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 15 毫秒
1.
Peter F.  Jenkins Allan J.  Baker 《Ibis》1984,126(4):510-524
Chaffinches Fringilla coelebs were introduced to New Zealand from Great Britain over 100 years ago, and since then their songs have diverged from British ones in both syllable structure and basic organization of syllable sequences. The New Zealand populations seem to be unique in that their songs have undergone differentiation of trill segments by progressive elaboration of syllable morphology and hp ascending and descending changes of pitch. Published sonagrams of British song types have significantly more trill phrases and significantly fewer syllables in the end phrase than do Yew Zealand ones. Many New Zealand song types have much elaborated end phrases and concomitantly simpler trill segments, with songs quite commonly having only one trill phrase. This reversal of complexity between the trill and end phrase in New Zealand seems to have been derived by progressive reduction of the ultimate trill phrase to one syllable, and by recombination of end phrase syllables from different song types into one compound end phrase. The significance of the increased complexity in the end phrases of many song types may relate to the sound transmission properties of dense pine forests in New Zealand, in which Chaffinches are ubiquitous. Elaborate end phrases degrade much less from reverberation in pine forests because individual syllables have more dispersed temporal patterning.
Recombination of syllables to form new song types is a major mechanism of song differentiation in New Zealand. Although whole song copying is the predominant mode of replication, very few song types in a locality sample are composed of a unique set of syllables. Rather, song types in an area are interconnected by different combinations of shared syllables, suggesting that the incorporation of some local syllables in a bird's repertoire is sufficient to signal its status as a member of a neighbourhood and also allows the evolution of broadcast complexity.  相似文献   

2.
3.
Phylogenetic relationships of 13 accessions and a cultivar representing the sweetpotato, Ipomoea batatas (L.) Lam., and its wild progenitors, were investigated using the nucleotide sequence variation of a nuclear-encoded beta-amylase gene. A 1.1-1.3 kb fragment of the gene spanning two exons separated by a long intron was PCR-amplified, cloned, and sequenced. Exon sequences proved highly conservative, while intron sequences yielded large differences. Intron analyses grouped species in a phylogenetic context according to the presence of two genome types: A and B. These groups are consistent with results of previous analyses, save for the novel placement of I. tiliacea, among the A-genome species. Sequences specific to both A and B genome species have been identified. Exon sequences indicate that I. ramosissima and I. umbraticola are quite different from other A-genome species. Placement of I. littoralis is questionable; its intron is similar to other B-genome species, but its exons are quite different. Exon evolution indicates that the B-genome has evolved faster than the A-genome. Interspecific intron and exon variation indicates I. trifida, I. tabascana, and I. batatas form a monophyletic group.  相似文献   

4.
Calls of Ctenodactylus gundi living in semi-natural conditions in our laboratory were recorded during various interactions : sexual, agonistic, maternal.The physical characteristics of the sounds lead us to describe five major structural groups and eleven vocal types. Two of them were recorded only in young animals. Intermediate calls and some complex sequences formed by association of two vocal types were observed.When emitting sounds, adult gundis can produce eight vocal sequences. In two of these phrases a constant association of two different calls can be shown. Seven sequences can be related to one of three kinds of social interactions : sexual intercourse, withdrawal or aggressivity. In each,vocal types are arranged in a gradual order based on the intensity of the interaction. The alarm call and two calls produced by young gundis when interacting with their mother must be added to the seven sequences described above.Gundi's calls appear then to be related both to the quality of social interactions and to the degree of arousal of the emitter. Functional problems are discussed and compared with available data from some other Rodents.  相似文献   

5.
The analysis of nuclear-encoded chitinase sequences from various angiosperms has allowed the categorization of the chitinases into discrete classes. Nucleotide sequences of their catalytic domains were compared in this study to investigate the evolutionary relationships between chitinase classes. The functionally distinct class III chitinases appear to be more closely related to fungal enzymes involved in morphogenesis than to other plant chitinases. The ordering of other plant chitinases into additional classes mainly relied on the presence of auxiliary domains—namely, a chitin-binding domain and a carboxy-terminal extension—flanking the main catalytic domain. The results of our phylogenetic analyses showed that classes I and IV form discrete and well-supported monophyletic groups derived from a common ancestral sequence that predates the divergence of dicots and monocots. In contrast, other sequences included in classes I* and II, lacking one or both types of auxiliary domains, were nested within class I sequences, indicating that they have a polyphyletic origin. According to phylogenetic analyses and the calculation of evolutionary rates, these chitinases probably arose from different class I lineages by relatively recent deletion events. The occurrence of such evolutionary trends in cultivated plants and their potential involvement in host–pathogen interactions are discussed. Received: 5 July 1996 / Accepted: 9 January 1997  相似文献   

6.
Animal acoustic communication often takes the form of complex sequences, composed of multiple distinct acoustic units, which can vary in their degree of stereotypy. Studies of sequence variation may contribute to our understanding of the structural flexibility of primates' songs, which can provide essential ecological and behavioral information about variability at the individual, population, and specific level and provide insights into the mechanisms and drivers responsible for the evolutionary change of communicative traits. Several methods have been used for investigating different levels of structural information and sequence similarity in acoustic displays. We studied intra and interindividual variation in the song structuring of a singing primate, the indri (Indri indri), which inhabits the montane rain forests of Madagascar. Indri groups emit duets and choruses in which they combine long notes, short single units, and phrases consisting of a variable number of units (from two to six) with slightly descending frequency. Males' and females' contributions to the song differ in the temporal and frequency structure of song units and repertoire size. We calculated the similarity of phrase organization across different individual contributions using the Levenshtein distance, a logic distance that expressed the minimum cost to convert a sequence into another and can measure differences between two sequences of data. We then analyzed the degree of similarity within and between individuals and found that: (a) the phrase structure of songs varied between reproductive males and females: female structuring of the song showed a higher number of phrases if compared to males; (b) male contributions to the song were overall more similar to those of other males than were female contributions to the song of other females; (c) male contributions were more stereotyped than female contributions, which showed greater individual flexibility. The picture emerging from phrase combinatorics in the indris is in agreement with previous findings of rhythmic features and song repertoire size of the indris, which also suggested that female songs are potentially less stereotyped than those of males.  相似文献   

7.
Resistance Gene Candidate2 (RGC2) genes belong to a large, highly duplicated family of nucleotide binding site-leucine rich repeat (NBS-LRR) encoding disease resistance genes located at a single locus in lettuce (Lactuca sativa). To investigate the genetic events occurring during the evolution of this locus, approximately 1.5- to 2-kb 3' fragments of 126 RGC2 genes from seven genotypes were sequenced from three species of Lactuca, and 107 additional RGC2 sequences were obtained from 40 wild accessions of Lactuca spp. The copy number of RGC2 genes varied from 12 to 32 per genome in the seven genotypes studied extensively. LRR number varied from 40 to 47; most of this variation had resulted from 13 events duplicating two to five LRRs because of unequal crossing-over within or between RGC2 genes at one of two recombination hot spots. Two types of RGC2 genes (Type I and Type II) were initially distinguished based on the pattern of sequence identities between their 3' regions. The existence of two types of RGC2 genes was further supported by intron similarities, the frequency of sequence exchange, and their prevalence in natural populations. Type I genes are extensive chimeras caused by frequent sequence exchanges. Frequent sequence exchanges between Type I genes homogenized intron sequences, but not coding sequences, and obscured allelic/orthologous relationships. Sequencing of Type I genes from additional wild accessions confirmed the high frequency of sequence exchange and the presence of numerous chimeric RGC2 genes in nature. Unlike Type I genes, Type II genes exhibited infrequent sequence exchange between paralogous sequences. Type II genes from different genotype/species within the genus Lactuca showed obvious allelic/orthologous relationships. Trans-specific polymorphism was observed for different groups of orthologs, suggesting balancing selection. Unequal crossover, insertion/deletion, and point mutation events were distributed unequally through the gene. Different evolutionary forces have impacted different parts of the LRR.  相似文献   

8.
Like many other callitrichids, golden lion tamarins, Leontopithecus rosalia, emit Long Calls. Recordings of four free-ranging groups were made to explore different types of Long Calls. Three Long Call types were identified acoustically, and analyzed sonographically. The calls usually started with an Introductory Syllable (a chirp, a trill, or a whine) which was followed by either one, two, or three different phrases in a fixed sequential order. Each of the three phrases was unique and contained a typical number of syllables of characteristic shape, frequencies, and durations. Possible functions of these calls are discussed. © 1994 Wiley-Liss, Inc.  相似文献   

9.
The calling song of the field cricket, Teleogryllus taiwanemma, is usually considered to consist of sequences of separate chirps. However, sometimes it comprises a phrase of several chirps in a row, with one long chirp (chirp) and a few short chirps (trills). In this study, I compared the phrase containing only chirps with that containing both chirps and trills by analyzing male songs and conducting playback experiments of male songs to females. The song analyses showed significant differences between chirps and trills for all song parameters except bandwidth. To test whether female preference differed with respect to the two phrases, I performed two-speaker playback experiments. When the same numbers of phrases were presented per unit time, females preferred the song with trills to that without trills. This result may reflect female preference for songs with greater sound density. In subsequent playback experiments, I equalized the total sound duration per unit time (duty cycle) in songs with and without trills. The numbers of females that preferred songs with and without trills did not differ significantly. This suggests that trills can attract females like chirps do, even though the two sounds have different components.  相似文献   

10.
Alanine-rich α-helical (type I) antifreeze proteins (AFPs) are produced by a variety of fish species from three different orders to protect against freezing in icy seawater. Interspersed amongst and within these orders are fishes making AFPs that are completely different in both sequence and structure. The origin of this variety of types I, II, III and antifreeze glycoproteins (AFGPs) has been attributed to adaptation following sea-level glaciations that occurred after the divergence of most of the extant families of fish. The presence of similar types of AFPs in distantly related fishes has been ascribed to lateral gene transfer in the case of the structurally complex globular type II lectin-like AFPs and to convergent evolution for the AFGPs, which consist of a well-conserved tripeptide repeat. In this paper, we examine the genesis of the type I AFPs, which are intermediate in complexity. These predominantly α-helical peptides share many features, such as putative capping structures, Ala-richness and amphipathic character. We have added to the type I repertoire by cloning additional sequences from sculpin and have found that the similarities between the type I AFPs of the four distinct groups of fishes are not borne out at the nucleotide level. Both the non-coding sequences and the codon usage patterns are strikingly different. We propose that these AFPs arose via convergence from different progenitor helices with a weak affinity for ice and that their similarity is dictated by the propensity of specific amino acids to form helices and to align water on one side of the helix into an ice-like pattern.  相似文献   

11.
Songs of wild male Anna hummingbirds (Calypte anna) consist of syllables grouped into phrases. Nearest neighbors tend to share similar syllable types, rhythms and syntax. Songs from different localities contain different syllable types, syntax and repetition indices. A male raised by hand in isolation produced a song consisting of highly variable syllable types of a wide frequency range. The song was simple in structure, and syllables were not grouped into phrases. Three males raised by hand as a group sang songs containing two stereotyped syllable types sung in alternating sequence and without phrase structure. These three males shared syllable types and syntax. The data from our study indicate that despite its relatively simple syrinx the Anna hummingbird learns syllable types, frequency, rhythm and syntax (as do oscines with their more complex syringes) during the song development process.  相似文献   

12.
Piscine reovirus (PRV) is a double stranded non-enveloped RNA virus detected in farmed and wild salmonids. This study examined the phylogenetic relationships among different PRV sequence types present in samples from salmonids in Western Canada and the US, including Alaska (US), British Columbia (Canada) and Washington State (US). Tissues testing positive for PRV were partially sequenced for segment S1, producing 71 sequences that grouped into 10 unique sequence types. Sequence analysis revealed no identifiable geographical or temporal variation among the sequence types. Identical sequence types were found in fish sampled in 2001, 2005 and 2014. In addition, PRV positive samples from fish derived from Alaska, British Columbia and Washington State share identical sequence types. Comparative analysis of the phylogenetic tree indicated that Canada/US Pacific Northwest sequences formed a subgroup with some Norwegian sequence types (group II), distinct from other Norwegian and Chilean sequences (groups I, III and IV). Representative PRV positive samples from farmed and wild fish in British Columbia and Washington State were subjected to genome sequencing using next generation sequencing methods. Individual analysis of each of the 10 partial segments indicated that the Canadian and US PRV sequence types clustered separately from available whole genome sequences of some Norwegian and Chilean sequences for all segments except the segment S4. In summary, PRV was genetically homogenous over a large geographic distance (Alaska to Washington State), and the sequence types were relatively stable over a 13 year period.  相似文献   

13.
Maliarchuk BA  Derenko MV 《Genetika》2000,36(1):105-108
Nucleotide sequences of the 16126C types of hypervariable segment I from the major noncoding region of human mitochondrial DNA in eastern Slavs from Magadan (N = 19) were analyzed. The mitochondrial DNA sequences were subsumed within three Caucasoid-specific mitochondrial haplogroups, T, J, and JT*. Haplogroup T in eastern Slavs proved to be the most rich in different hypervariable segment I types (nucleotide diversity 1.03%). Haplogroup J was remarkably less heterogeneous (0.28%). Data on the frequency distribution of haplogroup T and J subgroups among eastern Slavs in comparison with some other populations of Eastern Europe are presented.  相似文献   

14.
Summary Mutagenic DNA repair is a function of many naturally occurring plasmids belonging to several different incompatibility groups. A DNA probe corresponding to the impCAB operon of the IncIl plasmid TP110, which encodes such functions, was used to investigate the distribution of homologous sequences in both related and unrelated plasmids. Southern blotting was used to demonstrate considerable sequence conservation amongst a number of plasmid types, with imp-related sequences being found on plasmids belonging to the I1, I1/B, B and FIV incompatibility groups. However, no homology was detected amongst plasmids of the N and L/M incompatibility groups, many of which carry functionally similar gene clusters. It appears that sequences determining mutagenic repair functions have been largely conserved within any one incompatibility group, but that significant divergent evolution has occurred between groups.  相似文献   

15.
Complete nucleotide sequences were determined by cDNA cloning of peplomer (S), integral membrane (M) and nucleocapsid (N) genes of feline infectious peritonitis virus (FIPV) type I strain KU-2, UCD1 and Black, and feline enteric coronavirus (FECV) type II strain 79–1683. Only M and N genes were analyzed in strain KU-2 and strain 79–1683, which still had unknown nucleotide sequences. Deduced amino acid sequences of S, M and N proteins were compared in a total of 7 strains of coronaviruses, which included FIPV type II strain 79–1146, canine coronavirus (CCV) strain Insavc-1 and transmissible gastroenteritis virus of swine (TGEV) strain Purdue. Comparison of deduced amino acid sequences of M and N proteins revealed that both M and N proteins had an identity of at least 90% between FIPV type I and type II. The phylogenetic tree of the M and N protein-deduced amino acid sequences showed that FIPV type I and type II form a group with FECV type II, and that these viruses were evolutionarily distant from CCV and TGEV. On the other hand, when the S protein-deduced amino acid sequences was compared, identity of only about 45% was found between FIPV type I and type II. The phylogenetic tree of the S protein-deduced amino acid sequences indicated that three strains of FIPV type I form a group, and that it is a very long distance from the FIPV type II, FECV type II, CCV and TGEV groups.  相似文献   

16.
Many species of animals deliver vocalizations in sequences presumed to be governed by internal rules, though the nature and complexity of these syntactical rules have been investigated in relatively few species. Here I present an investigation into the song syntax of fourteen male Cassin’s Vireos (Vireo cassinii), a species whose song sequences are highly temporally structured. I compare their song sequences to three candidate models of varying levels of complexity–zero-order, first-order and second-order Markov models–and employ novel methods to interpolate between these three models. A variety of analyses, including sequence simulations, Fisher’s exact tests, and model likelihood analyses, showed that the songs of this species are too complex to be described by a zero-order or first-order Markov model. The model that best fit the data was intermediate in complexity between a first- and second-order model, though I also present evidence that some transition probabilities are conditioned on up to three preceding phrases. In addition, sequences were shown to be predictable with more than 54% accuracy overall, and predictability was positively correlated with the rate of song delivery. An assessment of the time homogeneity of syntax showed that transition probabilities between phrase types are largely stable over time, but that there was some evidence for modest changes in syntax within and between breeding seasons, a finding that I interpret to represent changes in breeding stage and social context rather than irreversible, secular shifts in syntax over time. These findings constitute a valuable addition to our understanding of bird song syntax in free-living birds, and will contribute to future attempts to understand the evolutionary importance of bird song syntax in avian communication.  相似文献   

17.
To test our hypothesis that microbial autotrophic CO2 fixation plays an important role in subsurface systems of two large groundwater remediation projects, several anaerobic/microaerobic aquifer and groundwater samples were taken and used to investigate the distribution and phylogenetic diversity of ribulose-1,5-bisphosphate carboxylase/oxygenase (RubisCO) large-subunit genes. Two primer sets were designed for amplifying partial-subunit genes of RubisCO forms I and II from the DNA, directly extracted from the samples. PCR products were used to construct five clone libraries with putative RubisCO form I sequences, and two libraries of DNA amplified by form II primers. Selected clones were screened for variation by restriction fragment length polymorphism analysis, and a total of 28 clone inserts were sequenced and further analyzed. The phylogenies constructed from amino acid sequences derived from the partial RubisCO large-subunit sequences showed a distinct pattern. Diverse sequences affiliated to the cluster of green-like type IA RubisCO sequences were found, representing various obligate and facultative chemolithoautotrophic Proteobacteria, whereas type II RubisCO sequences detected were most closely related to those of thiobacilli species. An isolate obtained from aquifer enrichment culture, which has been provisionally named Halothiobacillus sp. RA13 on the basis of its 16S rDNA sequence, was found to contain both types of RubisCO genes, i.e., forms I and II. Physiological and ecological considerations are discussed in the context of additional microbial data and physicochemical properties.  相似文献   

18.
Although turtles (order Testudines) constitute one of the major reptile groups, their phylogenetic relationships remain largely unresolved. Hence, we attempted to elucidate their phylogeny using the SINE (short interspersed repetitive element) method, in which the sharing of a SINE at orthologous loci is indicative of synapomorphy. First, a detailed characterization of the tortoise polIII/SINE was conducted using 10 species from eight families of hidden-necked turtles (suborder Cryptodira). Our analysis of 382 SINE sequences newly isolated in the present study revealed two subgroups, namely Cry I and Cry II, which were distinguishable according to diagnostic nucleotides in the 3' region. Furthermore, four (IA-ID) and five (IIA-IIE) different SINE types were identified within Cry I and Cry II subgroups, respectively, based on features of insertions/deletions located in the middle of the SINE sequences. The relative frequency of occurrence of the subgroups and the types of SINEs in this family were highly variable among different lineages of turtles, suggesting active differential retroposition in each lineage. Further application of the SINE method using the most retrotranspositionally active types, namely IB and IC, challenged the established phylogenetic relationships of Bataguridae and its related families. The data for 11 orthologous loci demonstrated a close relationship between Bataguridae and Testudinidae, as well as the presence of the three clades within Bataguridae. Although the SINE method has been used to infer the phylogenies of a number of vertebrate groups, it has never been applied to reptiles. The present study represents the first application of this method to a phylogenetic analysis of this class of vertebrates, and it provides detailed information on the SINE subgroups and types. This information may be applied to the phylogenetic resolution of relevant turtle lineages.  相似文献   

19.
吕占军  王秀芳  翟羽  宋淑霞 《遗传》2003,25(1):30-36
同样的基因在不同的分化细胞中表达不同,基因的选择性表达问题涉及分化和衰老的本质。转录基因对DNaseⅠ(DNA酶Ⅰ)消化敏感,本文研究了RNA对小鼠重组染色质白蛋白基因DNaseⅠ消化敏感性的影响。分离BALB/c小鼠脑细胞核,加入终浓度为2mol/L的NaCl破坏核小体结构,加入不同量、不同来源的RNA,装透析袋,逐渐降低离子强度进行染色质重组。重组染色质中加入DNaseⅠ消化DNA,PCR扩增白蛋白基因的外显子1到外显子2约1200bp区段,PAGE电泳后,用银染色观察不同来源RNA促进DNaseⅠ对白蛋白基因的消化作用。不同组织来源(肝、肺、肾、脑)RNA对小鼠重组染色质中白蛋白基因DNaseⅠ消化敏感性均有促进作用,其中肝和肺RNA促进消化作用较强;酵母tRNA无显著促进消化作用;消化促进作用与RNA剂量有关。RNA能增加DNaseⅠ对白蛋白基因的消化敏感性且有组织(细胞)来源特异性。又委托丹麦Chemical R D 实验室合成2条与白蛋白基因互补的各23核苷酸的RNA,用其进行重组试验。结果表明,重组混合物中含有低至0.2μg/mL的RNA,即可以发挥显著的DNase I消化促进作用。  相似文献   

20.
Acetyl-coenzyme A synthases (ACS) are Ni-Fe-S containing enzymes found in archaea and bacteria. They are divisible into 4 classes. Class I ACS's catalyze the synthesis of acetyl-CoA from CO2 + 2e-, CoA, and a methyl group, and contain 5 types of subunits (alpha, beta, gamma, delta, and epsilon). Class II enzymes catalyze essentially the reverse reaction and have similar subunit composition. Class III ACS's catalyze the same reaction as Class I enzymes, but use pyruvate as a source of CO2 and 2e-, and are composed of 2 autonomous proteins, an alpha 2 beta 2 tetramer and a gamma delta heterodimer. Class IV enzymes catabolize CO to CO2 and are alpha-subunit monomers. Phylogenetic analyses were performed on all five subunits. ACS alpha sequences divided into 2 major groups, including Class I/II sequences and Class III/IV-like sequences. Conserved residues that may function as ligands to the B- and C-clusters were identified. Other residues exclusively conserved in Class I/II sequences may be ligands to additional metal centers in Class I and II enzymes. ACS beta sequences also separated into two groups, but they were less divergent than the alpha's, and the separation was not as distinct. Class III-like beta sequences contained approximately 300 residues at their N-termini absent in Class I/II sequences. Conserved residues identified in beta sequences may function as ligands to active site residues used for acetyl-CoA synthesis. ACS gamma-sequences separated into 3 groups (Classes I, II, and III), while delta-sequences separated into 2 groups (Class I/II and III). These groups are less divergent than those of alpha sequences. ACS epsilon-sequence topology showed greater divergence and less consistency vis-à-vis the other subunits, possibly reflecting reduced evolutionary constraints due to the absence of metal centers. The alpha subunit phylogeny may best reflect the functional diversity of ACS enzymes. Scenarios of how ACS and ACS-containing organisms may have evolved are discussed.  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