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1.
Although predation is thought to affect species divergence, the effects of predator-mediated natural selection on species divergence and in nonadaptive radiations have seldom been studied. Wing melanization in Calopteryx damselflies has important functions in sexual selection and interspecific interactions and in species recognition. The genus Calopteryx and other damselfly genera have also been put forward as examples of radiations driven by sexual selection. We show that avian predation strongly affects natural selection on wing morphology and male wing melanization in two congeneric and sympatric species of this genus (Calopteryx splendens and Calopteryx virgo). Predation risk was almost three times higher for C. virgo, which has an exaggerated degree of wing melanization, than it was for the less exaggerated, sympatric congener C. splendens. Selective predation on the exaggerated species C. virgo favored a reduction and redistribution of the wing melanin patch. There was evidence for nonlinear selection involving wing patch size, wing patch darkness, and wing length and width in C. splendens but weaker nonlinear selection on the same trait combinations in C. virgo. Selective predation could interfere with species divergence by sexual selection and may thus indirectly affect male interspecific interactions, reproductive isolation, and species coexistence in this genus.  相似文献   

2.
Problems in species recognition are thought to affect the evolution of secondary sexual characters mainly through avoidance of maladaptive hybridization. Another, but much less studied avenue for the evolution of sexual characters due to species recognition problems is through interspecific aggression. In the damselfly, Calopteryx splendens, males have pigmented wing spots as a sexual character. Large-spotted males resemble males of another species, Calopteryx virgo, causing potential problems in species recognition. In this study, we investigate whether there is character displacement in wing spot size and whether interspecific aggression could cause this pattern. We found first that wing spot size of C. splendens in populations decreased with increasing relative abundance of C. virgo. Secondly, C. virgo males were more aggressive towards large- than small-spotted C. splendens males. Thirdly, in interspecific contests C. virgo males had better territory holding ability than C. splendens males. These results suggest that interspecific aggression may have caused character displacement in wing spot size of C. splendens, because the intensity of aggression towards large-spotted males is likely to increase with relative abundance of C. virgo males. Thus, interspecific aggression may be an evolutionarily significant force that is able to cause divergence in secondary sexual characters.  相似文献   

3.
Prolonged periods of allopatry might result in loss of the ability to discriminate against other formerly sympatric species, and can lead to heterospecific matings and hybridization upon secondary contact. Loss of premating isolation during prolonged allopatry can operate in the opposite direction of reinforcement, but has until now been little explored. We investigated how premating isolation between two closely related damselfly species, Calopteryx splendens and C. virgo , might be affected by the expected future northward range expansion of C. splendens into the allopatric zone of C. virgo in northern Scandinavia. We simulated the expected secondary contact by presenting C. splendens females to C. virgo males in the northern allopatric populations in Finland. Premating isolation toward C. splendens in northern allopatric populations was compared to sympatric populations in southern Finland and southern Sweden. Male courtship responses of C. virgo toward conspecific females showed limited geographic variation, however, courtship attempts toward heterospecific C. splendens females increased significantly from sympatry to allopatry. Our results suggest that allopatric C. virgo males have partly lost their ability to discriminate against heterospecific females. Reduced premating isolation in allopatry might lead to increased heterospecific matings between taxa that are currently expanding and shifting their ranges in response to climate change.  相似文献   

4.
By comparing the phenotypic (P) variance-covariance matrices between closely related taxa or conspecific populations, one can study the outcome of the interplay between selection and developmental constraints in phenotypic evolution. Shared patterns of phenotypic integration are also of interest and might result from similarities in either selection or developmental pathways. We compared P-matrices and phenotypic integration indices between populations and species of the damselfly genus Calopteryx. P(max)-comparisons between parapatric C. splendens populations revealed stronger conserved phenotypic covariance structure than P(max)-comparisons between species, suggesting that divergence in its early stages proceeds along phenotypic lines of least resistance. Within- and among-population correlations in C. splendens were highly concordant, in further support of initial divergence along P(max). Despite some similarities in overall phenotypic integration between C. splendens and C. virgo, these two species only had several P-matrix eigenvectors in common, indicating that after reproductive isolation, divergence has proceeded against P(max).  相似文献   

5.
The tribe Inuleae (Asteraceae) has 10 species endemic to the Macaronesian islands, including the three endemic genera Allagopappus, Schizogyne, and Vierea. Phylogenetic analyses of DNA sequence data from the internal transcribed spacers (ITS) of the nuclear ribosomal DNA of 47 taxa were performed using all Macaronesian endemics and representative species from 21 of the 36 genera of the Inuleae. The resulting ITS phylogeny reveals that Allagopappus is sister to a large clade that contains all genera with a predominantly Mediterranean distribution. This finding suggests that Allagopappus may represent an ancient lineage that found refuge in the Canary Islands following the major climatic and/or geologic changes in the Mediterranean basin after the Tertiary. The Macaronesian endemic genus Schizogyne is sister to Limbarda from the Mediterranean. The third Macaronesian endemic genus, Vierea, is sister to Perralderia, which is restricted to Morocco and Algeria. Pulicaria canariensis is sister to P. mauritanica, a species endemic to Morocco and Algeria. In contrast, P. diffusa from the Cape Verde Islands is sister to a broadly distributed species, P. crispa, that occurs from North Africa to the Arabian peninsula. Based on the ITS data, the genera Blumea, Inula, and Pulicaria are not monophyletic. The ITS trees suggested that Blumea mollis belongs to the tribe Plucheeae, a finding that is congruent with recent morphological evidence. A possible southern African origin for the core of the Laurasian taxa of the Inuleae is also suggested.  相似文献   

6.
The internal transcribed spacers (ITS) of nuclear ribosomal DNA were sequenced for 52 species from 32 genera and eight subtribes of Anthemideae. Phylogenetic analyses of ITS data generated trees that are largely incongruent with the recent classification of Anthemideae; most of the subtribes examined are not resolved as monophyletic. However, ITS trees are congruent with morphological, isozyme, phytochemical, and chloroplast DNA (cpDNA) restriction site data in supporting a Mediterranean origin for Argyranthemum, the largest endemic genus of the Atlantic oceanic islands. A combined analysis of ITS sequences and cpDNA restriction sites indicates that Argyranthemum is sister to the other three genera of Chrysantheminae (i.e., Chrysanthemum, Heteranthemis, and Ismelia). Times of divergence of Argyranthemum inferred from the ITS sequences ranged between 0.26 and 2.1 million years ago (mya) and are lower than values previously reported from isozyme and cpDNA data (1.5-3.0 mya). It is likely that rate heterogeneity of the ITS sequences in the Anthemideae accounts for the low divergence-time estimates. Comparison of data for 20 species in Argyranthemum and Chrysantheminae indicates that the cpDNA restriction site approach provided much more phylogenetic information than ITS sequences. Thus, restriction site analyses of the entire chloroplast genome remain a valuable approach for studying recently derived island plants.  相似文献   

7.
During copulation, males of some calopterygid damselfly species displace the sperm stored in the spermatheca: the male genital appendages enter into the spermathecal ducts and physically remove sperm. In Calopteryx haemorrhoidalis, the genital appendages are too wide to penetrate the spermathecae, but males use a different mechanism in which the aedeagus stimulates the vaginal sensilla that control spermathecal sperm release. Since these sensilla are used during egg fertilization and oviposition, it was hypothesized that this function evolved before the male stimulatory ability. I investigated this using Hetaerina cruentata, a species whose position in the Calopterygidae phylogeny is more basal than Calopteryx. Given this position and having determined that males of this species are not able to displace sperm of their conspecific females during copulation, it was expected that H. cruentata females would eject sperm when stimulated with the aedeagi of C. haemorrhoidalis but not when stimulated with the aedeagi of their conspecifics. This prediction was confirmed. In order to investigate the widespread nature of this result, some other Calopteryx species-Calopteryx xanthostoma and Calopteryx virgo-were investigated. The results were similar to those of H. cruentata: conspecific males were unable to stimulate their females, but females ejected sperm when stimulated with C. haemorrhoidalis aedeagi. Morphometric analysis suggests that the mechanistic explanation for the stimulatory ability of C. haemorrhoidalis genitalia is that the aedeagal region that makes contact with the vaginal sensilla is wider in C. haemorrhoidalis than in the other species. These results suggest that the sensory "bias" shown and shared by H. cruentata, Calopteryx splendens, C. virgo, and C. haemorrhoidalis females represents an ancestral condition and that the male stimulatory ability is absent in the evolutionary history of the clade. These pieces of evidence as well as another one presented elsewhere, which indicates that C. haemorrhoidalis males vary in their stimulatory ability, constitute the three criteria for a case of sexual selection via exploitation of a female sensory bias. These results also provide support to the sensory trap hypothesis that indicates that the female bias-in this case, egg fertilization and oviposition-evolved in a context different from sexual selection. Considering that the male genital appendages responsible for physically removing spermathecal sperm in other calopterygids are present in C. haemorrhoidalis, I suggest that males were once able to displace spermathecal sperm physically. Such ability may have been later impeded by a reduction in size of the spermathecal ducts. Possibly, one of the latest events in this sequence is the male's stimulatory ability. This hypothetical series of events suggests a coevolutionary scenario in which the central actor is the sperm stored in the spermathecae.  相似文献   

8.
Crambe L. (Brassicaceae) is an Old World genus with a disjunct distribution among four major centers of species diversity. A phylogenetic analysis of nucleotide sequences of the internal transcribed spacers (ITS) of the nuclear ribosomal repeat was conducted with 27 species of Crambe and 18 related genera. Cladistic analyses using weighted and unweighted parsimony support Crambe as a monophyletic genus with three major lineages. The first comprises those taxa endemic to the Macaronesian archipelagos. Taxa with a predominant Mediterranean distribution form the second assemblage, and a disjunction between east Africa (C. abyssinica) and the Mediterranean (C. hispanica) occurs in this clade. The third lineage includes all Eurosiberian-Asian taxa and C. kilimandscharica, a species from the highlands of east Africa. A basal biogeographic split between east Africa and Eurasia is present in the third clade. The patterns of relationships in the ITS tree are concordant with known climatic events in northern Africa and southwestern Asia since the middle Miocene. The ITS trees are congruent with the current sectional classification except for a few members of sections Crambe, Leptocrambe, and Orientecrambe (C. cordifolia, C. endentula, C. kilimandscharica, and C. kotschyana). Low levels of support in the basal branches do not allow resolution of which genera of the subtribes Raphaniae or Brassicinae are sister to Crambe. Both subtribes appear to be highly polyphyletic in the ITS trees.  相似文献   

9.
Aim Since the opening of the Suez Canal in 1869, many tropical taxa from the Indo‐West Pacific (IWP) realm have entered the Mediterranean Sea, which is experiencing rising temperatures. My aims are: (1) to compare biogeographically this tropical transformation of the Mediterranean biota with the tropical faunas of the Mediterranean and adjacent southern European and West African seas during the Late Oligocene to Pliocene interval; (2) to infer the relative contributions of the tropical eastern Atlantic and IWP to the tropical component of the marine biota in southern Europe; and (3) to understand why West Africa is not now a major source of warm‐water species. Location Southern Europe, including the Mediterranean Sea, and the coast of tropical West Africa. Methods I surveyed the literature on fossil and living shell‐bearing molluscs to infer the sources and fates of tropical subgenus‐level taxa living in southern Europe and West Africa during the Late Oligocene to Pliocene interval. Results Ninety‐four taxa disappeared from the tropical eastern Atlantic (including the Mediterranean) but persisted elsewhere in the tropics, mainly in the IWP (81 taxa, 86%) and to a lesser extent in tropical America (36 taxa, 38%). Nine taxa inferred to have arrived in the tropical eastern Atlantic from the west after the Pliocene did not enter the Mediterranean. The modern West African fauna is today isolated from that of other parts of the marine tropics. Main conclusions Taxa now entering the Mediterranean through the Suez Canal are re‐establishing a link with the IWP that last existed 16 million years ago. This IWP element, which evolved under oligotrophic conditions and under a regime of intense anti‐predatory selection, will continue to expand in the increasingly warm and increasingly oligotrophic Mediterranean. The IWP source fauna contrasts with the tropical West African biota, which evolved under productive conditions and in a regime of less anti‐predatory specialization. Until now, the post‐Pliocene West African source area has been isolated from the Mediterranean by cold upwelling. If further warming should reduce this barrier, as occurred during the productive and warm Early Pliocene, the Mediterranean could become a meeting place for two tropical faunas of contrasting source conditions.  相似文献   

10.
用 PCR技术从产于我国的 3种野生稻和亚洲栽培稻的 2个亚种中特异地扩增和测序了 r DNA的第一转录间隔区。普通野生稻 (Oryza rufipogon)、药用野生稻 (O.officinalis)、疣粒野生稻 (O.granu-lata)和栽培稻的两个亚种 (O.sativa ssp.indica,O.sativa ssp.japonica)的 ITS1序列为 1 93bp、1 94bp、2 1 8bp、1 94bp和 1 94bp,它们的 G/ C含量为 69.3%~ 72 .7% ,序列中位点趋异率为 1 .5%~ 1 0 .6%。序列的相似性比较和简约性分支分析的结果表明 ,普通野生稻与栽培稻的两个亚种之间的亲缘关系最为密切 ;药用野生稻与普通野生稻和与栽培稻的两个亚种的相似性都为 82 % ,说明它与 AA基因组有一定的亲缘关系 ;疣粒野生稻与普通野生稻、药用野生稻和栽培稻两个亚种的亲缘关系相对较远 ,它在稻属中可能是一个系统地位较独特的类群。以 ITS1序列构建的 3种野生稻和 2个栽培稻亚种的系统发育关系与前人用同工酶、叶绿体 DNA、线粒体 DNA和核 DNA资料重建的稻属的系统发育关系基本一致  相似文献   

11.
The genus Pimpinella L. comprises about 150 species, being one of the largest genera within the family Apiaceae (subfamily Apioideae). Previous molecular phylogenetic studies have shown that Pimpinella is a taxonomically complex group. In this study, evolutionary relationships among representatives from Western Europe have been inferred from phylogenetic analyses of nuclear ribosomal DNA internal transcribed spacer (ITS 1 and ITS 2) and plastid sequences (trnL intron and the trnL-F spacer), with a representative sampling included (168 accessions in the ITS analysis, representing 158 species; and 42 accessions in the cpDNA analysis representing 35 taxa of Pimpinella and closely related species). All analyses resolved that Pimpinella is a non-monophyletic group, and Pimpinella’s taxa that grow in Western Europe are part of phylogenetically independent groups that correspond to three different tribes of the subfamily Apioideae: Pimpinelleae (core group), Pyramidoptereae and Smyrnieae.  相似文献   

12.
Evolutionary relationships within Astragalus L. (Fabaceae) were inferred from nucleotide sequence variation in nuclear ribosomal DNA of both New World and Old World species. The internal transcribed spacer regions (ITS) of 18S–26S nuclear ribosomal DNA from representatives of 26 species of Astragalus, three species of Oxytropis DC., and two outgroup taxa were analyzed by polymerase chain reaction amplification and direct DNA sequencing. The length of the ITS 1 region within these taxa varied from 221 to 231 bp, while ITS 2 varied in length from 207 to 217 bp. Of the aligned, unambiguous positions, approximately 34% were variable in each spacer region. In pairwise comparisons among Astragalus species and outgroup taxa, sequence divergence at these sites ranged from 0 to 18.8% in ITS 1 and from 0 to 21.7% in ITS 2. Parsimony analyses of these sequences resulted in a well-resolved phylogeny that is highly concordant with previous cytogenetic and chloroplast DNA evidence for a major phylogenetic division in the genus. These data suggest that the New World aneuploid species of Astragalus form a monophyletic but morphologically cryptic group derived from euploid species of Old World (Eurasian) origin, which are consequently paraphyletic.  相似文献   

13.
This article documents the addition of 111 microsatellite marker loci to the Molecular Ecology Resources Database. Loci were developed for the following species: Acipenser oxyrinchus desotoi, Anopheles nuneztovari sensu lato, Asellus aquaticus, Calopteryx splendens, Calopteryx virgo, Centaurea aspera, Centaurea seridis, Chilina dombeyana, Proctoeces cf. lintoni and Pyrenophora teres f. teres.  相似文献   

14.
Genes coding for 45S ribosomal RNA are organized in tandem arrays of up to several thousand copies and contain 18S, 5.8S and 26S rRNA units separated by internal transcribed spacers ITS1 and ITS2. While the rRNA units are evolutionary conserved, ITS show high level of interspecific divergence and have been used frequently in genetic diversity and phylogenetic studies. In this work we report on the structure and diversity of the ITS region in 87 representatives of the family Musaceae. We provide the first detailed information on ITS sequence diversity in the genus Musa and describe the presence of more than one type of ITS sequence within individual species. Both Sanger sequencing of amplified ITS regions and whole genome 454 sequencing lead to similar phylogenetic inferences. We show that it is necessary to identify putative pseudogenic ITS sequences, which may have negative effect on phylogenetic reconstruction at lower taxonomic levels. Phylogenetic reconstruction based on ITS sequence showed that the genus Musa is divided into two distinct clades--Callimusa and Australimusa and Eumusa and Rhodochlamys. Most of the intraspecific banana hybrids analyzed contain conserved parental ITS sequences, indicating incomplete concerted evolution of rDNA loci. Independent evolution of parental rDNA in hybrids enables determination of genomic constitution of hybrids using ITS. The observation of only one type of ITS sequence in some of the presumed interspecific hybrid clones warrants further study to confirm their hybrid origin and to unravel processes leading to evolution of their genomes.  相似文献   

15.
Interspecific aggression originating from mistaken species recognition may cause selection on secondary sexual characters, but this hypothesis has remained untested. Here we report a field experiment designed to test directly whether interspecific aggression causes selection on secondary sexual characters, wing spots, in wild damselfly populations. Males of Calopteryx virgo are more aggressive toward males of C. splendens with large than with small wing spots. This differential interspecific aggression may cause negative selection on wing spot size. Indeed, our results show that directional survival selection on wing spot size of C. splendens males was changed by experimental removal of C. virgo males. Without removal, directional selection went from positive to negative with increasing relative abundance of C. virgo males. In populations where C. virgo males were removed, this relationship disappeared. These results verify that interspecific aggression can cause negative selection on sexual characters. Thus, interspecific aggression has the potential to cause divergence on these characters between two species offering an alternative explanation for reinforcement for generating character displacement in secondary sexual characters.  相似文献   

16.
横断山区是中国柴胡属Bupleurum植物的分布中心。本文对横断山区6个种2变种进行了染色体记数报道,其中4个种2变种是首次报道。对横断山区的10个种4个变种、中国北方(河北和黑龙江)的3个种的nrDNA ITS进行测序,同时从GenBank里面下载同属的来自非洲和地中海西部的16个nrDNA ITS序列数据,结合染色体数目变化结果,初步探讨了横断山区柴胡属植物的系统发育。结果表明横断山区可能是现代柴胡属植物的频度中心和多样分布中心之一。它们的祖先种可能是非洲北部的木本柴胡属植物B.fruticosum,或者是地中海西部的柴胡属植物,推测是通过中东和高加索扩散而形成的,其中与非洲南部特有种B.mundtii的亲缘关系也较近;染色体基数演化趋势是:8是较原始基数,6和7是次生基数,其染色体异基数变异和多倍化可能是物种形成、进化以及向外扩散的主要方式;在ITS系统发育树中,中国柴胡属植物染色体基数为8的种类聚为一支,染色体基数为6和7的种类聚为了一支,不支持舒璞等(1998)关于中国柴胡属的属下分类系统。结合已有的形态学、细胞学、孢粉学证据和ITS系统发育树,建议窄竹叶柴胡B.marginatum var.stenophyllum独立成种。  相似文献   

17.
A survey of the endophytic fungi in fronds of Livistona chinensis was carried out in Hong Kong. The endophyte assemblages identified using morphological characters consisted of 16 named species and 19 'morphospecies', the latter grouped based on cultural morphology and growth rates. Arrangement of taxa into morphospecies does not reflect species phylogeny, and therefore selected morphospecies were further identified based on ribosomal DNA (rDNA) sequence analysis. The 5.8S gene and flanking internal transcribed spacers (ITS1 and ITS2) regions of rDNA from 19 representative morphospecies were amplified by the polymerase chain reaction and sequenced. Phylogenetic analysis based on 5.8S gene sequences showed that these morphospecies were filamentous Ascomycota, belonging in the Loculoascomycetes and Pyrenomycetes. Further identification was conducted by means of sequence comparison and phylogenetic analysis of both the ITS and 5.8S regions. Results showed that MS704 belonged to the genus Diaporthe and its anamorph Phomopsis of the Valsaceae. MS594 was inferred to be Mycosphaerella and its anamorph Cladosporium of the Mycosphaerellaceae. MS339, MS366, MS370, MS395, MS1033, MS1083 and MS1092 were placed in the genus Xylaria of the Xylariaceae. MS194, MS375 and MS1028 were close to the Clypeosphaeriaceae. MS191 and MS316 were closely related to the Pleosporaceae within the Dothideales. The other 5 morphospecies, MS786, MS1043, MS1065, MS1076 and MS1095, probably belong in the Xylariales. The value of using DNA sequence analysis in the identification of endophytes is discussed.  相似文献   

18.
We present phylogenetic analyses of 37 taxa of Fritillaria (Liliaceae), 15 species of Lilium, and several outgroup taxa from Liliaceae s.s. to investigate the generic delimitation of Fritillaria in relation to Lilium as well as infrageneric relationships within Fritillaria. We used DNA sequences from the maturase-coding plastid matK gene and the trnK intron, the intron of the ribosomal protein-coding rpl16 plastid gene, and the nuclear ribosomal internal transcribed spacers (ITS). Phylogenetic analysis using maximum parsimony defined Fritillaria and Lilium (the latter including Nomocharis) as sister taxa. Fritillaria sections Fritillaria and Liliorhiza are supported in part, and some of the most enigmatic species usually included in Fritillaria (sections Petilium and Theresia and the monotypic genus Korolkowia) are closely related. The results support the new classification of Fritillaria proposed by Rix. We postulate independent origins of the underground bulbils found in Fritillaria davidii and the remainder of subgenus Liliorhiza.  相似文献   

19.
There is limited information about the species of rumen fluke (Family Paramphistomidae) in the Caribbean. However, knowledge of species distribution is needed to better understand disease risk and epidemiology. Morphological identification is challenging with more recent DNA sequencing enabling a better understanding of rumen fluke distribution. In this study, rumen fluke specimens, collected between 2015 and 2016 from cattle on the island of St. Kitts, West Indies, were analysed. The ribosomal internal transcribed spacer 2 (ITS-2) region of rDNA was amplified using generic trematode primers. Results from Sanger sequencing were compared to reference sequences in GenBank and indicated the species was Cotylophoron cotylophorum with 100% sequence identity and 91% query cover. The ITS2 sequences were then compared to previously published ITS2 sequences for the Cotylophoron genus. When all the St. Kitts C. cotylophorum ITS2 sequences were compared with all other Cotylophoron sequences from India, Kenya, and Zimbabwe, three variable nucleotide sites, resulting in five unique haplotypes, were identified. Nine ITS2 sequences shared haplotype 1, which included all those from St. Kitts and single representatives from India and Kenya, potentially indicating global movement of this species.  相似文献   

20.
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