What We’re Reading- June 16, 2017

Ectotherms and Climate Change
Ectotherms regulate their body temperature using external heat sources; for example, turtles bask in the sun or on hot rocks to warm up, then retreat to the shade when they become over heated.  Increasing temperatures due to climate change are expected to have physiological effects on animals and plants.  Heat shock proteins are molecular chaperones which assist in protein synthesis and folding, particularly when a cell is stressed (ex- very hot temperatures).  This paper (sub) experimentally manipulated the incubation temperature of loggerhead sea turtle (Caretta caretta) embryos, then generated transcriptomes of the brain.  The researchers then compared the heat stressed and control individuals for up- and down-regulated genes.  They found that 142 transcripts were up-regulated and many of these with known gene function belonged to the heat shock protein family or genes encoding proteins that facilitate heat shock proteins.  They also observed 37 transcripts that were down-regulated, of those with gene annotations many were related to development.  Embryos can not use behavior (i.e. basking or moving to shade) to regulate their temperature, thus gene expression or protein sequence changes may be the adaptive mechanisms needed for survival and proper development until hatching.

Side image of a loggerhead sea turtle hatching by Zankl via ARKive.

When Biological Reality Clashes with Conservation Policy
This paper (open) describes the complex relationship between conservation policy (particularly focusing on the US Endangered Species Act [ESA]) and the biological reality of species hybridization and admixture.  Hybridization is the process of two species or subspecies interbreeding after they previously diverged.  This process can be natural as species ranges shift over time or ecological niches change to bring species into secondary contact.  And since evolution is an ongoing process, hybridization may be ancient or recent.  Yet we often discuss recent hybridization as an anthropogenically assisted process, for example following the introduction of a non-native species which breeds with a native species.  Thus conservation policy has frequently been written to exclude hybrid populations and/or species from protection, even if they would meet the definitions of threatened and endangered otherwise.  The authors of this paper argue for more nuance within conservation policy that incorporates the idea of protecting recent natural hybrids as their own unique lineage within a web-of-life (versus perfectly bifurcating tree-of-life) framework.

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