The non-gradual nature of adaptive radiation

Abstract

Adaptive radiation is a major source of biodiversity. Still, many aspects of this evolutionary process remain poorly understood. Our recent integrative examination of the cichlid adaptive radiation in African Lake Tanganyika provides new insights into the process of explosive diversification. The in-depth phylogenetic comparative analysis of nearly all species occurring in that lake permitted us to trace patterns of eco-morphological evolution throughout the phylogenetic history of the radiation and revealed that it occurred in a non-gradual manner, in the form of time-shifted bursts of accelerated evolution. The temporal pattern of divergence along different axes of morphological evolution provides empirical support for a scenario that potentially unifies two popular models of adaptive radiation, the “early burst model” and the “stages model”.