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1.
The Australasian marsupial family Macropodidae includes potoroos and bettongs (Potoroinae) as well as larger kangaroos, wallabies, and pademelons (Macropodinae). Perhaps the most enigmatic macropodid is the banded hare wallaby, Lagostrophus fasciatus, a taxon listed as vulnerable by the IUCN. Lagostrophus had traditionally been grouped as a sister-taxon to hare wallabies (Lagorchestes), in a clade with hypsodont macropodines, or intercalated in some other fashion within Macropodinae. Flannery (1983, 1989) proposed a radically different hypothesis wherein Lagostrophus is outside of Macropodinae and is more closely related to extinct sthenurine (short-faced) kangaroos. Given this controversy, we addressed the phylogenetic placement of the banded hare wallaby using molecular sequences for three mitochondrial genes (12S rRNA, valine tRNA, 16S rRNA) and one nuclear gene (protamine P1). Diverse phylogenetic methods all provided robust support for a macropodine clade that excludes the banded hare wallaby. The split between macropodines and the banded hare wallaby was estimated at approximately 20 million years ago (mya) using the Thorne/Kishino relaxed molecular clock method. Whereas our molecular results neither corroborate nor refute the sthenurine hypothesis, since all short-faced kangaroos and their immediate ancestors are extinct, the overriding implication of molecular phylogenetic analyses is manifest: the banded hare wallaby is the only living relict of an ancient kangaroo lineage. Regardless of its precise relationships, special efforts should be directed at conserving this unique and endangered taxon, which has not been recorded from mainland Australia since 1906 and is now restricted to two tiny islands off the coast of Western Australia.Supplementary material to this paper is available in electronic form at http://dx.doi.org/10.1023/A:1022697300092  相似文献   

2.
Ornithischia is a morphologically and taxonomically diverse clade of dinosaurs that originated during the Late Triassic and were the dominant large‐bodied herbivores in many Cretaceous ecosystems. The early evolution of ornithischian dinosaurs is poorly understood, as a result in part of a paucity of fossil specimens, particularly during the Triassic. The most complete Triassic ornithischian dinosaur yet discovered is Eocursor parvus from the lower Elliot Formation (Late Triassic: Norian–Rhaetian) of Free State, South Africa, represented by a partial skull and relatively complete postcranial skeleton. Here, the anatomy of Eocursor is described in detail for the first time, and detailed comparisons are provided to other basal ornithischian taxa. Eocursor is a small‐bodied taxon (approximately 1 m in length) that possesses a plesiomorphic dentition consisting of unworn leaf‐shaped crowns, a proportionally large manus with similarities to heterodontosaurids, a pelvis that contains an intriguing mix of plesiomorphic and derived character states, and elongate distal hindlimbs suggesting well‐developed cursorial ability. The ontogenetic status of the holotype material is uncertain. Eocursor may represent the sister taxon to Genasauria, the clade that includes most of ornithischian diversity, although this phylogenetic position is partially dependent upon the uncertain phylogenetic position of the enigmatic and controversial clade Heterodontosauridae. © 2010 The Linnean Society of London, Zoological Journal of the Linnean Society, 2010, 160 , 648–684.  相似文献   

3.
Tertiary cormorant fossils (Aves: Phalacrocoracidae) from Late Oligocene deposits in Australia are described. They derive from the Late Oligocene – Early Miocene (26–24 Mya) Etadunna and Namba Formations in the Lake Eyre and Lake Frome Basins, South Australia, respectively. A new genus, Nambashag gen. nov. , with two new species ( Nambashag billerooensis sp. nov. , 30 specimens; Nambashag microglaucus sp. nov. , 14 specimens), has been established. Phylogenetic analyses based on 113 morphological and two integumentary characters indicated that Nambashag is the sister taxon to the Early Miocene Nectornis miocaenus of Europe and all extant phalacrocoracids. As Nambashag, Nectornis, and extant phalacrocoracids constitute a strongly supported clade sister to Anhinga species, the fossil taxa have been referred to Phalacrocoracidae. Sulids and Fregata were successive sister taxa to the Phalacrocoracoidea, i.e. phalacrocoracids + Anhinga. As phalacrocoracids lived in both Europe and Australia during the Late Oligocene and no older phalacrocoracid taxa are known, the biogeographical origin of cormorants remains unanswered. The phylogenetic relationships of extant taxa were not wholly resolved, but contrary to previous morphological analyses, considerable concordance was found with relationships recovered by recent molecular analyses. Microcarbo is sister to all other extant phalacrocoracids, and all Leucocarbo species form a well‐supported clade. © 2011 The Linnean Society of London, Zoological Journal of the Linnean Society, 2011, 163 , 277–314.  相似文献   

4.
To evaluate the monophyletic status of the genus Monodelphis, and its species complexes, we used a 9.3‐kb multimarker alignment to build a phylogenetic tree based on the largest taxon sampling for this didelphid genus to date. Furthermore, using a Bayesian framework and six calibration points, we inferred the divergence times for the major Monodelphis lineages and their current geographical distribution to perform an ancestral state reconstruction for geographical areas. Our results indicate the monophyletic nature of Monodelphis and suggest ‘kunsi’ as a new species complex that includes Monodelphis kunsi and an undescribed species. Monodelphis is further subdivided into three clades showing a common vicariance pattern, with each major clade consisting of a northern South American lineage joined with an Atlantic Forest lineage. This geographic consistency suggests a vicariant event that might have been related to a warm period at the Oligocene/Miocene border, according to our time results. © 2015 The Linnean Society of London  相似文献   

5.
Recent molecular analyses of Dictyosphaerium strains revealed a polyphyletic origin of this morphotype within the Chlorellaceae. The type species Dictyosphaerium ehrenbergianum Nägeli formed an independent lineage within the Parachlorella clade, assigning the genus to this clade. Our study focused on three different Dictyosphaerium species to resolve the phylogenetic position of remaining species. We used combined analyses of morphology; molecular data based on SSU and internally transcribed spacer region (ITS) rRNA sequences; and the comparison of the secondary structure of the SSU, ITS‐1, and ITS‐2 for species and generic delineation. The phylogenetic analyses revealed two lineages without generic assignment and two distinct clades of Dictyosphaerium‐like strains within the Parachlorella clade. One clade comprises the lineages with the epitype strain of D. ehrenbergianum Nägeli and two additional lineages that are described as new species (Dictyosphaerium libertatis sp. nov. and Dictyosphaerium lacustre sp. nov.). An emendation of the genus Dictyosphaerium is proposed. The second clade comprises the species Dictyosphaerium sphagnale Hindák and Dictyosphaerium pulchellum H. C. Wood. On the basis of phylogenetic analyses, complementary base changes, and morphology, we describe Mucidosphaerium gen. nov with the four species Mucidosphaerium sphagnale comb. nov., Mucidosphaerium pulchellum comb. nov., Mucidosphaerium palustre sp. nov., and Mucidosphaerium planctonicum sp. nov.  相似文献   

6.
7.
We reassessed the phylogenetic relationships of dasyuromorphians using a large molecular database comprising previously published and new sequences for both nuclear (nDNA) and mitochondrial (mtDNA) genes from the numbat (Myrmecobius fasciatus), most living species of Dasyuridae, and the recently extinct marsupial wolf, Thylacinus cynocephalus. Our molecular tree suggests that Thylacinidae is sister to Myrmecobiidae + Dasyuridae. We show robust support for the dasyurid intrafamilial classification proposed by Krajewski & Westerman as well as for placement of most dasyurid genera, which suggests substantial homoplasy amongst craniodental characters presently used to generate morphology‐based taxonomies. Molecular dating with relaxed molecular clocks suggests that dasyuromorphian cladogenesis began in the Eocene, and that all three dasyuromorphian families originated prior to the end of this epoch. Radiation within Thylacinidae and Dasyuridae had occurred by the middle to late Oligocene, consistent with recognition of primitive thylacinids (e.g. Badjcinus turnbulli) in the later Oligocene and of putative dasyurids (e.g. Barinya wangala) by the early Miocene. We propose that all four extant dasyurid tribes were in existence by the early Miocene and that most modern dasyurid genera/species were established before the later Miocene. This is in marked contrast to the popularly accepted advocation of their origins in the latest Miocene–early Pliocene. © 2015 The Linnean Society of London  相似文献   

8.
A time‐calibrated phylogenetic tree indicates that the evolution of sympatric, montane, endemic species from closely related, co‐distributed lineages of the Hemiphyllodactylus harterti group were not the result of rapid, forest‐driven, climatic oscillations of the Last Glacial Maximum, but rather the result of infrequent episodes of environmental fluctuation during the Late Miocene. This hypothesis is supported by genetic divergences (based on the mitochondrial gene ND2) between the three major lineages of the H. harterti group (17.5–25.1%), their constituent species (9.4–14.3%), and the evolution of discrete, diagnostic, morphological, and colour pattern characteristics between each species. Sister species pairs from two of the three lineages occur in sympatry on mountain tops from opposite sides of the Thai–Malay Peninsula, but the lineages to which each pair belongs are not sister lineages. A newly discovered species from Gunung Tebu, Terengganu State, H emiphyllodactylus bintik sp. nov. , is described. © 2015 The Linnean Society of London  相似文献   

9.
Extant clades may differ greatly in their species richness, suggesting differential rates of species diversification. Based on phylogenetic trees, it is possible to identify potential correlates of such differences. Here, we examine species diversification in a clade of 82 tropical African forest butterfly species (Cymothoe), together with its monotypic sister genus Harma. Our aim was to test whether the diversification of the HarmaCymothoe clade correlates with end‐Miocene global cooling and desiccation, or with Pleistocene habitat range oscillations, both postulated to have led to habitat fragmentation. We first generated a species‐level phylogenetic tree for Harma and Cymothoe, calibrated within an absolute time scale, and then identified temporal and phylogenetic shifts in species diversification. Finally, we assessed correlations between species diversification and reconstructed global temperatures. Results show that, after the divergence of Harma and Cymothoe in the Miocene (15 Mya), net species diversification was low during the first 7 Myr. Coinciding with the onset of diversification of Cymothoe around 7.5 Mya, there was a sharp and significant increase in diversification rate, suggesting a rapid radiation, and correlating with a reconstructed period of global cooling and desiccation in the late Miocene, rather than with Pleistocene oscillations. Our estimated age of 4 Myr for a clade of montane species corresponds well with the uplift of the Eastern Arc Mountains where they occur. We conclude that forest fragmentation caused by changing climate in the late Miocene as well as the Eastern Arc Mountain uplift are both likely to have promoted species diversification in the Harma–Cymothoe clade. Cymothoe colonized Madagascar much later than most other insect lineages and, consequently, had less time available for diversification on the island. We consider the diversification of Cymothoe to be a special case compared with other butterfly clades studied so far, both in terms of its abrupt diversification rate increase and its recent occurrence (7 Myr). It is clear that larval host plant shift(s) cannot explain the difference in diversification between Cymothoe and Harma; however, such a shift(s) may have triggered differential diversification rates within Cymothoe. © 2013 The Linnean Society of London, Biological Journal of the Linnean Society, 2013, ●● , ●●–●●.  相似文献   

10.
The exceptionally high plant diversity of the Greater Cape Floristic Region (GCFR) comprises a combination of ancient lineages and young radiations. A previous phylogenetic study of Aizoaceae subfamily Ruschioideae dated the radiation of this clade of > 1500 species in the GCFR to 3.8–8.7 Mya, establishing it as a flagship example of a diversification event triggered by the onset of a summer‐arid climate in the region. However, a more recent analysis found an older age for the Ruschioideae lineage (17 Mya), suggesting that the group may in fact have originated much before the aridification of the region 10–15 Mya. Here, we reassess the tempo of radiation of ice plants by using the most complete generic‐level phylogenetic tree for Aizoaceae to date, a revised calibration age and a new dating method. Our estimates of the age of the clade are even younger than initially thought (stem age 1.13–6.49 Mya), supporting the hypothesis that the radiation post‐dates the establishment of an arid environment in the GCFR and firmly placing the radiation among the fastest in angiosperms (diversification rate of 4.4 species per million years). We also statistically examine environmental and morphological correlates of richness in ice plants and find that diversity is strongly linked with precipitation, temperature, topographic complexity and the evolution of highly succulent leaves and wide‐band tracheids. © 2013 The Authors. Botanical Journal of the Linnean Society published by John Wiley & Sons Ltd on behalf of The Linnean Society of London, Botanical Journal of the Linnean Society, 2014, 174 , 110–129.  相似文献   

11.
In this paper we carry out a taxonomic revision and phylogenetic analysis of the linyphiid spider genus Solenysa Simon, 1894. A total of 12 species is treated here, including five new species collected from China and Japan: Solenysa akihisai Tu sp. nov., Solenysa lanyuensis Tu sp. nov., Solenysa retractilis Tu sp. nov., Solenysa tianmushana Tu sp. nov. , and Solenysa yangmingshana Tu sp. nov. Solenysa circularis Gao, Zhu & Sha, 1993 is a junior synonym of Solenysa protrudens Gao, Zhu & Sha, 1993. We have assembled two different character matrices to reconstruct the phylogenetic relationships of Solenysa. In the first matrix (Matrix 1), five representative species of Solenysa were added to the morphological dataset of Miller & Hormiga to test the monophyly of the genus and its placement within Linyphiidae. The genitalic structures and somatic morphology of Solenysa were studied by means of scanning electron microscopy for the first time. To infer the species‐level phylogenetic relationships of Solenysa we produced a second matrix (Matrix 2) that includes all 12 Solenysa species and six outgroup species chosen from the results of the analysis of the first matrix. The two most parsimonious trees from the analysis of Matrix 1 support the monophyly of Solenysa and its placement within the ‘Distal Erigonines’ clade. The single most parsimonious tree resulting from the analysis of the second matrix suggests that the Solenysa clade includes four monophyletic groups, each group represented by a distinct genitalic pattern. The morphology of Solenysa, both somatic and genitalic, is highly autapomorphic. © 2011 The Linnean Society of London, Zoological Journal of the Linnean Society, 2011, 161 , 484–530.  相似文献   

12.
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.  相似文献   

13.
Puffins, auks and their allies in the wing‐propelled diving seabird clade Pan‐Alcidae (Charadriiformes) have been proposed to be key pelagic indicators of faunal shifts in Northern Hemisphere oceans. However, most previous phylogenetic analyses of the clade have focused only on the 23 extant alcid species. Here we undertake a combined phylogenetic analysis of all previously published molecular sequence data (~ 12 kb) and morphological data (n = 353 characters) with dense species level sampling that also includes 28 extinct taxa. We present a new estimate of the patterns of diversification in the clade based on divergence time estimates that include a previously vetted set of twelve fossil calibrations. The resultant time trees are also used in the evaluation of previously hypothesized paleoclimatic drivers of pan‐alcid evolution. Our divergence dating results estimate the split of Alcidae from its sister taxon Stercorariidae during the late Eocene (~ 35 Ma), an evolutionary hypothesis for clade origination that agrees with the fossil record and that does not require the inference of extensive ghost lineages. The extant dovekie Alle alle is identified as the sole extant member of a clade including four extinct Miocene species. Furthermore, whereas an Uria + Alle clade has been previously recovered from molecular analyses, the extinct diversity of closely related Miocepphus species yields morphological support for this clade. Our results suggest that extant alcid diversity is a function of Miocene diversification and differential extinction at the Pliocene–Pleistocene boundary. The relative timing of the Middle Miocene climatic optimum and the Pliocene–Pleistocene climatic transition and major diversification and extinction events in Pan‐Alcidae, respectively, are consistent with a potential link between major paleoclimatic events and pan‐alcid cladogenesis.  相似文献   

14.
The Paucituberculata is an endemic group of South American marsupials, recorded from the early Cenozoic up to the present. In this report, the most comprehensive phylogenetic analysis of Paucituberculata to date is presented. Fifty‐seven terminal species were scored for 74 new and re‐examined characters. Homologies of dental characters used in previous systematic studies were critically reviewed to evaluate their inclusion in the analysis. Phylogenetic results corroborated two major paucituberculatan clades, Palaeothentoidea and Caenolestoidea, and the main palaeothentoid groupings: Pichipilidae, Palaeothentidae, and Abderitidae. Taxon sampling and reinterpretations of molar cusp and crest homologies played an important role in the generation of new phylogenetic hypotheses. The main differences with respect to previous phylogenies were focused on palaeothentoid relationships: Palaeothentes boliviensis and Pilchenia lucina are not members of Palaeothentidae but instead clustered with Pilchenia intermedia and P. antiqua, forming the sister‐group of a Palaeothentidae + Abderitidae clade, and Titanothentes simpsoni, previously considered a palaeothentine, is nested within the Acdestinae clade. Based on the time‐calibrated phylogeny, the following stages in the paucituberculatan evolutionary history are suggested: origin of the group, in the Paleocene to early Eocene at the latest, split of Caenolestoidea and Palaeothentoidea clades during the late early to middle Eocene, evolutionary radiation of palaeothentid and abderitid lineages near the Oligocene–Eocene boundary, and decreased diversity and extinction of palaeothentoids during the middle Miocene. © 2013 The Linnean Society of London, Biological Journal of the Linnean Society, 2013, 109 , 441–465.  相似文献   

15.
The taxonomic value and evolutionary significance of 30 leaf epidermal characters from 238 samples representing 127 species of all seven genera in the tribe Gaultherieae (Ericaceae) and two outgroup genera were investigated by scanning electron microscopy. The character states were coded and optimized onto a maximum‐likelihood tree based on previous molecular data with Fitch parsimony and hierarchical Bayesian analysis to trace the evolution of character states throughout all internodes in the phylogenetic tree for Gaultherieae. Leaf epidermal characters were found to be largely consistent within species, but highly variable at interspecific and higher taxonomic levels. The most recent common ancestral states of 15 characters diagnosed various lineages recovered from prior studies, some with no prior morphological support. Relatively high frequencies of state change occur in the eastern Asian clade Gaultheria series Gymnobotrys + Diplycosia, the American clade G. subsection Dasyphyta p.p., the core East Asian clade and the Australia/New Zealand clade. The characters with the highest frequencies of state change are the outer stomatal ledge ornamentation type, the stomatal apparatus level, stomatal density and area, and the type of abaxial trichomes. These character state change patterns may provide insight into the ecological adaptions of Gaultherieae during their evolutionary history. © 2015 The Linnean Society of London, Botanical Journal of the Linnean Society, 2015, 178 , 686–710.  相似文献   

16.
The phylogenetic relationships within the genus Plecotus were assessed using molecular as well as morphological methods. With only three species missing, our study is based on an almost comprehensive taxonomic sampling. The genetic analysis comprised 151 individuals from throughout the range. Sequences of two mitochondrial sections, parts of the 16S rRNA gene (16S) and of the control region (CR) were analysed. The morphological analysis of cranial and external characters comprised 697 individuals, including 10 holotypes and one lectotype. Data from 15 craniometric characters of 442 specimens were used in the multivariate analyses. The molecular data identified nine primary clades representing 11 species, 10 of which could be assigned to described taxa, whereas one was described as a new species, Plecotus strelkovi Spitzenberger sp. nov. The tree based on 16S revealed two major lineages, one consisting of only one primary clade restricted to the Mediterranean, the other consisting of eight primary clades representing Eurasian taxa. The morphological analysis revealed five additional species, two of them not described. Together with the recently described P. taivanus, P. sardus and P. balensis, which were not included in our analysis, the genus Plecotus comprises at least 19 more or less cryptic species. Phylogenetic and phenetic analyses resulted in similar but not completely concordant arrangements of the species. The proposed classification relies mainly on the tree based on 16S sequences. The current distribution indicates that 16 species can be linked to arboreal refugia, three to eremial refugia. We assume that speciation within the gleaning, rather slow flying long‐eared bats is due to a multitude of disruption and isolation processes within a formerly continuous range of the broad‐leaved Arcto‐Tertiary forest in which Plecotus probably originated. An exact calibrated molecular dating of the splits is not possible. The Early Oligocene age of the presumed ancestor of the Plecotini and a correlation of the molecular diversifications with palaeogeographic reconstructions suggest that the divergence of the two major lineages may have occurred already during the Middle Miocene, 14.5 Mya.  相似文献   

17.
A new spider cricket (Orthoptera: Gryllidae: Phalangopsinae) is described from an adult female preserved in Early Miocene (Burdigalian) amber from the Dominican Republic. Araneagryllus dylani gen. et sp. nov. represents the first fossil record of Phalangopsinae, and is assigned to the tribe Luzarini, subtribe Amphiacustina stat. nov. A cladistic analysis of Amphiacustina places Araneagryllus gen. nov. within a clade comprising Arachnopsita, Leptopedetes, Longuripes, Mayagryllus, Nemoricantor, and Prolonguripes. This clade is the sister group to a clade comprising Amphiacusta, Cantrallia, and Noctivox. The results of this analysis suggest that: (1) the common ancestor of all Amphiacustina was epigean, and was likely to have been cavicolous and/or straminicolous; (2) strict troglobitism evolved twice within Amphiacustina, once in the lineage leading to Noctivox and again in the clade comprising Mayagryllus, Arachnopsita, Longuripes, and Prolonguripes; and (3) Prolonguripes is secondarily epigean, having reverted to life above ground. The occurrence of Araneagryllus gen. nov. in amber indicates that it was not troglobitic, but was instead more likely to have been straminicolous, living on the ground and foraging amongst leaf litter. Araneagryllus gen. nov. possesses a number of characters that are usually considered to be adaptive to a troglobitic life history, suggesting that many so‐called troglobiomorphies are not adaptations to life in caves, but are instead likely to have been exaptive. © 2010 The Linnean Society of London, Zoological Journal of the Linnean Society, 2010, 158 , 56–65.  相似文献   

18.
The Central Asian racerunner, Eremias velox, is a widely distributed lizard of the Eurasian lacertid genus Eremias. Nucleotide sequences of mitochondrial genes, cyt b and 12S rDNA from 13 geographically distant localities in Iran and Central Asia, were analysed. Phylogenetic analyses of the sequence data unambiguously recovered five major clades within the E. velox complex with a high level of genetic divergence, indicating long periods of isolation. The basal position of the Iranian clades in the phylogenetic trees suggests that the E. velox clade originated on the Iranian plateau in the Middle Miocene. According to our calibrations, the northern Iranian clade diverged first some 10–11 Ma and that the Central Asian lineages split from the northeastern Iranian lineage approximately 6 Ma, most likely as a result of uplifting of the Kopet‐Dagh Mountains in the northern margin of the Iranian plateau. Topology of the phylogenetic trees, combined with the degree of the genetic distances among the independent lineages recovered in this study, provide a solid foundation for a fundamental revision of the taxonomic status of the major clades within this species complex.  相似文献   

19.
Little information on evolutionary relationships of Neotropical organisms or on the factors that have shaped the diversity currently encountered in this region is available. However, it is clear that biotic interactions and abiotic aspects have played important roles for species diversification in the region. This study focuses on Dolichandra (Bignonieae, Bignoniaceae), a clade of Neotropical lianas that is distributed broadly across different habitats and with diverse pollination and dispersal systems. We used sequences from two plastid DNA markers (ndhF and rpl32‐trnL) and one nuclear gene (PepC) to infer phylogenetic relationships in Dolichandra using parsimony and Bayesian approaches. We then used this phylogenetic framework as basis to study the biogeographic history, reconstruct the evolution of morphological characters and test the impact of morphology and environment on the diversification of the genus. More specifically, we: (1) time‐calibrate the phylogenetic tree of Dolichandra; (2) estimate the ancestral areas of the various lineages; (3) estimate the ancestral states of discrete and continuous morphological traits; (4) test for phylogenetic signal in environmental and phenotypic data; and (5) test whether morphological characters and/or niche evolution are correlated with cladogenesis. All Dolichandra spp. are monophyletic in the combined molecular phylogeny; relationships among species are generally well resolved, although poorly supported in some instances. The genus is inferred to have originated 36.43–26.23 Mya, possibly in eastern South America. Ancestral state reconstructions of continuous and discrete floral characters inferred a mixed morphology as the ancestral condition for the group. Phylogenetic signal differed between perianth and sexual whorls and gradual evolution was recovered for all traits except style length and anther length. Environmental variables showed no phylogenetic signal and a pattern of variation that was not correlated with branch length, suggesting that environmental transitions were concomitant with speciation. Dispersal is inferred to be the main driver of the differential distribution observed among species. In addition, climatic preferences and floral characters seem to have been important reproductive barriers in Dolichandra. © 2015 The Linnean Society of London, Botanical Journal of the Linnean Society, 2015, 179 , 403–420.  相似文献   

20.
The genus Ixchela Huber is composed of 20 species distributed from north‐eastern Mexico to Central America, including the five new species described here from Mexico: I xchela azteca sp. nov. , I xchela jalisco sp. nov. , I xchela mendozai sp. nov. , I xchela purepecha sp. nov. and I xchela tlayuda sp. nov. We test the monophyly and investigate the phylogenetic relationships among species of the genus Ixchela using morphological and molecular data. Parsimony (PA) analysis of 24 taxa and 40 morphological characters with equal and implied weights supported the monophyly of Ixchela with eight morphological synapomorphies. The PA analyses with equal and implied weights, and separate Bayesian inference (BI) analyses for the CO1 gene (506 characters), concatenated gene fragments CO1 + 16S (885 characters), morphology + CO1 (546 characters) and the combined evidence data set (morphology + CO1 + 16S) (925 characters) support the monophyly of Ixchela. Our preferred topology shows two large clades; clade 1 has a natural distribution in the Mesoamerican biotic component, whereas clade 2 predominates in the Mexican Montane biotic component. The genus Ixchela diverged in the late Miocene, and the divergence between the internal clades in the genus occurred in the late Pliocene; by contrast, most of the speciation events seem to have occurred mainly during the Pleistocene, where climatic changes brought on by repeated glaciations played an important role in the diversification of the genus. © 2015 The Linnean Society of London  相似文献   

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