Environmental News: Week 8


“Species in the Amazon evolve more slowly than those in North America, U of T research finds”

I chose this bit of news because it includes two things that really interest me: evolution and the Amazon. Due to the fact that the Amazon has a huge number of different bird species, it has always been assumed that this is because birds from the Amazon evolved at a higher rate. This has been disproven by Jason Weir, a researcher from University of Toronto. Weir conducted an ongoing experiment in Peru and North America that studied bird’s reactions to the calls of ‘related but physically far away species’. Their reactions allowed him to determine if the birds still considered these calls to be of birds of the same species; if they no longer recognized the call as one of their own and ignored the song then it could be assumed that evolution has taken place (if they recognized it as a bird from their own species they would act aggressively in order to protect their territory). Weir concluded that extinction rates have more to do with the large number of species in the Amazon than evolution rates. The stable and consistent climate in the rainforest has proved to be a reason for lower extinction rates in the Amazon while the inconsistent and changing climate (over millions of years) in North America could cause higher extinction rates in birds. Also, there are physical barriers that cause new populations to pop up, for example Weir said “In the Amazon, birds do not cross rivers and sometimes two different species will evolve on either side of the barrier. There isn’t much selection to differ their songs, which impacts their ability to discriminate songs. This leads to slower rates of evolution, but a lower chance of going extinct.”

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