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1.
Abstract Over 35 days in January–February 2003, wildfires burnt across much of the subalpine/alpine landscape of south‐eastern Australia, including about 70% of the land above 1500 m in the Snowy Mountains. At the time of the fire, studies of two subalpine faunal assemblages were being undertaken. The opportunity to resurvey the assemblages was taken in order to examine the immediate impact of fire in an environment where it is uncommon but predicted to occur increasingly with global warming. A study area in the Whites River Valley, where the number of bird species was counted monthly from 1996 to 2003, and weekly in late winter–spring from 2000 to 2003, was burnt in one fire. As well as the expected decrease in the number of individual birds, the fire resulted in an immediate decrease in the number of bird species, unlike in previously studied montane forest, with only the regularly wintering species plus the olive whistler and the ground‐feeding flame robin remaining. During the post‐winter avian immigration, few regular spring migrants appeared on burnt sites despite their nearby presence on the unburnt side of the valley. Five of six small mammal trapping grids were burnt. As with fires at lower altitudes, there was an immediate reduction in mammal numbers on burnt grids following the fire, but in addition, one species, Mastacomys fuscus, declined further in the ensuing 2 months both on burnt and unburnt sites. Numbers of Antechinus swainsonii and Rattus fuscipes stabilized until autumn/winter when there was a further decline due to the unavailability of subnivean space to allow winter foraging, allied with a concentration of fox predation on areas still carrying populations of small mammals.  相似文献   

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四川卧龙自然保护区天牛区系及其起源与演化的研究   总被引:2,自引:0,他引:2  
卧龙自然保护区位于东经102°52′—103°24′,北纬30°45′—31°25′。据1980—1983年的调查材料,该自然保护区的天牛共有45属、73种,其中,东洋种47种,占64.4%;古北种10种,占13.7%;广布种5种,占6.8%;特有种11种,占15.1%。从区系组成上看,这个地区似位于东洋区与古北区的过渡带上,并且有靠近东洋区的趋势。高道蓉等(1981)在对峨嵋山(东经103°20′,北纬29°31′)白蚁区系的研究中也认为,峨嵋山位于这条过渡带上。然而,这两个地区的地带性植被、气侯和昆虫组成都与古北区迥然不同,而且,这两个地区的古北种都分布在高海投带上。因此,卧龙自然保护区应属东洋区;昆虫的地理区划主要应以地带性植被、气侯和昆虫组成为依据。 卧龙天牛的垂直分布可分为四个带:(1)亚热带常绿阔叶林带(海拔1120—1600米);(2)常绿、落叶阔叶混交林带(海拔1600—2000米);(3)针、阔叶混交林带(海拔2000—2600米);(4)亚高山针叶林带(海拔2600—3600米)。第1带(基带)东洋种占88.9%,没有古北种;第2带东洋种占50%,古北种占14.3%;第3带东洋种占44.4%,古北种占33.3%;第4带全部为古北种。与中国东部的植被相似,天牛分布每向上移一个垂直带,其成员在水平上也向北移一个带。研究结果还表明,在水平方向分布广的种类在垂直方向也表现  相似文献   

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Volker Nicolai 《Oecologia》1991,88(1):132-137
Summary The arthropod communities living on the bark of the oak species Quercus macrocarpa and Q. ellipsoidalis were investigated in a North American oak savanna. Differences were found in the community structure of the arthropods living on the bark of these two tree species, although they have the same fissured bark type. In the North American oak savanna ecosystem the most important disturbance factor is fire, which maintains species richness. Highest numbers of species and specimens were found at moderately disturbed sites. Three main ecological groups of arthropods living on the bark of trees can be distinguished in relation to the degree of disturbance: (1) Inhabitants of bark of trees restricted to undisturbed sites: they do not occur in fire-disturbed areas; (2) Inhabitants of bark of trees adapted to a moderate degree of disturbance: many species occur in high numbers only in moderately disturbed areas; and (3) Specialist inhabitants of bark of trees in heavily disturbed areas. The number of specimens of these species increases per trunk with the frequency of disturbance.  相似文献   

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In social species, breeding system and gregarious behavior are key factors influencing the evolution of large‐scale population genetic structure. The killer whale is a highly social apex predator showing genetic differentiation in sympatry between populations of foraging specialists (ecotypes), and low levels of genetic diversity overall. Our comparative assessments of kinship, parentage and dispersal reveal high levels of kinship within local populations and ongoing male‐mediated gene flow among them, including among ecotypes that are maximally divergent within the mtDNA phylogeny. Dispersal from natal populations was rare, implying that gene flow occurs without dispersal, as a result of reproduction during temporary interactions. Discordance between nuclear and mitochondrial phylogenies was consistent with earlier studies suggesting a stochastic basis for the magnitude of mtDNA differentiation between matrilines. Taken together our results show how the killer whale breeding system, coupled with social, dispersal and foraging behaviour, contributes to the evolution of population genetic structure.  相似文献   

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Internal transcribed spacer (ITS nuclear rDNA) data have been obtained from 190 terrestrial orchid species, encompassing all genera and the great majority of the widely recognized species of Orchidinae, a heterogeneous selection of species of Habenariinae, and single species of Satyriinae and Disinae (the latter serving as outgroup). The resulting parsimony‐based phylogeny reveals 12 well‐resolved clades within the Orchidinae, based on Anacamptis s.l., Serapias, Ophrys, SteveniellaHimantoglossum s.l. (including ‘Comperia’ and ‘Barlia’, most species being 2n = 36), Neotinea s.l., TraunsteineraChamorchis, Orchis s.s., PseudorchisAmerorchisGalearisNeolindleyaPlatanthera s.l. (most 2n = 42), Dactylorhiza s.l., Gymnadenia s.l. (most 2n = 40, 80), Ponerorchis s.l.Hemipilia s.l.AmitostigmaNeottianthe, and Brachycorythis (most 2n = 42). Relationships are less clearly resolved among these 12 clades, as are those within Habenariinae; the subtribe appears either weakly supported as monophyletic or as paraphyletic under maximum parsimony, and the species‐rich genus Habenaria is clearly highly polyphyletic. The triphyly of Orchis as previously delimited is confirmed, and the improved sampling allows further generic transfers to Anacamptis s.l. and Neotinea s.l. In addition, justifications are given for: (1) establishing Steveniella as the basally divergent member of an appreciably expanded Himantoglossum that incorporates the former genera ‘Barlia’ and ‘Comperia’, (2) reuniting ‘Piperia’ with a broadly defined Platanthera as section Piperia, necessitating ten new combinations, (3) broadening Ponerorchis to include Chusua, and Hemipilia to include single ‘orphan’ species of Ponerorchis and Habenaria, and (4) recognizing ‘Gymnadeniacamtschatica as the monotypic Neolindleya camtschatica within the PseudorchisPlatanthera clade. Few further generic transfers are likely in Orchidinae s.s., but they are anticipated among habenariid genera, on acquisition of additional morphological and molecular evidence; one probable outcome is expansion of Herminium. Species‐level relationships are also satisfactorily resolved within most of the major clades of Orchidinae, with the notable exceptions of Serapias, the derived sections of Ophrys, Himantoglossum s.s., some sections within Dactylorhiza, the former genus ‘Nigritella’ (now tentatively placed within Gymnadenia s.l.), Hemipilia s.l., and possibly Ponerorchis s.s. Relationships among the 12 major clades broadly accord with bona fide records of intergeneric hybridization. Current evidence supports the recently recognized 2n = 36 clade; it also indicates a 2n = 40 clade that is further diagnosed by digitate root‐tubers, and is derived relative to the recently recognized clade of exclusively Asian genera (Ponerorchis s.l.Hemipilia s.l.AmitostigmaNeottianthe). This in turn appears derived relative to the Afro‐Asiatic Brachycorythis group; together, these two clades identify the plesiomorphic chromosome number as 2n = 42. If the African genus Stenogolottis is correctly placed as basally divergent within a monophyletic Habenariinae, the tribe Orchideae and subtribes Orchidinae and Habenariinae could all have originated in Africa, though in contrast the Asiatic focus of the basally divergent members of most major clades of Orchidinae suggests an Asiatic radiation of the subtribe. Morphological characters informally ‘mapped’ across the molecular phylogeny and showing appreciable levels of homoplasy include floral and vegetative pigmentation, flower shape, leaf posture, gynostemium features, and various pollinator attractants. Qualitative comparison of, and reciprocal illumination between, degrees of sequence and morphological divergence suggests a nested set of radiations of progressively decreasing phenotypic magnitude. Brief scenarios, both adaptive and non‐adaptive, are outlined for specific evolutionary transitions. Recommendations are made for further species sampling, concentrating on Asian Orchidinae (together with the Afro‐Asiatic Brachycorythis group) and both Asian and Southern Hemisphere Habenariinae, and adding plastid sequence data. Taxonomic changes listed are: Anacamptis robusta (T.Stephenson) R.M.Bateman, comb. nov. , A. fragrans (Pollini) R.M.Bateman, comb. nov. , A. picta (Loiseleur) R.M.Bateman, comb. nov. , Neotinea commutata (Todari) R.M.Bateman, comb. nov. , N. conica (Willdenow) R.M.Bateman, comb. nov. , Platanthera elegans Lindley ssp. maritima (Rydberg) R.M.Bateman, comb. nov. , P. elegans Lindley ssp. decurtata (R.Morgan & Glicenstein) R.M.Bateman, comb. nov. , P. elongata (Rydberg) R.M.Bateman, comb. nov. , P. michaelii (Greene) R.M.Bateman, comb. nov. , P. leptopetala (Rydberg) R.M.Bateman, comb. nov. , P. transversa (Suksdorf) R.M.Bateman, comb. nov. , P. cooperi (S.Watson) R.M.Bateman, comb. nov. , P. colemanii (R.Morgan & Glicenstein) R.M.Bateman, comb. nov. , P. candida (R.Morgan & Ackerman) R.M.Bateman, comb. nov. and P. yadonii (R.Morgan & Ackerman) R.M.Bateman, comb. nov. © 2003 The Linnean Society of London, Botanical Journal of the Linnean Society, 2003, 142 , 1–40.  相似文献   

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N. Malchus 《Palaeontology》2004,47(6):1539-1574
A study of ligaments of larval, postlarval and adult shells of fossil and recent pteriomorphian bivalves leads to the following observations and hypotheses: (1) Ligament growth passively follows the general growth pattern of the mantle margin. No independent genetic information fixes the anterior, ventral, or posterior growth direction of the ligament. Further growth constraints relate to physical availability of space on the ligament area and to heterochronic processes. (2) The disjunct ligament and the repetition of fibrous or lamellar sublayers are phenotypic aspects of the same derived ligament Bauplan 1. All Pteriomorphia possess the ability to produce repetitive ligaments. This ability and space reductions of the ligament area in independent phylogenetic lineages are responsible for the iterative evolution of ligament grades. (3) Spondylidae and Plicatulidae are duplivincular, and the Ostreoidea are plesiomorphically multivincular. (4) Larval anterior-helical growth of the soft tissue produces opisthogyrate shells and possibly caused the evolution of the alivincular-multivincular grade. Duplivincular-alivincular and multivincular-alivincular grades can be distinguished if larval shell characters are known. (5) The taxonomic distribution of ligament grades as amended in this paper is largely consistent with modern phylogeny hypotheses based on genetic or morphologic or combined character sets. However, the resolution of early phylogenetic nodes requires more data on larval shells of Lower Palaeozoic taxa.  相似文献   

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Abstract The present study uses differences among frugivore faunas of the southern hemisphere landmasses to test whether frugivore characteristics have influenced the evolution of fruit traits. Strong floristic similarities exist among southern landmasses; for example, 75% of New Zealand vascular plant genera also have species in Australia. However, plants in Australia and South America have evolved in the presence of a range of mammalian frugivores, whereas those in New Zealand, New Caledonia and the Pacific Islands have not. In addition, the avian frugivores in New Zealand and New Caledonia are generally smaller than those of Australia. If frugivore characteristics have influenced the evolution of fruit traits, predictable differences should exist between southern hemisphere fruits, particularly fruit size and shape. Fruit dimensions were measured for 77 New Zealand species and 31 Australian species in trans‐Tasman genera. New Zealand fruits became significantly more ellipsoid in shape with increasing size. This is consistent with frugivore gape size imposing a selective pressure on fruit ingestability. This result is not a product of phylogenetic correlates, as fruit length and width scaled isometrically for Australian species in genera shared with New Zealand. Within‐genus contrasts between New Zealand and Australian species in 20 trans‐Tasman genera showed that New Zealand species have significantly smaller fruits than their Australian counterparts. Within‐genus contrasts between New Zealand and South American species in nine genera gave the same result; New Zealand species had significantly smaller fruits than their South American counterparts. No difference was found in fruit size or shape between New Zealand and New Caledonia congeneric species from 12 genera. These results are consistent with the broad characteristics of the frugivore assemblage influencing the evolution of fruit size and shape in related species. The smaller‐sized New Zealand frugivore assemblage has apparently influenced the evolution of fruit size of colonizing taxa sometimes within a relatively short evolutionary timeframe.  相似文献   

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Summary In terms of chromosome morphology, karyotype organisation, taxonomy and genetic relationship as judged from chromosome pairing in the Fl hybrid, A. cepa and A.fistulosum are two closely related species. But large variation in nuclear DNA amounts has occurred during the evolution of the two species. A comparison of the molecular composition of DNA in the two species has confirmed that the excess DNA acquired during evolution was predominantly repetitive sequences (sequences which do not encode genetic information). However, its distribution within the chromosome complements was equal in all chromosomes irrespective of the differences in chromosome size. The even distribution of the excess DNA within complements suggests strong constraints underlying evolutionary changes in genome organisation. The nature of the constraints is discussed, and it is shown that such constraints can influence the direction of karyotype evolution during speciation.  相似文献   

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The earliest euprimates to arrive in North America were larger‐bodied notharctids and smaller‐bodied omomyids. Through the Eocene, notharctids generally continued to increase in body size, whereas omomyids generally radiated within small‐ and increasingly mid‐sized niches in the middle Eocene. This study examines the influence of changing body size and diet on the evolution of the lower fourth premolar in Eocene euprimates. The P4 displays considerable morphological variability in these taxa. Despite the fact that most studies of primate dental morphology have focused on the molars, P4 can also provide important paleoecological insights. We analyzed the P4 from 177 euprimate specimens, representing 35 species (11 notharctids and 24 omomyids), in three time bins of approximately equal duration: early Wasatchian, late Wasatchian, and Bridgerian. Two‐dimensional surface landmarks were collected from lingual photographs, capturing important variation in cusp position and tooth shape. Disparity metrics were calculated and compared for the three time bins. In the early Eocene, notharctids have a more molarized P4 than omomyids. During the Bridgerian, expanding body size range of omomyids was accompanied by a significant increase in P4 disparity and convergent evolution of the semimolariform condition in the largest omomyines. P4 morphology relates to diet in early euprimates, although patterns vary between families. Am J Phys Anthropol 153:15–28, 2014. © 2013 Wiley Periodicals, Inc.  相似文献   

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The importance of body mass prediction from several cranial, dental and appendicular variables in living Equini are studied. Relationships between the body mass changes and the ecogeographic picture of Equini evolution are also analysed. The metapodial and phalanx variables, particularly antero-posterior diameters, are better correlated with body mass than cranial variables in living Equini. Large sized species are correlated with cold climates, open habitats and/or soft soils; small ones are correlated with warm climates, more closed habitats and/or hard soils. Pleistocene horses from Europe and Africa follow an evolutionary trend opposite to their North American counterparts, from larger sized species to smaller ones. In South America the pattern of body size is different to those of the other continents. Species of Hippidion reaching large body mass, whereas some species of Equus, E. andium , follow a diminishing trend.  相似文献   

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The role played by stream transfers and reversals in the postglacial dispersal of fish populations in the Yukon and Mackenzie River drainages of Canada was analysed using genetic and meristic data from longnose sucker (Catostomus catostomus Forrester) populations. The hypothesis the suckers dispersed from the Yukon River into the Mackenzie River via the Peel River was evaluated. Meristic data (gill rakers and lateral line scales) were uninformative for this analysis. Genetic affinity between the Yukon River and upper Peel River populations, and between Mackenzie and lower Peel River populations is suggested by transferrin allele frequencies. These affinities support the view that longnose suckers inhabiting the middle and upper regions of the Peel River are derived from Beringian and Mississippian ancestors, while suckers in the lower Peel are descended from Mississippian stock. Evidence for dispersal by way of the Eagle River was not found. Affinities of sucker populations in other river systems in the region are also described.  相似文献   

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Ferinestrix vorax is an extinct mustelid carnivoran of enigmatic relationships, known from a partial mandible and femur collected from the 3.2‐ and 3.6‐Myr‐old deposits of Hagerman Fossil Beds National Monument, Idaho, USA. Here, we report Ferinestrix rapax sp. nov. based on 80 remains of skull and dentition from a 3.1–3.6‐Myr‐old deposit of Udunga, Transbaikal, Russia. We demonstrate that Ferinestrix is a stem genus of the badger subfamily Melinae. This genus is distinctly larger and more carnivorous than any other total‐clade meline. We show that Ferinestrix originated in Asia and immigrated to North America no later than at the early (Zanclean) to late (Piacenzian) Pliocene transition, and that the North American F. vorax and Asian F. rapax underwent parallel evolution toward increased carnivory. © 2013 The Linnean Society of London, Zoological Journal of the Linnean Society, 2013, 167 , 208–226.  相似文献   

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Multituberculate petrosals with well-preserved, three-dimensional internal anatomy from the Late Cretaceous/early Paleocene Bug Creek Anthills, Montana, U.S.A., are described from X-radiographic and SEM images, as well as from conventional visual observations, and are compared with the anatomy of the osseous inner ear in monotremes and in primitive non-therian and therian mammals. Results of this study indicate that: (1) the cochlea of at least some multituberculates retained a lagena, previously known only in monotremes among mammals; (2) an enlarged vestibule evolved in several lineages of multituberculates independently, and hence is not a synapomorphy of the order; (3) the cochlear canal lacks osseous laminae in support of the short, wide basilar membrane, which was probably inefficient in responding to high-frequency airborne vibrations; and (4) consequently, bone-conducted hearing in some multituberculate species may have been important in interpretation of their surroundings. Comparisons with the inner ear of monotremes and primitive therians indicate that curvature of the cochlea and cribriform plates for passage of vestibulocochlear nerve branches through the petrosal are unlikely homologues between monotremes and therians. From non-therian to therian mammals, there is a distinct morphological gap in the inner ear transition, characterized by acquisition of a number of neomorphs in the therian inner ear; an intermediate stage has yet to be discovered.  相似文献   

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Aim We examined the genetic structure of Quercus garryana to infer post‐glacial patterns of seed dispersal and pollen flow to test the hypotheses that (1) peripheral populations are genetically distinct from core populations and from one another; (2) genetic diversity declines towards the poleward edge of the species’ range; and (3) genetic diversity in the chloroplast genome, a direct measure of seed dispersal patterns, declines more sharply with increasing latitude than diversity in the nuclear genome. We address our findings in the context of known historical oak distribution from pollen core data derived from previously published research. Location Oak–savanna ecosystems from southern Oregon, USA (core populations/non‐glaciated range) northward to Vancouver Island, British Columbia, Canada (peripheral populations/glaciated range). Methods We genotyped 378 trees from 22 sites with five chloroplast and seven nuclear microsatellite loci. For both sets of markers, we estimated genetic diversity and differentiation using an analysis of molecular variance and generated Mantel correlograms to detect genetic and geographical distance correlations. For the nuclear markers, we also used a Bayesian approach to infer population substructure. Results There was a large degree of population differentiation revealed by six chloroplast haplotypes, with little (≤ 3) or no haplotype diversity within sites. Peripheral island locations shared the same, maternally inherited chloroplast haplotype, whereas locations in mainland Washington had greater haplotype diversity. In contrast, genetic diversity of the nuclear markers was high at all locations sampled. Populations clustered into two groups and were significantly positively correlated over large spatial scales (≤ 200 km), although allele richness decreased significantly with latitude. Population substructure was observed between core and peripheral populations because rare alleles were absent in peripheral localities and common allele frequencies differed. Main conclusions The observed pattern of chloroplast haplotype loss at the northern periphery suggests restricted seed dispersal events from mainland sites to peripheral islands. This pattern was unexpected, however, as refugial oak populations remained near the current post‐glacial range even during the Last Glacial Maximum. Using nuclear markers, we found high within‐population diversity and population differentiation only over large spatial scales, suggesting that pollen flow is relatively high among populations.  相似文献   

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