Why are some groups of organisms and some regions of Earth more diverse than others?
Explaining the diversity of life is among the most persistent challenges of biology. We use innovative techniques and cutting-edge datasets to investigate behavioural, ecological and evolutionary processes driving the dynamics of species radiations and the evolution of organism traits. We use these insights to further our understanding of why species diversity is so strikingly variable among groups of organisms and across geographical space.
Explaining the diversity of life is among the most persistent challenges of biology. We use innovative techniques and cutting-edge datasets to investigate behavioural, ecological and evolutionary processes driving the dynamics of species radiations and the evolution of organism traits. We use these insights to further our understanding of why species diversity is so strikingly variable among groups of organisms and across geographical space.
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Phenotypic evolution
Studying differences in the tempo and mode of phenotypic evolution among species can provide powerful insights into the forces generating biological diversity. By using 3D scans of bill morphology from >2,000 bird species in museum collections, we showed that bill shape diversity accumulated dramatically soon after birds first originated before later slowing down, thus establishing birds a case of adaptive radiation on a ‘mega-evolutionary’ scale (Cooney et al. 2017). We have also investigated the impact of climatic niche evolution on diversification in birds by estimating rates of niche evolution for >7900 bird species (Cooney et al. 2016). |
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Speciation
A major component of our research has been to investigate the factors promoting speciation and lineage diversification. We have shown that high rates of evolution in key climatic variables are associated with increased diversification at two different taxonomic levels in birds (Cooney et al. 2016). We have also shown that sexual selection does not drive elevated rates of speciation (Cooney et al. 2017), even in recently diverged lineages as once thought. Additionally, earlier work has shown that patterns of species and subspecies richness in Amazonian birds are best predicted by a suite of avian specialisms common in tropical avifaunas but rare in temperate zones (Salisbury et al. 2012), implying that dispersal constraints caused by ecological specialisation contributes to the latitudinal diversity gradient in birds. |
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Co-existence
Speciation in animals is often viewed as a cyclical process beginning with divergence in allopatry and ending with coexistence in sympatry once the evolution of reproductive isolation permits the overlap of geographic ranges. The rate at which species achieve sympatry (i.e. range overlap) following speciation is therefore fundamental to the build-up of diversity and potentially influenced by a combination of factors. By measuring plumage colouration for thousands of avian sister species, we showed for the first time that sexual selection accelerates the rate at which young lineages achieve geographical range overlap (Cooney et al. 2017), consistent with a ‘differential fusion’ model whereby divergent sexual selection reduces rates of fusion among lineages undergoing secondary contact. |
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