26 February 2008

Species vulnerability traits

Near the end of October 2007, there was a workshop in London hosted by IUCN Species Survival Commission and some other organizations. The report of the workshop is available here.

The workshop attendants put together a list of species traits that they considered to be "indicative of vulnerability to extinction due to a range of threats and generally applicable across all taxonomic groups." I think this list will be quite useful in assessing extinction risks of threatened species.

I have a few comments.

•The potential protection offered to a species against climate changes by its microhabitat is one of the traits under the category Range characteristics. Can any animal species be perennially buffered against the drastic climate changes that may be taking place in its overall environment? This is an intriguing question. Microhabitats, by maintaining a more or less stable microclimate, could indeed provide protection against macroclimatic changes for short periods. But I think they would fail sooner or later. For example, many invertebrates take refuge under rocks where they find a humid habitat away from sunlight and predators; the undersides of rocks are their microhabitat. But, for example, if there were a long-term drought or a permanent change in rainfall patterns (macroclimate), the microclimate of the microhabitats would also gradually change. Nevertheless, at least for the assessment of the short-term risks a particular species is facing, the characteristics of its microhabitat certainly need to be taken into account.

•A trait listed under the category of Breeding system is self incompatibility. I don't know what that means. But what is missing is the ability to self, which refers to the ability of a hermaphroditic animal, for example, a terrestrial pulmonate snail, to fertilize its eggs with its own sperm. This would be a critically vital trait during times when the population of a species may be thinned out and mates may be hard to come by.

•A requirement to experience a cold-induced dormancy prior to reproduction (vernalization) that I discussed here and here would be covered under the category Phenology. Although vernalization per se is not mentioned in the list of phenological cues, various reproductive behaviors and climatic triggers are included.

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