Conservation in the News: Some Like It Hot

It's another exciting semester in Conservation Biology and I am helping my students find an excuse to read the newspapers with a little newsy assignment.  The assignment even distracted me briefly from obsessively reading about politics (notice my very neutral tone, achieved with the restraint of every saintly virtue I possess [which is remarkable given how very few saintly virtues I actually possess]). And there's more than climate change out there in the news...there's also vertebrates and climate change!

I came across an interesting report by Chelsea Harvey in Scientific American on a new study that examined the niche evolution and the distribution of vertebrate diversity of endotherms (birds & mammals) relative to ectotherms (amphibians & reptiles) by Rolland and colleagues, and it looks like bad news for our beloved ectotherms.  Those of us who have been obsessed with amphibian population declines since the 1990s will not be terribly surprised, but this study does make one ponder. Rolland et al.’s  data set had over 18 million occurrences of over 11,000 extant birds, mammals, reptiles, & amphibians combined with occurrence documented with fossils.  They found that endothermy was associated with faster niche evolution than ectotherms (see their figure below), which may result from a wider distribution across latitudes, greater dispersal abilities, and greater warming and feeding of their offspring compared with ectotherms.  

So basically, the ectotherms do not appear to be as flexible to responding to environmental change, while endotherms have be able to expand their distribution to a greater extent and evolve at faster rates, all of which Rolland et al. argues has serious repercussions in the midst of global climate change.  All organisms have thermal limits, but because reptiles and amphibians often use behavioral thermoregulation to maintain their body temperature at optimal levels, rapid environmental changes may leave them outside of the optimal temperatures more often, which may negatively impact population persistence and result in range contractions or extinction. 

I wonder how life history traits, like longevity and generation time, may also contribute to a species ability to respond to climatic change.  Many argue the furry megafauna have been doomed since the arrival of humans, and surely they are not able to respond to environmental changes as quickly.  In the end, it may be the furry and feathered underdogs who have the advantage.  With world enough and time, and political leaders with no willingness to deal curb the effects of climate change, I suppose we will find out.  [That is reality, so no saintly restraint appeared to be needed.]

P.S. I hope the journalist realizes that amphibians are not reptiles—they appeared to be equally doomed, yet she seemed to forget them.  Don’t get me wrong, I love reptiles more than the next person, but amphibians put the C in cool.  Given the unprecedented declines in amphibians, limits to climatic niche evolution may be yet another factor that could contribute and one that we have not be explicitly considering.

P.P.S. Birds are reptiles. I know, it's crazy. It's not what we learned back in the olden days, but in the 21st century, birds are reptiles. 

Refs:

Harvey, C.  2018. Warming threatens reptiles more than birds and mammals.  Scientific American, January 30, 2018.  https://www.scientificamerican.com/article/warming-threatens-reptiles-more-than-birds-and-mammals/

Rolland, J., D. Silvestro, D. Schluter, A. Guisan, O. Broennimann, and N. Salamin. 2018. The impact of endothermy of the climatic niche evolution and the distribution of vertebrate diversity.  Nature Ecology & Evolution doi:10.1038/s41559-017-0451-9.