TROPHIC NOVELTY IS LINKED TO EXCEPTIONAL RATES OF MORPHOLOGICAL DIVERSIFICATION IN TWO ADAPTIVE RADIATIONS OF CYPRINODON PUPFISH
Article first published online: 11 APR 2011
© 2011 The Author(s). Evolution© 2011 The Society for the Study of Evolution.
Volume 65, Issue 8, pages 2197–2212, August 2011
How to Cite
Martin, C. H. and Wainwright, P. C. (2011), TROPHIC NOVELTY IS LINKED TO EXCEPTIONAL RATES OF MORPHOLOGICAL DIVERSIFICATION IN TWO ADAPTIVE RADIATIONS OF CYPRINODON PUPFISH. Evolution, 65: 2197–2212. doi: 10.1111/j.1558-5646.2011.01294.x
- Issue published online: 26 JUL 2011
- Article first published online: 11 APR 2011
- Accepted manuscript online: 21 MAR 2011 01:46PM EST
- Received July 22, 2010, Accepted March 2, 2011
- Brownian motion;
- comparative method;
- divergent selection;
- ecological speciation;
Adaptive radiations are known for rapid morphological and species diversification in response to ecological opportunity, but it remains unclear if distinct mechanisms drive this pattern. Here, we show that rapid rates of morphological diversification are linked to the evolution of novel ecological niches in two independent Cyprinodon radiations nested within a wide-ranging group repeatedly isolated in extreme environments. We constructed a molecular phylogeny for the Cyprinodontidae, measured 16 functional traits across this group, and compared the likelihoods of single or multiple rates of morphological diversification. We found that rates of morphological diversification within two sympatric Cyprinodon clades containing unique trophic specialists are not part of an adaptive continuum with other clades, but are instead extreme outliers with rates up to 131 times faster than other Cyprinodontidae. High rates were not explained by clade age, but were instead linked to unique trophic niches within Cyprinodon, including scale-eating, zooplanktivory, and piscivory. Furthermore, although both radiations occur in similar environments and have similar sister species, they each evolved unique trophic specialists and high rates of morphological diversification in different sets of traits. We propose that the invasion of novel ecological niches may be a key mechanism driving many classic examples of adaptive radiation.