Joe McCormick
speaker
4,384 appearances
9 recordings
1 series
first heard Sep 2026
last heard yesterday
Joe McCormick’s voice in public audio — every appearance, attributed to the second.
Trend
recordings per month · last 12 monthsRecordings per month over the last 12 months — 9 in all, peaking in Sep 2026 with 9.
Appearances
Why would that be?
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Why the asymmetry?
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Some answers lie in characteristics of the organisms.
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Maybe some organisms are just more adaptable.
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They're better at dispersing into new environments.
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Maybe they're better at evolving more quickly and changing what they're adapted to.
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But some answers, on the other hand, might lie in characteristics of the land and environment on either side of the new corridor or within the corridor itself.
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What if something about the geography favors dispersal one way but not the other?
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And to be clear here, the authors do not argue that Wallace was wrong about the deep ocean trench in the Lombok Strait being a barrier to dispersal.
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It it is.
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It does stop a lot of exchange.
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And they note that the only mammals which seem to have successfully crossed that boundary naturally are bats and rodents.
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Big mammals seemingly do not cross.
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But of the animals that have crossed, one thing that is clear is which way the asymmetry goes.
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Over the last twenty million years, way more animals from Asia have successfully crossed the barrier and made their way into New Guinea and onto the Australian continent.
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Relatively little dispersal has gone the other direction from Australia and New Guinea to the west into Asia.
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Why would that be?
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Well, the authors argue, based on analysis of a huge data set and a sophisticated computer model, that the answer has to do with the climate of the islands within and on either side of Wallacea, especially how wet or dry those islands are and the precipitation tolerance of the animals that evolved on either side.
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So to quote the authors, quote, here, analysis of more than 20,000 vertebrate species with a model of geoclimate and biological diversification shows that broad precipitation tolerance and dispersal ability were key for exchange across the deep time precipitation gradient spanning the region.
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Sundanian, meaning Southeast Asian lineages, evolved in a climate similar to the humid stepping stones of Wallacea, facilitating colonization of the Sahulian, meaning Australian, continental shelf.
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Showing 201–220 of 4,384 · page 11 of 220
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