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.
Summary The pallid bat (Antrozous p. pallidus) uses passive sound localization to capture terrestrial prey. This study of captive pallid bats examined the roles of echolocation and passive sound localization in prey capture, and focused on their spectral requirements for accurate passive sound localization.Crickets were used as prey throughout these studies. All tests were conducted in dim, red light in an effort to preclude the use of vision. Hunting performance did not differ significantly in red light and total darkness, nor did it differ when visual contrast between the terrestrial prey and the substrate was varied, demonstrating that the bats did not use vision to locate prey.Our bats apparently used echolocation for general orientation, but not to locate prey. They did not increase their pulse emission rate prior to prey capture, suggesting that they were not actively scanning prey. Instead, they required prey-generated sounds for localization. The bats attended to the sound of walking crickets for localization, and also attacked small, inanimate objects dragged across the floor. Stationary and/or anesthetized crickets were ignored, as were crickets walking on substrates that greatly attenuated walking sounds. Cricket communication sounds were not used in prey localization; the bats never captured stationary, calling crickets.The accuracy of their passive sound localization was tested with an open-loop passive sound localization task that required them to land upon an anesthetized cricket tossed on the floor. The impact of a cricket produced a single 10–20 ms duration sound, yet with this information, the bats were able to land within 7.6 cm of the cricket from a maximum distance of 4.9 m. This performance suggests a sound localization accuracy of approximately ±1° in the horizontal and vertical dimensions of auditory space. The lower frequency limit for accurate sound localization was between 3–8 kHz. A physiological survey of frequency representation in the pallid bat inferior colliculus suggests that this lower frequency limit is around 5 kHz.  相似文献   

2.
Despite increasing information about postglacial recolonization of European freshwater systems, very little is known about pre-Pleistocene history. We used data on the recent distribution and phylogenetic relationships of stone loach mitochondrial lineages to reconstruct the initial colonization pattern of the Danube river system, one of the most important refuges for European freshwater ichthyofauna. Fine-scale phylogeography of the Danubian populations revealed five highly divergent lineages of pre-Pleistocene age and suggested the multiple origin of the Danubian stone loach. The mean sequence divergence among lineages extended from 7.0% to 13.4%, which is the highest intraspecific divergence observed so far within this river system. Based on the phylogeographical patterns, we propose the following hypothesis to relate the evolution and dispersal of the studied species with the evolution of the Danube river system and the Carpathian Mountains: (i) during the warmer period in the Miocene, the areas surrounding the uplifting Alps and Carpathians served as mountainous refuges for cold-water adapted fish and promoted the diversification of its populations, and (ii) from these refuges, colonization of the emerging Danube river system may have taken place following the retreat of the Central Paratethys. Co-existence of highly divergent mtDNA lineages in a single river system shows that range shifts in response to climatic changes during the Quaternary did not cause extensive genetic homogenization in the stone loach populations. However, the wide distribution of some mtDNA lineages indicates that the Pleistocene glaciations promoted the dispersal and mixing of populations through the lowlands.  相似文献   

3.
The crystal darter, Crystallaria asprella, exists in geographically isolated populations that may be glacial relicts from its former, wide distribution in the Eastern U.S. An initial phylogeographic survey of C. asprella based upon the mitochondrial cytochrome b (cyt b) gene indicated that there were at least four distinct populations within the species: Ohio River basin, Upper Mississippi River, Gulf coast, and lower Mississippi River. In particular, the most divergent population was the most recently discovered, from the Elk River, WV, in the Ohio River basin, and it was postulated that this population represents an undescribed, potentially threatened species. However, differentiation observed at a single gene region is generally not considered sufficient evidence to establish taxonomic status. In the present study, nucleotide variation at the mitochondrial control region and a nuclear S7 ribosomal gene intron were compared to provide independent verification of phylogeographic results between individuals collected from the same five disjunct populations previously surveyed. Variation between populations at the control region was substantial (except between Gulf drainages) and was concordant with patterns of sequence divergence from cyt b. Only the Elk River population was resolved as monophyletic based upon nuclear S7, but significant differences based upon ΦST statistics were observed between most populations. Morphometric data were consistent with molecular data regarding the distinctiveness of the Elk River population. It is proposed that populations of C. asprella consist of at least four distinct population segments, and that the Elk River group likely constitutes a distinct species.  相似文献   

4.
Devitt TJ 《Molecular ecology》2006,15(14):4387-4407
The Western Lyresnake (Trimorphodon biscutatus) is a widespread, polytypic taxon inhabiting arid regions from the warm deserts of the southwestern United States southward along the Pacific versant of Mexico to the tropical deciduous forests of Mesoamerica. This broadly distributed species provides a unique opportunity to evaluate a priori biogeographical hypotheses spanning two major distinct biogeographical realms (the Nearctic and Neotropical) that are usually treated separately in phylogeographical analyses. I investigated the phylogeography of T. biscutatus using maximum likelihood and Bayesian phylogenetic analysis of mitochondrial DNA (mtDNA) from across this species' range. Phylogenetic analyses recovered five well-supported clades whose boundaries are concordant with existing geographical barriers, a pattern consistent with a model of vicariant allopatric divergence. Assuming a vicariance model, divergence times between mitochondrial lineages were estimated using Bayesian relaxed molecular clock methods calibrated using geological information from putative vicariant events. Divergence time point estimates were bounded by broad confidence intervals, and thus these highly conservative estimates should be considered tentative hypotheses at best. Comparison of mtDNA lineages and taxa traditionally recognized as subspecies based on morphology suggest this taxon is comprised of multiple independent lineages at various stages of divergence, ranging from putative secondary contact and hybridization to sympatry of 'subspecies'.  相似文献   

5.
We analysed genetic variation in mitochondrial DNA (mtDNA) control region in the Diceros bicornis minor and D. b. michaelianimals at the Western Plains Zoo, which form part of an international ex-situ breeding program. Six of the nine D. b. minor animals were wild-caught from Zimbabwe during the 1990s, and our study revealed five distinct mtDNA haplotypes, and a haplotype diversity of 0.86 in the colony. Phylogenetic relationships between mtDNA haplotypes analyzed using the neighbor joining method reveal that for the small sample available, D. b. minor and D. b. michaeli are reciprocally monophyletic and represent separate ancestral lineages. Nucleotide divergence between the black and and white rhinoceros(Ceratotherium simum) was 14.0%, and nucleotide divergencebetween the D. b. minor and the D. b. michaeli subspecies was 2.6%. This suggests a divergence time for the two blackrhinoceros subspecies of between 0.93 MY and 1.3 MY.  相似文献   

6.
Several species of freshwater unionid mussels in the genus Lampsilis exhibit a remarkable reproductive strategy. Female mussels of these species enclose their larvae in a minnow-like lure, called a 'superconglutinate', to attract piscivorous fishes. When a fish attempts to ingest the superconglutinate the lure ruptures and the larvae are released to parasitize the fish. Of the four species of mussel which exhibit this strategy and are endemic to the Gulf Coast drainages of the southeastern United States, three are protected under the Endangered Species Act, and one is recognized as imperiled. Phylogenetic analysis of nucleotide sequences of the mitochondrial 16S ribosomal RNA and the first subunit of the cytochrome oxidase c genes was conducted on 18 individual specimens representing these four species and six outgroup taxa. Phylogenetic analyses of these data support the monophyly of the superconglutinate-producing mussels, and indicates a strong geographical component to the data. The zoogeographic patterns of the four taxa included in the study are congruent with those seen in freshwater vertebrates, and are consistent with a vicariant pattern resulting from fluctuations in sea level during the Pleistocene. Despite the strong geographical structuring of the data, only one species, Lampsilis subangulata, was recovered as monophyletic. The authors attribute the lack of support for the monophyly of the remaining species to insufficient sequence variation and the recent origin of the ancestor of these taxa. Based on these data, any future captive breeding projects aimed at augmenting or re-establishing populations should do so only from the appropriate source populations so as to maintain the genetic integrity of these nascent species.  相似文献   

7.
Aim Kangaroo mice, genus Microdipodops Merriam, are endemic to the Great Basin and include two species: M. pallidus Merriam and M. megacephalus Merriam. The pallid kangaroo mouse, M. pallidus, is a sand‐obligate desert rodent. Our principal intent is to identify its current geographical distribution and to formulate a phylogeographical hypothesis for this taxon. In addition, we test for orientation patterns in haplotype sharing for evidence of past episodes of movement and gene flow. Location The Great Basin Desert region of western North America, especially the sandy habitats of the Lahontan Trough and those in south‐central Nevada. Methods Mitochondrial DNA sequence data from portions of three genes (16S ribosomal RNA, cytochrome b, and transfer RNA for glutamic acid) were obtained from 98 individuals of M. pallidus representing 27 general localities sampled throughout its geographical range. Molecular sequence data were analysed using neighbour‐joining, maximum‐parsimony, maximum‐likelihood and Bayesian methods of phylogenetic inference. Directional analysis of phylogeographical patterns, a novel method, was used to examine angular measurements of haplotype sharing between pairs of localities to detect and quantify historical events pertaining to movement patterns and gene flow. Results Collecting activities showed that M. pallidus is a rather rare rodent (mean trapping success was 2.88%), and its distribution has changed little from that determined three‐quarters of a century ago. Two principal phylogroups, distributed as eastern and western moieties, are evident from the phylogenetic analyses (mean sequence divergence for cytochrome b is c. 8%). The western clade shows little phylogenetic structure and seems to represent a large polytomy. In the eastern clade, however, three subgroups are recognized. Nine of the 42 unique composite haplotypes are present at two or more localities and are used for the orientation analyses. Axial data from haplotype sharing between pairwise localities show significant, non‐random angular patterns: a north‐west to south‐east orientation in the western clade, and a north‐east to south‐west directional pattern in the eastern clade. Main conclusions The geographical range of M. pallidus seems to be remarkably stable in historical times and does not show a northward (or elevationally upward) movement trend, as has been reported for some other kinds of organism in response to global climate change. The eastern and western clades are likely to represent morphologically cryptic species. Estimated times of divergence of the principal clades of M. pallidus (4.38 Ma) and between M. pallidus and M. megacephalus (8.1 Ma; data from a related study) indicate that kangaroo mice diverged much earlier than thought previously. The phylogeographical patterns described here may serve as a model for other sand‐obligate members of the Great Basin Desert biota.  相似文献   

8.
Anolis carolinensis is an emerging model species and the sole member of its genus native to the United States. Considerable morphological and physiological variation has been described in the species, and the recent sequencing of its genome makes it an attractive system for studies of genome variation. To inform future studies of molecular and phenotypic variation within A. carolinensis, a rigorous account of intraspecific population structure and relatedness is needed. Here, we present the most extensive phylogeographic study of this species to date. Phylogenetic analyses of mitochondrial DNA sequence data support the previous hypothesis of a western Cuban origin of the species. We found five well‐supported, geographically distinct mitochondrial haplotype clades throughout the southeastern United States. Most Florida populations fall into one of three divergent clades, whereas the vast majority of populations outside Florida belong to a single, shallowly diverged clade. Genetic boundaries do not correspond to major rivers, but may reflect effects of Pleistocene glaciation events and the Appalachian Mountains on migration and expansion of the species. Phylogeographic signal should be examined using nuclear loci to complement these findings.  相似文献   

9.
A phylogeographic analysis of mitochondrial DNA variation was performed in order to test the hypothesis of a postglacial recolonization of mid- and north-European rivers from a Danubian refuge. Over 345 chub specimens from European rivers covering most of the species' native range were investigated using 600 bp of the cytochrome b gene. Chub in European rivers belong to four highly divergent mitochondrial groups (lineages) differing by mean divergence estimates from 5.2% to 7.89%. These four lineages have a largely allopatric distribution, implying four geographical sets: two Mediterranean, and two north-European sets. This pattern provided strong evidence for: (i) the eradication of this species from most of Europe during maximum ice extent; (ii) its survival in four refugia (Adriatic side of the Balkans, eastern Greece (Aegean Rivers), southern tributaries of the Danube, and periphery of Black and Caspian Seas); (iii) a differential postglacial recolonization of mid- and northern Europe from the last two refugia only; (iv) the occurrence of this recolonization in two steps for the Danubian (western) lineage that entered western Europe (Rhine-Rhone-Loire drainages) during the Riss-Würm interglacial period and survived the last glaciation there before colonizing Garonne, UK and German drainages up to the Elbe during the Holocene; and (v) the occurrence of this recolonization in a single step for the Ponto-Caspian (eastern) lineage that entered the Baltic area as far as the Oder in the Holocene. Both lineages came into contact in the River Elbe without evident mixing.  相似文献   

10.
Climatic oscillations during the Pleistocene epoch had a dramatic impact on the distribution of biota in the northern hemisphere. In order to trace glacial refugia and postglacial colonization routes on a global scale, we studied mitochondrial DNA sequence variation in a freshwater fish (burbot, Lota lota; Teleostei, Gadidae) with a circumpolar distribution. The subdivision of burbot in the subspecies Lota lota lota (Eurasia and Alaska) and Lota lota maculosa (North America, south of the Great Slave Lake) was reflected in two distinct mitochondrial lineages (average genetic distance is 2.08%). The lota form was characterized by 30 closely related haplotypes and a large part of its range (from Central Europe to Beringia) was characterized by two widespread ancestral haplotypes, implying that transcontinental exchange/migration was possible for cold-adapted freshwater taxa in recent evolutionary time. However, the derived mitochondrial variants observed in peripheral populations point to a recent separation from the core group and postglacial recolonization from distinct refugia. Beringia served as refuge from where L. l. lota dispersed southward into North America after the last glacial maximum. Genetic variation in the maculosa form consisted of three mitochondrial clades, which were linked to at least three southern refugia in North America. Two mitochondrial clades east of the Continental Divide (Mississippian and Missourian clades) had a distinct geographical distribution in the southern refuge zones but intergraded in the previously glaciated area. The third clade (Pacific) was exclusively found west of the Continental Divide.  相似文献   

11.
We investigated the phylogeography of wood turtles, Glyptemys insculpta, in North America using 750 bp of the mitochondrial control region from 117 individuals sampled at 29 localities across the species' range. A total of 21 haplotypes were identified and little genetic variation was found. The highest pairwise difference was 2%. From nested clade analysis (NCA), one main postglacial dispersal route was inferred along the east coast, with subsequent westward dispersal. NCA further revealed some patterns of restricted gene flow/dispersal. We propose that wood turtles experienced a combined effect of bottleneck during the Pleistocene as well as of selective sweep, which produced the low level of variation observed. Following the Pleistocene, wood turtles would have undergone a rapid northward expansion from a common southern refugium as glaciers retreated. These findings shed light on where to direct conservation priorities, on conservation strategies needed, and on the potential effects of interpopulation transfers for this vulnerable species.  相似文献   

12.
Phylogeographic studies are often focused on temperate European species with relict footholds in the Mediterranean region. Past climatic oscillations usually induced range contractions and expansions from refugial areas located in southern Europe, and spatial distribution of genetic diversity show that northward expansions were usually pioneer-like. Actually, few studies have focused on circum-Mediterranean species, which probably were not influenced in the same way by climatic oscillations. We present the phylogeography of the bark beetle Tomicus destruens, which is restricted to the whole Mediterranean basin and the Atlantic coasts of North Africa and Portugal. We systematically sequenced 617 bp of the mitochondrial genes COI and COII for 42 populations (N = 219). Analysis revealed 53 haplotypes geographically structured in two clades, namely eastern and western clades, that diverged during the Pleistocene. A contact zone was identified along the Adriatic coast of Italy. Interestingly, we found contrasting levels of genetic structure within each clade. The eastern group was characterized by a significant phylogeographic pattern and low levels of gene flow, whereas the western group barely showed a spatial structure in haplotype distribution. Moreover, the main pine hosts were different between groups, with the Aleppo-brutia complex in the east and the maritime pine in the west. Potential roles of host species, climatic parameters and geographical barriers are discussed and the phylogeographic patterns are compared to classical models of postglacial recolonization in Europe.  相似文献   

13.
The phylogeography of Atlantic brown trout ( Salmo trutta ) was analysed using mitochondrial DNA control region complete sequences of 774 individuals from 57 locations. Additionally, the available haplotype information from 100 published populations was incorporated in the analysis. Combined information from nested clade analysis, haplotype trees, mismatch distributions, and coalescent simulations was used to characterize population groups in the Atlantic basin. A major clade involved haplotypes assigned to the Atlantic (AT) lineage, but another major clade should be considered as a distinct endemic lineage restricted to the Iberian Peninsula. The phylogeography of the Atlantic populations showed the mixed distribution of several Atlantic clades in glaciated areas of Northern Europe, whereas diverged haplotypes dominated the coastal Iberian rivers. Populations inhabiting the Atlantic rivers of southern France apparently contributed to postglacial colonization of northern basins, but also comprised the source of southern expansions during the Pleistocene.  © 2009 The Linnean Society of London, Biological Journal of the Linnean Society , 2009, 97 , 904–917.  相似文献   

14.
The Pampas deer ( Ozotoceros bezoarticus L. 1758) is the most endangered neotropical cervid, and in the past occupied a wide range of open habitats including grassland, pampas, savanna, and cerrado (Brazil) from 5° to 41° S. To better understand the effect of habitat fragmentation on gene flow and genetic variation, and to uncover genetic units for conservation, we examined DNA sequences from the mitochondrial control region of 54 individuals from six localities distributed throughout the present geographical range of the Pampas deer. Our results suggest that the control region of the Pampas deer is one of the most polymorphic of any mammal. This remarkably high variability probably reflects large historic population sizes of millions of individuals in contrast to numbers of fewer than 80 000 today. Gene flow between populations is generally close to one migrant per generation and, with the exception of two populations from Argentina, all populations are significantly differentiated. The degree of gene flow was correlated with geographical distance between populations, a result consistent with limited dispersal being the primary determinant of genetic differentiation between populations. The molecular genetic results provide a mandate for habitat restoration and reintroduction of Pampas deer so that levels of genetic variation can be preserved and historic patterns of abundance can be reconstructed. However, the source of individuals for reintroduction generally should be from populations geographically closest to those now in danger of extinction.  相似文献   

15.
We gathered mitochondrial DNA sequences (557 bp from the control region in 935 specimens and 668 bp of the cytochrome b gene in 139 specimens) of Pacific herring collected from 20 nearshore localities spanning the species' extensive range along the North Pacific coastlines of Asia and North America. Haplotype diversity and nucleotide diversity were high, and three major phylogeographic lineages (sequence divergences ca. 1.5%) were detected. Using a variety of phylogenetic methods, coalescent reasoning, and molecular dating interpreted in conjunction with paleoclimatic and physiographic evidence, we infer that the genetic make-up of extant populations of C. pallasii was shaped by Pleistocene environmental impacts on the historical demography of this species. A deep genealogical split that cleanly distinguishes populations in the western vs. eastern North Pacific probably originated as a vicariant separation associated with a glacial cycle that drove the species southward and isolated two ancestral populations in Asia and North America. Another deep genealogical split may have involved either a vicariant isolation of a third herring lineage (perhaps originally in the Gulf of California) or it may have resulted simply from the long coalescent times that are possible in large populations. Coalescent analyses showed that all the three evolutionary lineages of C. pallasii experienced major expansions in their most recent histories after having remained more stable in the preceding periods. Independent of the molecular calibration chosen, populations of C. pallasii appear to have remained stable or grown throughout the periods that covered at least two major glaciations, and probably more.  相似文献   

16.
17.
The koala, Phascolarctos cinereus, is a geographically widespread species endemic to Australia, with three currently recognized subspecies: P.c. adustus, P.c. cinereus, and P.c. victor. Intraspecific variation in the mitochondrial DNA (mtDNA) control region was examined in over 200 animals from 16 representative populations throughout the species’ range. Eighteen different haplotypes were defined in the ≈ 860 bp mtDNA control region, as determined by heteroduplex analysis/temperature gradient gel electrophoresis (HDA/TGGE). Any single population typically possessed only one or two haplotypes yielding an average within-population haplotypic diversity of 0.180 ± 0.003, and nucleotide diversity of 0.16%. Overall, mtDNA control region sequence diversity between populations averaged 0.67%, and ranged from 0% to 1.56%. Nucleotide divergence between populations averaged 0.51%, and ranged from 0% to 1.53%. Neighbour-joining methods revealed limited phylogenetic distinction between geographically distant populations of koalas, and tentative support for a single evolutionarily significant unit (ESU). This is consistent with previous suggestions that the morphological differences formalized by subspecific taxonomy may be interpreted as clinal variation. Significant differentiation in mtDNA-haplotype frequencies between localities suggested that little gene flow currently exists among populations. When combined with microsatellite analysis, which has revealed substantial differentiation among koala populations, we conclude that the appropriate short-term management unit (MU) for koalas is the local population.  相似文献   

18.
Phylogeographical analyses conducted in the Pacific Northwestern United States have often revealed concordant patterns of genetic diversity among taxa. These studies demonstrate distinct North/South genetic discontinuities that have been attributed to Pleistocene glaciation. We examined phylogeographical patterns of red tree voles (Phenacomys longicaudus) in western Oregon by analysing mitochondrial control region sequences for 169 individuals from 18 areas across the species' range. Cytochrome b sequences were also analysed from a subset of our samples to confirm the presence of major haplotype groups. Phylogenetic network analyses suggested the presence of two haplotype groups corresponding to northern and southern regions of P. longicaudus' range. Spatial genetic analyses (samova and Genetic Landscape Shapes) of control region sequences demonstrated a primary genetic discontinuity separating northern and southern sampling areas, while a secondary discontinuity separated northern sampling areas into eastern and western groups divided by the Willamette Valley. The North/South discontinuity likely corresponds to a region of secondary contact between lineages rather than an overt barrier. Although the Cordilleran ice sheet (maximum approximately 12,000 years ago) did not move southward to directly affect the region occupied by P. longicaudus, climate change during glaciation fragmented the forest landscape that it inhabits. Signatures of historical fragmentation were reflected by positive associations between latitude and variables such as Tajima's D and patterns associated with location-specific alleles. Genetic distances between southern sampling areas were smaller, suggesting that forest fragmentation was reduced in southern vs. northern regions.  相似文献   

19.
Lenk P  Fritz U  Joger U  Wink M 《Molecular ecology》1999,8(11):1911-1922
The phylogeny and phylogeography of Emys orbicularis was inferred from mitochondrial nucleotide sequences of the cytochrome b gene analysed by DNA sequencing and RNA heteroduplex analysis. Within the family Emydidae the monotypic genus Emys is affiliated with the nearctic taxa Emydoidea blandingii and Clemmys marmorata. The analysis of 423 individuals of E. orbicularis, originating throughout its distribution range, revealed a remarkable intraspecific differentiation in 20 different haplotypes with distinct geographical ranges. Maximum parsimony analysis produced a star-like phylogeny with seven main lineages which may reflect separations in the late Pliocene. The haplotype distribution examined by partial Mantel tests and analysis of molecular variance revealed a substantial effect of glacial periods. This historical perspective suggests the existence of multiple glacial refugia and considerable Holocene range expansion which was modulated by climatic traits. Further support is gained for the occurrence of long-term parapatry in glacial refugia.  相似文献   

20.
In this study, we present a phylogeographic analysis of a group of lizards distributed in north‐western Patagonia, the Liolaemus elongatus complex. We sequenced 581 individuals for one mitochondrial gene (cytochrome‐b), and for a subset, we sequenced another mitochondrial gene (12S rRNA) and two nuclear genes: kinesin family member 24 (KIF24) and the anonymous nuclear locus LDAB1D. We estimated gene trees, mitochondrial and nuclear haploytpe networks, standard molecular diversity indices, genetic distances between lineages and Bayesian skyline plots. Our results provide evidence for recognition of seven species previously described within the L. elongatus complex: Liolaemus antumalguen, Liolaemus chillanensis, Liolaemus carlosgarini, Liolaemus burmeisteri, Liolaemus smaug, Liolaemus elongatus and Liolaemus crandalli, but we did not find sufficient evidence to support Liolaemus choique, Liolaemus shitan or Liolaemus sp. 6 as distinct species. We identified four candidate species (Liolaemus sp. 1, Liolaemus sp. 2, Liolaemus sp. 3 and Liolaemus sp. 7), and we discuss evolutionary processes that may have contributed to the origin of these lineages and their taxonomic and conservation implications.  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