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1.
Among Artiodactylamorpha, dichobunoids are some of the oldest fossil species that have been associated with Artiodactyla, the crown clade that includes hippopotamids, camelids, suoids, ruminants, and cetaceans. These important fossil species are known from early Eocene rocks of North America, Europe, and Asia, but their phylogenetic position has yet to be well resolved. Before generating such a phylogeny, it is first critical to document all of the anatomy of known dichobunoid fossils. Here we use CT scans to describe previously undescribed anatomy of the petrosal bone, a complex part of the mammalian skull that contains many variable and phylogenetically informative features. Results show that these extinct species share a number of features that are not documented in modern species including a lateral process of the epitympanic wing constituting the medial border of the piriform fenestra, and a tegmen tympani foramen that may have given passage to the ramus superior of the stapedial artery. Future comprehensive phylogenetic studies may show that many of these characters are plesiomophic for Artiodactylamopha. Some species (Diacodexis, Homacodon and ?Helohyus) exhibit a dorsolateral exposure of the mastoid region of the petrosal on the temporal part of the cranium. This uncommon feature has, to our knowledge, not been reported in another euungulate group.  相似文献   

2.
Conservation biologists and community ecologists have increasingly begun to quantify the phylogenetic diversity and phylogenetic dispersion in species assemblages. In some instances, the phylogenetic trees used for such analyses are fully bifurcating, but in many cases the phylogenies being used contain unresolved nodes (i.e. polytomies). The lack of phylogenetic resolution in such studies, while certainly not preferred, is likely to continue particularly for those analyzing diverse communities and datasets with hundreds to thousands of taxa. Thus it is imperative that we quantify potential biases and losses of statistical power in studies that use phylogenetic trees that are not completely resolved. The present study is designed to meet both of these goals by quantifying the phylogenetic diversity and dispersion of simulated communities using resolved and gradually ‘unresolved’ phylogenies. The results show that: (i) measures of community phylogenetic diversity and dispersion are generally more sensitive to loss of resolution basally in the phylogeny and less sensitive to loss of resolution terminally; and (ii) the loss of phylogenetic resolution generally causes false negative results rather than false positives.  相似文献   

3.
The preference-performance and phylogenetic conservatism hypotheses have been postulated to explain the mechanisms driving host-use patterns of phytophagous insects. The preference-performance hypothesis predicts that insects will use plants that provide higher offspring fitness, while the phylogenetic conservatism hypothesis predicts that insects will use phylogenetically closely related plants over more distantly related plants. Although some studies have supported these two hypotheses, others have not. Simultaneous tests of the two hypotheses on more than one species are lacking, and this limits comparative interpretation of previous studies. We undertook a comparative investigation to determine whether preference-performance and/or the phylogenetic conservatism hypothesis can explain host-use patterns of two phytophagous insects, the fruit flies Bactrocera cucumis and B. tryoni. Within a nested, plant phylogenetic framework, oviposition preference and offspring performance of the two fruit fly species were tested on fruits of plant species from across different plant families, from within a family and across cultivars within a species. The results show that both the preference-performance and the phylogenetic conservatism hypotheses can, depending on the host plant taxonomic level, explain host usage patterns in B. cucumis, while neither theory explained the host patterns seen in B. tryoni. In the light of increasing recognition of the complexity of host plant–herbivore relationships, and of ongoing studies which as often as not fail to find support for these theories as those that do, we discuss the limited value of either theory as a basis for future research.  相似文献   

4.
We investigated genetic variation and evolutionary history of closely related taxa of Picris subsect. Hieracioides with major focus on the widely distributed P. hieracioides and its closely related congeners, P. hispidissima, P. japonica, P. olympica, and P. nuristanica. Accessions from 140 sample sites of the investigated Picris taxa were analyzed on the infra- and the inter-specific level using nuclear (ITS1-5.8S-ITS2 region) and chloroplast (rpl32-trnL (UAG) region) DNA sequences. Genetic patterns of P. hieracioides, P. hispidissima, and P. olympica were shown to be incongruent and, in several cases, both plastid and nuclear alleles transcended borders of the taxa and genetic lineages. The widespread P. hieracioides was genetically highly variable and non-monophyletic across both markers, with allele groups having particular geographic distributions. Generally, all gene trees and networks displayed only a limited and statistically rather unsupported resolution among ingroup taxa causing their phylogenetic relationships to remain rather unresolved. More light on these intricate evolutionary relationships was cast by the Bayesian coalescent-based analysis, although some relationships were still left unresolved. A combination of suite of phylogenetic analyses revealed the ingroup taxa to represent a complex of genetically closely related and morphologically similar entities that have undergone a highly dynamic and recent evolution. This has been especially affected by the extensive and recurrent gene flow among and within the studied taxa and/or by the maintenance of ancestral variation. Paucity of phylogenetically informative signal further hampers the reconstruction of relationships on the infra- as well as on the inter-specific level. In the present study, we have demonstrated that a combination of various phylogenetic analyses of datasets with extremely complex and incongruent phylogenetic signal may shed more light on the interrelationships and evolutionary history of analysed species groups.  相似文献   

5.
Fifteen taxa of the genus Cicer L. growing naturally in Turkey and out-groups were classified by phylogenetic and cladistic analysis. Taxa of the genus Cicer and the out-group taxa belonging to the closest genera Phaseolus L., Vicia L., Lathyrus L. and Ononis L., which are placed in Phaseoleae, Vicieae and Ononideae tribes, respectively, were used in molecular studies in order to derive their phylogenetic relationships. Morphological, palynological and seed characters were used on the basis of 143 traits. The micromorphological characters of seed and pollen grains were revealed by SEM. Lathyrus L. and Vicia L. species were used as out-groups for numerical analysis. Ten specimens were used for the measurements of metric characters related to the morphological structures of the taxa used for statistical analysis via PAUP and NTSYS-pc packages. Phylogenetic relationships between species and populations of the same species growing in different locations and their variations were determined using molecular methods performed on regions of the Inter Simple Sequence Repeat (ISSR). DNA was isolated from the collected samples, using modified CTAB protocols. ISSR was used for phylogenetic fingerprinting. The data were analyzed with NTSYS-pc package. Standardized data were used to generate a dendrogram that revealed the phylogenetic relationships of the taxa. Geographic distribution of the Cicer taxa appears to be closely related to the Anatolian Diagonal. As a result of this study, four new endemic taxa were added and evaluated for the first time.  相似文献   

6.
Taxonomic studies on scolopendrid centipedes have often documented variability at the individual and population levels and applied those data to questions of species delimitation, but these investigations have mostly lacked an explicit phylogenetic framework. A molecular phylogeny and recent taxonomic revision for Indian species of the scolopendrid Digitipes Attems, 1930, permit variability of traditional taxonomic characters for Scolopendridae to be mapped onto a phylogeny. Based on their fit to the tree using maximum likelihood, reliable species-level characters include the number of glabrous antennal articles, presence of a median ridge on the tergites, and presence or absence of a tarsal spur on leg 20. Characters that are conserved within and diagnostic for particular species but labile within others (typically with geographic structure) include the first tergite with paramedian sutures, presence or absence of a lateral spine on the coxopleuron, and the number of spines in a ventromedial row on the ultimate leg prefemur. Comparisons with published accounts of variability in species of other scolopendrid genera, particularly Scolopendra and Otostigmus, show that Indian Digitipes has conserved morphology in some characters that are taxonomically useful elsewhere in the family, and most of its taxonomically informative characters have analogous patterns of variability in other genera. The approach used in this study to evaluate morphological variation in a phylogenetic framework can be applied to other taxa in which morphologically cryptic species have been reported and where species diagnosis requires a combination of characters.  相似文献   

7.

Background

The Tibetan Plateau is not only the highest and largest plateau on earth; it is also home to numerous freshwater lakes potentially harbouring endemic faunal elements. As it remains largely unknown whether these lakes have continuously existed during the Last Glacial Maximum (LGM), questions arise as to whether taxa have been able to exist on the plateau since before the latest Pleistocene, from where and how often the plateau was colonized, and by which mechanisms organisms conquered remote high altitude lentic freshwater systems. In this study, species of the plateau-wide distributed freshwater gastropod genus Radix are used to answer these biogeographical questions.

Methodology/Principal Findings

Based on a broad spatial sampling of Radix spp. on the Tibetan Plateau, and phylogenetic analyses of mtDNA sequence data, three probably endemic and one widespread major Radix clade could be identified on the plateau. Two of the endemic clades show a remarkably high genetic diversity, indicating a relatively great phylogenetic age. Phylogeographical analyses of individuals belonging to the most widely distributed clade indicate that intra-plateau distribution cannot be explained by drainage-related dispersal alone.

Conclusions/Significance

Our study reveals that Radix spp. persisted throughout the LGM on the Tibetan Plateau. Therefore, we assume the continuous existence of suitable water bodies during that time. The extant Radix diversity on the plateau might have been caused by multiple colonization events combined with a relatively long intra-plateau evolution. At least one colonization event has a Palaearctic origin. In contrast to freshwater fishes, passive dispersal, probably by water birds, might be an important mechanism for conquering remote areas on the plateau. Patterns found in Radix spp. are shared with some terrestrial plateau taxa, indicating that Radix may be a suitable model taxon for inferring general patterns of biotic origin, dispersal and survival on the Tibetan Plateau.  相似文献   

8.
《Mammalian Biology》2007,72(5):257-282
Recent studies have improved our knowledge about the evolution and phylogeny of feliform taxa. Detailed study on new fossil remains of extinct feliform nimravides allows a new hypothesis concerning interrelationships within this family. Many factors indicate lack of sister relationships of Nimravinae and Barbourofelinae. However, only further investigations may bring full acceptance of this hypothesis. The paraphyly of Viverridae has been resolved by excluding the taxa Nandinia, Prionodon and Cryptoprocta and Fossa, which today are placed basally to all remaining Feliformia (family Nandiniidae), as sister taxon of Felidae (family Prionodontidae) and as Malagasy Carnivora lineage basal to hyaenid–herpestid clade, respectively. Still, incongruence among results concerning the systematic position of these taxa exhibits the necessity of further investigation. Detailed study revealed inconsistencies within genet and genet-like taxa phylogeny, which have still to be resolved. Malagasy Carnivora belong to a separate lineage, which originated from herpestid–hyaenid ancestors and colonised Madagascar during a single colonisation event. However, interrelationships among Malagasy Carnivora are poorly resolved. The situation of the social mongooses clade was resolved by including ethologic data to phylogenetic analyses; however, there is little information on solitary mongooses, which have a paraphyletic status today. Felid morphology and taxonomic revision attained during recent years show greater evolutionary differentiation. Nevertheless, no clear taxonomy has been achieved. New investigating methods are required. In the hyaenid family, which includes only four living species, some investigations related to the ecomorphological evolutionary path have been performed. The comparisons of fossil and subfossil remains with modern feliforms, combined with recent molecular methods, may improve our knowledge.  相似文献   

9.
《Mycoscience》2020,61(5):249-258
The classification system and evolutionary history of Erysiphaceae have been studied based on the results of molecular phylogenetic analyses. However, the sequence data used for these phylogenetic estimations have been limited to the nrDNA of ca., 50 taxa, and the relationships among higher taxonomic groups are not well understood. To provide a phylogenetic overview of Erysiphaceae, we performed phylogenetic estimations based on nrDNA and MCM7 sequences obtained from ca., 270 taxa. The phylogenetic tree showed a similar topology to the trees obtained in previous studies, although the branching order between Golovinomyceteae and Phyllactinieae was different and Phyllactinieae was not monophyletic. Phyllactinieae and Erysipheae were estimated to diversify after the divergence of Golovinomyceteae, suggesting an evolutionary trend in which non-catenate conidia + endoparasitic or non-catenate conidia + ectoparasitic lineages were derived from catenate conidia + ectoparasitic lineages. Phyllactinieae was divided into a clade of Phyllactinia + Leveillula and other clade(s) consisting of Pleochaeta and Queirozia. The phylogenetic hypothesis of Erysiphaceae was updated based on the largest dataset to date, but the higher-level phylogenetic relationships remain unclear. For a more robust phylogenetic hypothesis of Erysiphaceae, further sequence data, including protein coding regions, should be added to the dataset of nrDNA sequences.  相似文献   

10.
In this paper the cranial arteries, cranial arterial foramina, and bony canals of the Cheloniidae, Chelydridae, Pelomedusidae, and Chelidae are described in detail. From skull studies and published material, the general cranial arterial patterns of all the turtle families can be inferred. Sea turtles, the Cheloniidae and Dermochelyidae, possess both a large stapedial artery and a large artery supplying the orbit, which is possibly similar to the primitive cranial arterial pattern for turtles. From a primitive pattern in which stapedial and palatine arteries supply the orbit, the Chelydridae and Testudinidae retained a large stapedial artery and reduced the palatine artery, while the Kinosternidae and Dermatemydidae developed a large palatine artery and reduced the stapedial artery. The Trionychidae and probably the Carettochelyidae evolved a complex arterial pattern in which the stapedial artery was reduced somewhat and the pseudopalatine artery was substituted for the palatine artery. Pleurodires in general retained a large stapedial artery and reduced or eliminated the palatine artery. The Podocneminae, including the Madagascar species, developed a highly modified carotid canal, which is found in no other turtle group. The facts which have been presented should aid in fossil skull studies and in understanding the evolutionary background of recent turtles.  相似文献   

11.
ABSTRACT

Background: Several studies have documented the variation in species diversity patterns along elevational gradients in the Himalaya, but few have reported the evolutionary and biogeographic processes behind these patterns.

Aims: To understand whether evolutionary history and phylogeny have any role in structuring plant species communities along an elevational gradient in the Sikkim Himalaya.

Methods: We used data on endemic plant species occurrence from primary and secondary sources to construct family-level phylogenetic supertrees for different growth forms with the help of Phylomatic tool of Phylocom. These phylogenetic supertrees were used as a base for testing phylogenetic diversity (PD), niche conservatism, diversification time patterns and phylogenetic structure of various plant growth forms along an elevational gradient.

Results: PD was the highest at mid-elevations for all growth forms and PD had a significant positive correlation with endemic species richness. Species at mid-elevations were dominated by the ancestral/primitive taxa. There was phylogenetic clustering at higher elevations and phylogenetic overdispersion at lower and mid-elevations for the majority of the growth forms.

Conclusions: Time-for-speciation effect and niche conservatism along elevation (retention of niche-related ancestral elevational distribution over evolutionary time scale by species) together determine plant species diversity patterns in the Himalaya.  相似文献   

12.
The utility and reliability of mitochondrial DNA sequences in phylogenetic and phylogeographic studies may be compromised by widespread and undetected nuclear mitochondrial copies (numts) as well as heteroplasmy within individuals. Both numts and heteroplasmy are likely to be common across diverse taxa yet few studies have characterised their frequencies and variation at the intra-specific level. Here we report the presence of both numts and heteroplasmy in the mitochondrial control region of the Chinese horseshoe bat Rhinolophus sinicus. In total we generated 123 sequences from 18 bats, which contained two different numt clades (i.e. Numt-1 and Numt-2) and one mtDNA clade. The sequence divergence between Numt-1 and Numt-2 was 16.8% and each numt type was found in all four R. sinicus taxa, suggesting either two ancient translocations of mitochondrial DNA into the nucleus from the same source taxon, or a single translocation from different source taxa that occurred before the split of R. sinicus into different lineages. Within the mtDNA clade, phylogenetic relationships among the four taxa of R. sinicus were similar to those seen in previous results. Based on PCR comparisons, heteroplasmy was inferred between almost all individuals of R. sinicus with respect to sequence variation. Consistent with introgression of mtDNA between Central sinicus and septentrionalis, individuals from these two taxa exhibited similar signatures of repeated sequences in the control region. Our study highlights the importance of testing for the presence of numts and heteroplasmy when applying mtDNA markers to phylogenetic studies.  相似文献   

13.
14.
Ectocranial suture fusion patterns have been shown to contain biological and phylogenetic information. Previously the patterns of Homo, Pan, and Gorilla have been described. These data reflect the phylogenetic relationships among these species. In this study, we applied similar methodology to Pongo to determine the suture synostosis progression of this genus, and to allow comparison to previously reported data on other large‐bodied hominoids. We hypothesized these data would strengthen the argument that suture synostosis patterns reflect the phylogeny of primate taxa. Results indicate that the synostosis of vault sutures in Pongo is similar to that reported for Gorilla (excluding Pan and Homo). However, the lateral‐anterior pattern of fusion, in which there is a strong superior to inferior pattern, for Pongo is unique among these species, reflecting its phylogenetic distinctness among great ape taxa. Am J Phys Anthropol, 2010. © 2010 Wiley‐Liss, Inc.  相似文献   

15.
Taxonomy of the genus Leveillula has long been considered as a challenge in powdery mildew systematics. The rDNA diversity has recently been used for phylogenetic analysis of several specimens of the genus Leveillula. In the present study, additional rDNA ITS sequences are provided and a new phylogenetic analysis is carried out aiming at a better understanding of the genetic diversity in the genus Leveillula. New analyses confirmed that L. taurica is unique in the genus, as it exhibits an intraspecific gene sequence diversity considerably higher than in other species. In several cases L. taurica s. lat. on a certain host plant species has a sequence different from L. taurica on other host plants. Moreover, DNA data indicated different lineages among L. taurica specimens which were hardly distinguishable by morphology. More than one genotype occurring on a single host is sometimes possible. According to these results, several races such as Leveillula on Artemisia, Acroptilon, Onobrychis, are molecularly well characterized. While there is enough molecular evidence to delimit such races as independent taxa, clear morphological delimitations between these new and already published taxa are very difficult or even impossible. However, ecological features, and above all, host specificity for biotrophic fungi such as powdery mildew, would be a good criterion to discriminate cryptic taxa along with rDNA sequences. In fact, many collections of Leveillula strains on different hosts show their own type of conidial morphology, which is usually consistent for a strain on a single host species. Hence, we have proposed to describe new species for Leveillula on some host plants such as Artemisia, Acroptilon, Echinops and Onobrychis.  相似文献   

16.
We report the discovery of three isolated primate petrosal fragments from the fossiliferous locality of Chambi (Tunisia), a primate-bearing locality dating from the late early to the early middle Eocene. These fossils display a suite of anatomical characteristics otherwise found only in strepsirhines, and as such might be attributed either to Djebelemur or/and cf. Algeripithecus, the two diminutive stem strepsirhine primates recorded from this locality. Although damaged, the petrosals provide substantial information regarding the ear anatomy of these advanced stem strepsirhines (or pre-tooth-combed primates), notably the patterns of the pathway of the arterial blood supply. Using μCT-scanning techniques and digital segmentation of the structures, we show that the transpromontorial and stapedial branches of the internal carotid artery (ICA) were present (presence of bony tubes), but seemingly too small to supply enough blood to the cranium alone. This suggests that the ICA was not the main cranial blood supply in stem strepsirhines, but that the pharyngeal or vertebral artery primitively ensured a great part of this role instead, an arterial pattern that is reminiscent of modern cheirogaleid, lepilemurid lemuriforms and lorisiforms. This could explain parallel loss of the ICA functionality among these families. Specific measurements made on the cochlea indicate that the small strepsirhine primate(s) from Chambi was (were) highly sensitive to high frequencies and poorly sensitive to low frequencies. Finally, variance from orthogonality of the plane of the semicircular canals (SCs) calculated on one petrosal (CBI-1-569) suggests that Djebelemur or cf. Algeripithecus likely moved (at least its head) in a way similar to that of modern mouse lemurs.  相似文献   

17.
In several studies we used the 5′-trnL(UAA)–trnF(GAA) region of the chloroplast DNA for phylogeographic reconstructions, gene diversity calculations and phylogenetic analyses among the genera Arabidopsis and Boechera. Despite the fact that extensive gene duplications are rare within the chloroplast genome of higher plants, within several genera of the Brassicaceae the anticodon domain of the trnF(GAA) gene exhibit extensive gene duplications with 1–12 tandemly repeated copies in close 5′-proximity of the functional gene. A recent re-examination and additional analysis of trnL(UAA)–trnF(GAA) regions from numerous cruciferous taxa not only reveal extensive trnF gene duplications, but also favour the hypothesis that in cruciferous taxa at least four independent phylogenetic lineages are characterized by these pseudogenes. Among these lineages there is one major clade of taxa carrying pseudogenes indicating an ancient split in crucifer evolution. In two case studies, Boechera and Arabidopsis, intra- and inter-molecular recombinations have been shown to be the reason for the reciprocal exchange of several similar motifs. However, functional constraints might favour two to three or five to six copies as shown for Arabidopsis and Boechera. Herein, we compare the occurrence and distribution of pseudogene copy number in the framework of a comprehensive survey of cpDNA haplotype variation in Boechera, the former genus Cardaminopsis and Arabidopsis thaliana and comment on the value of such kind of mutations in phylogenetic and evolutionary reconstructions.  相似文献   

18.
Phylogenetic analyses of nuclear and mitochondrial DNA sequences were used to test a recent phylogenetic hypothesis for the avian genus Gallicolumba that relied heavily on preserved museum study skins for DNA samples. Our comparisons show that several published gene sequences represent pseudogenes or chimeras of multiple taxa, and these sequences had an adverse influence on phylogeny estimation. A new phylogenetic hypothesis strongly supports the monophyly of Philippine bleeding-hearts, the monophyly of Gallicolumba sensu stricto, and places Leucosarcia as part of an Australasian radiation rather than sister to Alopecoenas. These findings clarify Gallicolumba biogeography and also highlight the need for greater caution in the use of suboptimal source material in molecular systematic studies.  相似文献   

19.
The Seychelles is a remarkably interesting archipelago for evolutionary studies, but only recently have molecular markers been used to explore its biogeographic patterns. Here we used morphological and molecular data to examine diversity and phylogenetic relationships of two endemic skink sister‐species from this archipelago: Trachylepis sechellensis and Trachylepis wrightii. Mitochondrial DNA genealogy rendered a monophyletic T. wrightii nested within a paraphyletic T. sechellensis, whereas nuclear DNA sequences from five unlinked markers reflected the accepted taxonomy. Hybridization and massive mtDNA introgression leading to the complete replacement of the native mtDNA lineage of T. sechellensis in some of the islands were invoked to explain this result, and morphological variation also seemed to reflect this pattern of reticulation. A Mio‐Pliocene divergence between both species is suggested. Multilocus molecular data were used to uncover biogeographic patterns within the archipelago, which reflected shared patterns with other co‐distributed lizard taxa; specifically a north–south marked structure, a close relationship between populations from Fregate and the southern islands, and a detectable isolation within the southern group, between Mahé, and Silhouette and North Islands. Gene flow from these latter islands towards the northern group was also suggested. These results add to the growing body of evidence of the influence of geographic distance and sea‐level oscillations in shaping the genetic structure of Seychellois taxa and of the existence of common biogeographic patterns across the archipelago.  相似文献   

20.
The influence of Quaternary climate oscillations on the diversification of the South American fauna is being increasingly explored. However, most of these studies have focused on taxa that are endemic to tropical environments, and relatively few have treated organisms restricted to subtropical biomes. Here we used an integrative phylogeographical framework to investigate the effects of these climate events on the ecological niche and genetic patterns of the subtropical orb-weaver spider Araneus omnicolor (Araneidae). We analyzed the mitochondrial (Cytochrome Oxidase I, COI) and nuclear (Internal Transcribed Subunit II, ITS2) DNA of 130 individuals throughout the species’ range, and generated distribution models in three different climate scenarios [present, Last Glacial Maximum (LGM), and Last Interglacial Maximum (LIG)]. Additionally, we used an Approximate Bayesian Computation (ABC) approach to compare possible demographic scenarios and select the hypothesis that better explains the genetic patterns of A. omnicolor. We obtained high haplotype diversity but low nucleotide variation among sequences. The population structure and demographic analyses showed discrepancies between markers, suggesting male-biased dispersal in the species. The time-calibrated COI phylogenetic inference showed a recent diversification of lineages (Middle/Late Pleistocene), while the paleoclimate modeling indicated niche stability since ~120 Kya. The ABC results agreed with the niche models, supporting a panmictic population as the most likely historical scenario for the species. These results indicate that A. omnicolor experienced no niche or population reductions during the Late Pleistocene, despite the intense landscape modifications that occurred in the subtropical region, and that other factors beside LGM and LIG climate oscillations might have contributed to the demographic history of this species. This pattern may be related to the high dispersal ability and wide environmental tolerance of A. omnicolor, highlighting the need for more phylogeographical studies with invertebrates and other generalist taxa, in order to understand the effects of Quaternary climate changes on Neotropical biodiversity.  相似文献   

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