Hybrid species and conservation 4 Sep 2009 Here’s what Elio Schaechter calls a Talmudic Question – if two endangered species hybridise, are their biodiversities conserved? I ask because this is exactly what happens frequently in, say, birds, and because there are a lot of debates over what hybrid species signify. Ecology and Biodiversity Species concept
Ecology and Biodiversity A kiwi on moas 24 Sep 2007 This is a nice post by Christopher Taylor at Catalogue of Organisms, a kiwi studying spider systematics (and what’s not to love about that; cephalopods be buggered!) on the species of moas that used to live in New Zealand. I didn’t realise they’d be forest dwellers. It’s a worthwhile blog… Read More
Ecology and Biodiversity Gore, peace and the “errors” 12 Oct 2007 The International Herald Tribune worries that Gore’s receiving the Peace Prize is going to denigrate the award because it “strays from traditional Nobel definitions of peace work”. Huh. As Tom Lehrer said, when Henry Kissinger can win the Peace Prize, the time for political satire is long past. If anything,… Read More
Species concept A review at Arnhart 18 Sep 2009 and a fair one I think. Not that I agree with him about Darwin, but there’s room for honest disagreement. Read More
This question was raised briefly at Tet Zoo. As I said there, I suppose it depends to a certain extent on whether (and in what proportion, and which of) the genes of both parents actually persist, or whether one or the other disappears as a result of drift or selection.
Of course it depends on whether what we are measuring in biodiversity is the number of taxa, of genes, or of ecological roles, and the relationship between them.
If they can hybridise and their offspring are normally fertile (either between hybrids or back to their parent’s species) then weren’t they just one species?
Only if they do this regularly enough so that there is frequent mixis. Overall, though, these are populations with some introgression but not a whole lot, and they remain constant and distinct over evolutionary time.
Thank you. Then there is loss of species assuming the original species cease to be (plus a gain of the hybrid species). The genetic diversity might be retained, but I don’t normally think of conservation at the gene level.
In so far as the question relies on tetrapyloctic issues , the question certainly is more talmudic than most of the questions that he labels as such which are much more often just of the form “why don’t we see _ where we’d expect to see it in nature.” It might depend on how frequently the two hybridize in nature. If the two hybridized more rarely I’d be more inclined to say that species conservation had failed than if they hybridize frequently. But this is based more on intuition than any coherent thought process. A related question that I was thinking about a while ago: There’s evidence that some arthropods which we label as different species only have reproductive barriers due to the presence of differing strains of Wolbachia infections. Given that, if we wipe out the Wolbachia infections have we destroyed a species of arthropod?
My mom’s a bird-watcher and involved in bird conservation. They have this argument all the time over many different species. Hummingbirds and sparrows, for example, frequently hybridize, as do many of the grouse family. Typically, even though the offspring are generally fertile, the hybrid males have a very hard time attracting mates because they’re “inferior” to the full-species mates the hybrid females would have available to to them. The biggest controversy I remember her relating had to do with the dusky seaside sparrow. There was a lot of fighting over whether the hybrid offspring should be considered “dusky seaside” sparrows… It finally got to the point they were down to just a solitary male and they wanted to cross-breed it with the regular seaside sparrow. Ultimately the sub-species went extinct. I THINK because there was a decision made to not hybridize them and, at that point in desperate times, there were no females. Personally, I think it was stupid not too… Conserving the genes, even if hybridized, could have lead to back-breeding for specific characteristics and the rebuilding of an extremely similar, albeit hybridized, population that could have possibly evolved even closer to the original.