Selective pressures are a known factor in evolution, like when the predatory lizard, Leiocephalus carinatus, caused its favorite prey, Anolis sagrei, to become longer legged to better flee.
A new paper published in Science, Evolvability predicts macroevolution under fluctuating selection, shows that evolvability, which is the ability of populations to evolve and adapt over just a few generations, can help us understand how evolution works on deeper time scales. While our relatively stable past environment has limited selective pressures, current climate change has caused more rapid change, with long-term implications uncertain.
Sacha Vignieri’s Editor’s Summary
There are two scales to consider when studying evolution. Macroevolution pertains to patterns over long time scales and change across diverged lineages. Microevolution, on the other hand, operates on ecological time scales and populations, and questions of local adaptation are often the focus. Rectifying patterns observed across these scales has long been a goal of evolutionary biology. Holstad et al. used a large database of fossil and extant species to test several hypotheses and concluded that evolvability (as measured by genetic variation within a population) shapes divergence due to the ability, or inability, of populations to track environmental fluctuations (see the Perspective by Uyeda and McGlothlin).
Abstract
Heritable variation is a prerequisite for evolutionary change, but the relevance of genetic constraints on macroevolutionary timescales is debated. By using two datasets on fossil and contemporary taxa, we show that evolutionary divergence among populations, and to a lesser extent among species, increases with microevolutionary evolvability. We evaluate and reject several hypotheses to explain this relationship and propose that an effect of evolvability on population and species divergence can be explained by the influence of genetic constraints on the ability of populations to track rapid, stationary environmental fluctuations.
