Why What Lives Where:
By the Somero Lab

“In the struggle for survival, the fittest win out at the expense of their rivals because they succeed in adapting themselves best to their environment.”

Charles Darwin

As Charles Darwin eloquently illustrates in this quotation, it is no accident that certain organisms inhabit certain places, while others simply do not and can not. This concept brings to mind a number of questions, but perhaps most pressing is how do organisms adapt themselves to specific environments? A complex issue to be sure, but for decades members of Dr. George Somero’s lab have been attempting to resolve it.

Over the years, the search for answers has become a global pursuit. Our research has taken us from some of the deepest, darkest parts of the ocean, all the way up to the ephemeral, sun-lit intertidal zone. And from distant Antarctica at the bottom of the earth, to the Pacific Ocean lying just outside our lab door. Importantly, what have emerged are some truly remarkable stories.

For example, millions of years of evolution at incredibly cold and stable temperatures have lead one species of Antarctic fish to lose much of its ability to tolerate increases in temperature. Incredibly, this species of fish perishes at a water temperature of 4°C, a mere 3-5°C warmer than ambient Antarctic Ocean temperatures.

Closer to home, crabs that inhabit the intertidal zone outside Hopkins Marine Station are routinely encountering temperatures very near their thermal limit. The take home message: even a shift in temperature of a few degrees C will have dramatic consequences on the distribution and survival of these organisms.

At the other end of the spectrum, some species are capable of tolerating extreme fluctuations in their environments. A species of fish inhabiting highly dynamic sloughs in central and southern California have evolved to tolerate temperatures from a few degrees above 0°C to in excess of 40°C. That same species can endure salinities ranging from freshwater to three times that of seawater. Meanwhile, an exotic species of mussel, which went undetected for decades, has currently invaded Monterey Bay from the Mediterranean, and is proving more adaptable by out-competing native mussel species.

How is it that certain species can be so exceptionally tolerant of environmental change and others be almost completely intolerant? Taken in the context of global climate change and our increasing impact on our earth’s environment, it becomes clear how vital addressing this question is.

We at the Somero lab have currently focused our attention to the molecular level, and are attempting to determine how protein evolution and gene expression interact with abiotic factors, such as temperature, to affect physiology, species distribution, and ultimately survival. We believe many more important (and interesting) stories will develop in the years to come.