Tuesday, December 31, 2019

Species Self-Annihilation by Denialism

I saw an article in the Wall Street Journal early December indicating that songbirds have shrunk in size:

Hotz, Robert Lee (2019, December 5). Songbirds shrink in size, study finds. The Wall Street Journal, p. A3.

The article cites a 40 year study that attributes the shrinking size to warming temperatures:
Brian C. Weeks, David E. Willard, Aspen A. Ellis, Max L. Witynski, Mary Hennen, Benjamin M. Winger (2019). Shared morphological consequences of global warming in North American migratory birds.bioRxiv 610329; doi: https://doi.org/10.1101/610329 Now published in Ecology Letters doi: 10.1111/ele.13434

Increasing temperatures associated with climate change are predicted to cause reductions in body size, a key determinant of animal physiology and ecology. Using a four-decade specimen series of 70,716 individuals of 52 North American migratory bird species, we demonstrate that increasing annual summer temperature over the 40-year period drove consistent reductions in body size across these diverse taxa. Concurrently, wing length – which impacts nearly all aspects of avian ecology and behavior – has consistently increased across taxa. Our findings suggest that warming-induced body size reduction is a general response to climate change, and reveal a similarly consistent shift in an ecologically-important dimension of body shape. We hypothesize that increasing wing length represents a compensatory adaptation to maintain migration as reductions in body size have increased the metabolic cost of flight. An improved understanding of warming-induced morphological changes, and their limits, are important for predicting biotic responses to global change.
Møller, A., Bonisoli-Alquati, A., Rudolfsen, G., Mousseau, T. (2011). Chernobyl birds have smaller brains. PlOS One, 6(2), e16862, 1-6. DOI: 10.1371/journal.pone.0016862.
H. J. Muller demonstrated that genetic damage incurred in one generation is transmitted through germ line cells across generations, with too many mutations ultimately being expressed in genetic instabilities, mosaicism, and potential species extinction (see my discussion here and ongoing research here NIH Director's Blog on Genetic Mosaicism ).
Today, we know that epigenetic changes can also occur, impacting expression of genes (gene function) without observable damage to DNA structure.