No abstract

Interspecific variation in climatic niche breadth underlies many ecological phenomena, yet only recently have studies-focused explicitly on the evolution of climatic niche breadth. Here, we integrate data on geographical distributions, bioclimatic variables, and phylogenetic relationships of 18,404 terrestrial vertebrate species to investigate the evolution of climatic niche breadth. We demonstrate that the evolutionary rates of upper and lower climatic niche boundaries are largely uncoupled. For instance, the rate of evolution of low temperature limits was nearly twice that of high-temperature limits, whereas low-and high-precipitation limits remained relatively constant despite a considerable variation in average precipitation. These results suggest that the evolution of climatic niche breadth is fundamentally different between axes. Finally, we found no relationship between climatic niche breadth and speciation rates. The consistency of these patterns across taxa suggests that they represent general principles governing the evolution of climatic niche breadth.

Aim: Variation in the size and position of geographical ranges is a key variable that underlies most biogeographical patterns. However, relatively little is known in terms of general principles driving their evolution, particularly in the marine realm. In this study we explore several fundamental properties regarding the evolution of reef fish latitudinal ranges, namely the degree of similarity in range size between ancestor and descendant lineages (i.e. phylogenetic signal); the evolution of range limits; and the latitudinal distribution of range sizes, particularly with respect to Rapoport's rule. Location: Global.Taxon: Reef-associated fishes. Methods:We integrate data on the latitudinal distribution and evolutionary history of 5,071 reef fish species with phylogenetic comparative methods to assess the level of phylogenetic signal in latitudinal range size, low-and high-latitude limits and range midpoints, and to estimate rates of evolution of those traits. Finally, we test whether latitudinal ranges become smaller near the equator, as predicted by Rapoport's rule, using phylogenetic generalized least squares.Results: There were varying levels of phylogenetic signal in latitudinal range size, lowand high-latitude limits and range midpoints. Despite these differences, latitudinal midpoints were consistently shown to have the highest phylogenetic signal among all measured geographical features. Interestingly, the position of high-latitude limits in general evolved at substantially faster rates than their low-latitude counterparts.Finally, we confirm for the first time the existence of an inverse Rapoport's rule in reef-associated fishes using phylogenetic comparative methods. Indeed, mean latitudinal range size of tropical species is nearly twice the size of their temperate counterparts (2,067 ± 1,431 km vs. 1,168 ± 725 km respectively). Main conclusions:We uncovered several congruent patterns in phylogenetic signal and rates of evolution of latitudinal ranges, despite vastly disparate biogeographical distributions and ecological differences between the studied fish lineages. Such broad congruence across different taxa and oceans, as well as with previous data from terrestrial environments, suggests that the observed patterns might represent general principles governing geographical range evolution.

Ecological and evolutionary studies traditionally assume that species are comparable units of biodiversity. However, not only this assumption is rarely tested, but also there have been few attempts even to assess variation in most emergent, species-level traits and their corresponding underlying mechanisms. One such trait is species age, here defined as the time since the most recent common ancestor between a given species and its sister lineage. In this study, we demonstrate that different terrestrial vertebrate clades vary considerably in the age of their constituent species. In particular, species ages were youngest in mammals and birds as opposed to squamates and amphibians, although considerable variation was found within those clades as well. Sensitivity analyses showed that these results are unaffected by phylogenetic uncertainty or incomplete taxonomic sampling. Interestingly, there was little geographical correspondence in mean species age across taxa, as well as with temperature and precipitation stability over the past 21,000 years. We discuss candidate mechanisms that might explain differences in species ages among clades, and explore the implications of these findings in relation to recent advances in age-dependent speciation and extinction models of diversification.

Interspecific differences in species abundances are one of the oldest and most universal patterns in ecology, yet little is known about how these differences are generated over evolutionary time. In this study, we test whether there is evidence for phylogenetic signal in population densities of four large groups of terrestrial vertebrates, namely birds, mammals, amphibians, and squamates. In addition, we test the hypothesis that the relative number of species in a clade might be a predictor of the abundance of its constituent species. However, given that the number of species in a clade is the outcome of both its age and diversification rate, and each of these factors was tested separately. Our results provide strong support for phylogenetic signal in species densities for all clades, regardless of differences in how species density was computed, or phylogenetic uncertainty. On the other hand, there was no evidence for a relationship between species abundance and the diversity of its encompassing clade. The implications of phylogenetic signal are discussed in the context of models of species abundance distributions, including Hubbell's neutral theory of biodiversity and biogeography.