Organisms within an ecosystem interact in a web of complex relationships. Small changes to the mix of species (and so these interactions) can cause profound changes to an ecosystem. If a species is lost it may have unforeseen consequences – another species might multiply to become a pest or drop in numbers. This change to the second species might affect a third and so on. So while an organism may not directly benefit to us - their presence or absence can have profound effects on the ecosystems we depend on for resources.
For this reason, one of PISCO’s goals is to study the health of individual organisms living along the Californian Current Large Marine Ecosystem (CCLME) and how they adapt to changes in their environment.
Organisms need to adapt to any large-scale change to their environment if they are to thrive. If they cannot adapt (or move to a better environment) organisms are unlikely to use ecosystem resources efficiently, and may be outcompeted by other organisms, or even die.
Adaptation is the process of change that makes an organism better suited to its environment. How an individual species adapts to environmental changes can have effects that ripple throughout an ecosystem.
The study of adaptation is becoming increasingly important as climate change alters ecosystems worldwide. These changes include the formation of low oxygen (hypoxic) dead zones that has been killing marine life off the coast of Oregon since at least 2002. The ocean is acidifying and the average surface seawater temperature is rising with greater temperature variability than in the past, because of the increasing levels of atmospheric CO2.
A significant proportion of PISCO’s research focuses on how marine organisms along the west coast of the US are adapting the effects of climate change. This information will feed into management decisions so that marine ecosystems and the resources they provide can be preserved sustainably.
One of the best ways to study adaptation is to look at the physiological response of an organism to changes in its environment. Physiology can be studied on many levels from the molecular to the cellular up to the whole organism level. Many of the studies below use physiology to determine how well organisms are adapting to changing conditions.
PISCO uses many approaches in the study of adaptation from laboratory experiments to field studies and observations:
PISCO researchers have developed a gene chip capable of simultaneously sampling all 28,000 protein coding genes of the purple sea urchin (Strongylocentrotus purpuratus) by assaying the DNA base variation at 77,000 places. This powerful new tool has been used to examine the genetic differentiation between populations of urchins from Oregon and from San Diego. 50 genes were identified that are significantly genetically differentiated between the two populations which suggest that they may be important in adapting to environmental change. Ongoing analysis indicates a greater proportion of these identified genes are expressed during the larval stage of the urchin’s life cycle, suggesting adaptation has a greater role in the larval stage of the purple sea urchin compared with the adult stage.
PISCO scientists have just published results of a study that compared 6 closely related limpet species (Lottia sp.). They examined the differences in the structure and function of cytosolic malate dehydrogenase enzymes (cMDH) under elevated temperatures. These enzymes are important in many metabolic functions, such as amino acid synthesis and maintenance of the oxidation/reduction balance. Each of the six Lottia species studied have different vertical and latitudinal zonation. Tolerance to increased temperature was compared between these species by measuring the thermal stability of this enzyme. Species from mid- to high-intertidal, low latitude species L. scabra and L. gigantea withstood the highest temperatures while the low- to mid-intertidal, high latitude species L. scutum and L. pelta were the most sensitive. These differences in thermal sensitivity were due to small changes in the amino acid sequences of these cMDH enzymes. These enzymes differ by 1 to 17 amino acids indicating that tiny differences in enzyme structure are important for thermal tolerance.