PULSES, COURT JESTERS AND RED QUEENS: THE EFFECT OF CLIMATE CHANGE, SPECIES ECOLOGY AND DIVERSITY ON EVOLUTIONARY DYNAMICS

The fact that hominin evolution occurs against a backdrop of major climatic change has naturally generated interest in the relationship between the two. Gloriously named models (Pulse-Turnover, Court Jester, Red Queen, Variability Selection) have been proposed that range from a direct and causal relationship to only a weak link. However, just as we now know that the pattern of climate change is not simple, neither are evolutionary processes. Speciation, rate of phenotypic change, diversity and extinction, for example, are all equally part of evolution, and yet may have distinct relationships with climate. Speciation itself is not the passing of a genetic threshold, but a complex ecological process. This complexity needs to be incorporated into models of climate-organism interactions. This paper will consider the pattern of hominin evolution in the context of a general threshold model of speciation and the different signals of evolutionary change (speciation, extinction, diversity, range size, adaptive novelty and dispersals) that interact, not just with climate, but also with local ecology (competition) and phylogenetic diversity.