A True Fish Story: Adaptive Responses to Global Warming

The simplistic notion that organisms are “dumb” when it comes to changing environments goes like this: Species X lives in a relatively stable environment and with a certain defined range of temperature. So, if the temperature changes enough, species X will go extinct.

In resuming our series on biological adaptation to environmental change, we are going to be looking in depth at the evolutionary and environmental nuances that—with some limits—invalidate the simple point of view. And, in doing so, we will discover important implications for environmental and climate-related policies.

We begin with revolutionary classic in evolutionary biology published in 1984 by Peter Hochachka and George Somero called “Biochemical Adaptation.” It summarized and expanded on much of their earlier work on what they called “phenotypic plasticity”.

Pre-Hochachka thinking had it that our DNA codes for specific proteins, which do their thing (often serving as catalysts for complex biochemical syntheses) and are pretty much static, which would lead automatically to the “dumb” organism when it comes to environmental change. But, among other things, Hochachka and Somero can show that, depending upon temperature, many critical proteins actually change their shape as temperature rises (or falls), greatly broadening the environmental range of many species.

A wonderful example of this concerns marine fish living in tropical waters, which tend to experience much smaller seasonal variations in temperature than fish inhabiting other latitudes. Without phenotypic plasticity, there are concerns that tropical fish maintain narrow temperature tolerance and that they might presently be close to their optimal temperature limit. If temperatures were to therefore rise in the future in response to CO2-induced global warming, many tropical fish species might experience widespread decline and possible extinction.

Given plasticity, does this hypothesis hold any water?

A five-member…

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