首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 31 毫秒
1.
Populations of the lizard Zootoca vivipara (Juaquin, 1787) (Lacertidae, Sauria) from Western and Central Europe are poorly differentiated in morphology. However, they differ from each other by several karyotype markers and their reproductive mode (oviparous and viviparous types). Here we report for the first time the results of combined investigations of Z. vivipara from Eastern Europe (the Baltic Sea basin of Western Russia). The karyotype and reproductive mode of the specimens from four previously not examined populations in Kaliningrad region have been studied. It has been shown that these lizards have viviparous mode of reproduction and their karyotypes vary on morphology of W-sex chromosomes. Females possess 2n = 35 : 32 A + Z1Z2W, with W--SV and 2n = 35 : 32 A + Z1Z2W, with W--A/ST. We have identified these populations karyologically and have first revealed that they belong to two different viviparous forms of nominative subspecies Z. v. vivipara, namely to its "western" and "Russian (eastern)" forms. These data have confirmed that the Baltic Sea basin in Eastern Europe is a zone of secondary contact of these chromosomal forms of Z. v. vivipara. The results obtained do not now allow us to speak about their sympatry, parapatry and (or) hybridization events. The results suggest that during postglasial time "western" form might colonize this region from western Europe whereas "Russian (eastern)" form might do it from Southern-Eastern Europe. It has been recommended to save the biodiversity of Z. vivipara in Kaliningrad region, namely the peripheral and very rare on vast territory of Russia "western" form and unique for western region of Russia "Russian (eastern)" form.  相似文献   

2.
Viviparous Festuca especially from the North Atlantic area have been examined. Based on especially the chromosome numbers they are divided into three subspecies and a number of hybrids: 1) F. vivipara (L.) Sm. ssp. vivipara , 2) F. vivipara ssp. hirsuta (Schol.) Frederiksen stat. nov., 3) F. vivipara ssp. glabra Frederiksen ssp. nov. Hybrids between F. vivipara on the one hand and F. rubra L. or F. ovina L. on the other were found to be common.  相似文献   

3.
The lizard Lacerta ( Zootoca ) vivipara has two modes of reproduction and is variable karyologically. We describe its karyological variation from literature data and from new data on two viviparous populations from France, on two oviparous populations from the Pyrenees in south-western France and on three oviparous populations recently discovered in Slovenia. Males have 36 chromosomes, whereas females have only 35 chromosomes in all viviparous populations and in the Pyrenean oviparous populations. This karyotype has been interpreted to result from a fusion of an ancestral sexual W chromosome with an autosome from the Zl or from the Z2 pair. The karyotype formula is 32 autosomes + ZIZ2W for the female and 32 autosomes + Z1Z1Z2Z2 for the male. The karyotype of the Slovenian oviparous populations, 34 autosomes + ZW in the male and 34 autosomes +ZW in the female, represents an evolutionary stage that preceded the chromosomal fusion. There is minor karyological variation, mainly concerning the W and Z2 chromosomes, within the Pyrenean oviparous populations. This parallels the geographic variation of the W-linked alleles of the MPI enzyme and suggests that allopatric differentiation of these oviparous populations might have occurred in the vicinity of the Pyrenees during the Pleistocene.
The viviparous populations from western Europe carry a metacentric W chromosome, whereas oviparous populations from south-western Europe and eastern viviparous populations both show an acrocentrie, or a subtelocentrie. W chromosome. This suggests that the acrocentric-subtelocentric W is a primitive character and that viviparity probably arose in an eastern lineage of the species.  相似文献   

4.
The lacertid lizard Lacerta vivipara is one of the few squamate species with two reproductive modes. We present the intraspecific phylogeny obtained from neighbor-joining and maximum-parsimony analyses of the mtDNA cytochrome b sequences for 15 individuals from Slovenian oviparous populations, 34 individuals from western oviparous populations of southern France and northern Spain, 92 specimens from European and Russian viviparous populations, and 3 specimens of the viviparous subspecies L. v. pannonica. The phylogeny indicates that the evolutionary transition from oviparity to viviparity probably occurred once in L. vivipara. The western oviparous group from Spain and southern France is phylogenetically most closely related to the viviparous clade. However, the biarmed W chromosome characterizing the western viviparous populations is an apomorphic character, whereas the uniarmed W chromosome, existing both in the western oviparous populations and in the geographically distant eastern viviparous populations, is a plesiomorphic character. This suggests an eastern origin of viviparity. Various estimates suggest that the oviparous and viviparous clades of L. vivipara split during the Pleistocene. Our results are discussed in the framework of general evolutionary models: the concept of an oviparity-viviparity continuum in squamates, the cold climate model of selection for viviparity in squamates, and the contraction-expansion of ranges in the Pleistocene resulting in allopatric differentiation.  相似文献   

5.
Two variants of intraspecific morphological differentiation of 7 palearctic species of Ixodidae and respectively two variants of their intraspecific taxonomic pattern have been revealed on the basis of the study of geographic variation of each species. Three species--Ixodes pavlovskyi Pom., 1946, Haemaphysalis erinacei Pavesi, 1884, Hyalomma asiaticum Sch. et Schl., 1929, are subdivided into subspecies, and four ones--I. ricinus (L., 1758), I. persulcatus Sch., 1930, I. crenulatus Koch, 1844, Dermacentor marginatus (Sulzer, 1776),--into morphotypes by the degree of distinction of the whole complex of active stages in ontogenesis. Acknowledging the conventional character of the categories of subspecies and morphotype their criteria have been formulated for ixodid ticks. Paleogeographic and ecological grounds are given. Some data of geographic variation of immature stages favour the identification of closely related species in concrete localities.  相似文献   

6.
The present study examined karyotypes of 16 genera and, along with previous reports, chromosomal data are now available for 18 of the 23 recognized batagurine genera. There are no karyotypic data available for the members of McDowell's (1964) Hardella complex. The Batagur, Heosemys and Geoemyda complexes retain the hypothesized primitive karyotype for the subfamily (2n=52). All the genera in these three complexes have been examined except Batagur and Annamemys. The Orlitia complex is karyotypically distinct with 2n=50 and the NOR located terminally on a large microchromosome. The genus Malayemys inclusion in the Batagur complex is not supported. Malayemys is characterized by a 2n=50 karyotype, with the NOR located interstitially on a large microchromosome. The Malayemys complex is erected to contain this genus at a point intermediate between the Orlitia complex and the subfamily Emydinae. Malayemys and the emydines are karyotypically indistinguishable. The Neotropical genus Rhinoclemmys (Geoemyda complex) differs only slightly from the primitive batagurine karyotype in the position of the NOR. The species R. funerea and R. punctularia further differ in possessing one less metacentric macrochomosome. An interesting situation involves two subspecies of R. punctularia. The nominate subspecies is characterized by a 2n=56 karyotype, while R. p. melanosterna reportedly has a 2n=52 karyotype. Such a difference is interpreted as indicative of genetic differentiation between the two forms of a magnitude inconsistent with considering them as conspecific. Taken together with zoogeographic considerations, the karyotypic difference between the forms R. p. punctularia and R. p. melanosterna seem sufficient to warrant species distinction for R. melanosterna as previously suggested by Pritchard (1979b).  相似文献   

7.
Turnera sidoides, with the most southerly distribution of all Turnera species in America, is a complex of obligately outcrossing perennial herbs. Karyotypes of the five subspecies of T. sidoides (x = 7) are described for the first time utilizing root-tip mitotic metaphases. Different ploidy levels were found for all of the subspecies, ranging from diploid to octoploid. The results obtained, coupled with available meiotic and preliminary biosystematic data, support the hypothesis of autopolyploidy within this species complex. Although detailed karyotype analysis shows a high degree of intraspecific uniformity, subspecies may be differentiated by the number, type, and position of satellites, suggesting that chromosome rearrangements may also be involved in the karyotypic evolution of T. sidoides. Karyotype data, coupled with morphological and anatomical features, suggest the removal of T. sidoides from series Leiocarpae.  相似文献   

8.
Anthyllis vulneraria L. (Fabaceae) s. lato includes many cryptic taxa, ranging from 25 to 60 subspecies according to different authors. The delimitation of intraspecific taxa of A. vulneraria s. lato has always been complicated and inconsistent. Different data sets (multivariate analyses of morphological variation, allozymes, chloroplast SSRs and ITS) have not resolved the existing problem with distinguishing some subspecies. We used the amplified fragment length polymorphism (AFLP) analysis to describe the differentiation in this species complex and to characterize variation on a geographic scale. Some correlation was found between genetic variability and geographic distribution (western-eastern directional variation), but AFLP data analysis did not reveal clear intraspecific structure of the seven analysed taxa. The analysed specimens did not comprise groups correlated with the subspecies.  相似文献   

9.
Timulla oculata (Fabr.) is redescribed and ten nominal species of Oriental Timulla are placed in synonymy with it. Fourteen subspecies, including two new ones (T. oculata rosemariae subsp.n. and T. oculata timorensis subsp.n.), are recognised and keys to the subspecies are given. Geographic variation and the application of the polytypic species concept are discussed. The structure of the male genitalia of Timulla is related to dispersal strategies. The distribution and subspeciation of T. oculata is discussed in relation to the geological history of South East Asia and the Malay Archipelago.  相似文献   

10.
Previous studies have shown a dynamic karyotype evolution and the presence of complex sex chromosome systems in three cryptic Leptidea species from the Western Palearctic. To further explore the chromosomal particularities of Leptidea butterflies, we examined the karyotype of an Eastern Palearctic species, Leptidea amurensis. We found a high number of chromosomes that differed between the sexes and slightly varied in females (i.e. 2n = 118–119 in females and 2n = 122 in males). The analysis of female meiotic chromosomes revealed multiple sex chromosomes with three W and six Z chromosomes. The curious sex chromosome constitution [i.e. W1–3/Z1–6 (females) and Z1–6/Z1–6 (males)] and the observed heterozygotes for a chromosomal fusion are together responsible for the sex‐specific and intraspecific variability in chromosome numbers. However, in contrast to the Western Palearctic Leptidea species, the single chromosomal fusion and static distribution of cytogenetic markers (18S rDNA and H3 histone genes) suggest that the karyotype of L. amurensis is stable. The data obtained for four Leptidea species suggest that the multiple sex chromosome system, although different among species, is a common feature of the genus Leptidea. Furthermore, inter‐ and intraspecific variations in chromosome numbers and the complex meiotic pairing of these multiple sex chromosomes indicate the role of chromosomal fissions, fusions, and translocations in the karyotype evolution of Leptidea butterflies.  相似文献   

11.
Zamia is unique among Cycadales in its diversity of morphology, ecology and chromosome numbers. The chromosome numbers in Zamia range from 16 to 28, excluding 20, manifest as both interspecific and intraspecific series. It has long been recognized that Robertsonian transformations (chromosomal fission or fusion) probably dominate karyotype evolution in Zamiaceae, although it has been debated whether chromosome numbers are increasing or decreasing. We re‐analyse published karyotypes of Zamia spp., relating both chromosome forms and sizes to recent phylogenetic data. We show that karyotype evolution is most probably moving towards increased asymmetry, with higher numbers of smaller chromosomes, thus supporting chromosomal fission. We also address additional hypotheses for increasing chromosome numbers, namely pericentric inversions and unequal translocations. Finally, we discuss the role of these chromosomal changes in evolutionary radiations. © 2011 The Linnean Society of London, Botanical Journal of the Linnean Society, 2011, 165 , 168–185.  相似文献   

12.
The viviparous lizard Lacerta (Zootoca) vivipara exhibits several alleles of the mannose-6-phosphate isomerase (MPI) enzyme that are carried exclusively on the female W sex-chromosome. Previous studies showed that both the oviparous and viviparous forms of L. (Zootoca) vivipara have these female sex-linked alleles. We document the existence of geographic variation of these alleles among the oviparous populations of southwestern France and northwestern Spain. Two oviparous subgroups were identified: all females from the eastern and central Pyrenees and most females from Aquitaine and from the northern slope of the western Pyrenees exhibited the fast migrating alleles MPI110 or MPI120, whereas all females from the Cantabric mountains, Spanish Basque country, and from the south slope of the western Pyrenees exhibited the slow migrating allele MPI90. Populations with both fast and slow migrating alleles occurred at some stations in the upper Ossau valley (western Pyrenees) and also at a lowland station of south Aquitaine. The hypothesis that several oviparous forms could have retreated to different places of the Pyreneo-Iberian refugia during the Quaternary glaciations could explain the conservation or the evolution of the polymorphism of the MPI alleles, and that is consistent with the phylogeographic scenario previously proposed to account for the reproductive and cytogenetical variation observed in this species.  相似文献   

13.
Three species are often accepted in Taeniatherum Nevski. Analysis of morphological characters show that indistinct limits occur between them. All taxa are found to be diploid (2n=14), with the same karyotype, but artificial hybridization shows genetical barrier to exist. For these reasons subspecific level is chosen for the taxa, viz. T. caput-medusae (L.) Nevski ssp. caput-medusae, T. caput-medusae ssp. crinitum (Schreb.) Melderis and T. caput-medusae ssp. asperum (Simk.) Melderis. Map showing known distribution of the subspecies is presented.  相似文献   

14.
The 125 species of the satyrid butterfly tribe Pronophilini known from the three Andean Cordilleras of Colombia are listed, together with two species whose Colombian status is doubtful. The biological, ecological and biogeographical features of the tribe are described, using the listed species as examples. The features include restriction to moist conditions at high altitudes, endemism in the Cordilleras and in areas and on slopes within them, allopatric speciation and subspeciation, parapatric distributions of related species up the altitude gradients, intraspecific variation and polymorphism and apparent mimicry. The criteria used for classifying the taxa and assessing their relationships are discussed. Seventeen new species, three new subspecies and one new form are described. At the species level, 11 new synonymies are established, two synonymies are rejected, the status of 15 other taxa is revised, and 23 new combinations are made. At the generic level, two new synonymies are established, and one genus is resurrected.  相似文献   

15.
Zingiber teres S. Q. Tong & Y. M. Xia and Z. xishuangbannaense S. Q. Tong are reduced to be synonyms of Z. smilesianum Craib and Z. thorelii Gagnep.,respectively. Z. cochinchinense Gagnep. is changed to be a subspecies of Z. zerumbet (L.) Sm.  相似文献   

16.
In 1906, Lönnberg identified a native subspecies of Red deer Cervus elaphus scoticus L., in Britain after examining a sample of stags' skulls from Glenquoich (Inverness-shire, Scotland). In north-west England, it is commonly believed that "Red deer of indigenous stock have persisted in this area (Furness Fells, Lancashire, England) from time immemorial…" (Chard, 1966). Arrangements were made to introduce animals into a park within this area in 1970, which, in view of this local opinion, would have been the only Red deer within the district not of native origin. Therefore, it was thought desirable to examine all the stocks of wild or feral Red deer in Britain and to determine which, if any, of them could be considered native and thus deserving of special measures to ensure their survival.
After examining samples of skulls, using multivariate analysis, it appeared that, within the limits of the material representing the various subspecies of the world, there was little support for the concept of subspeciation in Red deer. In Great Britain, however, there appeared to be two distinct forms of Red deer leading a free existence, one presumed to be native and the other to be of park derivation. Visually, the differences were indetectable and could be demonstrated only by discriminant analyses.  相似文献   

17.
菰属系统与演化研究—胚形态   总被引:1,自引:1,他引:0  
陈守良  杨光 《植物研究》1993,13(4):346-352
本文采用光学显微镜对全世界菰属4种2亚种及其有关属种共4属7种的胚形态进行系统研究后,获得菰属Zizania L.与山涧草Chikusichloa apuatica Koidz.的胚型为F+FP,稻Oryza sativa L.与拟菰Zizaniopsis miliacea(Michx.)Doell & Aschers.的胚型为F+FP,其中山涧草的胚型为首次报导。根据胚型,这4属均应位在禾本科G  相似文献   

18.
Hybridization processes can lead to evolutionary changes, particularly in co-introduced congeneric plant species, such as Carpobrotus spp. which are recognized as invasive in Mediterranean climate regions. Morphological and karyological comparisons have therefore been made between native Carpobrotus edulis and C. acinaciformis in South Africa and their invasive counterparts in Provence (C. edulis and C. aff. acinaciformis). Morphological data exhibited the most significant differences in invasive C. aff. acinaciformis that forms a new phenotypic variant. Unexpected chromosomal restructuring has been highlighted for both taxa in Provence, with in particular a clear decrease in asymmetry, an increase in the intraspecific variability, and an interspecific convergence of karyotypes. These changes suggest a drift that has facilitated various crosses, and has been amplified through hybridization/introgression. Furthermore, several morphological and karyological transgressive characters have been found in the two invasive taxa. These results stress the important role and the rapidity of karyological changes in invasive processes.  相似文献   

19.
Techniques of horizontal starch gel electrophoresis were employed to estimate levels of genetic variation within and genetic differentiation among populations of the three Florida subspecies of Helianthus debilis. The subspecies are H. d. debilis, H. d. vestitus, and H. d. tardiflorus. These taxa are very similar with respect to levels of genetic variability. The average values across all populations for proportion of polymorphic loci (25.5%) and number of alleles per polymorphic locus (2.35) are comparable to those found in other outcrossing plants. The average frequency of heterozygotes per locus (0.05) is lower than that found in other outcrossers. Local populations within each subspecies are genetically very similar. The average genetic distance between local populations is D = 0.010 ± 0.001. Subspecies vestitus and subspecies tardiflorus are also genetically very similar (D = 0.015 ± 0.001). However, subspecies debilis is differentiated from both subspecies vestitus (D = 0.121 ± 0.006) and subspecies tardiflorus (D = 0.103 ± 0.005). This genetic differentiation parallels morphological differentiation. The average genetic distance among all three subspecies is D = 0.080 ± 0.003. A moderate amount of genetic differentiation accompanies the process of subspeciation in Helianthus debilis.  相似文献   

20.
The lacertid lizard Lacerta vivipara is one of the few squamate species with two reproductive modes. We present the intraspecific phylogeny obtained from neighbor-joining and maximum-parsimony analyses of the mtDNA cytochrome b sequences for 15 individuals from Slovenian oviparous populations, 34 individuals from western oviparous populations of southern France and northern Spain, 92 specimens from European and Russian viviparous populations, and 3 specimens of the viviparous subspecies L. v. pannonica. The phylogeny indicates that the evolutionary transition from oviparity to viviparity probably occurred once in L. vivipara. The western oviparous group from Spain and southern France is phylogenetically most closely related to the viviparous clade. However, the biarmed W chromosome characterizing the western viviparous populations is an apomorphic character, whereas the uniarmed W chromosome, existing both in the western oviparous populations and in the geographically distant eastern viviparous populations, is a plesiomorphic character. This suggests an eastern origin of viviparity. Various estimates suggest that the oviparous and viviparous clades of L. vivipara split during the Pleistocene. Our results are discussed in the framework of general evolutionary models: the concept of an oviparity–viviparity continuum in squamates, the cold climate model of selection for viviparity in squamates, and the contraction–expansion of ranges in the Pleistocene resulting in allopatric differentiation.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号