Extent and timing of floristic exchange between Australian and Asian rain forests

Aim We tested an entrenched concept – that the Australian rain forest flora is essentially a Gondwanan relict. We also assessed the role of regional‐level source–sink dynamics in the assembly of this flora. Location Eastern Australia. Methods To avoid potential biases inherent in selective studies undertaken to date, we used an analytical, whole‐of‐flora approach integrated with the fossil record. We identified disjunctions between woody Australian rain forest plant taxa and relatives on other land masses. To test the strength of the fossil evidence for the regional antiquity of this flora, we evaluated the proportion of these disjunct clades represented in the Australian fossil record, and to minimize the effects of biases in this record, we compared late Quaternary (i.e. late Pleistocene and Holocene, 126–0 ka), Pliocene and late Oligocene–early Miocene Australian pollen records interpreted as tropical rain forest. Using within‐species disjunctions as a proxy, we assessed the role of recent immigration from Asia into Australia. To assess the role of source–sink dynamics, we performed comparative analyses of disjunctions in major rain forest categories representing a north–south/climatic gradient. Results Southern Australian, cool temperate (microthermal) rain forests contain many floristic disjunctions with Gondwanan fragments and most of these clades have Gondwanan fossils. Disjunct clades in Australian mesothermal rain forest mostly occur in Asia/Malesia and a low proportion of these clades show pre‐Neogene records. Many clades in lowland tropical and ‘dry’ rain forest show disjunctions with Asia/Malesia and few have Australian fossil records. Rates of recent immigration from Asia/Malesia are high in these northern forests, and outweigh rates of recent emigration approximately nine‐fold. The late Quaternary fossil record has many more rain forest angiosperms than Oligocene–Miocene and Pliocene floras, consistent with extensive late Cenozoic immigration. Main conclusions The microthermal rain forests are largely Gondwanan relicts, but there is progressively greater, and more recent contribution from Asia/Malesia into more northern, and more lowland tropical rain forests. This variation reflects a strong gradient in geographic and ecological proximity between these forests and source floras in Asia/Malesia, and is consistent with a source–sink size model of immigration driven by late Cenozoic contractions and expansions of Australian rain forest.     

Australian biogeographical connections and the phylogeny of large genera in the plant family Myrtaceae

Aim To compare the phylogeny of the eucalypt and melaleuca groups with geological events and ages of fossils to discover the time frame of clade divergences. Location Australia, New Caledonia, New Guinea, Indonesian Archipelago. Methods We compare published molecular phylogenies of the eucalypt and melaleuca groups of the plant family Myrtaceae with geological history and known fossil records from the Cretaceous and Cenozoic. Results The Australasian eucalypt group includes seven genera, of which some are relictual rain forest taxa of restricted distribution and others are species‐rich and widespread in drier environments. Based on molecular and morphological data, phylogenetic analyses of the eucalypt group have identified two major clades. The monotypic Arillastrum endemic to New Caledonia is related in one clade to the more species‐rich Angophora, Corymbia and Eucalyptus that dominate the sclerophyll vegetation of Australia. Based on the time of rifting of New Caledonia from eastern Gondwana and the age of fossil eucalypt pollen, we argue that this clade extends back to the Late Cretaceous. The second clade includes three relictual rain forest taxa, with Allosyncarpia from Arnhem Land the sister taxon to Eucalyptopsis of New Guinea and the eastern Indonesian archipelago, and Stockwellia from the Atherton Tableland in north‐east Queensland. As monsoonal, drier conditions evolved in northern Australia, Arnhem Land was isolated from the wet tropics to the east and north during the Oligocene, segregating ancestral rain forest biota. It is argued also that the distribution of species in Eucalyptopsis and Eucalyptus subgenus Symphyomyrtus endemic in areas north of the stable edge of the Australian continent, as far as Sulawesi and the southern Philippines, is related to the geological history of south‐east Asia‐Australasia. Colonization (dispersal) may have been aided by rafting on micro‐continental fragments, by accretion of arc terranes onto New Guinea and by land brought into closer proximity during periods of low sea‐level, from the Late Miocene and Pliocene. The phylogenetic position of the few northern, non‐Australian species of Eucalyptus subgenus Symphyomyrtus suggests rapid radiation in the large Australian sister group(s) during this time frame. A similar pattern, connecting Australia and New Caledonia, is emerging from phylogenetic analysis of the Melaleuca group (Beaufortia suballiance) within Myrtaceae, with Melaleuca being polyphyletic. Main conclusion The eucalypt group is an old lineage extending back to the Late Cretaceous. Differentiation of clades is related to major geological and climatic events, including rifting of New Caledonia from eastern Gondwana, development of monsoonal and drier climates, collision of the northern edge of the Australian craton with island arcs and periods of low sea level. Vicariance events involve dispersal of biota.     

Early Pleistocene vegetation change in upland south‐eastern Australia

Aim This study aims to improve our understanding of the late Cenozoic history of Australian rain forest and sclerophyll biomes by presenting a detailed pollen record demonstrating the floristic composition and orbital‐scale patterns of change in forest communities of upland south‐eastern Australia, during the Early Pleistocene. The record is examined in order to shed light on the nature of the transition from rain forest‐dominated ‘Tertiary’ Australian vegetation to open‐canopied ‘Quaternary’ vegetation. Location Stony Creek Basin (144.13° E, 37.35° S, 550 m a.s.l), a small, infilled palaeolake in the western uplands of Victoria, Australia. Methods A c. 40‐m‐long sediment core was recovered from the infilled palaeolake. Palynology was used to produce a record of changing vegetation through time. Multivariate analyses provided a basis for interpreting the composition of rain forest and sclerophyll forest communities and for identifying changes in these communities over successive insolation cycles. Results Early Pleistocene upland south‐eastern Australian vegetation was characterized by orbital‐scale, cyclic alternation between rain forest and sclerophyll forests. Individual intervals of forest development underwent patterns of sequential taxon expansion that recurred in successive vegetation cycles. Diverse rain forests included a number of angiosperm and gymnosperm taxa now extinct regionally to globally. Sclerophyll forests were also diverse, and occurred under warm and wet climate conditions. Main conclusions The Stony Creek Basin record demonstrates that as recently as c. 1.5 Ma diverse rain forests persisted in southern Australia beyond the modern continental range of rain forest. The importance of conifers in these rain forests emphasizes that they have no modern Australian analogue. Alternation in dominance between these forests and diverse, sclerophyllous open canopied forests was apparently driven by changes in seasonality, and may have been promoted by fire.     

Out of the Bassian province: historical biogeography of the Australasian platycercine parrots (Aves,Psittaciformes)

Schweizer, M., Güntert, M. & Hertwig, S. T. (2012). Out of the Bassian province: historical biogeography of the Australasian platycercine parrots (Aves, Psittaciformes). —Zoologica Scripta, 42, 13–27. Aridification from mid‐Miocene onwards led to a fragmentation of mesic biomes in Australia and an expansion of arid habitats. This influenced the diversification of terrestrial organisms, and the general direction of their radiations is supposed to have been from mesic into drier habitats. We tested this hypothesis in the platycercine parrots that occur in different habitats in Australia and also colonized Pacific islands. We inferred their temporal and spatial diversification patterns using a Bayesian relaxed molecular clock approach based on three nuclear and two mitochondrial genes and model‐based biogeographic reconstructions. The Bassian biota was found to be the centre of origin of platycercine parrots and diversification within two of their three clades coincided with the beginning of aridification of Australia. The associated habitat changes may have catalysed their radiation through adaptation to arid environments and vicariance because of the fragmentation of non‐arid habitats. The small oceanic islands of Melanesia contributed as stepping stones for the colonization of New Zealand from Australia.     

Historical biogeography and phenotype‐phylogeny of Chroodiscus (lichenized Ascomycota: Ostropales: Graphidaceae)

Aim To analyse the historical biogeography of the lichen genus Chroodiscus using a phenotype‐based phylogeny in the context of continental drift and evolution of tropical rain forest vegetation. Location All tropical regions (Central and South America, Africa, India, Southeast Asia, north‐east Australia). Methods We performed a phenotype‐based phylogenetic analysis and ancestral character state reconstruction of 14 species of the lichen genus Chroodiscus, using paup * and mesquite ; dispersal–vicariance analysis (DIVA) and dispersal–extinction–cladogenesis (DEC) modelling to trace the geographical origin of individual clades; and ordination and clustering by means of pc‐ord , based on a novel similarity index, to visualize the biogeographical relationships of floristic regions in which Chroodiscus occurs. Results The 14 species of Chroodiscus show distinctive distribution patterns, with one pantropical and one amphi‐Pacific taxon and 12 species each restricted to a single continent. The genus comprises four clades. DIVA and DEC modelling suggest a South American origin of Chroodiscus in the mid to late Cretaceous (120–100 Ma), with subsequent expansion through a South American–African–Indian–Southeast Asian–Australian dispersal route and late diversification of the argillaceus clade in Southeast Asia. Based on the abundance of extant taxa, the probability of speciation events in Chroodiscus is shown to be extremely low. Slow dispersal of foliicolous rain forest understorey lichens is consistent with estimated phylogenetic ages of individual species and with average lengths of biological species intervals in fungi (10–20 Myr). Main conclusions The present‐day distribution of Chroodiscus can be explained by vicariance and mid‐distance dispersal through the interconnection or proximity of continental shelves, without the need for recent, trans‐oceanic long‐distance dispersal. Phylogenetic reconstruction and age estimation for Chroodiscus are consistent with the ‘biotic ferry’ hypothesis: a South American origin and subsequent eastward expansion through Africa towards Southeast Asia and north‐eastern Australia via the Indian subcontinent. The present‐day pantropical distributions of many clades and species of foliicolous lichens might thus be explained by eastward expansion through continental drift, along with the evolution of modern rain forests starting 120 Ma, rather than by the existence of a hypothetical continuous area of pre‐modern rain forest spanning South America, Africa and Southeast Asia during the mid and late Cretaceous.     

Radiation of the Australian flora: what can comparisons of molecular phylogenies across multiple taxa tell us about the evolution of diversity in present-day communities?

The Australian fossil record shows that from ca. 25 Myr ago, the aseasonal-wet biome (rainforest and wet heath) gave way to the unique Australian sclerophyll biomes dominated by eucalypts, acacias and casuarinas. This transition coincided with tectonic isolation of Australia, leading to cooler, drier, more seasonal climates. From 3 Myr ago, aridification caused rapid opening of the central Australian arid zone. Molecular phylogenies with dated nodes have provided new perspectives on how these events could have affected the evolution of the Australian flora. During the Mid-Cenozoic (25-10 Myr ago) period of climatic change, there were rapid radiations in sclerophyll taxa, such as Banksia, eucalypts, pea-flowered legumes and Allocasuarina. At the same time, taxa restricted to the aseasonal-wet biome (Nothofagus, Podocarpaceae and Araucariaceae) did not radiate or were depleted by extinction. During the Pliocene aridification, two Eremean biome taxa (Lepidium and Chenopodiaceae) radiated rapidly after dispersing into Australia from overseas. It is clear that the biomes have different histories. Lineages in the aseasonal-wet biome are species poor, with sister taxa that are species rich, either outside Australia or in the sclerophyll biomes. In conjunction with the fossil record, this indicates depletion of the Australian aseasonal-wet biome from the Mid-Cenozoic. In the sclerophyll biomes, there have been multiple exchanges between the southwest and southeast, rather than single large endemic radiations after a vicariance event. There is need for rigorous molecular phylogenetic studies so that additional questions can be addressed, such as how interactions between biomes may have driven the speciation process during radiations. New studies should include the hitherto neglected monsoonal tropics.     

Phylogeny and historical biogeography of ancient assassin spiders (Araneae: Archaeidae) in the Australian mesic zone: evidence for Miocene speciation within Tertiary refugia

The rainforests, wet sclerophyll forests and temperate heathlands of the Australian mesic zone are home to a diverse and highly endemic biota, including numerous old endemic lineages restricted to refugial, mesic biomes. A growing number of phylogeographic studies have attempted to explain the origins and diversification of the Australian mesic zone biota, in order to test and better understand the mode and tempo of historical speciation within Australia. Assassin spiders (family Archaeidae) are a lineage of iconic araneomorph spiders, characterised by their antiquity, remarkable morphology and relictual biogeography on the southern continents. The Australian assassin spider fauna is characterised by a high diversity of allopatric species, many of which are restricted to individual mountains or montane systems, and all of which are closely tied to mesic and/or refugial habitats in the east and extreme south-west of mainland Australia. We tested the phylogeny and vicariant biogeography of the Australian Archaeidae (genus Austrarchaea Forster & Platnick), using a multi-locus molecular approach. Fragments from six mitochondrial genes (COI, COII, tRNA-K, tRNA-D, ATP8, ATP6) and one nuclear protein-coding gene (Histone H3) were used to infer phylogenetic relationships and to explore the phylogeographic origins of the diverse Australian fauna. Bayesian analyses of the complete molecular dataset, along with differentially-partitioned Bayesian and parsimony analyses of a smaller concatenated dataset, revealed the presence of three major Australian lineages, each with non-overlapping distributions in north-eastern Queensland, mid-eastern Australia and southern Australia, respectively. Divergence date estimation using mitochondrial data and a rate-calibrated relaxed molecular clock revealed that major lineages diverged in the early Tertiary period, prior to the final rifting of Australia from East Antarctica. Subsequent speciation occurred during the Miocene (23-5.3 million years ago), with tropical and subtropical taxa diverging in the early-mid Miocene, prior to southern and temperate taxa in the mid-late Miocene. Area cladograms reconciled with Bayesian chronograms for all known Archaeidae in southern and south-eastern Australia revealed seven potentially vicariant biogeographic barriers in eastern Queensland, New South Wales and southern Australia, each proposed and discussed in relation to other mesic zone taxa. Five of these barriers were inferred as being of early Miocene age, and implicated in the initial vicariant separation of endemic regional clades. Phylogeographic results for Australian Archaeidae are congruent with a model of sequential allopatric speciation in Tertiary refugia, as driven by the contraction and fragmentation of Australia’s mesic biomes during the Miocene. Assassin spiders clearly offer great potential for further testing historical biogeographic processes in temperate and eastern Australia, and are a useful group for better understanding the biology and biogeography of the Australian mesic zone.     

Fossil‐based comparative analyses reveal ancient marine ancestry erased by extinction in ray‐finned fishes

The marine‐freshwater boundary is a major biodiversity gradient and few groups have colonised both systems successfully. Fishes have transitioned between habitats repeatedly, diversifying in rivers, lakes and oceans over evolutionary time. However, their history of habitat colonisation and diversification is unclear based on available fossil and phylogenetic data. We estimate ancestral habitats and diversification and transition rates using a large‐scale phylogeny of extant fish taxa and one containing a massive number of extinct species. Extant‐only phylogenetic analyses indicate freshwater ancestry, but inclusion of fossils reveal strong evidence of marine ancestry in lineages now restricted to freshwaters. Diversification and colonisation dynamics vary asymmetrically between habitats, as marine lineages colonise and flourish in rivers more frequently than the reverse. Our study highlights the importance of including fossils in comparative analyses, showing that freshwaters have played a role as refuges for ancient fish lineages, a signal erased by extinction in extant‐only phylogenies.     

Biogeography of the Australian monsoon tropics

Aim This paper reviews the biogeography of the Australian monsoon tropical biome to highlight general patterns in the distribution of a range of organisms and their environmental correlates and evolutionary history, as well as to identify knowledge gaps. Location Northern Australia, Australian Monsoon Tropics (AMT). The AMT is defined by areas that receive more than 85% of rainfall between November and April. Methods Literature is summarized, including the origin of the monsoon climate, present‐day environment, biota and habitat types, and phylogenetic and geographical relationships of selected organisms. Results Some species are widespread throughout the AMT while others are narrow‐range endemics. Such contrasting distributions correspond to present‐day climates, hydrologies (particularly floodplains), geological features (such as sandstone plateaux), fire regimes, and vegetation types (ranging from rain forest to savanna). Biogeographical and phylogenetic studies of terrestrial plants (e.g. eucalypts) and animals (vertebrates and invertebrates) suggest that distinct bioregions within the AMT reflect the aggregated effects of landscape and environmental history, although more research is required to determine and refine the boundaries of biogeographical zones within the AMT. Phylogenetic analyses of aquatic organisms (fishes and prawns) suggest histories of associations with drainage systems, dispersal barriers, links to New Guinea, and the existence of Lake Carpentaria, now submerged by the Gulf of Carpentaria. Complex adaptations to the landscape and climate in the AMT are illustrated by a number of species. Main conclusions The Australian monsoon is a component of a single global climate system, characterized by a dominant equator‐spanning Hadley cell. Evidence of hot, seasonally moist climates dates back to the Late Eocene, implying that certain endemic elements of the AMT biota have a long history. Vicariant differentiation is inferred to have separated the Kimberley and Arnhem Land bioregions from Cape York Peninsula/northern Queensland. Such older patterns are overlaid by younger events, including dispersal from Southeast Asia, and range expansions and contractions. Future palaeoecological and phylogenetic investigations will illuminate the evolution of the AMT biome. Understanding the biogeography of the AMT is essential to provide a framework for ecological studies and the sustainable development of the region.     

DIVERSIFICATION AND PERSISTENCE AT THE ARID–MONSOONAL INTERFACE: AUSTRALIA‐WIDE BIOGEOGRAPHY OF THE BYNOE'S GECKO (HETERONOTIA BINOEI; GEKKONIDAE)

Late Neogene aridification in the Southern Hemisphere caused contractions of mesic biota to refugia, similar to the patterns established by glaciation in the Northern Hemisphere, but these episodes also opened up new adaptive zones that spurred range expansion and diversification in arid‐adapted lineages. To understand these dynamics, we present a multilocus (nine nuclear introns, one mitochondrial gene) phylogeographic analysis of the Bynoe's gecko (Heteronotia binoei), a widely distributed complex spanning the tropical monsoon, coastal woodland, and arid zone biomes in Australia. Bayesian phylogenetic analyses, estimates of divergence times, and demographic inferences revealed episodes of diversification in the Pliocene, especially in the tropical monsoon biome, and range expansions in the Pleistocene. Ancestral habitat reconstructions strongly support recent and independent invasions into the arid zone. Our study demonstrates the varied responses to aridification in Australia, including localized persistence of lineages in the tropical monsoonal biome, and repeated invasion of and expansion through newly available arid‐zone habitats. These patterns are consistent with those found in other arid environments in the Southern Hemisphere, including the South African succulent karoo and the Chilean lowlands, and highlight the diverse modes of diversification and persistence of Earth's biota during the glacial cycles of the Pliocene and Pleistocene.     

Environment predicts repeated body size shifts in a recent radiation of Australian mammals*

Closely related species that occur across steep environmental gradients often display clear body size differences, and examining this pattern is crucial to understanding how environmental variation shapes diversity. Australian endemic rodents in the Pseudomys Division (Muridae: Murinae) have repeatedly colonized the arid, monsoon, and mesic biomes over the last 5 million years. Using occurrence records, body mass data, and Bayesian phylogenetic models, we test whether body mass of 31 species in the Pseudomys Division can be predicted by their biome association. We also model the effect of eight environmental variables on body mass. Despite high phylogenetic signal in body mass evolution across the phylogeny, we find that mass predictably increases in the mesic biome and decreases in arid and monsoon biomes. As per Bergmann's rule, temperature is strongly correlated with body mass, as well as several other variables. Our results highlight two important findings. First, body size in Australian rodents has tracked with climate through the Pleistocene, likely due to several environmental variables rather than a single factor. Second, support for both Brownian motion and predictable change at different taxonomic levels in the Pseudomys Division phylogeny demonstrates how the level at which we test hypotheses can alter interpretation of evolutionary processes.     

Phylogeny of Australasian agamid lizards based on nuclear and mitochondrial genes: implications for morphological evolution and biogeography

Recent mtDNA phylogenies of Australasian agamid lizards are highly incongruent with existing morphological views. To resolve this discrepancy we sequenced two nuclear gene regions, c- mos and brain-derived neurotrophic factor (BDNF). These were highly concordant with each other and the mtDNA phylogeny, but not the morphology. A combined molecular analysis reveals substantial hidden support (additional phylogenetic signal that emerges only when the data sets interact in a combined analysis). Bayesian posteriors, and a partitioned bootstrap procedure introduced here, indicate strong support for most nodes. The resultant tree implies extensive morphological homoplasy, with many genera emerging as non-monophyletic ( Amphibolurus , Rankinia , Ctenophorus , Physignathus , Diporiphora ). The water and forest dragons ( Physignathus and Hypsilurus ) form a paraphyletic basal assemblage to the more derived Australian forms such as Amphibolurus and Ctenophorus , which include almost all the xeric taxa. However, the thorny devil Moloch horridus is a basal lineage and not closely related to the other arid forms. Tree topology, inferred divergence dates, palaeogeographical and palaeoclimatic data are all consistent with Miocene immigration into Australia from the north by mesic forest ecomorphs, followed by initial diversification in mesic habitats before radiation into xeric habitats facilitated by increasing aridity.  © 2008 The Linnean Society of London, Biological Journal of the Linnean Society , 2008, 93 , 343–358.     

Leaf shape and size track habitat transitions across forest–grassland boundaries in the grass family (Poaceae)

Grass leaf shape is a strong indicator of their habitat with linear leaves predominating in open areas and ovate leaves distinguishing forest‐associated grasses. This pattern among extant species suggests that ancestral shifts between forest and open habitats may have coincided with changes in leaf shape or size. We tested relationships between habitat, climate, photosynthetic pathway, and leaf shape and size in a phylogenetic framework to evaluate drivers of leaf shape and size variation over the evolutionary history of the family. We also estimated the ancestral habitat of Poaceae and tested whether forest margins served as transitional zones for shifts between forests and grasslands. We found that grass leaf shape is converging toward different shape optima in the forest understory, forest margins, and open habitats. Leaf size also varies with habitat. Grasses have smaller leaves in open and drier areas, and in areas with high solar irradiance. Direct transitions between linear and ovate leaves are rare as are direct shifts between forest and open habitats. The most likely ancestral habitat of the family was the forest understory and forest margins along with an intermediate leaf shape served as important transitional habitat and morphology, respectively, for subsequent shifts across forest–grassland biome boundaries.     

Australian parasitic Ogyris butterflies: east–west divergence of highly‐specialized relicts

Not all butterflies are innocuous plant‐feeders. A small number of taxa in the family Lycaenidae have graduated from mutualistic partnerships with ants to predatory or parasitic associations. These highly‐specialized life histories, involving butterfly larvae living inside ant colonies, are often associated with rarity and vulnerability to extinction. In the present study, we examined the evolutionary relationships of a poorly‐known group of seven taxa herein referred to as the idmo‐group within the Australian lycaenid genus Ogyris. The idmo‐group has a relictual distribution across southern Australia and includes taxa with highly‐specialized phytophagous and myrmecophagous life histories. A phylogeny based on mitochondrial DNA (cytochrome oxidase I and cytochrome b] and the nuclear DNA locus elongation factor 1α (EF1α), generally agrees with current taxonomy and supports the recent elevation of endangered taxon Ogyris halmaturia to full species status. The transition to myrmecophagy was dated to the mid‐Miocene (approximately 16 Mya), when southern Australia experienced a humid climate and extensive mesic biome. The arid Nullarbor Plain, a major biogeographical feature of central southern Australia, divides the remnants of this mesic biome into south‐eastern and south‐western isolates. Late‐Miocene to Pliocene divergence estimates for polytypic Ogyris species across the Nullarbor were older than estimates made for similarly distributed birds, butterflies, mammals, and reptiles, which mostly date to the Pleistocene. The concept of highly‐specialized life histories as evolutionary dead‐end strategies is well exemplified by the idmo‐group. Data compiled on the known extant subpopulations for idmo‐group taxa show that all of these extraordinary butterflies are scarce and several face imminent threat of extinction. © 2013 The Linnean Society of London, Biological Journal of the Linnean Society, 2014, 111 , 473–484.     

The phylogeny and biogeography of Hakea (Proteaceae) reveals the role of biome shifts in a continental plant radiation

The frequency of evolutionary biome shifts during diversification has important implications for our ability to explain geographic patterns of plant diversity. Recent studies present several examples of biome shifts, but whether frequencies of biome shifts closely reflect geographic proximity or environmental similarity of biomes remains poorly known. We explore this question by using phylogenomic methods to estimate the phylogeny of Hakea, a diverse Australian genus occupying a wide range of biomes. Model‐based estimation of ancestral regions indicates that Hakea began diversifying in the Mediterranean biome of southern Australia in the Middle Eocene–Early Oligocene, and dispersed repeatedly into other biomes across the continent. We infer around 47 shifts between biomes. Frequencies of shifts between pairs of biomes are usually similar to those expected from their geographic connectedness or climatic similarity, but in some cases are substantially higher or lower than expected, perhaps reflecting how readily key physiological traits can be modified to adapt lineages to new environments. The history of frequent biome‐shifting is reflected in the structure of present‐day assemblages, which tend to be more phylogenetically diverse than null‐model expectations. The case of Hakea demonstrates that the radiation of large plant clades across wide geographic areas need not be constrained by dispersal limitation or conserved adaptations to particular environments.     

Ancestral state reconstruction of body size in the Caniformia (Carnivora, Mammalia): the effects of incorporating data from the fossil record

A recent molecular phylogeny of the mammalian order Carnivora implied large body size as the ancestral condition for the caniform subclade Arctoidea using the distribution of species mean body sizes among living taxa. "Extant taxa-only" approaches such as these discount character state observations for fossil members of living clades and completely ignore data from extinct lineages. To more rigorously reconstruct body sizes of ancestral forms within the Caniformia, body size and first appearance data were collected for 149 extant and 367 extinct taxa. Body sizes were reconstructed for four ancestral nodes using weighted squared-change parsimony on log-transformed body mass data. Reconstructions based on extant taxa alone favored large body sizes (on the order of 10 to 50 kg) for the last common ancestors of both the Caniformia and Arctoidea. In contrast, reconstructions incorporating fossil data support small body sizes (< 5 kg) for the ancestors of those clades. When the temporal information associated with fossil data was discarded, body size reconstructions became ambiguous, demonstrating that incorporating both character state and temporal information from fossil taxa unambiguously supports a small ancestral body size, thereby falsifying hypotheses derived from extant taxa alone. Body size reconstructions for Caniformia, Arctoidea, and Musteloidea were not sensitive to potential errors introduced by uncertainty in the position of extinct lineages relative to the molecular topology, or to missing body size data for extinct members of an entire major clade (the aquatic Pinnipedia). Incorporating character state observations and temporal information from the fossil record into hypothesis testing has a significant impact on the ability to reconstruct ancestral characters and constrains the range of potential hypotheses of character evolution. Fossil data here provide the evidence to reliably document trends of both increasing and decreasing body size in several caniform clades. More generally, including fossils in such analyses incorporates evidence of directional trends, thereby yielding more reliable ancestral character state reconstructions.     

Contrasting mechanisms of resilience at mesic and semi-arid boundaries of fynbos,a mega-diverse heathland of South Africa

Biome boundaries are expected to be sensitive to changes in climate and disturbance, because it is here that ecological communities are at environmental, ecological or disturbance limits. Using palaeoecology to study ecosystem dynamics at biome boundaries provides opportunities for understanding ecosystem resilience or sensitivity at ecologically meaningful timescales, and under varying climatic and disturbance conditions.The fynbos biome is a megadiverse Mediterranean type shrubland, found only in South Africa, that is threatened by climate change, land-use change and invasion by alien species. We used palaeoecological records from the semi-arid and mesic boundaries of the fynbos biome to test hypotheses regarding ecosystem resilience over timescales of centuries to millennia. We hypothesised that fynbos would expand at its mesic boundary at the expense of afrotemperate forest under drier and / or more fire prone conditions. In contrast, we hypothesised that at the semi-arid boundary, fynbos would expand at the expense of succulent karoo under wetter and cooler and / or more fire-prone conditions. Contrary to our expectations, the fossil pollen record at both biome boundaries showed remarkable stability at centennial - millennial timescales. To explain our results, we generated new hypotheses exploring possible mechanisms that might confer resilience.At the mesic (temperate) boundary, we suggest that decreased seasonality of rainfall during drier phases favoured fire and fynbos persistence, while in wetter periods, increased seasonality of rainfall resulted in enhanced summer drought stress, inhibiting forest expansion. At this boundary, internal reorganisation from grassy to proteoid fynbos states conferred resilience through resistance. At the succulent karoo boundary, we suggest that increased aridity was offset by less seasonality of rainfall, which enhanced biomass and allowed fire to persist, favouring persistence of fynbos. At this boundary, fynbos sensu stricto retreated during arid phases but recovered during climate amelioration, consistent with resilience through recovery. In both cases, this mega-diverse, disturbance-adapted flora provided a range of traits that enabled fynbos to persist despite environmental perturbation. Our findings agree with general observations that for ecosystems in regions of ample resource availability (i.e. at the mesic boundary), biotic interactions and disturbance tend to become more important in ecosystem dynamics, whereas in regions of scarce resources (in this case water scarcity at the semi-arid boundary) abiotic stress is more important. Our findings contribute to debates over the mechanisms that confer resistance and resilience to environmental change. Understanding and conserving the processes and mechanisms underpinning its resilience will be critical to effective conservation planning.     

Phylogeography of Plectostylus Beck, 1837 (Gastropoda: Stylommatophora: Orthalicoidea): Origin and isolation of the Fray Jorge forest relicts in northern Chile

Among the questions surrounding the biogeographical history of the Chilean biota, none has gathered more interest than the origin of the Fray Jorge (FJ) forest relict and its biota. Inserted in a semi‐desert area, this forest enclave exists due to the existence of a very particular microclimate in this region. The age of the disjunction and the historical relationship between the FJ biota with the remaining components of South America are explained by two distinct, competing hypotheses: the first suggests that it would have become isolated during the climatic changes of the Paleogene/Neogene, while the second suggests that the isolation is a product of Quaternary glaciations. To discriminate between these competing hypotheses, we used DNA sequence phylogeny methods and molecular genetic dating to the study of a genus of land snails (Plectostylus) that occurs in the FJ relict and throughout Chile. The phylogeny shows a clear distinction between forest and arid clades, and each of these clades is formed by many geographically circumscribed populations. The FJ fragment snails form a clade that is sister to all other forest clades. The separation between the Fray Jorge clade and the other forest clades dates back to the Paleogene/Neogene. Our data suggest that the FJ forest is a relict from the forests that occupied that landscape during the Paleogene/Neogene and retreated due to the aridification of the region. We also observe that the current taxonomy of the Plectostylus genus must be re‐evaluated.     

Biogeography and diversification of colletid bees (Hymenoptera: Colletidae): emerging patterns from the southern end of the world

Aim The evolutionary history of bees is presumed to extend back in time to the Early Cretaceous. Among all major clades of bees, Colletidae has been a prime example of an ancient group whose Gondwanan origin probably precedes the complete break‐up of Africa, Antarctica, Australia and South America, because modern lineages of this family occur primarily in southern continents. In this paper, we aim to study the temporal and spatial diversification of colletid bees to better understand the processes that have resulted in the present southern disjunctions. Location Southern continents. Methods We assembled a dataset comprising four nuclear genes of a broad sample of Colletidae. We used Bayesian inference analyses to estimate the phylogenetic tree topology and divergence times. Biogeographical relationships were investigated using event‐based analytical methods: a Bayesian approach to dispersal–vicariance analysis, a likelihood‐based dispersal–extinction–cladogenesis model and a Bayesian model. We also used lineage through time analyses to explore the tempo of radiations of Colletidae and their context in the biogeographical history of these bees. Results Initial diversification of Colletidae took place at the Late Cretaceous (≥ 70 Ma). Several (6–14) lineage exchanges between Australia and South America via Antarctica during the Late Cretaceous and Eocene epochs could explain the disjunctions observed between colletid lineages today. All biogeographical methods consistently indicated that there were multiple lineage exchanges between South America and Australia, and these approaches were valuable in exploring the degree of uncertainty inherent in the ancestral reconstructions. Biogeographical and dating results preclude an explanation of Scrapterinae in Africa as a result of vicariance, so one dispersal event is assumed to explain the disjunction in relation to Euryglossinae. The net diversification rate was found to be highest in the recent history of colletid evolution. Main conclusions The biogeography and macroevolutionary history of colletid bees can be explained by a combination of Cenozoic vicariance and palaeoclimatic changes during the Neogene. The austral connection and posterior break‐up of South America, Antarctica and Australia resulted in a pattern of disjunct sister lineages. Increased biome aridification coupled with floristic diversification in the southern continents during the Neogene may have contributed to the high rates of cladogenesis in these bees in the last 25–30 million years.     

Early evolutionary history of the flowering plant family Annonaceae: steady diversification and boreotropical geodispersal

Aim Rain forest‐restricted plant families show disjunct distributions between the three major tropical regions: South America, Africa and Asia. Explaining these disjunctions has become an important challenge in biogeography. The pantropical plant family Annonaceae is used to test hypotheses that might explain diversification and distribution patterns in tropical biota: the museum hypothesis (low extinction leading to steady accumulation of species); and dispersal between Africa and Asia via Indian rafting versus boreotropical geodispersal. Location Tropics and boreotropics. Methods Molecular age estimates were calculated using a Bayesian approach based on 83% generic sampling representing all major lineages within the family, seven chloroplast markers and two fossil calibrations. An analysis of diversification was carried out, which included lineage‐through‐time (LTT) plots and the calculation of diversification rates for genera and major clades. Ancestral areas were reconstructed using a maximum likelihood approach that implements the dispersal–extinction–cladogenesis model. Results The LTT plots indicated a constant overall rate of diversification with low extinction rates for the family during the first 80 Ma of its existence. The highest diversification rates were inferred for several young genera such as Desmopsis, Uvariopsis and Unonopsis. A boreotropical migration route was supported over Indian rafting as the best fitting hypothesis to explain present‐day distribution patterns within the family. Main conclusions Early diversification within Annonaceae fits the hypothesis of a museum model of tropical diversification, with an overall steady increase in lineages possibly due to low extinction rates. The present‐day distribution of species within the two largest clades of Annonaceae is the result of two contrasting biogeographic histories. The ‘long‐branch clade’ has been diversifying since the beginning of the Cenozoic and underwent numerous geodispersals via the boreotropics and several more recent long‐distance dispersal events. In contrast, the ‘short‐branch clade’ dispersed once into Asia via the boreotropics during the Early Miocene and further dispersal was limited.