update: Shadows of the past: paleo-reconstructions, phylogenies, and macroecological hypotheses - eScholarship

ISSN 1948‐6596 news and update update Shadows of the past: paleo‐reconstructions, phylogenies, and macroecological hypotheses Macroecology has come a long way in providing a synthetic framework mainly by linking ecology and biogeography. Nevertheless, it has expanded its focus thanks to studies considering large temporal scales or which include species evolutionary infor‐ mation. Additionally, data are now available to reconstruct the climatic conditions and habitats at different locations in the past. This deep‐time per‐ spective allows more comprehensive analyses and fosters the integration of different approaches within the common framework provided by mac‐ roecology (Beck et al. 2012). A recent study by Kissling et al. (2012) represents a good example of this trend and its implications for a comprehensive understanding of biodiversity patterns. Kissling and colleagues took advantage of the existence of a palm genera supertree and applied community phylogenetic, macroecological, and paleogeographic methods to understand the causes of current phylogenetic structure in palm species assemblages. Linking specific historical processes to par‐ ticular outcomes in assemblages’ properties is not an easy task. Kissling et al. (2012) exemplify how framing specific hypotheses can help in this en‐ deavor (Table 1). They explicitly evaluated the ef‐ fect of past events—such as habitat availability and biome loss over the Cenozoic—and climate change during the Quaternary on the phylogenetic structure of palm assemblages at different spatial scales (global, hemispheric, and biogeographic realms). By evaluating different spatial scales, they were able to infer which process acted at each scale and compare them among geographic regions of the world. Their results support an ef‐ fect of in situ diversification and geographic isola‐ tion producing phylogenetic clustering, but not supporting the idea that time‐integrated‐area is a strong predictor of phylogenetic structure. Never‐ theless, there were differences among bio‐ geographic realms related to tropical forest loss during the Cenozoic. Furthermore, Quaternary climate change was responsible for phylogenetic clustering in South America and Africa. Interest‐ ingly, Kissling et al. (2012) found phylogenetic overdispersion at transitional areas where biotas Hypotheses Predictions H1: Geographic isolation has caused Phylogenetic clustering within re‐ dispersal limitation and in situ di‐ gions increases with an increasing versification spatial scale of the sampling pool Higher phylogenetic clustering in H2: Large areas over deep geologi‐ cal time have greater diversification areas stable over deep geological rates (“time‐integrated species‐ time area effect” of Fine and Ree 2006) H3: Cenozoic biome losses de‐ creases diversification rates (higher extinction rates, less speciation) Lower phylogenetic clustering in regions suffering greater biome loss H4: Quaternary climate change fil‐ ters species able to survive and/or recolonize Phylogenetic clustering increases in paleoclimatically low‐stable regions Results Agreement with H1: Higher phyloge‐ netic clustering with increasing sam‐ pling pool (e.g., South America, Indo‐ malaya, Australasia) Disagreement with H2: Phylogenetic clustering does not increase in stable areas (e.g., Africa) Agreement with H3: Random phy‐ logenetic clustering in areas with greater Cenozoic biome loss (e.g., Africa) Agreement with H4: Higher phyloge‐ netic clustering within Quaternary unstable areas (e.g., South America) Table 1. A summary of the hypotheses, predictions and main results in Kissling et al. (2012). © 2012 the authors; journal compilation © 2012 The International Biogeography Society — frontiers of biogeography 4.2, 2012