross breeding introduces healthy genes from the two breeds that can compensate for defective genes in each of the pure bred animals.

True hybrids are the result of crosses between two different species, such as a horse and a donkey producing a mule. They may be healthy as individuals but they are sterile, and cannot be said to be vigorous. Therefore, the Salinas Valley salamanders are more like cross breeds within species, rather than hybrids between species. Therefore, the conservationists should leave them to breed and keep the species strong.

Fitzpatrick’s comment reminds us that there are no such things as “indigenous” or native species. The reason there are different animals in different places in the world is not because they evolved there. All the land dwelling, air breathing animals on earth today are descendents of the animals that got off Noah’s ark and spread out all over the world. Therefore, they were fully formed, distinct kinds when they arrived in any land. Since then some kinds may have been split up into smaller groups, and these may have been classified into different species, but they are still the same kind, so when given the opportunity to breed again they do. (Ref.environment, selection, amphibians)

Evidence News 28 Nov 2007

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