Life history influences rates of climatic niche evolution in flowering plants

Abstract

Across angiosperms, variable rates of molecular substitution are linked with life-history attributes associated with woody and herbaceous growth forms. As the number of generations per unit time is correlated with molecular substitution rates, it is expected that rates of phenotypic evolution would also be influenced by differences in generation times. Here, we make the first broad-scale comparison of growth-form-dependent rates of niche evolution. We examined the climatic niches of species on large time-calibrated phylogenies of five angiosperm clades and found that woody lineages have accumulated fewer changes per million years in climatic niche space than related herbaceous lineages. Also, climate space explored by woody lineages is consistently smaller than sister lineages composed mainly of herbaceous taxa. This pattern is probably linked to differences in the rate of climatic niche evolution. These results have implications for niche conservatism; in particular, the role of niche conservatism in the distribution of plant biodiversity. The consistent differences in the rate of climatic niche evolution also emphasize the need to incorporate models of phenotypic evolution that allow for rate heterogeneity when examining large datasets.

Fossil evidence for a herbaceous diversification of early eudicot angiosperms during the Early Cretaceous

“…This discovery contributes to an emerging pattern of early eudicots and eudicot-like plants as small herbs rather than woody plants as previously thought. An initially herbaceous radiation of eudicots that included the origin of the crown-group makes sense in the context of angiosperm reproductive innovations that promote short seed-to-seed time [66][67][68], because herbs tend to reach reproductive maturity earlier, have higher nucleotide substitution rates and have faster rates of climate niche evolution compared to their woody counterparts [69][70][71][72][73][74]. Therefore, the herbaceous habit may have been a key trait allowing eudicots to diversify in Early Cretaceous communities that were still dominated by gymnosperms and ferns.…”

Are species' responses to global change predicted by past niche evolution?

“…Further, phylogenetic inference of past rates of niche evolution can help to identify life-history traits that have triggered or impeded niche evolution [11,12], and to distinguish between species and lineages that have been prone to niche conservatism versus niche lability [13 -15]. Paralleling the prediction that past evolution should affect current-day dynamics of living organisms [16], past niche evolution might be expected to influence species' responses to global change.…”

Trophic specialization influences the rate of environmental niche evolution in damselfishes (Pomacentridae)

“…While rapid environmental niche shifts within radiating clades have been demonstrated [6,7], the idea that species retain their ancestral niche during diversification has also recently received support [8]. The variation in propensity of species to retain their niche can be linked with important differences in life-history traits, such as growth form in flowering plants, that influence the rate of climatic niche evolution [9]. In this context, the emergence of a novel trait that allows the exploitation of untapped resources may favour the colonization of novel environments and be followed by species radiation.…”

“…This suggests feedback between evolutionary and ecological processes that potentially plays a role in shaping adaptation of species to their environment [3]. Investigating how the niche evolves in interaction with the emergence of novel characters can illustrate how key phenotypic traits constrain or amplify the rate of environmental niche evolution [4,9].…”