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Re: Packing in the bats



Possible reasons why flyers might have high species packing: ability to
exploit steep or vertical surfaces; mobility - ability to use scattered
resources.

Good call; those could definitely have an impact.

It is probably worth mentioning, however, that not all flyers tend towards high species packing. Small-bodied, short-range taxa have a strong tendency to produce heterogenous, species-rich clades with high species packing. Larger and/or wider ranging species produce the opposite, however. Both "modes" persist over time, but probably for slightly different reasons: Long-distance flyers with wide geographic ranges are robust to local pertubations. Many seabirds and raptors, as well as several pterosaur lineages, have both long durations in the fossil record, and I suspect that this is a result of have large ranges. By contrast, species like passerines and vespertilionid bats probably have higher turnover rates, but they more than make up for it with a higher speciation rate. In essence, at a higher clade level, both types of lineages persist for long periods of time, but the wide-rangers have a few morphs over a large area, while short-rangers are dominated by heterogenous distributions (many morphs, each with a small range, that altogether cover a wide area).

The difference in average home range, as well as emergent extinction/speciation rates probably have an impact on species packing. That's my best hypothesis at the moment, in any case.

Cheers,

--Mike H.