Evolutionary straitjacket means flies can’t take the heat
Many species of fruit fly lack the ability to adapt effectively to predicted increases in global temperatures and may face extinction in the near future, according to new research.
In a study published today in Proceedings of the National Academy of Sciences, researchers from Monash University, The University of Melbourne and Danish collaborators showed that many species of fruit fly appear to be constrained within an evolutionary straitjacket and can’t readily adapt to climate change-related temperature increases.
Dr Vanessa Kellermann from Monash University’s School of Biological Sciences said current projections predict a 3ºC increase in mean annual temperature in the next century and even greater increases in extremes.
“Given our findings, these expected increases pose a major threat to biodiversity in the near future. Particularly as Drosophila or fruit fly findings are often more broadly applicable,” Dr Kellermann said.
By examining nearly 100 species of fruit fly from around the world, the researchers showed that species had evolved to the temperature extremes and humidity of their environments. However, they had very little flexibility in being able to change their levels of heat resistance and seem unable to adapt to increased temperatures in the future.
High heat resistance is a feature of only some branches of the phylogeny – the tree that shows how species are related through evolution – of Drosophila. Other branches had very limited ability to change their levels of heat resistance; even when flies native to cooler areas grew up in a warm environment, their heat tolerance was not significantly altered.
“The problem is that only a handful of species have adapted to hot environments while most species have not and it seems very difficult to switch once you are stuck on a phylogenetic branch,” Dr Kellermann said.
The researchers looked at species’ prospects for dealing with projected temperature increases in the near future.
“If a species can only withstand temperatures of 36ºC and the maximum temperature of the environment is already 36ºC, an increase of even 1ºC would already put this species over the edge towards extinction,” Dr Kellermann said.
Using this method, the researchers identified at-risk species and found that most tropical and mid-latitude species fell into this category.
“Without rapid adaptation, which now seems very unlikely, a lot of species may fall over under even a mild increase in temperature,” Dr Kellermann said.
I’m sure the people who have battled the Mediterranean Fruit Fly will be happy to hear this. It seems though this is just old recycled news used to paint GW in a scary light, here’s a paper from 1986:
Developmental temperature and life span in Drosophila melanogaster. I. Constant developmental temperature: evidence for physiological adaptation in a wide temperature range.
The concept of an inverse relationship between life span of adult Drosophila and their developmental temperature is probably the result of an unwarranted generalization. Rather, in a wild-type laboratory strain the present study revealed a plateau phase in this relationship between 16 and 29 degrees C in which life span of both male and female flies was roughly independent of developmental temperature. Below and above this range, life span dropped drastically, development being impossible below 12 and above 32.5 degrees C. Simultaneous study of growth characteristics showed that the plateau phase corresponded to a ‘physiological’ range of developmental temperature, development being apparently disturbed outside that range. Within that physiological range, the growth rate of the flies varied varied 2-fold, while life span remained constant corroborating our previous conclusion that growth rate per se does not determine life span.
I find it humorous that Nature so poorly equipped flies over the billions of years of existence that they’ll just “fall over” once the temperature gets to 37C. So much for evolution and survival of the fittest. Contrast this to claims that GW will cause mosquitoes and others pests to flourish.
I wonder where David Suzuki stands on this news?