August 10, 2015

Re-thinking ‘adaptive radiation’ – one of biology’s most important concepts

(August 10, 2015)  A lizard lineage which has evolved over the last 19 million years has helped scientists to re-think one of the most important concepts of modern biology.

‘Adaptive radiation’ is recognised as a pillar of evolutionary science. It describes the development of new biodiversity, and is triggered when a species encounters a new environment with plenty of available resources – this is called ‘ecological opportunity’. This single species then makes the most of these resources and multiplies rapidly into several new forms. When all these resources have been used up by new species, the process of biodiversity proliferation slows down dramatically.

‘Early-bursts’ of new species diversification have previously been seen as a central part of this process – scientists have for decades referred to this trend as a key component of adaptive radiation. However, new research published in the academic journal BMC Evolutionary Biology suggests that the term should not be defined by these early rapid surges.

The revelation comes from scientists at the University of Lincoln, UK, who have been investigating the evolution of the Liolaemus lizard – one of the most species-rich and ecologically diverse lineages of vertebrates.

Their study suggests that the gradual uplifts of the Andes mountain range in South America over millions of years led to the episodic emergence of ecological opportunity, which in turn caused several waves of diversification in this group of lizards. As a result, they found a number of peaks of originations diversification of new Liolaemus lizard species, rather than one ‘early-burst’.

Dr Daniel Pincheira-Donoso, Senior Lecturer in the School of Life Sciences at the University of Lincoln, explained: “Our research shows that the diversification of the Liolaemus lizards has occurred in a number of episodes over an extended period of time. As the Andes uplifted, new ecological opportunity continued to emerge and new bursts of diversification took place – there was never an early explosion followed by a slow-down, but instead, constant pulses of new species evolution.

journal reference (Open Access) >>