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1.
Aim  To determine genetic substructuring within the lacertid lizard Psammodromus algirus . To compare levels of variation across a geological barrier, the Strait of Gibraltar, and to compare this against the known age of the barrier using a molecular clock hypothesis. To compare the effect of the barrier within this species with previously published data from other organisms.
Location  The Iberian Peninsula and North Africa.
Methods  Partial sequences from the mitochondrial cytochrome b , 12S rRNA and 16S rRNA genes were obtained from 101 specimens belonging to the subfamily Gallotiinae and used in this study. The data set was aligned using C lustal X and phylogenetic trees produced using both maximum-parsimony and maximum-likelihood methods. Maximum likelihood estimates of divergence times for the combined data set (12S + 16S + cytochrome b ) were obtained after discovery of lineage rate constancy across the tree using a likelihood ratio test.
Results  Psammodromus algirus contains divergent eastern and western mtDNA clades within the Iberian Peninsula. The western clade has northern and southern lineages in Iberia and one in North Africa. This phylogeographical pattern indicates that the lizard invaded North Africa after the opening of the Strait, presumably by natural rafting.
Main conclusions  As in several other species, current patterns of genetic diversity within P. algirus are not directly related to the opening of the Strait of Gibraltar. Widespread sampling on both sides of the barrier is necessary to determine its effect on species in this area accurately.  相似文献   

2.
Sequence data derived from a 306 bp fragment of mitochondrial cytochrome b and molecular variance estimates were used to investigate the genetic population structure of the endangered and endemic lizard Podarcis atrata of the Columbretes archipelago (Mediterranean, Spain). Our results show a very high and significant among-population genetic differentiation. F ST values and phylogenetic analyses confirm the evolutionary distinctiveness of P. atrata populations, suggesting that the populations of these islands deserve special protection measures. The populations of the two islands Columbrete Grande and Mancolibre are less differentiated than those of Foradada and Lobo, and seem to have retained mainland haplotypes. This situation needs further attention as the origin of the mainland haplotypes is still unclear. If they are a result of recent introductions from mainland specimens, then they may represent a threat to the endemic lizards of the Columbretes islands.  相似文献   

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In this work, we employed molecular markers and confirmed the occurrence of two mole species, Talpa stankovici and Talpa europaea in Greece. For the first species, all analyses revealed three major phylogroups, exhibiting great genetic divergence, possibly due to a vicariant event. This event was probably the Peloponnisos’ insulation during the Pliocene and the following sea level fluctuations. A scenario of stable, large‐sized populations for a long period rather than rapid growth from small‐sized populations or founder events is supported. Additionally, T. stankovici’s distribution area is extended to a southernmost limit. For T. europaea there is evidence of low genetic divergence between Greek and Central and North European populations.  相似文献   

5.
Ancient mitochondrial DNA sequences (378 base pairs of cytochrome b and 368 of 12S rRNA) extracted from a mummified extinct giant lizard, Gallotia goliath , from eastern Tenerife, Canary Islands, were used to assess the species status and relationship of this form within the genus. G. goliath is clearly a member of the G. simonyi group of the western Canary islands (Tenerife, La Gomera, El Hierro and La Palma) and is not closely related to the giant G. stehlini of Gran Canaria. Contrary to recent opinion, it is phylogenetically distinct, within the G. simonyi group, from the extant G. simonyi of El Hierro and also from the recently discovered live G. gomerana on La Gomera and from G. intermedia in north-western Tenerife. It may be the sister taxon of either all the other members of the G. simonyi group or of G. intermedia . The phylogenetic distinctness of G. goliath makes Tenerife unique among oceanic islands in having had one giant and two medium-sized lizard species that were probably substantially herbivorous, the others being G. intermedia and G. galloti . Gallotia shows great community differences on other islands in the Canaries, two having a single small species, one a single giant, and three a giant and a medium-sized form. © 2003 The Linnean Society of London, Biological Journal of the Linnean Society , 2003, 80 , 659–670.  相似文献   

6.
Long-finned pilot whales in the Strait of Gibraltar are distributed over the main shipping routes. This exposes them to risks of collisions and probable acoustic and physical disturbance. This species is also the target of whale-watching operations. The aim of this study was to estimate the annual population size, survival rate, and population growth rate of pilot whales occurring in the Strait and their inter-annual variation using photo-identification. A robust design was used to estimate all three parameters. A total of 10,784 individual pilot whale fins were photographed and analyzed. The population size estimation in summer ranged from a low of 147 individuals in 1999 to a high of 265 individuals in 2003. The annual population growth rate was estimated from mark recapture models to be 5.5%. The survival rate of adults was estimated at 0.982 (95% CI: 0.955–0.993). The same individuals have been observed between years. This suggests that this population is resident in the Strait, at least during summer. This study provides baseline knowledge prior to a predicted increase in shipping traffic throughout the main foraging area due to the opening in 2007 of a major shipping harbor along the Moroccan coast of the Strait.  相似文献   

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The Strait of Gibraltar (SG) is reputed for being both a bridge and a geographic barrier to biological exchanges between Europe and Africa. Major genetic breaks associated with this strait have been identified in various taxa, but it is unknown whether these disjunctions have been produced simultaneously or by independent biogeographic processes. Here, the genetic structure of five conifers distributed on both sides of the SG was investigated using mitochondrial (nad1 b/c, nad5-1, nad5-4 and nad7-1) and chloroplast (Pt1254, Pt15169, Pt30204, Pt36480, Pt71936 and Pt87268) DNA markers. The distribution of genetic variation was partially congruent between types of markers within the same species. Across taxa, there was a significant overlapping between the SG and the genetic breaks detected, especially for the four Tertiary species surveyed (Abies pinsapo complex, Pinus nigra, Pinus pinaster and Taxus baccata). For most of these taxa, the divergence of populations across the SG could date back to long before the Pleistocene glaciations. However, their strongly different cpDNA G(ST) and R(ST) values point out that they have had dissimilar population histories, which might include contrasting amounts of pollen-driven gene flow since their initial establishment in the region. The fifth species, Pinus halepensis, was genetically depauperated and homogenous on both sides of the SG. A further analysis of nuclear DNA sequences with coalescent-based isolation with migration models suggests a Pleistocene divergence of P. halepensis populations across the SG, which is in sharp contrast with the pre-Pleistocene divergence dates obtained for P. pinaster. Altogether, these results indicate that the genetic breaks observed across this putative biogeographical barrier have been produced by independent evolutionary processes related to the biological history of each individual species instead of a common vicariant phenomenon.  相似文献   

9.
The radiation of Partula land snails has produced a large array of distinct morphological, ecological and behavioural types occupying many tropical volcanic islands in the Pacific Ocean. Within the Society Islands of French Polynesia, the mode of evolution is thought to have involved a single colonization event on each island, with later speciation occurring largely in situ. The present study examines genetic variation in the mitochondrial cytochrome b gene among taxa within the Society Island archipelago. Levels of intraspecific variation are found to be high, but variation among species is sometimes small. Mitochondrial variants do not always cluster according to island and some species are found to be polyphyletic in the cytochrome b tree, despite other morphological and molecular evidence that strongly supports their monophyly. A possible explanation for the polyphyly of species is that different variants are derived from ancestral mitochondrial polymorphisms that have been retained despite speciation events. Although it is possible that there has been some gene flow among islands, the distribution of mitochondrial lineages across islands strongly indicates that their origins predate the colonization of the islands in the study, and that they are very unlikely to have evolved entirely in situ.  相似文献   

10.
The schism between North Africa and Southern Europe caused by the opening of the Strait of Gibraltar and the consequent refilling of the Mediterranean basin at the end of Messinian salinity crisis (MSC), 5.33 million years ago, has been advocated as the main event shaping biogeographical patterns in the western Mediterranean as exemplified by the distribution of species and subspecies and genetic variation within the ocellated lizard group. To reassess the role of the MSC, partial sequences of three mitochondrial DNA genes (cytochrome b , 12S and 16S ribosomal RNA) and two nuclear genes (β-fibrinogen and C-mos) from species of the ocellated lizard group were analysed. Three alternative hypotheses were tested: that divergence was initiated (i) by post-MSC vicariance as the basin filled, (ii) when separate populations established either side of the strait by pre-MSC overseas dispersal, and (iii) by post-MSC overseas dispersal. The pattern and level of divergence detected clearly refute the post-MSC vicariance hypothesis, and support a model of divergence initiated by earlier overseas dispersal. Indeed, our best estimate is that the basal Euro-African divergence predates the MSC event by several million years. The estimated divergence times among the populations in former Miocene Mediterranean islands, the current Betic and Rifian mountains, from adjacent mainland populations suggest overseas dispersal for the former and overland dispersal, or perhaps vicariance, for the latter. These results suggest that the MSC may have played a much less important role in shaping the current western Mediterranean biogeographical patterns than might have been anticipated from the dramatic nature of the episode.  相似文献   

11.
Two new species of the genus Caprella (Crustacea:Amphipoda:Caprellidea) are described based on specimens collected from the Strait of Gibraltar (Southern Spain and Northern Africa). Both species were found living in sandy bottoms. Caprella pseudorapax n. sp. is very close to the species C. rapax (Mayer, 1890) and C. lilliput (Krapp-Schickel & Ruffo, 1987). Caprella sabulensis n. sp. resembles C. cavediniae (Krapp-Schickel & Vader, 1998).  相似文献   

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Recent molecular studies have provided estimates of phylogeny for nearly all living and recently extinct species in the Order Dasyuromorphia, the dominant clade of insectivorous‐carnivorous marsupials in Australasia. We review these studies along with morphology‐based ones, and present an analysis of all cytochrome b, 12S rRNA, and protamine Pl gene sequences available. In light of these results, we provide a revised suprageneric classification and assess the implications of molecular and paleontological data for dasyurid cladogenesis. Molecular results divide extant dasyurids (Dasyuridae) into four major clades apart from the numbat (Myrmecobiidae) and thylacines (Thylacinidae). We recognize these clades as tribes Dasyurini (Dasyurus, Phascolosorex, and allied genera) and Phascogalini (Antechinus, Murexia, Phascogale) in the Subfamily Dasyurinae, and tribes Sminthopsini (Sminthopsis, Ningaui, Antechinomys) and Planigalini (Planigale) in the Subfamily Sminthopsinae. Each tribe shows a basal radiation of lineages corresponding to genera or species groups. Our results concur with the most recent previous synthesis of dasyurid phylogeny in many respects, but subsumption of New Guinean ‘phascolosoricines’ and ‘muricines’ within Dasyurini and Phascogalini, respectively, constitute significant differences. In particular, the sister‐pairing of ‘phascolosoricines’ with a Dasyurus‐Sarcophilus clade implied by molecular data is difficult to reconcile with anatomy. Divergence rates of mitochondrial sequences are calibrated approximately by comparing thylacine‐to‐dasyurid distances with the age of the oldest thylacinid (Badjcinus, latest Oligocene). Estimated cladogenic dates suggest that extant subfamilies shared a common ancestor around 24 Mya and that major radiations began late in the mid‐Miocene, consistent with the results of previous paleontological studies. The late‐middle and late Miocene corresponds to an episode of faunal turnover in Australian marsupials (including the decline of thylacinid and bandicoot genera, as well as the rise of dasyurids) and to a time when uplift of the New Guinean highlands accelerated the transition from rainforest to drier habitats. Our findings are consistent with the hypothesis that continent‐wide climate changes modulated macroevolution across these independent marsupial clades.  相似文献   

14.
A phylogeny of West Palearctic Salamandridae based on 1208 bp of mtDNA sequences (300 bp of cytb, 346 bp of 12S rRNA and 562 bp of 16S rRNA) indicates the European brook newts (Euproctus) are polyphyletic. To reflect revised relationships, the Tyrrhenian species (E. montanus ( Savi, 1838 ) and E. platycephalus ( Gravenhorst, 1829 )) are retained in Euproctus Genè, 1839 , while the genus Calotriton Gray, 1858 is resurrected to include the Pyrenean brook newt ( Calotriton asper ( Dugès, 1852 ) comb. nov. ) and a new species from the massif of El Montseny, Catalonia, Spain, described herein as Calotriton arnoldi sp. nov. , which is both morphologically and genetically distinct. Although according to the principle of priority Megapterna Savi, 1838 should take precedence over Euproctus Genè, 1839 , for the sake of nomenclatural stability and in line with Art. 23.9.1 of the International Code of Zoological Nomenclature, Megapterna is considered a nomen oblitum and Euproctus a nomen protectum. The polyphyly of Euproctus (s.l.) contradicts previous, well‐accepted, biogeographical hypotheses and represents a clear case of convergence, involving several morphological traits and a unique reproductive behaviour that is advantageous in stream situations. Molecular dating suggests the Western brook newt lineage (C. asper+C. arnoldi) originated towards the end of the Miocene (8.3 ± 0.11 Mya) and is part of a well‐supported monophyletic assemblage, which also includes Neurergus kaiseri ( Schmidt, 1952 ) and a clade formed by Triturus karelinii ( Strauch, 1870 ), T. carnifex ( Laurenti, 1768 ), T. pygmaeus ( Wolterstoff, 1905 ) and T. marmoratus ( Latreille, 1800 ). Speciation separating E. montanus and E. platycephalus might have coincided with the onset of the Messinian salinity crisis. © 2005 The Linnean Society of London, Zoological Journal of the Linnean Society, 2005, 145 , 555–582.  相似文献   

15.
The interrelationships of the three mammalian groups, Monotremata, Marsupialia, and Eutheria, have been studied using DNA sequences from the mitochondrial 12S ribosomal RNA gene. The results suggest that the monotremes diverged from the living therians only shortly before eutherians and marsupials separated from each other, although there is some evidence for a slowdown in rate of base change in the monotreme lineage. Whtin the Monotremata, the two extant species of tachyglossids show a very close genetic relationship and the data suggest a very recent divergence. We have also confirmed that the Patagonian Monito del Monte,Dromiciops australis, is more closely related to the australidephian marsupials than it is to other South American species.  相似文献   

16.
用mtDNA 12S rRNA序列变异检验鲤形目鱼类系统发育关系   总被引:9,自引:0,他引:9  
刘焕章 《遗传学报》2004,31(2):137-142
通过对鲤形目鱼类5个科的代表类群的完整线粒体12S rRNA进行测序和分析,以检验目前的形态学假说。经序列比对后,有1000个位点,其中467个位点在茎区,533个在环区;有395个位点为变化位点,其中267个为系统发育信息位点。采用邻接法和最大简约法进行了系统发育分析,其结果支持鲤科鱼类成为一个单系群,非鲤科的鲤形目鱼类成为另一个单系群的观点,这与Siebert提出的假说相一致。鲤科鱼类包含3个主要的分支,即鱼丹系、鲤系和雅罗鱼系;但在非鲤科鲤形目鱼类中,其关系不能得到很好的解决,其中鳅科是复系,平鳍鳅科、条鳅亚科和花鳅亚科可能有较近的亲缘关系。  相似文献   

17.
Systematic studies on the family Phytoseiidae were first conducted at the beginning of the 20th century but increased greatly after the Second World War. Various classifications have been proposed based on different characters such as: dorsal, ventral, and leg chaetotaxy; the shape of ventrianal and sternal shields; the shape of the insemination apparatus (spermatheca) and spermatodactylus; the number of teeth on the movable digit of chelicera; and dorsal and ventral adenotaxy. The genus concepts developed over the last five decades can be divided into two main categories or hypotheses. The first, supported mainly by Chant and McMurtry, focuses on dorsal and ventral chaetotaxy, and the genera so defined usually include a great number of species. The second category, proposed by Athias‐Henriot, considers the shape of the insemination apparatus as the key character, and the genera so defined usually include a limited number of species. From a diagnostic point of view, both classifications have a valid structure, but the question investigated herein was: which of the two classifications or hypotheses fits phylogenetic evolution? To answer this, we conducted molecular phylogenetic analyses (using the genes ITS and 12S rRNA) on the genus Neoseiulus, which has been subjected to classification based on the two main genus concepts. The results showed that the first hypothesis (Chant and McMurtry) leads to polyphyly of the genus Neoseiulus, while the second (Athias‐Henriot) leads to paraphyly of the genus. The results show that acarologists who first decided that the insemination apparatus was of evolutive importance could be correct as the shape of the insemination apparatus seems to better fit evolutive clades than dorsal and ventral chaetotaxy. The morphology of this organ, however, must be more accurately studied to better define homologies. The present paper investigates the two main hypotheses proposed until now for classification of Phytoseiidae and thereby opens the way for improved classification. © 2012 The Linnean Society of London, Zoological Journal of the Linnean Society, 2012, 165 , 253–273.  相似文献   

18.
In an effort to develop species-specific identification markers, we examined genetic variants and molecular signatures within genes encoding mitochondrial cytochrome b and 16S rRNA in eight endangered Pecoran species endemic to the Indian peninsula. Our results revealed that the cytochrome b gene exhibited higher sequence diversity than the 16S rRNA gene, both between and within species. However, the 16S rRNA gene harboured a larger number of species-specific mutation sites compared with the cytochrome b gene, suggesting that it could be useful for species identification. Indeed, we successfully used 'forensically informative nucleotide sequencing' (FINS) analysis of the 16S rRNA gene to identify two previously unknown biological specimens.  相似文献   

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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.  相似文献   

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