Rapid expansion and diversification into new niche space by fluvicoline flycatchers

The fluvicoline New World flycatchers (subfamily Fluvicolinae, family Tyrannidae) inhabit a broad range of forest and non‐forest habitats in all parts of the New World. Using a densely sampled phylogeny we depict the diversification and expansion of this group in time and space. We provide evidence that a shift in foraging behaviour allowed the group to rapidly expand in a wide range of tropical and subtropical habitats in South America. The results support that four main clades expanded into and specialized to distinct habitats and climates (closed to open, and warm to cold), respectively, and subsequently underwent vicariant speciation within their respective ecoregions. The group soon reached a significant species diversity over virtually all of South and North America, and with parallel trajectories of speciation slow‐down in all four clades. The genus Muscisaxicola is an exception, as it invaded the most inhospitable and barren environments in the Andes where they underwent rapid diversification in the Plio‐Pleistocene.     

Search strategies of tyrant flycatchers

Aspects of searching behaviour among free-living South American flycatchers (Aves: Tyrannidae) are compared quantitatively. Flycatchers forage with stationary searching periods, followed either by an attempted prey capture (sally) or a ‘give-up’ flight to a new perch. Search times are proportional to body size within each of three categories of foraging behaviour: aerial hawking, sally-gleaning, and perch-gleaning. Over the family as a whole, search times are directly proportional to the size of the visual field scanned during the search. Intraspecific variations in search times are caused by local variations in prey density or visual complexity of the habitat. Between foraging modes, differences in searching and movement patterns are related to prey dispersion characteristics. Aerial hawkers regularly return to favoured perches, but foliage gleaners, which reduce the resources surrounding a perch by sallying only once, rarely return to a perch. In contrast to aerial hawkers, foliage gleaners appear to follow an organized scanning procedure on each perch, by searching nearby surfaces before they examine more distant prey substrates. Throughout the family, the median flight distance after a perch is abandoned is approximately twice the median search radius. Comparisons of search time distributions preceding sallies with those preceding give-up flights suggest that there is no single, optimal give-up time in a given habitat. Foliage-gleaning species appear to assess the amount of search time each perch warrants, presumably based on the degree of complexity of the search area. They either sally at prey before that time, or give-up when the allotted time has elapsed.     

Phylogeny and character evolution in the Empidonax group of tyrant flycatchers (Aves: Tyrannidae): a test of W. E. Lanyon's hypothesis using mtDNA sequences

We sequenced mitochondrial DNA from four protein-coding genes for 26 taxa to test W. E. Lanyon's hypothesis of intergeneric relationships and character evolution in the Empidonax group of tyrant flycatchers. Three genera in this group (Empidonax, Contopus, and Sayornis) successfully occupy north temperate habitats for breeding, while the remaining genera (Mitrephanes, Cnemotriccus, Aphanotriccus, Lathrotriccus, and Xenotriccus) are restricted to neotropical latitudes. Lanyon hypothesized two major clades in the group based on differences in syringeal morphology and proposed relationships among genera using a combination of morphologic, behavioral, and allozymic characters. The mtDNA data strongly support Lanyon's division of genera into two clades. In addition, the molecular and nonmolecular data sets agree in uniting Aphanotriccus and Lathrotriccus as sister taxa, with Cnemotriccus as basal to these genera. Species of Aphanotriccus, Lathrotriccus, and Cnemotriccus form a clade that exploits a distinctive nesting niche relative to other members of the Empidonax group. Within the second major clade, mtDNA sequences support a reconstruction based on allozymes that places Contopus and Empidonax as sister taxa. This hypothesis contradicts that of Lanyon, who allied Contopus with Mitrephanes on the basis of similarity in foraging mode. Genera in the Empidonax group are members of a larger assemblage that radiated in South America. Occupancy of temperate habitats by certain genera in this group is coincident with their evolution of migratory behavior and with independent diversification in foraging modes that reduces potential competition in sympatry.     

The striking polyphyly of Suiriri: Convergent evolution and social mimicry in two cryptic Neotropical birds

Two species of Suiriri (Aves: Tyrannidae) inhabit semi‐open habitats in South America: the polytypic Suiriri Flycatcher (S. suiriri) and the monotypic Chapada Flycatcher (S. affinis). The phylogenetic relationship between these congeneric species has never been investigated in detail. Here we used molecular tools—three nuclear introns and two mitochondrial genes—to investigate the systematic position of the Chapada Flycatcher, comparing the results found with morphological and behavioral data. We found that the polytypic Suiriri Flycatcher to be monophyletic and that it is included in a clade of Elaeniini flycatchers including Phyllomyias, Phaeomyias, and Capsiempis among other genera. The Chapada Flycatcher, on the other hand, is a member of the Fluvicolini, sister to Sublegatus, and should be allocated on its own monospecific genus, which we herein describe. We suggest that social mimicry is responsible for the remarkable convergence in size, shape, plumage coloration, and behavior in the adults of the Suiriri Flycatcher and the Chapada Flycatcher.     

Towards resolving the evolutionary history of Caucasian pears (Pyrus,Rosaceae)—Phylogenetic relationships,divergence times and leaf trait evolution

With approximately 25 endemic species, the genus Pyrus (pears) is highly diverse in the Caucasus ecoregion. The majority of Caucasian pears inhabit xerophytic open woodlands or similar habitats, to which they display morphological adaptations, such as narrow leaves. The other species, both Caucasian and non‐Caucasian taxa, mainly inhabit mesophytic forests and display broad leaves. Using a representative taxon sampling of Pyrus from the Caucasus, Europe and Asia, we reconstruct phylogenetic relationships in the genus based on multiple plastid regions. We also estimate the divergence times of major clades in Pyrus, reconstruct the evolution of leaf shapes, and discuss the emergence of xeromorphic leaf traits. Our results confirm the monophyly of Pyrus and the existence of two major clades: (a) an E Asian clade with a crown group age of 15.7 (24.02–8.37 95% HPD) My, and (b) a W Eurasian clade that comprises species from Europe, SW Asia and the Caucasus and that displays a slightly younger crown group of 12.38 (19.02–6.41 95% HPD) My. The existing infrageneric classification of Pyrus was found partially incongruent with the inferred phylogenetic trees. Several currently accepted species were not recovered as monophyletic, indicating that current species limits require re‐evaluation. Ancestral character state reconstructions revealed several independent transitions from broad‐ to narrow‐shaped leaves in Pyrus, probably via intermediate‐shaped leaves.     

Do migrants influence the foraging behaviour of the insectivorous Cyprus Wheatear,Oenanthe cypriaca,at a stopover site? (Aves: Passeriformes)

During their staging at stopover sites, migrants may compete with resident species over food resources (“resource competition hypothesis”), or migrants feed on surplus that is not utilised by the residents. Here, I studied foraging behaviour of the Cyprus Wheatear, Oenanthe cypriaca, a ubiquitous and common species with a broad niche range, on Cyprus, which is an important stopover site during intercontinental spring migration. During adverse weather conditions, perch height and aerial sallying were lower and perch/pounce activity was higher. Average perch height and sallying increased over the season, while perch-pounce foraging decreased. There was no influence of clock time. Bivariate correlations suggested an influence of migrants on perch height but not on other variables. Using a series of regression analyses with sex, time of day, date, weather conditions and number of migrants as independent variables revealed no influence of the number of migrants on the foraging behaviour of the Cyprus Wheatear. This suggests that the abundance of migrants does not lead to a change in the behaviour of the Cyprus Wheatear.     

Nuclear DNA from a 180‐year‐old study skin reveals the phylogenetic position of the Kinglet Calyptura Calyptura cristata (Passeriformes: Tyrannides)

The Kinglet Calyptura Calyptura cristata is one of the most enigmatic bird species in South America, known only from specimens collected in the 19th century and a few recent observations. Knowledge of its biology is scanty and its systematic position is obscure. Traditionally, Calyptura was placed in the Cotingidae, but associated with genera that are now known to fall outside the Cotingidae. In an attempt to clarify its phylogenetic position, sequence data from four nuclear markers were obtained from a 180‐year‐old museum study skin of Calyptura, and incorporated into a comprehensive dataset of tyrant flycatchers, cotingas, manakins and allies. Our analyses demonstrate that Calyptura is most closely related to Platyrinchus and Neopipo and that these three genera constitute a deep branch in the clade containing the Rhynchocyclidae (tody‐tyrants and flatbills) and Tyrannidae (typical tyrant flycatchers). The Calyptura specimen is one of the oldest avian museum specimens from which a substantial amount of nuclear DNA sequence data have been obtained, and highlights the immense value of museum collections for DNA‐based phylogenetic studies.     

Independent trophic behavior and breeding success of a resident flycatcher and a coexisting migratory congener

Historical biases towards the study of Palearctic and Nearctic bird migration systems has resulted in a dearth of information on the ecology of intratropical migrants, which likely also play important ecological roles within their communities. For instance, there is little information on the foraging ecology and breeding biology of co‐occurring migrants and residents within the intratropical migratory system. Thus, we used two congeneric flycatchers – the resident Plain‐crested Elaenia Elaenia cristata (Aves: Tyrannidae), and the migrant Lesser Elaenia E. chiriquensis (Tyrannidae) – to check whether either of them showed foraging niche plasticity mediating their coexistence and the effects of such syntopy on their breeding behavior and fitness. To do so, we used an ensemble of methods that included the evaluation of food resource phenology, foraging behavior observations, stable isotope ratio analysis in birds’ tissues, and nest monitoring. Our results confirmed that residents have foraging behavior plasticity but reveals its trophic behavior and breeding success is independent of the coexistence with migrants. Since such results depart from the predictions based on the current (and often Northern‐biased) theories of bird migration, we discuss alternative hypotheses explaining our findings, including the influence of physiology on diet and the behavioral responses of nest predators. Once there is a clear knowledge gap about the interspecific interactions between residents and intratropical migrants, our study represents a simple, yet important, step towards understanding the mechanisms underlying this system.     

Biogeography of the Monimiaceae (Laurales): a role for East Gondwana and long‐distance dispersal,but not West Gondwana

Aim The biogeography of the tropical plant family Monimiaceae has long been thought to reflect the break‐up of West and East Gondwana, followed by limited transoceanic dispersal. Location Southern Hemisphere, with fossils in East and West Gondwana. Methods We use phylogenetic analysis of DNA sequences from 67 of the c. 200 species, representing 26 of the 28 genera of Monimiaceae, and a Bayesian relaxed clock model with fossil prior constraints to estimate species relationships and divergence times. Likelihood optimization is used to infer switches between biogeographical regions on the highest likelihood tree. Results Peumus from Chile, Monimia from the Mascarenes and Palmeria from eastern Australia/New Guinea form a clade that is sister to all other Monimiaceae. The next‐deepest split is between the Sri Lankan Hortonia and the remaining genera. The African Monimiaceae, Xymalos monospora, then forms the sister clade to a polytomy of five clades: (I) Mollinedia and allies from South America; (II) Tambourissa and allies from Madagascar and the Mascarenes; (III) Hedycarya, Kibariopsis and Leviera from New Zealand, New Caledonia and Australia; (IV) Wilkiea, Kibara, Kairoa; and (V) Steganthera and allies, all from tropical Australasia. Main conclusions Tree topology, fossils, inferred divergence times and ances‐tral area reconstruction fit with the break‐up of East Gondwana having left a still discernible signature consisting of sister clades in Chile and Australia. There is no support for previous hypotheses that the break‐up of West Gondwana (Africa/South America) explains disjunctions in the Monimiaceae. The South American Mollinedia clade is only 28–16 Myr old, and appears to have arrived via trans‐Pacific dispersal from Australasia. The clade apparently spread in southern South America prior to the Andean orogeny, fitting with its first‐diverging lineage (Hennecartia) having a southern‐temperate range. The crown ages of the other major clades (II–V) range from 20 to 29 Ma, implying over‐water dispersal between Australia, New Caledonia, New Zealand, and across the Indian Ocean to Madagascar and the Mascarenes. The endemic genus Monimia on the Mascarenes provides an interesting example of an island lineage being much older than the islands on which it presently occurs.     

Evidence of hypoxic foraging forays by yellow perch (Perca flavescens) and potential consequences for prey consumption

1. Previous studies in a variety of ecosystems have shown that ecologically and economically important benthic and bentho‐pelagic fishes avoid hypoxic (<2 mg O₂ L^?1) habitats by moving vertically or horizontally to more oxygenated areas. While avoidance of hypoxic conditions generally leads to a complete shift away from preferred benthic prey, some individual fish continue to consume benthic prey items in spite of bottom hypoxia, suggesting complex habitat utilisation and foraging patterns. For example, Lake Erie yellow perch (Perca flavescens) continue to consume benthic prey, despite being displaced vertically and horizontally by hypolimnetic hypoxia. 2. We hypothesised that hypolimnetic hypoxia can negatively affect yellow perch by altering their distribution and inducing energetically expensive foraging behaviour. To test this hypothesis, we used drifting hydroacoustics and trawl sampling to quantify water column distribution, sub‐daily vertical movement and foraging behaviour of yellow perch within hypoxic and normoxic habitats of Lake Erie’s central basin during August‐September 2007. We also investigated the effects of rapid changes in ambient oxygen conditions on yellow perch consumption potential by exposing yellow perch to various static and fluctuating oxygen conditions in a controlled laboratory experiment. 3. Our results indicate that, while yellow perch in general avoid hypoxic conditions, some individuals undertake foraging forays into hypoxic habitats where they experience greater fluctuations in abiotic conditions (pressure, temperature and oxygen concentration) than at normoxic sites. However, laboratory results suggest short‐term exposure to low oxygen conditions did not negatively impact consumption potential of yellow perch. 4. Detailed understanding of sub‐daily individual behaviours may be crucial for determining interactive individual‐ and ecosystem‐level effects of stressors such as hypoxia.     

Molecular phylogenetic analysis of all members of the genus Elminia confirms their presence within the Stenostiridae clade

The genus Elminia has had a jumbled taxonomic history, being placed among ‘old world flycatchers’ or ‘monarch flycatchers’, where it was for a long time lumped with Trochocercus. It was recently suggested that it might represent a deep clade in the large sylvioid radiation. Using one mitochondrial protein‐coding gene (ND2, 1041 bp) and one nuclear intron (myoglobin intron 2, 700 bp) DNA sequences, we obtained robust evidence for the phylogenetic placement of Elminia in the new family Stenostiridae, which is strongly supported by a synapomorphic insertion of one base in the nuclear myoglobin intron 2 sequence. Our analyses confirm the monophyly of Elminia and resolve relationships within this genus, but cannot confidently identify its sister‐taxon within the stenostirid clade. Two clades were strongly supported within the genus Elminia: one with the two fairy blue flycatchers and another with the three white‐tailed crested‐flycatchers. Within the first clade, Elminia longicauda appears non‐monophyletic but remains strongly related to E. albicauda. In the second clade, E. albiventris is sister to E. albonotata while the Dusky Crested Flycatcher (E. nigromitrata) appears in a basal position within this clade. According to our molecular dating, several geological events in western Africa and the Albertine Rift area seem to be related to the historical distribution of Elminia. Thus, the differentiation between E. albonotata and E. albiventris could be directly related to the tectonic history of these two regions. According to our molecular dating, at least one intercontinental dispersal event involving Culicicapa took place within the Stenostiridae clade at a time when the Middle East was forested.     

Molecular phylogeny of the Eremias persica complex of the Iranian plateau (Reptilia: Lacertidae), based on mtDNA sequences

The Persian racerunner Eremias persica Blanford, 1875 is confined to the Iranian plateau, and forms one of the most widespread but rarely studied species of the family Lacertidae. With many local populations inhabiting a variety of habitats, and exhibiting considerable morphological, genetic, and ecological variations, it represents a species complex. We analysed sequences of mitochondrial cytochrome b and 12S ribosomal RNA (rRNA) genes derived from 13 geographically distant populations belonging to the E. persica complex. Using our knowledge of palaeogeographical events, a molecular clock was calibrated to assess the major events in fragmentation, radiation, and intraspecific variation. The sequence data strongly support a basal separation of the highland populations of western Iran from those of the open steppes and deserts, occurring in the east. The subsequent radiation, fragmentation, and evolution of these major assemblages have led to several discernable geographical lineages across the wide area of the Iranian plateau. The results indicate a middle‐Miocene origin for the clade as a whole. The first split, isolating the western and eastern clades, appears to have occurred 11–10 Mya. Further fragmentations and divergence within the major clades began about 8 Mya, with an evolutionary rate of 1.6% sequence divergence per million years among the lineages in the genes studied (combined data set). Molecular and morphological data strongly support a taxonomic revision of this species complex. At least four of the discovered clades should be raised to species, and two to subspecies, rank. © 2009 The Linnean Society of London, Zoological Journal of the Linnean Society, 2010, 158 , 641–660.     

Diversification rates have no effect on the convergent evolution of foraging strategies in the most speciose genus of bats,Myotis*

Adaptive radiations are defined as rapid diversification with phenotypic innovation led by colonization to new environments. Notably, adaptive radiations can occur in parallel when habitats with similar selective pressures are accessible promoting convergent adaptions. Although convergent evolution appears to be a common process, it is unclear what are the main drivers leading the reappearance of morphologies or ecological roles. We explore this question in Myotis bats, the only Chiropteran genus with a worldwide distribution. Three foraging strategies—gleaning, trawling, and aerial netting—repeatedly evolved in several regions of the world, each linked to characteristic morphologies recognized as ecomorphs. Phylogenomic, morphometric, and comparative approaches were adopted to investigate convergence of such foraging strategies and skull morphology as well as factors that explain diversification rates. Genomic and morphometric data were analyzed from ～80% extant taxa. Results confirm that the ecomorphs evolved multiple times, with trawling evolving more often and foliage gleaning most recently. Skull morphology does not reflect common ancestry and evolves convergently with foraging strategy. Although diversification rates have been roughly constant across the genus, speciation rates are area‐dependent and higher in taxa with temperate distributions. Results suggest that in this species‐rich group of bats, first, stochastic processes have led divergence into multiple lineages. Then, natural selection in similar niches has promoted repeated adaptation of phenotypes and foraging strategies. Myotis bats are thus a remarkable case of ecomorphological convergence and an emerging model system for investigating the genomic basis of parallel adaptive radiation.     

An osteology‐based appraisal of the phylogeny and evolution of kangaroos and wallabies (Macropodidae: Marsupialia)

Macropodids are the most diverse group of marsupial herbivores ever to have evolved. They have been the subject of more phylogenetic studies than any other marsupial family, yet relationships of several key clades remain uncertain. Two important problem areas have been the position of the merrnine (Lagostrophus fasciatus) and the phylogenetic proximity of tree‐kangaroos and rock‐wallabies. Our osteological analysis revealed strong support for a plesiomorphic clade ( Lagostrophinae subfam. nov. ) containing Lagostrophus and Troposodon, which is likely to have originated in the early Miocene. The extinct short‐faced kangaroos (Sthenurinae) emerged in the middle Miocene as the sister lineage to a clade containing all other living kangaroos and wallabies (Macropodinae). New Guinea forest wallabies ( Dorcopsini trib. nov. ) are the most plesiomorphic macropodines; the other two main lineages include tree‐kangaroos and rock‐wallabies (Dendrolagini), and ‘true’ kangaroos and wallabies (Macropodini). These phylogenetic outcomes are broadly consistent with the results of recent molecular studies, although conflicts remain over the relative positions of some macropodins (e.g. Setonix, Onychogalea, and Wallabia). Given the presence of derived dendrolagins and macropodins in early Pliocene localities, it is probable that most macropodine genera originated in the late Miocene. Key functional–adaptive trajectories within the craniodental and locomotory systems of the dominant macropodid lineages represent varying responses to the spread of drier, open habitats following the Miocene Climatic Optimum. © 2010 The Linnean Society of London, Zoological Journal of the Linnean Society, 2010, 159 , 954–987.     

Granite boulders act as deep-time climate refugia: A Miocene divergent clade of rupicolous Cnemaspis Strauch, 1887 (Squamata: Gekkonidae) from the Mysore Plateau,India, with descriptions of three new species

We describe a divergent clade and three new rupicolous species of dwarf geckos of the genus Cnemaspis from the Mysore Plateau, southern India. Cnemaspis bangarasp. nov., C. graniticola sp. nov., and C.yelagiriensis sp. nov. differ from each other by 9%–18% uncorrected ND2 sequence divergence and other South Asian Cnemaspis by 17%–33% and are morphologically distinguishable from all regional congeners and each other. The new species are known from only granite boulders in montane habitats (>1,000 m asl.), just 60–120 km straight-line distance apart from each other. A fossil-calibrated timetree and ancestral area reconstructions indicate South Asian Cnemaspis originated in Western Ghats forests with initial divergence in the Paleocene-Eocene making it perhaps the oldest Indian squamate clade. Cnemaspis that occur in Peninsular India in the dry zone outside the Western Ghats form three independently derived clades that occur in significantly warmer and drier habitats than those in the Western Ghats. The discovery of a Miocene divergent clade from rocky hills on the southern edge of the Mysore Plateau reveals these habitats as novel, long-term climate refugia. This adds to the body of work revealing ancient origins of taxa in the Indian dry zone and supports the Mysore Plateau as an important and overlooked hot spot of lizard biodiversity.     

Molecular systematics of New World suboscine birds

Phylogenetic relationships among New World suboscine birds were studied using nuclear and mitochondrial DNA sequences. New World suboscines were shown to constitute two distinct lineages, one apparently consisting of the single species Sapayoa aenigma, the other made up of the remaining 1000+ species of New World suboscines. With the exception of Sapayoa, monophyly of New World suboscines was strongly corroborated, and monophyly within New World suboscines of a tyrannoid clade and a furnarioid clade was likewise strongly supported. Relationships among families and subfamilies within these clades, however, differed in several respects from current classifications of suboscines. Noteworthy results included: (1) monophyly of the tyrant-flycatchers (traditional family Tyrannidae), but only if the tityrines (see below) are excluded; (2) monophyly of the pipromorphine flycatchers (Pipromorphinae of ) as one of two primary divisions of a monophyletic restricted Tyrannidae; (3) monophyly of the tityrines, consisting of the genus Tityra plus all sampled species of the Schiffornis group (), as sister group to the manakins (traditional family Pipridae); (4) paraphyly of the ovenbirds (traditional family Furnariidae), if woodcreepers (traditional family Dendrocolaptidae) are excluded; and (5) polyphyly of the antbirds (traditional family Formicariidae) and paraphyly of the ground antbirds (Formicariidae sensu stricto). Genus Melanopareia (the crescent-chests), although clearly furnarioid, was found to be distant from other furnarioids and of uncertain affinities within the Furnarii. Likewise, the species Oxyruncus cristatus (the Sharpbill), although clearly tyrannoid, was distantly related to other tyrannoids and of uncertain affinities within the Tyranni. Results of this study provide support for some of the more novel features of the suboscine phylogeny of, but also reveal key differences, especially regarding relationships among suboscine families and subfamilies. The results of this study have potentially important implications for the reconstruction of character evolution in the suboscines, especially because the behavioral evolution of many suboscine groups (e.g., Furnariidae) is of great interest.     

Morphology and foraging behaviour of Siberian Phylloscopus warblers

There are seven species of Phylloscopus warblers breeding sympatrically in Central Siberia. In general they are very similar in morphology and behaviour. Slight differences in morphology, however, are often interpreted as having arisen through adaptation to distinct foraging ecologies, thereby mediating species coexistence. We studied the morphology and foraging behaviour of these warblers, taking into account phylogenetic relationships using Felsenstein's method of independent contrasts. Striking correlations were found between morphology and foraging techniques, as well as between morphology and microhabitat selection. Species with large hind limbs and short wings foraged in dense vegetation near the ground using gleaning techniques. In contrast, species with long wings and large bills favoured open vegetation, and foraged using sallying manoeuvres. Independently of these trends, small species foraged at higher levels in the vegetation, and used hoverflight more often than did larger species. Foraging methods were highly correlated with vegetation structure. Coniferous trees were exploited using hoverflight when they had short needles and gleaning when needles were long. Sallying predominated in light deciduous vegetation whereas gleaning was used most in dense, deciduous bushes. After controlling for the effects of vegetation structure on foraging behaviour, species differences became less pronounced, but were still significant. It is therefore concluded that morphology may be regarded as having adapted to enable more efficient exploitation of certain microhabitats. A preference for these microhabitats then further increases the observed behavioural differences between species. Morphology may therefore partly determine a species' ability to colonise new habitats.     

Biogeography of the grasses (Poaceae): a phylogenetic approach to reveal evolutionary history in geographical space and geological time

The grasses (Poaceae) are the fifth most diverse family of angiosperms, including 800 genera and more than 10 000 species. Few phylogenetic studies have tried to investigate palaeo‐biogeographical and palaeo‐ecological scenarios that may have led to present‐day distribution and diversity of grasses at the family level. We produced a dated phylogenetic tree based on combined plastid DNA sequences and a comprehensive sample of Poaceae. Furthermore, we produced an additional tree using a supermatrix of morphological and molecular data that included all 800 grass genera so that ancestral biogeography and ecological habitats could be inferred. We used a likelihood‐based method, which allows the estimation of ancestral polymorphism in both biogeographical and ecological analyses for large data sets. The origin of Poaceae was retrieved as African and shade adapted. The crown node of the BEP + PACCMAD clade was dated at 57 Mya, in the early Eocene. Grasses dispersed to all continents by approximately 60 million years after their Gondwanan origin in the late Cretaceous. PACCMAD taxa adapted to open habitats as early as the late Eocene, a date consistent with recent phytolith fossil data for North America. C₄ photosynthesis first originated in Africa, at least for Chloridoideae in the Eocene at c. 30 Mya. The BEP clade members adapted to open habitats later than PACCMAD members; this was inferred to occur in Eurasia in the Oligocene. © 2010 The Linnean Society of London, Botanical Journal of the Linnean Society, 2010, 162 , 543–557.     

Phylogeny and biogeography of tetralophodont rodents of the tribe Oryzomyini (Cricetidae: Sigmodontinae)

Oryzomyini is the richest tribe among the Sigmodontine rodents, encompassing 32 living and extinct genera and including an increasing number of recently described species and genera. Some Oryzomyini are tetralophodont showing a reduction in the number of molar folds to four, while most taxa in this tribe retain the plesiomorphic pentalophodont state. We applied phylogenetic methods, molecular dating techniques and ancestral area analyses to members of an oryzomyini clade informally named ‘D’ in former studies and included related fossil tetralophodont forms. Based on 98 morphological characters and sequences of five gene fragments, we found that the tetralophodont condition is paraphyletic. Among living taxa, Pseudoryzomys is sister to Holochilus, and Lundomys is derived from a basal divergence. A clade formed by living Holochilus and the fossils Noronhomys and Carletonomys is sister to Holochilus primigenus, making Holochilus paraphyletic. Therefore, we describe a new genus that accommodates the fossil H. primigenus. Because trans‐Andean taxa currently share a common ancestor with taxa of cis‐Adean distribution, the northern Andes uplift may have worked as a postdispersal barrier. The tetralophodont lineages diverged during the Pliocene from a cis‐Andean ancestor, and the Great Plains in South America may have favoured the diversification of tetralophodont forms adapted to open habitats during the Pliocene.