Long-legged lizard challenges Darwinian evolution
Survival of the fittest, according to Darwin's theory of evolution, is a slow biological process that takes place in a species over many generations. But Spanish researcher Marta López Darias and colleagues had a different idea. Her EU-funded research contributes to the growing body of evidence pointing to "rapid evolution in action".
Naturalist Charles Darwin’s theories on natural selection – species evolve from one generation to the next to survive – have endured for150 years or so. His work, ‘On the origin of species’, became a cornerstone of modern biology greatly influencing scientists and evolutionary biologists.
But European and US research is helping to write a whole new chapter in natural history along the lines that species, such as lizard populations in The Bahamas and the Canaries, can undergo major physical changes not only in one generation but even from one season to the next.
Dr López Darias combined her passion for nature and an intimate knowledge of the Canary Islands where she grew up to establish the ‘Island selection and lizard ecology’ (ISLE) project. The researcher accepted a three-year Marie Curie fellowship grant enabling her to study for two years under respected biologists Thomas W. Schoener (University of California) and Jonathan B. Losos (Harvard University). She spent the third year working back at the Spanish National Research Council under the supervision of Manuel Nogales.
Her research on highly adaptable lizards suggested an animal can make structural (muscle and bone) changes in the space of half a year when faced with new (or introduced) predators.
Armed with a new theory and a raincoat
Schoener and Losos first proposed a revision of the Darwinian evolutionary theory in an article published in Nature back in 1997. In it, they argued that it might be more accurate to think of evolution as a series of relatively rapid and discrete events rather than prolonged and continuous change, and that evolution is highly influenced by environmental changes.
Armed with a new theory about the effect of weather on the evolution of species, and a raincoat, the Marie Curie fellow journeyed to Abaco Island in The Bahamas archipelago to revisit Schoener and Losos’ lizard populations (both prey and predators). She confirmed that cold and rainy periods affect the predator-prey interaction. Changing behaviour and habitat use, it was concluded, led to changes in the lizard’s body structure (its morphology).
“The prey actually developed bigger legs, adapted for a life on the ground and where predators are less equipped to survive”, she says. “But in dry and sunny periods the prey went back to the trees and their legs shortened to make climbing easier and safer.”
After her time in the United States, the Marie Curie fellow returned to the Canary Islands in order to test the new ideas on lizards found locally (Gallotia genus). Focusing on areas or islands where prey and predator lizards coexist, she studied the morphology among different species in the genus for signs of similar fast-track evolution.
Her research is described in the 2012 article ‘Predators determine how weather affects the spatial niche of a lizard prey’, which was recently accepted by the journal Ecology. It provides empirical evidence of the universal value of Schoener and Losos’ theories – a major accomplishment for the young scientist.
“The Marie Curie grant provided an excellent chance to work and network with world-renowned international researchers,” acknowledges Dr López Darias. It was also a career and life-changing experience: “It gave me the opportunity to reconcile my personal and professional life as a mother and researcher, which is not always easy!” she concludes.