Understanding tropical rainforest biodiversity with treefrogs and ecological history

September 27, 2011 11:25 AM

Lush climates alone do not account for the vast biodiversity in tropical rainforests. Research on treefrogs from around the world, covering 123 sites and gathering DNA sequence data for 360 species of treefrogs, has provided a new understanding of biodiversity in tropical rainforests: some groups of treefrogs have existed together in the Amazon Basin for more than 60 million years. A more recent publication supports this finding, noting that forests in Canada and Europe may have much more in common with tropical rainforests than previously believed, but tropical forests have not been subjected to glaciations and mass extinctions, allowing for much greater biodiversity.
posted by filthy light thief (9 comments total)

This is super interesting, thanks for posting!
posted by clockzero at 11:38 AM on September 27, 2011 [1 favorite]

I remember reading Redmond O'Hanlon's Congo Journey (a magnificent book), where he describes the forests of the Congo Basin as having remained unchanged geologically (save for flooding) for millions of years thanks to no glaciation.
posted by KokuRyu at 11:46 AM on September 27, 2011 [1 favorite]

Here's the original paper discussed in the last link (no paywall!).
posted by Tsuga at 11:47 AM on September 27, 2011 [1 favorite]

So to link that last tag, we need posts on ferns, sharks and horseshoe crabs... what else?
posted by cog_nate at 12:07 PM on September 27, 2011

Climate.
posted by semmi at 1:32 PM on September 27, 2011

I had heard that the virgin grasslands of the US supported a biodiversity greater (per-acre) than that of the rainforests. On that basis, I rejected the notion that lush = diverse.

Then I heard that Europe has some of the least diversity on earth, and postulated that (millenia humans have lived there) is proportional to (reduction in diversity): irrigation, cultivation, weed-burning, extinction of most-desirable species (from Ohio forest bison to Lebanese cedars), competition from domesticated species...
posted by IAmBroom at 2:24 PM on September 27, 2011

The sounds of tree frogs and howler monkeys in Costa Rica
posted by homunculus at 6:00 PM on September 27, 2011

So the latitudinal diversity gradient is one of the most observable patterns in ecology and the research in the first two links is paying lip-service to one of the proposed hypotheses: the effect of increased evolutionary time in high diversity areas. While the researcher seems to downplay some of the other explanations, this really shouldn't be taken as the last word on the subject. For example, he says that there being a favorable climate won't cause animals to evolve, and indeed it won't in and of itself, but good conditions for a species may allow more coexistence and thus opportunities to fill different ecological niches, eventually resulting in evolution.
Also, in the third link, the diversity they are talking about (as it says in the link) is beta diversity, or the rate of change in present species moving from one area to the next (or, more simply, a comparison of unique species between habitats). The link says that beta diversity remains stable between places as a ratio of the biodiversity in those areas (alpha diversity). I wasn't aware that this was unexpected and seems in line with the relative smoothness of the LDG.
posted by Wyatt at 9:50 PM on September 27, 2011 [1 favorite]

I grew up in a northern rainforest that has such a history of recent glaciation that there are areas of young forest that were under ice within my lifetime. This is an area with plenty of rain and lush growth in the summer, but the diversity of plants and insects (especially insects and spiders!) in forests in the contiguous U.S. makes my area feel like a freakin' monoculture.

I've always chalked it up to both historical glaciation and generally-lower summer temperatures. It should be noted that with rising average annual temperatures, we're seeing insects that weren't common here increase in population, most noticeably ones that kill spruce trees.
posted by D.C. at 8:22 AM on September 28, 2011