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1.
Here, we present a comprehensive phylogenetic analysis based on nuclear and mitochondrial DNA sequences of rodents of the subfamily Sigmodontinae. The emphasis is placed on the large tribe Phyllotini; sampling includes for the first time in any molecular‐based phylogenetic analysis representatives of several genera traditionally considered to be phyllotines. Given the broad taxonomic sampling, results provide substantial improvements in our knowledge on both the structure of the sigmodontine radiation and of phyllotine phylogenetic relationships. For instance, the tribe Ichthyomyini was not recovered monophyletic. Similarly, in a novel hypothesis on the contents of the tribe Phyllotini, it is shown that unlike Galenomys, the genera Chinchillula, Neotomys and Punomys are not phyllotines. The later genera together with Andinomys, Euneomys, Irenomys and Juliomys form part of novel generic clades of mostly Andean sigmodontine rodents. More in general, results strongly suggest the occurrence of several instances of putative morphological convergence among distinct sigmodontine lineages (e.g. among now considered to be ichthyomyines; between Phyllotini and some Andean taxa; among EuneomysNeotomys and Reithrodon). Finally, we suggest that the historical biogeography of the sigmodontine rodents is far more complex than earlier envisioned.  相似文献   

2.
The extant distribution of sigmodontine rodents encompasses most of the New World, and the majority of the species in this subfamily inhabit South America. Nevertheless, the basal lineages of the Sigmodontinae are distributed in North and Central America, and the fossil record indicates a North American origin. This evidence has produced contentious theories concerning the evolution of these rodents. The dispute usually stems from a disagreement about the way in which sigmodontines reached South America, which was an isolated landmass during most of the Cenozoic. Fundamentally, the debate is associated with the role of Panamanian Isthmus formation and the Great American Biotic Interchange (GABI) in the diversification of the clade. An early hypothesis implies that sigmodontines arrived in South America before the complete rise of the Panamanian Isthmus, whereas a late hypothesis directly correlates the diversification of the lineage with this event. To address this question, we have sequenced nuclear and mitochondrial sequences, as well as the first Sigmodontinae mitochondrial genomes (Akodon montensis and Wiedomys cerradensis) and performed a Bayesian dating analysis. Our results showed that the most recent common ancestor of the subfamily lived at approximately 15 Ma. Although the diversification of sigmodontines was not associated with the complete rise of the Panamanian Isthmus, we cannot exclude the hypothesis that this event played a relevant role in the evolution of the lineage during the Miocene.  相似文献   

3.
The aim of this study was to assess the phylogenetic position of the South American cricetid genus Neotomys using two molecular markers: one nuclear (Irbp) and one mitochondrial (mt-cyb). This genus is currently considered as incertae sedis in the Sigmodontinae radiation. The phylogenetic relationships were estimated using three approaches: Bayesian inference, maximum likelihood and parsimony. We found the genus Neotomys closely related to the genera Euneomys and Irenomys, which are also considered incertae sedis. Our results suggest a common origin for this group of genera; this fact should be reflected in the taxonomy as a supra generic group with a tribal level. However, further and deeper analysis of both molecular and morphological data are needed to diagnose and formalize the proposed tribe. The relationships of this clade to the other members of Sigmodontinae were not clear as assessed by these data sets. The three genera are distributed around the Central and Southern Andes in South America evidencing that the Andes have played an important role in the diversification of several tribes of sigmodontine rodents.  相似文献   

4.
Phylogenetic relationships among South American sigmodontine rodents were examined based on the complete sequence for the mitochondrial cytochrome b gene [1140 base pairs (bp)] for 66 species and between 759 and 1140 bp for an additional 19 species. Thirty-eight South American genera were represented, coming from eight of nine tribes. Outgroups included the North American murid rodents Peromyscus, Reithrodontomys, Scotinomys, and Neotoma, the Old World murine rodents Mus and Rattus, and the geomyoid genera Thomomys, Geomys, Dipodomys, and Perognathus as the most distant outgroup. The South American sigmodontines were supported as a monophyletic lineage. Within this radiation several clear-cut suprageneric groupings were identified. Many of the currently recognized tribal groupings of genera were found fairly consistently, although not always with high levels of bootstrap support. The various tribes could not be linked hierarchically with any confidence. In addition, several genera stand out as unique entities, without any apparent close relatives. The overall pattern suggests a rapid radiation of the sigmodontines in South America, followed by differentiation at the tribal and generic levels.  相似文献   

5.
The murid rodent subfamily Sigmodontinae contains 79 genera which are distributed throughout the New World. The time of arrival of the first sigmodontines in South America and the estimated divergence time(s) of the different lineages of South American sigmodontines have been controversial due to the lack of a good fossil record and the immense number of extant species. The "early-arrival hypothesis" states that the sigmodontines must have arrived in South America no later than the early Miocene, at least 20 MYA, in order to account for their vast present-day diversity, whereas the "late-arrival hypothesis" includes the sigmodontines as part of the Plio-Pleistocene Great American Interchange, which occurred approximately 3.5 MYA. The phylogenetic relationships among 33 of these genera were reconstructed using mitochondrial DNA (mtDNA) sequence data from the ND3, ND4L, arginine tRNA, and ND4 genes, which we show to be evolving at the same rate. A molecular clock was calibrated for these genes using published fossil dates, and the genetic distances were estimated from the DNA sequences in this study. The molecular clock was used to estimate the dates of the South American sigmodontine origin and the main sigmodontine radiation in order to evaluate the "early-" and "late-arrival" scenarios. We estimate the time of the sigmodontine invasion of South America as between approximately 5 and 9 MYA, supporting neither of the scenarios but suggesting two possible models in which the invading lineage was either (1) ancestral to the oryzomyines, akodonts, and phyllotines or (2) ancestral to the akodonts and phyllotines and accompanied by the oryzomyines. The sigmodontine invasion of South America provides an example of the advantage afforded to a lineage by the fortuitous invasion of a previously unexploited habitat, in this case an entire continent.   相似文献   

6.
With about 400 living species and 82 genera, rodents of the subfamily Sigmodontinae comprise one of the most diverse and more broadly distributed Neotropical mammalian clades. There has been much debate on the origin of the lineage or the lineages of sigmodontines that entered South America, the timing of entrance and different aspects of further diversification within South America. The ages of divergence of the main lineages and the crown age of the subfamily were estimated by using sequences of the interphotoreceptor retinoid binding protein and cytochrome b genes for a dense sigmodontine and muroid sampling. Bayesian inference using three fossil calibration points and a relaxed molecular clock estimated a middle Miocene origin for Sigmodontinae (~12 Ma), with most tribes diversifying throughout the Late Miocene (6.9–9.4 Ma). These estimates together results of analyses of ancestral area reconstructions suggest a distribution for the most recent common ancestor of Sigmodontinae in Central-South America and a South American distribution for the most recent common ancestor of Oryzomyalia.  相似文献   

7.
Larvae, nymphs and females of Ixodes sigelos Keirans, Clifford and Corwin (Ixodidae) were collected in 13 localities of the Patagonian region of Argentina parasitizing eight species of sigmodontine rodents. We report for the first time adults of I. sigelos for Argentina. Besides, we extend the southern limit of its geographical distribution, and six species of sigmodontines are added as new host species of I. sigelos (Phyllotis xanthopygus, Euneomys chinchilloides, Calomys musculinus, Reithrodon auritus, Loxodontomys micropus and Eligmodontia morgani). The presence of larvae, nymphs and females on sigmodontines, as well as more than 50% of the individuals engorged, indicate that I. sigelos can develop the complete parasitic phase of its life cycle on these small mammals. The geographical distribution of I. sigelos is restricted to the biogeographical Andean Region in Argentina and Chile.  相似文献   

8.
Populations of Trichuris spp. isolated from six species of sigmodontine rodents from Argentina were analyzed based on morphological characteristics and ITS2 (rDNA) region sequences. Molecular data provided an opportunity to discuss the phylogenetic relationships among the Trichuris spp. from Noth and South America (mainly from Argentina). Trichuris specimens were identified morphologically as Trichuris pardinasi, T. navonae, Trichuris sp. and Trichuris new species, described in this paper. Sequences analyzed by Maximum Parsimony, Maximum Likelihood and Bayesian inference methods showed four main clades corresponding with the four different species regardless of geographical origin and host species. These four species from sigmodontine rodents clustered together and separated from Trichuris species isolated from murine and arvicoline rodents (outgroup). Different genetic lineages observed among Trichuris species from sigmodontine rodents which supported the proposal of a new species. Moreover, host distribution showed correspondence with the different tribes within the subfamily Sigmodontinae.  相似文献   

9.
Evolutionary relationships among cetaceans within the family Delphinidae have been difficult to resolve due to the high number of species and their relatively rapid radiation. This is the case for the dolphin species currently placed in the genus Lagenorhynchus, and their relations to Cephalorhynchus and Lissodelphis species. Phylogenetic relationships among these species have been investigated using multiple lines of evidence, and that evidence consistently suggests that the six species currently assigned to Lagenorhynchus do not form a monophyletic group. Here, we summarize findings from studies of morphology, genetics, historical biogeography, and acoustics that offer insight into the phylogenetics of these taxa. We present the taxonomic basis for revision of Lagenorhynchus, propose retention of Lagenorhynchus albirostris and reassignment of the remaining five species into other existing generic names, namely Leucopleurus acutus, Sagmatias australis, Sagmatias cruciger, Sagmatias obliquidens, and Sagmatias obscurus. Making these revisions now so that the taxonomy better reflects evolutionary relationships among these species will ensure that future studies include the most appropriate taxa for investigating the complex phylogenetic and systematic relationships among cetaceans. However, comprehensive analyses using multiple lines of evidence are still needed to clarify the phylogenetic relationships within and among the Lissodelphininae genera Cephalorhynchus, Lissodelphis, and Sagmatias.  相似文献   

10.
We investigated the diversity, cophylogenetic relationships, and biogeography of hoplopleurid sucking lice (Phthiraptera: Anoplura) parasitizing rodents (Muridae: Sigmodontinae) in the Manu National Park and Biosphere Reserve. Our morphological and molecular studies reveal that 15 distinct louse species parasitize 19 rodent species. Three of these louse species are new to science, and all but two of the host associations were previously unknown. We find that hoplopleurid lice in South America parasitize multiple host species across a large geographic area, and that Peru represents a new geographic locality for almost all the louse species collected in the present study. Phylogenetic analyses of mitochondrial and nuclear data reveal that the louse family Hoplopleuridae and the genera Hoplopleura and Pterophthirus are not monophyletic, and lice do not appear to group by host tribe, collecting locality, or collection elevation. The lack of monophyly for these apparently natural groups (taxonomic, locality, and elevation) indicates that host switching with or without parasite speciation may be prevalent among hoplopleurid lice. © 2008 The Linnean Society of London, Biological Journal of the Linnean Society, 2008, 95 , 598–610.  相似文献   

11.
Evolutionary radiations are among the most intriguing natural phenomena. Sigmodontine rodents form a megadiverse group for which doubts exist about the adaptive or non‐adaptive nature of its radiation. We analysed whether or not the rates of diversification of species of Sigmodontinae are related to the rates of diversification of the climatic niches occupied by the species. Our results show a clear association between niche diversification and speciation processes. However, this association is linked to recent and independent processes of diversification in sigmodontines, as opposed to an early link that would indicate a niche‐filling consistent with an adaptive radiation of the subfamily.  相似文献   

12.
13.
Osvaldo A.  Reig 《Journal of Zoology》1980,192(2):257-281
A new genus and species of sigmodontine cricetids, Cholomys pearsonl , from the Lower Pleistocene Vorohué Formation of south-eastern Buenos Aires Province. Argentina, is described. Its closest relative among the extant and extinct cricetids proved to be the living Wiedomys pyrrhorhinus of Brazil. Wiedomys and Cholomys are included in a new tribe of the Sigmodontinae, Wiedomyini. The distinction between the North American and the South American cricetids is stressed, the two groups being postulated to pertain to different subfamilies. The names Neotominae and Sigmodontinae are chosen for these two taxa, respectively. A tribal classification of the Sigmodontinae is advanced. Oryzomyini, Akodontini, Scapteromyini, Phyllotini, Sigmodontini, lehthyomyini and Wiedomyini are recognized as natural tribes of the Sigmodontinae. This broad array of suprageneric groupings reflecting different adaptive types strongly supports the hypothesis that the differentiation of the Sigmodontinae took place in South America from a primitive cricetid immigrant stock which entered South America, probably from North America, not later than during Miocene times.  相似文献   

14.
Sigmodontine rodents are the most diverse family-level mammalian clade in the Neotropical region, with about 70 genera and 320 recognized species. Partial sequences (1266 bp) from the first exon of the nuclear gene encoding the Interphotoreceptor Retinoid Binding Protein (IRBP) were used to infer the phylogenetic relationships among 44 species representing all 16 currently recognized genera of the largest sigmodontine tribe, the Oryzomyini. Monophyly of the tribe was assessed relative to 15 non-oryzomyine sigmodontine taxa representing all major sigmodontine lineages. Twelve taxa from seven muroid subfamilies were used as outgroups. The resulting matrix included 71 taxa and 386 parsimony-informative characters. Phylogenetic analysis of this matrix resulted in 16 equally parsimonious cladograms, which contained the following well-supported groups: (i). a monophyletic Oryzomyini, (ii). a clade containing all oryzomyines except Scolomys and Zygodontomys, (iii). a clade containing Oecomys, Handleyomys, and several species of forest-dwelling Oryzomys, and (iv). a clade containing the remaining oryzomyine taxa. The last clade is composed of two large subclades, each with lower nodal support, containing the following taxa: (i). Microryzomys, Oligoryzomys, Neacomys, and Oryzomys balneator; (ii). Holochilus, Lundomys, Pseudoryzomys, Nectomys, Amphinectomys, Sigmodontomys, and several species of open-vegetation or semiaquatic Oryzomys. Regarding relationships among non-oryzomyine taxa, sigmodontines, neotomines, and tylomyines do not form a monophyletic group; a clade containing Rheomys and Sigmodon is basal relative to all other sigmodontines; and the remaining sigmodontines are grouped in three clades: the first containing Thomasomyini, Akodontini, and Reithrodon; the second containing Abrothrichini, and Phyllotini, plus Wiedomys, Juliomys, Irenomys, and Delomys; and the third containing the oryzomyines. No conflict is observed between IRBP results and previous robust hypotheses from mitochondrial data, while a single case of incongruence is present between the IRBP topology and robust hypothesis from morphological studies.  相似文献   

15.
All methods used in historical biogeographical analysis aim to obtain resolved area cladograms that represent historical relationships among areas in which monophyletic groups of taxa are distributed. When neither widespread nor sympatric taxa are present in the distribution of a monophyletic group, all methods obtain the same resolved area cladogram that conforms to a simple vicariance scenario. In most cases, however, the distribution of monophyletic groups of taxa is not that simple. A priori and a posteriori methods of historical biogeography differ in the way in which they deal with widespread and sympatric taxa. A posteriori methods are empirically superior to a priori methods, as they provide a more parsimonious accounting of the input data, do not eliminate or modify input data, and do not suffer from internal inconsistencies in implementation. When factual errors are corrected, the exemplar presented by M.C. Ebach & C.J. Humphries (Journal of Biogeography, 2002, 29 , 427) purporting to show inconsistencies in implementation by a posteriori methods actually corroborates the opposite. The rationale for preferring a priori methods thus corresponds to ontological rather than to epistemological considerations. We herein identify two different research programmes, cladistic biogeography (associated with a priori methods) and phylogenetic biogeography (associated with a posteriori methods). The aim of cladistic biogeography is to fit all elements of all taxon–area cladograms to a single set of area relationships, maintaining historical singularity of areas. The aim of phylogenetic biogeography is to document, most parsimoniously, the geographical context of speciation events. The recent contribution by M.C. Ebach & C.J. Humphries (Journal of Biogeography, 2002, 29 , 427) makes it clear that cladistic biogeography using a priori methods is an inductivist/verificationist research programme, whereas phylogenetic biogeography is hypothetico‐deductivist/falsificationist. Cladistic biogeography can become hypothetic‐deductive by using a posteriori methods of analysis.  相似文献   

16.
The tribe Abrotrichini (five genera and 14 living species) is a small clade within the speciose subfamily Sigmodontinae (Rodentia, Cricetidae), representing one of the extant successful radiations of mammals at southern high latitudes of the Neotropics. Its distribution is mostly Andean, reaching its greatest diversity in southern Argentina and Chile. We evaluate the phylogenetic relationships within this tribe through parsimony and Bayesian approaches based on 99 morphological characters (including 19 integumental characters, 38 skull characters, 31 dental characters, three postcranial skeletal characters, seven from the male accessory glands and phallus and one from the digestive system) and six molecular markers (one mitochondrial and five nuclear). We include representatives of all, except one, of the currently recognized species of living Abrotrichini plus one fossil form. Based on total evidence, we recovered a primary division between the genus Abrothrix and a group including the long‐clawed Abrotrichini, Chelemys, Geoxus, Notiomys and Pearsonomys. Both clades are recognized and named here as subtribes. The large degree of morphological variation observed within Abrothrix suggests that species in the genus fall into four groups, which we recognize as subgenera. In addition, the two known species of Chelemys do not form a monophyletic group, and Geoxus was recovered as paraphyletic with respect to Pearsonomys. To reconcile classification and phylogenetics, we describe a new genus for Chelemys macronyx and include Pearsonomys as a junior synonym of Geoxus. Our results highlight the importance of both morphology and molecules in resolving the phylogenetic relationships within this tribe. Based on biogeographical analyses, we hypothesize that Abrotrichini originated in south‐western South America by vicariance and then diversified mostly by successive dispersal events.  相似文献   

17.
African diploid barbs (‘Barbus’, Clypeobarbus, Barboides, etc.) are a group of small cyprinids with a body size less than 20 cm and widely distributed in drainages across Africa. These species constitute a significant component of African freshwater fish fauna. This study is the first to focus on the molecular systematics and biogeography of African diploid barbs ‘Barbus’ and its African and Asian allies using both mitochondrial and nuclear genes. We test for monophyly of groups, determine interspecific relationships and estimate the time of divergence of 52 species of ‘Barbus’ and allies using two mitochondrial and four nuclear genes. Resulting trees demonstrate that ‘Barbus’ and allies (Systomus, Barboides, Clypeobarbus and African tetraploid barbs) form a strongly supported clade; however, ‘Barbus’ is not resolved as monophyletic. Divergence time analyses identify the separation between Systomus and ‘Barbus’ plus African allies may have occurred around 26 MYA. In addition to the phylogenetic results, these findings highlight the need for more thorough taxonomic and systematic studies on ‘Barbus’ and allies using morphological and additional molecular data and greater taxon sampling, including the type species of the genus Enteromius, ‘Barbus’ potamogalis.  相似文献   

18.
Despite considerable recent progress in understanding intergeneric relationships, a comprehensive analysis of Podocarpaceae at the species level using molecular data, biogeography, anatomy, and morphology has not been previously attempted. Here we present sequence analyses of rbcL, nrITS1 and NEEDLY intron 2 for two‐thirds (183 accessions of 145 taxa) of all Podocarpaceae species representing all genera except Parasitaxus. These analyses include many more species and accessions than previous studies and result in a more resolved phylogeny. The comprehensive anatomical and morphological study ensures that the identification of taxa is correct and also provides clade support. Bayesian and parsimony analyses were used to resolve 20 well‐supported monophyletic groups including 11 groups of the formerly poorly resolved subgenera Podocarpus and Foliolatus. The well‐resolved topology is supported by anatomical and morphological features and is highly congruent with geographical distribution. © The Willi Hennig Society 2011.  相似文献   

19.
Cordimus, a new genus of cricetid rodent, is described from Neogene deposits on the islands of Curaçao and Bonaire, Dutch Antilles. The genus is characterized by strongly cuspidate molars, the presence of mesolophs in most upper molars and the absence of mesolophids in lower molars. Similarities with the early cricetid Copemys from the Miocene of North America coupled with apparent derived characters shared with the subfamily Sigmodontinae suggest that Cordimus may be close to the root of the sigmodontine lineage, a possibility that remains to be tested through explicit phylogenetic analysis. Three species are recognized on the basis of size and details of molar morphology. Cordimus hooijeri sp. nov. is described from Bonaire on the basis of Holocene owl pellet material that consists of dentaries and postcranial material only. This species is presumed to be extinct, but focused surveys are needed to confirm this hypothesis. Cordimus debuisonjei sp. nov. and Cordimus raton sp. nov. are described from deposits on Tafelberg Santa Barbara in Curaçao. Although the age of these deposits is not known, they are most likely of late Pliocene or early Pleistocene age. Both are represented by numerous isolated molars and some osteological material.  相似文献   

20.
Vallinoto, M., Sequeira, F., Sodré, D., Bernardi, J. A. R., Sampaio, I. & Schneider, H. (2009). Phylogeny and biogeography of the Rhinella marina species complex (Amphibia, Bufonidae) revisited: implications for Neotropical diversification hypotheses. —Zoologica Scripta, 39, 128–140. A number of distinct hypotheses have been proposed to account for the origin of the considerable biological diversity found in the Neotropics, which is still a matter of intense debate. Here, we conducted a phylogenetic analysis of the Rhinella marina complex, a group of species widely distributed in Central and South America, combining published data with new sequences of three mtDNA genes (12S, 16S and cyt b) in order to clarify the evolutionary relationships and biogeographical history of the group. We included eight of the ten currently recognized R. marina group species and several outgroups. Maximum parsimony, maximum likelihood, and Bayesian inference analyses produced similar topologies, with two well‐supported main clades, each characterized by a deep subdivision. One of these major clades includes the samples of R. marina from Central America and Ecuador (west of the Andes), whereas the other comprises the remaining species of the group and samples of R. marina from the Amazon basin and other areas east of the Andes. A Bayesian coalescent‐based method (BEAST) dated the divergence between the two major clades, and between the Central American and Ecuadorian clades to the Miocene, matching the timing of other Central‐South American faunal divergences. Taken together, the results highlight the importance of Tertiary events such as the Pebas/marine incursions into the Amazon basin and Andean uplift for the diversification and historical biogeography of R. marina, making such taxa paraphyletic, and provide new perspectives on the debate on its species status.  相似文献   

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