Despite long-standing interest in the origin and maintenance of species diversity, little is known about historical drivers of species assemblage structure at large spatiotemporal scales. Here, we use global species distribution data, a dated genus-level phylogeny, and paleo-reconstructions of biomes and climate to examine Cenozoic imprints on the phylogenetic structure of regional species assemblages of palms (Arecaceae), a species-rich plant family characteristic of tropical ecosystems. We find a strong imprint on phylogenetic clustering due to geographic isolation and in situ diversification, especially in the Neotropics and on islands with spectacular palm radiations (e.g., Madagascar, Hawaii, and Cuba). Phylogenetic overdispersion on mainlands and islands corresponds to biotic interchange areas. Differences in the degree of phylogenetic clustering among biogeographic realms are related to differential losses of tropical rainforests during the Cenozoic, but not to the cumulative area of tropical rainforest over geological time. A largely random phylogenetic assemblage structure in Africa coincides with severe losses of rainforest area, especially after the Miocene. More recent events also appear to be influential: phylogenetic clustering increases with increasing intensity of Quaternary glacial-interglacial climatic oscillations in South America and, to a lesser extent, Africa, indicating that specific clades perform better in climatically unstable regions. Our results suggest that continental isolation (in combination with limited long-distance dispersal) and changing climate and habitat loss throughout the Cenozoic have had strong impacts on the phylogenetic structure of regional species assemblages in the tropics.biodiversity | biogeography | climate change | evolution | extinction D espite long-standing interest, the mechanisms behind the origin and maintenance of high tropical biodiversity remain elusive (1, 2). Much recent macroecological research has focused on explaining large-scale species richness gradients by contemporary climate (3-5), but the importance of evolutionary diversification and past environments has also been highlighted (2,(6)(7)(8). Over the past decades it has become increasingly clear that local community structure depends on both local processes and large-scale factors that influence regional species diversity (9, 10). Regional species assemblages are jointly shaped by within-region diversification and dispersal between regions, the former being constrained by time for speciation (7, 11) and by climatic or other factors influencing net diversification rates (12, 13), and the latter by the formation and disappearance of dispersal barriers (14, 15), time for dispersal (16), and phylogenetic niche conservatism (17). Understanding the historical assembly and present-day structure of regional species assemblages thus requires integration of ecological, paleogeographic, and phylogenetic information (10).Increasing availability of phylogenies has ignited interest in the phylogenetic str...

When taxa go extinct, unique evolutionary history is lost. If extinction is selective, and the intrinsic vulnerabilities of taxa show phylogenetic signal, more evolutionary history may be lost than expected under random extinction. Under what conditions this occurs is insufficiently known. We show that late Cenozoic climate change induced phylogenetically selective regional extinction of northern temperate trees because of phylogenetic signal in cold tolerance, leading to significantly and substantially larger than random losses of phylogenetic diversity (PD). The surviving floras in regions that experienced stronger extinction are phylogenetically more clustered, indicating that non-random losses of PD are of increasing concern with increasing extinction severity. Using simulations, we show that a simple threshold model of survival given a physiological trait with phylogenetic signal reproduces our findings. Our results send a strong warning that we may expect future assemblages to be phylogenetically and possibly functionally depauperate if anthropogenic climate change affects taxa similarly.

Aim  The relative importance of current climate and past historical legacies is hotly debated. Here, we assess their role in determining the global distribution and diversity patterns of palms (Arecaceae), a widespread, species‐rich group of keystone ecological importance in tropical ecosystems. Location  Global. Methods  We assembled country‐level species lists world‐wide and compiled associated data on potential contemporary environmental drivers (current climate, habitat heterogeneity, area, and insularity), Quaternary glacial–interglacial climate change and major biogeographic regions to evaluate to what extent the global distribution and species richness patterns in palms reflect Quaternary climatic oscillations or regional effects reflecting pre‐Quaternary legacies. We also assessed for the first time if historical legacies differ between continents and islands, providing novel insights into determinants of insular species richness. Results  Palm species richness was significantly affected by Quaternary climate changes and further differed between biogeographic regions even when both current environmental conditions and Quaternary climate changes were accounted for. In contrast, global limits to the distribution of the palm family were best explained by current temperature while biogeographic regional differences were unimportant and Quaternary climate change caused only a small constraint. Historical legacies were weak on islands, with only a small regional effect and no effect of Quaternary climate changes. Main conclusions  Strong historical legacies supplement current environment as determinants of palm species richness. These primarily comprise pre‐Quaternary historical effects, reflected in low African species richness (possibly linked to pre‐Quaternary extinctions) and outstandingly high Neotropical and Indomalayan palm species richness (possibly linked to these regions' long‐term climatic suitability for palms). In contrast to species richness, the global distribution of the family range is largely in equilibrium with current climate. The small historical effects on islands are consistent with climatic buffering from their oceanic environment.

Aim Species richness exhibits striking geographical variation, but the processes that drive this variation are unresolved. We investigated the relative importance of two hypothesized evolutionary causes for the variation in palm species richness across the New World: time for diversification and evolutionary (net diversification) rate. Palms have a long history in the region, with the major clades diversifying during the Tertiary (65-2 Ma).Location Tropical and subtropical America (34°N-34°S; 33-120°W).Methods Using range maps, palm species richness was estimated in a 1°· 1°g rid. Mean lineage net diversification was estimated by the mean phylogenetic root distance (MRD), the average number of nodes separating a species from the base of the palm phylogeny for the species in each grid cell. If evolutionary rate limits richness, then richness should increase with MRD. If time limits richness, then old, relict species (with low root distance) should predominantly occur in long-inhabited and therefore species-rich areas. Hence, richness should decrease with MRD. To determine the influence of net diversification across different time frames, MRD was computed for subtribe, genus and species levels within the phylogeny, and supplemented with the purely tip-level measure, mean number of species per genus (MS/G). Correlations and regressions, in combination with eigenvector-based spatial filtering, were used to assess the relationship between species richness, the net diversification measures, and potential environmental and geographical drivers.Results Species richness increased with all net diversification measures. The regression models showed that richness and the net diversification measures increased with decreasing (absolute) latitude and, less strongly, with increasing energy/temperature and water availability. These patterns therefore reflect net diversification at both deep and shallow levels in the phylogeny. Richness also increased with range in elevation, but this was only reflected in the MS/G pattern and therefore reflects recent diversification. Main conclusionsThe geographical patterns in palm species richness appear to be predominantly the result of elevated net diversification rates towards the equator and in warm, wet climates, sustained throughout most of the Tertiary. Late-Tertiary orogeny has caused localized increases in net diversification rates that have also made a mark on the richness pattern.

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To advance our understanding of the processes that govern the assembly of palm communities and the local coexistence of numerous palm species, we here synthesize available information in the literature on species diversity and growth-form composition in palm communities across the Americas. American palm communities surveyed had 4-48 (median 16) species in study plots covering 0.09-7.2 ha. Climate, soils, hydrology, and topography are the main factors determining palm community species richness. Tropical lowland terra firme rain forests are the most species-rich whereas forests that are inundated or grow on sandy soils or in areas with seasonal climate have much fewer species. Palm communities in the central-western Amazon and in Central America are significantly richer than the average region and those in the Caribbean significantly poorer in species. As for branching, the 789 species of tropical American palms belong to Corner's model (solitary, 268 species, 33%), Tomlinsons model (cespitose, 521 species, 66%) and Schoute's model (dichotomous branching, three species, <1%). We assigned the species to eight different growth forms: (i) Large tall-stemmed Palms (102 spp), (ii) Large-leaved medium-short-stemmed Palms (31 spp), (iii) Medium-sized Palms (95 spp), (iv) Medium/Small Palms with Stout Stem (42 spp), (v) Small Palms (423 spp), (vi) Large acaulescent Palms (28 spp), (vii) Small acaulescent Palms (56 spp), and (viii) Climbing Palms (12 spp). The eight growth forms are differently represented in the palm communities, and the categories Small Palms and Large tall-stemmed Palms dominate the communities both in terms of species richness and in number of individuals.

Bactridinae include about 150 species of spiny Neotropical palms in five genera that are ecologically important in several vegetation types such as open woodland (Acrocomia), lowland rainforest (Astrocaryum, Bactris), and montane forest (Aiphaness). The subtribe also includes the only exclusively lianescent palm genus in the Neotropics (Desmoncus). We present a fully resolved molecular phylogeny of 41 species of Bactridinae, representing all genera as well as most of the currently ac ‐ cepted infrageneric taxa (subgenera, sections etc.) and recently proposed informal groups. Analyses are based on five plastid DNA regions (matK, trnQ‐rps16, rps16 intron, trnD‐trnT, trnL‐trnF) and three nuclear markers (PRK, RPB2, ITS). A combined dataset was analysed with likelihood and parsimony methods. The results show that all accepted taxa at and above the generic level are monophyletic with high support. Astrocaryum alatum and A. mexicanum, recently segregated into a genus of their own (Hexopetion), form a strongly supported monophyletic group sister to the remaining Astrocaryum species. Desmoncus and Acrocomia are resolved as sister genera, and together they are sister to the remaining Bactridinae. This finding contrasts with that of two previous studies reporting Acrocomia to be sister to the rest of the subtribe. Aiphanes is resolved as sister to Bactris and Astrocaryum. Species‐level relationships recovered within Astrocaryum and Bactris disagree to a large extent with previous morphology‐based infrageneric classifications, suggesting that those characters are homoplasious, particularly within Bactris. A Bayesian dating analysis using the relaxed‐clock model indicates that most genera of Bactridinae diverged during a relatively short period around the Eocene–Oligocene boundary, which might explain the difficulties in resolving the phylogenetic backbone of the group. The mostly Andean genus Aiphanes shows an initial radiation of early lineages in the Oligocene (around 25 Ma ago) corresponding to an early uplift phase of the cordillera. These taxa are nowadays restricted to the mountain forests of Colombia and Ecuador. The main diversification of Andean Aiphanes began in the Miocene (around 11 Ma ago). This study provides the first substantial insight into Bactridinae phylogeny and sets the stage for more comprehensively sampled species‐level studies analysing drivers of diversity of Neotropical palms, speciation patterns, character evolution, or biogeography.

Visitors to palm inflorescences are attracted by rewards such as food, shelter and oviposition sites. The interaction between the palm and its visiting fauna represents a trade-off between the services provided by the potential pollinators and the antagonistic activities of other insect visitors. Evidence suggests that beetles constitute the most important group of pollinators in palms, followed by bees and flies. Occasional pollinators include mammals (e.g. bats and marsupials) and even crabs. Comparative studies of palm-pollinator interactions in closely related palm species document transitions in floral morphology, phenology and anatomy correlated with shifts in pollination vectors. Synecological studies show that asynchronous flowering and partitioning of pollinator guilds may be important regulators of gene flow between closely related sympatric taxa and potential drivers of speciation processes. Studies of larger plant-pollinator networks point out the importance of competition for pollinators between palms and other flowering plants and document how the insect communities in tropical forest canopies probably influence the reproductive success of palms. However, published studies have a strong geographical bias towards the South American region and a taxonomic bias towards the tribe Cocoseae. Future studies should try to correct this imbalance to provide a more representative picture of pollination mechanisms and their evolutionary implications across the entire family.