[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index][Subject Index][Author Index]

Re: flying Archie

2. Maybe not morally superior. Relative to speciation, passerines are definitely superior to ratites or penguins or birds of prey.


True, though I would suggest that 'superior' is a poor term in reference to speciation. There is a tendency to think of clade size as a measure of "success" in lineages. It is not a bad measure of such things (though trying to measure success in the first place is pretty subjective), but it is not the only one. And, in fact, I do not think it is the best. The main reason that there are 5,000+ species of passerines is because they isolate easily. While that is interesting and important biologically, I (personally) don't see isolation tendency as a measure of "success" (others may disagree, of course). Geographic range size is probably more important if speaking of resistance to extinction, and population size better indicates the ability to replace losses or decrease mortality. At the broadest scales, species durations seem just as good a measure of "success" as clade size. Measuring the tendency to form isolates strikes me as very important, but not a measure of adaptive "superiority", at least by the way I tend to view adaptive traits.


--Mike Habib