Global patterns in the divergence between phylogenetic diversity and species richness in terrestrial birds

Abstract

Aim The conservation value of sites is often based on species richness (SR). However, metrics of phylogenetic diversity (PD) reflect a community's evolutionary potential and reveal the potential for additional conservation value above that based purely on SR. Although PD is typically correlated with SR, localized differences in this relationship have been found in different taxa. Here, we explore geographical variation in global avian PD. We identify where PD is higher or lower than expected (from SR) and explore correlates of those differences, to find communities with high irreplaceability, in terms of the uniqueness of evolutionary histories. Location Global terrestrial.Methods Using comprehensive avian phylogenies and global distributional data for all extant birds, we calculated SR and Faith's PD, a widely applied measure of community PD, across the terrestrial world. We modelled the relationship between avian PD for terrestrial birds and its potential environmental correlates. Analyses were conducted at a global scale and also for individual biogeographical realms. Potential explanatory variables of PD included SR, long-term climate stability, climatic diversity (using altitudinal range as a proxy), habitat diversity and proximity to neighbouring realms.Results We identified areas of high and low relative PD (rPD; PD relative to that expected given SR). Areas of high rPD were associated with deserts and islands, while areas of low rPD were associated with historical glaciation. Our results suggest that rPD is correlated with different environmental variables in different parts of the world.Main conclusions There is geographical variation in avian rPD, much of which can be explained by putative drivers. However, the importance of these drivers shows pronounced regional variation. Moreover, the variation in avian rPD differs substantially from patterns found for mammals and amphibians. We suggest that PD adds additional insights about the irreplaceability of communities to conventional metrics of biodiversity based on SR, and could be usefully included in assessments of site valuation and prioritization.

Environmental factors explain the spatial mismatches between species richness and phylogenetic diversity of terrestrial mammals

“…Here, we demonstrate that regionally structured mismatches between richness and PD of terrestrial mammals are associated with the group biogeographical history and with the different ways in which both dimensions of biodiversity relate to current and past environmental factors. We found more complex spatial patterns than previously anticipated based on per‐realm analysis (Davies et al, ; Gouveia, Villalobos, Dobrovolski, Beltrão‐Mendes, & Ferrari, ; Voskamp et al, ), supporting our claim that geographically weighted path analysis and other GWR‐based methods are promising tools with which to explore complex systems with varying relationships over the space, overcoming the need to split the data arbitrarily into geographical sub‐regions. We argue that spatial variation in environmental–diversity relationships might emerge either from different mechanisms being at play or from different species pools having specific adaptations to environmental gradients (Fergnani & Ruggiero, ; Hawkins et al, ; Ricklefs, ).…”

Geographical patterns and current and short‐term historical correlates of phylogenetic diversity and endemism for New World primates

“…Evolutionary dynamics are important in shaping the patterns of diversity and formation of local biotas. The relatively recent integration of the evolutionary relationships among species into a macroecological framework has allowed a better understanding of how different dimensions of diversity are distributed across space (Davies & Buckley, ; López‐Aguirre et al, ; Rosauer & Jetz, ; Voskamp et al, ). Here, the geographical incongruencies between the patterns of phylogenetic diversity and primates endemism and their taxonomic counterparts suggest a strong signature of biogeographical dynamics of speciation and clade dispersal through the New World in shaping how the phylogenetic component of diversity is distributed.…”

Trophic interactions and abiotic factors drive functional and phylogenetic structure of vertebrate herbivore communities across the Arctic tundra biome

“…The interface of community ecology and biogeography has facilitated efforts to understand the environmental drivers of the phylogenetic and functional structure of communities at large spatial scales (Violle et al 2014, Hempson et al 2015, Thornhill et al 2017). These efforts have largely focussed on abiotic variables, and climatic factors in particular (Safi et al 2011, Voskamp et al 2017). However, our findings propose that trophic interactions can drive both phylogenetic and functional structure of trophic guilds just as strongly as abiotic conditions.…”

“…Phylogenetic diversity is lower in regions with shorter post-glacial history. Rationale: lower recolonization of more recently de-glaciated regions(Voskamp et al 2017) P1.2 Phylogenetic diversity differs between zoogeographical regions. Rationale: dispersal barriers limit some clades to some zoogeographic regions(Eiserhardt et al 2013)…”