Riparian areas as a conservation priority under climate change.

Identifying climatic refugia is important for long-term conservation planning under climate change. Riparian areas have the potential to provide climatic refugia for wildlife, but literature remains limited, especially for plants. This study was conducted with the purpose of identifying climatic refugia of plant biodiversity in the portion of the Mekong River Basin located in Xishuangbanna, China. We first predicted the current and future (2050s and 2070s) potential distribution of 50 threatened woody species in Xishuangbanna by using an ensemble of small models, then stacked the predictions for individual species to derive spatial biodiversity patterns within each 10 × 10 km grid cell. We then identified the top 17 % of the areas for spatial biodiversity patterns as biodiversity hotspots, with climatic refugia defined as areas that remained as biodiversity hotspots over time. Stepwise regression and linear correlation were applied to analyze the environmental correlations with spatial biodiversity patterns and the relationships between climatic refugia and river distribution, respectively. Our results showed potential upward and northward shifts in threatened woody species, with range contractions and expansions predicted. The spatial biodiversity patterns shift from southeast to northwest, and were influenced by temperature, precipitation, and elevation heterogeneity. Climatic refugia under climate change were related closely to river distribution in Xishuangbanna, with riparian areas identified that could provide climatic refugia. These refugial zones are recommended as priority conservation areas for mitigating the impacts of climate change on biodiversity. Our study confirmed that riparian areas could act as climatic refugia for plants and emphasizes the conservation prioritization of riparian areas within river basins for protecting biodiversity under climate change.

Spatial phylogenetics of the Chinese angiosperm flora provides insights into endemism and conservation.

The flora of China is well known for its high diversity and endemism. Identifying centers of endemism and designating conservation priorities are essential goals for biodiversity studies. However, there is no comprehensive study from a rigorous phylogenetic perspective to understand patterns of diversity and endemism and to guide biodiversity conservation in China. We conducted a spatial phylogenetic analysis of the Chinese angiosperm flora at the generic level to identify centers of neo- and paleo-endemism. Our results indicate that: (i) the majority of grid cells in China with significantly high phylogenetic endemism (PE) were located in the mountainous regions; (ii) four of the nine centers of endemism recognized, located in northern and western China, were recognized for the first time; (iii) arid and semiarid regions in Northwest China were commonly linked to significant PE, consistent with other spatial phylogenetic studies worldwide; and (iv) six high-priority conservation gaps were detected by overlaying the boundaries of China's nature reserves on all significant PE cells. Overall, we conclude that the mountains of southern and northern China contain both paleo-endemics (ancient relictual lineages) and neo-endemics (recently diverged lineages). The areas we highlight as conservation priorities are important for broad-scale planning, especially in the context of evolutionary history preservation.

Phylogenetic diversity and conservation of crop wild relatives in Colombia.

Crop wild relatives (CWR) are an important agricultural resource as they contain genetic traits not found in cultivated species due to localized adaptation to unique environmental and climatic conditions. Phylogenetic diversity (PD) measures the evolutionary relationship of species using the tree of life. Our knowledge of CWR PD in neotropical regions is in its infancy. We analysed the distribution of CWR PD across Colombia and assessed its conservation status. The areas with the largest concentration of PD were identified as being in the northern part of the central and western Andean mountain ranges and the Pacific region. These centres of high PD were comprised of predominantly short and closely related branches, mostly of species of wild tomatoes and black peppers. In contrast, the CWR PD in the lowland ecosystems of the Amazon and Orinoquia regions had deeply diverging clades predominantly represented by long and distantly related branches (i.e. tuberous roots, grains and cacao). We categorized 50 (52.6%) of the CWR species as 'high priority', 36 as 'medium priority' and nine as 'low priority' for further ex-situ and in situ conservation actions. New areas of high PD and richness with large ex-situ gap collections were identified mainly in the northern part of the Andes of Colombia. We found that 56% of the grid cells with the highest PD values were unprotected. These baseline data could be used to create a comprehensive national strategy of CWR conservation in Colombia.

A nuclear phylogenomic study of the angiosperm order Myrtales, exploring the potential and limitations of the universal Angiosperms353 probe set.

PREMISE: To further advance the understanding of the species-rich, economically and ecologically important angiosperm order Myrtales in the rosid clade, comprising nine families, approximately 400 genera and almost 14,000 species occurring on all continents (except Antarctica), we tested the Angiosperms353 probe kit. METHODS: We combined high-throughput sequencing and target enrichment with the Angiosperms353 probe kit to evaluate a sample of 485 species across 305 genera (76% of all genera in the order). RESULTS: Results provide the most comprehensive phylogenetic hypothesis for the order to date. Relationships at all ranks, such as the relationship of the early-diverging families, often reflect previous studies, but gene conflict is evident, and relationships previously found to be uncertain often remain so. Technical considerations for processing HTS data are also discussed. CONCLUSIONS: High-throughput sequencing and the Angiosperms353 probe kit are powerful tools for phylogenomic analysis, but better understanding of the genetic data available is required to identify genes and gene trees that account for likely incomplete lineage sorting and/or hybridization events.

Spatial phylogenetics of the native woody plant species in Hainan, China.

To better identify biodiversity hotspots for conservation on Hainan Island, a tropical island in southern China, we assessed spatial variation in phylogenetic diversity and species richness using 18,976 georeferenced specimen records and a newly reconstructed molecular phylogeny of 957 native woody plants. Within this framework, we delineated bioregions based on vegetation composition and mapped areas of neoendemism and paleoendemism to identify areas of priority for conservation. Our results reveal that the southwest of Hainan is the most important hot spot for endemism and plant diversity followed by the southeast area. The distribution of endemic species showed a scattered, rather than clustered, pattern on the island. Based on phylogenetic range-weighted turnover metrics, we delineated three major vegetational zones in Hainan. These largely correspond to natural secondary growth and managed forests (e.g., rubber and timber forests) in central Hainan, old-growth forests and natural secondary growth forest at the margins of Hainan, and nature reserves on the island (e.g., Jianfeng and Diaoluo National Nature Reserves). Our study helps to elucidate potential botanical conservation priorities for Hainan within an evolutionary, phylogenetic framework.

Global predictors of alien plant establishment success: combining niche and trait proxies.

Biological invasions are on the rise globally. To reduce future invasions, it is imperative to determine the naturalization potential of species. Until now, screening approaches have relied largely on species-specific functional feature data. Such information is, however, time-consuming and expensive to collect, thwarting the screening of large numbers of potential invaders. We propose to resolve such data limitations by developing indicators of establishment success of alien species that can be readily derived from open-access databases. These indicators describe key features of successfully established aliens, including estimates of potential range size, niche overlap with human-disturbed environments, and proxies of species traits related to their palaeoinvasions and local dominance capacities. We demonstrate the utility of this new approach by applying it to two large and highly invasive plant groups: Australian acacias and eucalypts. Our results show that these indicators robustly predict establishment successes and failures in each clade independently, and that they can cross-predict establishment in these two clades. Interestingly, the indicator identified as most important was species potential range size on Earth, a variable too rarely considered as a predictor. By successfully identifying key features that predispose Australian plants to naturalize, we provide an objective and cost-effective protocol for flagging high-risk introductions.

Do phytogeographic patterns reveal biomes or biotic regions?

We present the largest comparative biogeographical analysis that has complete coverage of Australia's geography (20 phytogeographical subregions), using the most complete published molecular phylogenies to date of large Australian plant clades (Acacia, Banksia and the eucalypts). Two distinct sets of areas within the Australian flora were recovered, using distributional data from the Australasian Virtual Herbarium (AVH) and the Atlas of Living Australia (ALA): younger Temperate, Eremaean and Monsoonal biomes, and older southwest + west, southeast and northern historical biogeographical regions. The analyses showed that by partitioning the data into two sets, using either a Majority or a Frequency method to select taxon distributions, two equally valid results were found. The dataset that used a Frequency method discovered general area cladograms that resolved patterns of the Australian biomes, whereas if widespread taxa (Majority method, with >50% of occurrences outside a single subregion) were removed the analysis then recovered historical biogeographical regions. The study highlights the need for caution when processing taxon distributions prior to analysis as, in the case of the history of Australian phytogeography, the validity of both biomes and historical areas have been called into question.

Facets of phylodiversity: evolutionary diversification, divergence and survival as conservation targets.

Biodiversity is often described as having multiple facets, including species richness, functional diversity and phylogenetic diversity. In this paper, we argue that phylogenetic diversity itself has three distinct facets-lineage diversification, character divergence and survival time-that can be quantified using distinct branch length metrics on an evolutionary tree. Each dimension is related to different processes of macroevolution, has different spatial patterns and is tied to distinct goals for conserving biodiversity and protecting its future resilience and evolutionary potential. We compared the landscapes identified as top conservation priorities by each of these three metrics in a conservation gap analysis for California, a world biodiversity hotspot, using herbarium data on the biogeography and evolutionary relationships of more than 5000 native plant species. Our analysis incorporated a novel continuous metric of current land protection status, fine-scale data on landscape intactness and an optimization algorithm used to identify complementary priority sites containing concentrations of taxa that are evolutionarily unique, vulnerable due to small range size and/or poorly protected across their ranges. Top conservation priorities included pockets of coastal and northern California that ranked highly for all three phylodiversity dimensions and for species richness, as well as sites uniquely identified by each metric whose value may depend on whether properties such as genetic divergence, high net diversification or independent survival experience are most desirable in an Anthropocene flora.This article is part of the theme issue 'Biological collections for understanding biodiversity in the Anthropocene'.

Spatial phylogenetics of the native California flora.

BACKGROUND: California is a world floristic biodiversity hotspot where the terms neo- and paleo-endemism were first applied. Using spatial phylogenetics, it is now possible to evaluate biodiversity from an evolutionary standpoint, including discovering significant areas of neo- and paleo-endemism, by combining spatial information from museum collections and DNA-based phylogenies. Here we used a distributional dataset of 1.39 million herbarium specimens, a phylogeny of 1083 operational taxonomic units (OTUs) and 9 genes, and a spatial randomization test to identify regions of significant phylogenetic diversity, relative phylogenetic diversity, and phylogenetic endemism (PE), as well as to conduct a categorical analysis of neo- and paleo-endemism (CANAPE). RESULTS: We found (1) extensive phylogenetic clustering in the South Coast Ranges, southern Great Valley, and deserts of California; (2) significant concentrations of short branches in the Mojave and Great Basin Deserts and the South Coast Ranges and long branches in the northern Great Valley, Sierra Nevada foothills, and the northwestern and southwestern parts of the state; (3) significant concentrations of paleo-endemism in Northwestern California, the northern Great Valley, and western Sonoran Desert, and neo-endemism in the White-Inyo Range, northern Mojave Desert, and southern Channel Islands. Multiple analyses were run to observe the effects on significance patterns of using different phylogenetic tree topologies (uncalibrated trees versus time-calibrated ultrametric trees) and using different representations of OTU ranges (herbarium specimen locations versus species distribution models). CONCLUSIONS: These analyses showed that examining the geographic distributions of branch lengths in a statistical framework adds a new dimension to California floristics that, in comparison with climatic data, helps to illuminate causes of endemism. In particular, the concentration of significant PE in more arid regions of California extends previous ideas about aridity as an evolutionary stimulus. The patterns seen are largely robust to phylogenetic uncertainty and time calibration but are sensitive to the use of occurrence data versus modeled ranges, indicating that special attention toward improving geographic distributional data should be top priority in the future for advancing understanding of spatial patterns of biodiversity.

Genus-wide variation in foliar polyphenolics in eucalypts.

Many studies quantify total phenolics or total tannins, but understanding the ecological role of polyphenolic secondary metabolites requires at least an understanding of the diversity of phenolic groups present. We used UPLC-MS/MS to measure concentrations of different polyphenol groups - including the four most common tannin groups, the three most common flavonoid groups, and quinic acid derivatives - in foliage from 628 eucalypts from the genera Eucalyptus, Angophora and Corymbia. We also tested for phylogenetic signal in each of the phenolic groups. Many eucalypts contained high concentrations of polyphenols, particularly ellagitannins, which have been relatively poorly studied, but may possess strong oxidative activity. Because the biosynthetic pathways of many phenolic compounds share either precursors or enzymes, we found negative correlations between the concentrations of several of the constituents that we measured, including proanthocyanidins (PAs) and hydrolysable tannins (HTs), HTs and flavonol derivatives, and HTs and quinic acid derivatives. We observed moderate phylogenetic signal in all polyphenol constituents, apart from the concentration of the prodelphinidin subunit of PAs and the mean degree of polymerisation of PAs. These two traits, which have previously been shown to be important in determining plants' protein precipitation capacity, may have evolved under selection, perhaps in response to climate or herbivore pressure. Hence, the signature of evolutionary history appears to have been erased for these traits. This study is an important step in moving away from analysing "totals" to a better understanding of how phylogenetic effects influence phenolic composition, and how this in turn influences ecological processes.

Spatial phylogenetics of the vascular flora of Chile.

Current geographic patterns of biodiversity are a consequence of the evolutionary history of the lineages that comprise them. This study was aimed at exploring how evolutionary features of the vascular flora of Chile are distributed across the landscape. Using a phylogeny at the genus level for 87% of the Chilean vascular flora, and a geographic database of sample localities, we calculated phylogenetic diversity (PD), phylogenetic endemism (PE), relative PD (RPD), and relative PE (RPE). Categorical Analyses of Neo- and Paleo-Endemism (CANAPE) were also performed, using a spatial randomization to assess statistical significance. A cluster analysis using range-weighted phylogenetic turnover was used to compare among grid cells, and with known Chilean bioclimates. PD patterns were concordant with known centers of high taxon richness and the Chilean biodiversity hotspot. In addition, several other interesting areas of concentration of evolutionary history were revealed as potential conservation targets. The south of the country shows areas of significantly high RPD and a concentration of paleo-endemism, and the north shows areas of significantly low PD and RPD, and a concentration of neo-endemism. Range-weighted phylogenetic turnover shows high congruence with the main macrobioclimates of Chile. Even though the study was done at the genus level, the outcome provides an accurate outline of phylogenetic patterns that can be filled in as more fine-scaled information becomes available.

Species richness and endemism in the native flora of California.

PREMISE OF THE STUDY: California's vascular flora is the most diverse and threatened in temperate North America. Previous studies of spatial patterns of Californian plant diversity have been limited by traditional metrics, non-uniform geographic units, and distributional data derived from floristic descriptions for only a subset of species. METHODS: We revisited patterns of sampling intensity, species richness, and relative endemism in California based on equal-area spatial units, the full vascular flora, and specimen-based distributional data. We estimated richness, weighted endemism (inverse range-weighting of species), and corrected weighted endemism (weighted endemism corrected for richness), and performed a randomization test for significantly high endemism. KEY RESULTS: Possible biases in herbarium data do not obscure patterns of high richness and endemism at the spatial resolution studied. High species richness was sometimes associated with significantly high endemism (e.g., Klamath Ranges) but often not. In Stebbins and Major's (1965) main endemism hotspot, Southwestern California, species richness is high across much of the Peninsular and Transverse ranges but significantly high endemism is mostly localized to the Santa Rosa and San Bernardino mountains. In contrast, species richness is low in the Channel Islands, where endemism is significantly high, as also found for much of the Death Valley region. CONCLUSIONS: Measures of taxonomic richness, even with greater weighting of range-restricted taxa, are insufficient for identifying areas of significantly high endemism that warrant conservation attention. Differences between our findings and those in previous studies appear to mostly reflect the source and scale of distributional data, and recent analytical refinements.

Interpreting the modern distribution of Myrtaceae using a dated molecular phylogeny.

The angiosperm family Myrtaceae has extant and fossil taxa from all southern continents and is assumed to be of Gondwanan origin. Many modern groups contain sister taxa that have disjunct transoceanic distributions, which can be interpreted as a result of either vicariance or long-distance dispersal and establishment (LDDE). Further, some Myrtaceae groups occur on Pacific islands with enigmatic geological histories. We tested hypotheses of vicariance and LDDE by estimating divergence times using a relaxed molecular clock calibrated with 12 fossils. In total, 88 genera and 202 species were sampled, representing both subfamilies and all tribes of Myrtaceae. We reconstructed the family as Gondwanan in origin. Of the 22 geographically disjunct sister groups in our study, up to six are potentially explained as the product of vicariance, three resulting from overland dispersal via new land connections, and 13 due to LDDE events. Nine of the 13 hypothesized LDDE events occurred in fleshy-fruited taxa. Our results indicate that most of the transoceanic distribution patterns in Myrtaceae have occurred since the Miocene due to LDDE, whereas inferred vicariance events all occurred before the Late Eocene. There are many instances of sister relationships between species-poor and species-rich groups in Myrtaceae, and at least three occurrences of geographically isolated taxa on long branches of the phylogeny (Arillastrum, Myrtus, and Tepualia), whose modern-day distributions are difficult to explain without additional fossil or geological evidence.

Continental scale patterns and predictors of fern richness and phylogenetic diversity.

Because ferns have a wide range of habitat preferences and are widely distributed, they are an ideal group for understanding how diversity is distributed. Here we examine fern diversity on a broad-scale using standard and corrected richness measures as well as phylogenetic indices; in addition we determine the environmental predictors of each diversity metric. Using the combined records of Australian herbaria, a dataset of over 60,000 records was obtained for 89 genera to infer richness. A molecular phylogeny of all the genera was constructed and combined with the herbarium records to obtain phylogenetic diversity patterns. A hotspot of both taxic and phylogenetic diversity occurs in the Wet Tropics of northeastern Australia. Although considerable diversity is distributed along the eastern coast, some important regions of diversity are identified only after sample-standardization of richness and through the phylogenetic metric. Of all of the metrics, annual precipitation was identified as the most explanatory variable, in part, in agreement with global and regional fern studies. However, precipitation was combined with a different variable for each different metric. For corrected richness, precipitation was combined with temperature seasonality, while correlation of phylogenetic diversity to precipitation plus radiation indicated support for the species-energy hypothesis. Significantly high and significantly low phylogenetic diversity were found in geographically separate areas. These separate areas correlated with different climatic conditions such as seasonality in precipitation. The phylogenetic metrics identified additional areas of significant diversity, some of which have not been revealed using traditional taxonomic analyses, suggesting that different ecological and evolutionary processes have operated over the continent. Our study demonstrates that it is possible and vital to incorporate evolutionary metrics when inferring biodiversity hotspots from large compilations of data.

Phylogenetic diversity meets conservation policy: small areas are key to preserving eucalypt lineages.

Evolutionary and genetic knowledge is increasingly being valued in conservation theory, but is rarely considered in conservation planning and policy. Here, we integrate phylogenetic diversity (PD) with spatial reserve prioritization to evaluate how well the existing reserve system in Victoria, Australia captures the evolutionary lineages of eucalypts, which dominate forest canopies across the state. Forty-three per cent of remaining native woody vegetation in Victoria is located in protected areas (mostly national parks) representing 48% of the extant PD found in the state. A modest expansion in protected areas of 5% (less than 1% of the state area) would increase protected PD by 33% over current levels. In a recent policy change, portions of the national parks were opened for development. These tourism development zones hold over half the PD found in national parks with some species and clades falling entirely outside of protected zones within the national parks. This approach of using PD in spatial prioritization could be extended to any clade or area that has spatial and phylogenetic data. Our results demonstrate the relevance of PD to regional conservation policy by highlighting that small but strategically located areas disproportionally impact the preservation of evolutionary lineages.

Assessing biodiversity and endemism using phylogenetic methods across multiple taxonomic groups.

Identifying geographical areas with the greatest representation of the tree of life is an important goal for the management and conservation of biodiversity. While there are methods available for using a single phylogenetic tree to assess spatial patterns of biodiversity, there has been limited exploration of how separate phylogenies from multiple taxonomic groups can be used jointly to map diversity and endemism. Here, we demonstrate how to apply different phylogenetic approaches to assess biodiversity across multiple taxonomic groups. We map spatial patterns of phylogenetic diversity/endemism to identify concordant areas with the greatest representation of biodiversity across multiple taxa and demonstrate the approach by applying it to the Murray-Darling basin region of southeastern Australia. The areas with significant centers of phylogenetic diversity and endemism were distributed differently for the five taxonomic groups studied (plant genera, fish, tree frogs, acacias, and eucalypts); no strong shared patterns across all five groups emerged. However, congruence was apparent between some groups in some parts of the basin. The northern region of the basin emerges from the analysis as a priority area for future conservation initiatives focused on eucalypts and tree frogs. The southern region is particularly important for conservation of the evolutionary heritage of plants and fishes.

Phylogenetic measures of biodiversity and neo- and paleo-endemism in Australian Acacia.

Understanding spatial patterns of biodiversity is critical for conservation planning, particularly given rapid habitat loss and human-induced climatic change. Diversity and endemism are typically assessed by comparing species ranges across regions. However, investigation of patterns of species diversity alone misses out on the full richness of patterns that can be inferred using a phylogenetic approach. Here, using Australian Acacia as an example, we show that the application of phylogenetic methods, particularly two new measures, relative phylogenetic diversity and relative phylogenetic endemism, greatly enhances our knowledge of biodiversity across both space and time. We found that areas of high species richness and species endemism are not necessarily areas of high phylogenetic diversity or phylogenetic endemism. We propose a new method called categorical analysis of neo- and paleo-endemism (CANAPE) that allows, for the first time, a clear, quantitative distinction between centres of neo- and paleo-endemism, useful to the conservation decision-making process.

Quantifying phytogeographical regions of Australia using geospatial turnover in species composition.

The largest digitized dataset of land plant distributions in Australia assembled to date (750,741 georeferenced herbarium records; 6,043 species) was used to partition the Australian continent into phytogeographical regions. We used a set of six widely distributed vascular plant groups and three non-vascular plant groups which together occur in a variety of landscapes/habitats across Australia. Phytogeographical regions were identified using quantitative analyses of species turnover, the rate of change in species composition between sites, calculated as Simpson's beta. We propose six major phytogeographical regions for Australia: Northern, Northern Desert, Eremaean, Eastern Queensland, Euronotian and South-Western. Our new phytogeographical regions show a spatial agreement of 65% with respect to previously defined phytogeographical regions of Australia. We also confirm that these new regions are in general agreement with the biomes of Australia and other contemporary biogeographical classifications. To assess the meaningfulness of the proposed phytogeographical regions, we evaluated how they relate to broad scale environmental gradients. Physiographic factors such as geology do not have a strong correspondence with our proposed regions. Instead, we identified climate as the main environmental driver. The use of an unprecedentedly large dataset of multiple plant groups, coupled with an explicit quantitative analysis, makes this study novel and allows an improved historical bioregionalization scheme for Australian plants. Our analyses show that: (1) there is considerable overlap between our results and older biogeographic classifications; (2) phytogeographical regions based on species turnover can be a powerful tool to further partition the landscape into meaningful units; (3) further studies using phylogenetic turnover metrics are needed to test the taxonomic areas.

Regional population expansion in Eucalyptus globulus.

Foundation tree species define the structure of forest habitat and influence their ecosystem dynamics. However, there is limited understanding of both the patterns and timing of population fluctuations in foundation trees and how they vary among geographical regions. We have reconstructed the demographic history of five genetically distinct populations of the Tasmanian blue gum (Eucalyptus globulus ssp. globulus) at the species and regional levels, using three nuclear loci sequenced from 104 individuals. Analysis using a Bayesian skyline plot indicated that the species experienced two periods of expansion, commencing in the Pliocene. Regional analyses showed that island populations expanded earlier, but that the rate of expansion was relatively slow when compared to that of the mainland group. This highlights the need for local demographic history to be taken into account when inferring local adaptation for candidate genes. Population growth throughout the Quaternary signals the ability of the species to persist and thrive under the predominantly harsh conditions of this period.

Are pollen fossils useful for calibrating relaxed molecular clock dating of phylogenies? A comparative study using Myrtaceae.

The identification and application of reliable fossil calibrations represents a key component of many molecular studies of evolutionary timescales. In studies of plants, most paleontological calibrations are associated with macrofossils. However, the pollen record can also inform age calibrations if fossils matching extant pollen groups are found. Recent work has shown that pollen of the myrtle family, Myrtaceae, can be classified into a number of morphological groups that are synapomorphic with molecular groups. By assembling a data matrix of pollen morphological characters from extant and fossil Myrtaceae, we were able to measure the fit of 26 pollen fossils to a molecular phylogenetic tree using parsimony optimisation of characters. We identified eight Myrtaceidites fossils as appropriate for calibration based on the most parsimonious placements of these fossils on the tree. These fossils were used to inform age constraints in a Bayesian phylogenetic analysis of a sequence alignment comprising two sequences from the chloroplast genome (matK and ndhF) and one nuclear locus (ITS), sampled from 106 taxa representing 80 genera. Three additional analyses were calibrated by placing pollen fossils using geographic and morphological information (eight calibrations), macrofossils (five calibrations), and macrofossils and pollen fossils in combination (12 calibrations). The addition of new fossil pollen calibrations led to older crown ages than have previously been found for tribes such as Eucalypteae and Myrteae. Estimates of rate variation among lineages were affected by the choice of calibrations, suggesting that the use of multiple calibrations can improve estimates of rate heterogeneity among lineages. This study illustrates the potential of including pollen-based calibrations in molecular studies of divergence times.