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L. G. Ashman J. G. Bragg P. Doughty M. N. Hutchinson S. Bank N. J. Matzke P. Oliver C. Moritz 《Evolution; international journal of organic evolution》2018,72(8):1553-1569
Ecological opportunity is a powerful driver of evolutionary diversification, and predicts rapid lineage and phenotypic diversification following colonization of competitor‐free habitats. Alternatively, topographic or environmental heterogeneity could be key to generating and sustaining diversity. We explore these hypotheses in a widespread lineage of Australian lizards: the Gehyra variegata group. This clade occurs across two biomes: the Australian monsoonal tropics (AMT), where it overlaps a separate, larger bodied clade of Gehyra and is largely restricted to rocks; and in the larger Australian arid zone (AAZ) where it has no congeners and occupies trees and rocks. New phylogenomic data and coalescent analyses of AAZ taxa resolve lineages and their relationships and reveal high diversity in the western AAZ (Pilbara region). The AMT and AAZ radiations represent separate radiations with no difference in speciation rates. Most taxa occur on rocks, with small geographic ranges relative to widespread generalist taxa across the vast central AAZ. Rock‐dwelling and generalist taxa differ morphologically, but only the lineage‐poor central AAZ taxa have accelerated evolution. This accords with increasing evidence that lineage and morphological diversity are poorly correlated, and suggests environmental heterogeneity and refugial dynamics have been more important than ecological release in elevating lineage diversity. 相似文献
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正确识别旅游活动作用下植被景观的类型及其分布格局,是景区管理者实施生态管理的现实课题。以芦芽山自然保护区为例,利用双向指示种分析（Two．Way Indicator Species Analysis,TWINSPAN）和除趋势对应分析（Detrended Correspondence Analysis,DCA）对此问题进行了研究。结果表明：（1）TWINSPAN将所有样地划分为5个不同等级的植被景观类型区,其结果比较客观地反映出旅游开发与植被景观间的生态关系,指示因子也充分地反映了植被区的人为环境和景观特征。与利用旅游影响系数进行的分类相比,TWINSPAN的结果更为科学合理,明显优于单纯依据一个因子划分的结果。（2）DCA第1轴从左到右旅游影响系数和敏感水平越来越小,信息指数越来越大。DCA第3轴从下而上旅游剔除程度逐渐减小。DCA结果能够识别植被景观类型在空间上分布的规律性,但是这种规律性需要根据生态学知识去加以分析和总结,直观性不强。（3）TWINSPAN结果与DCA结果基本一致。具有良好的可比性。 相似文献
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应用数量分类(TWINSPAN)和DCA排序方法,对我国特有裘皮用山羊(中卫山羊)核心产地——宁夏香山地区植物群落进行多元分析,根据TWINSPAN分类结果,并结合生态特征将所调查的28个样地植被分为6组,代表了该山地在海拔、地形、土壤、山坡坡度等环境作用下植被空间的分布格局。TWINSPAN分类结果与DCA排序结果较一致,DCA排序第一轴结果主要体现出海拔和山坡坡度对植被分布的作用,第二轴结果主要体现了地形(坡向)和土壤基质(沙地、石质山坡、土质山坡)对植被分布的作用。影响该干旱山地植被分布的主要环境因子有海拔和山坡的坡度,另外长期过度放牧对植被的空间分布影响较大,导致了该山地系统植被空间结构紊乱,并干扰了群落数量分析结果的准确性。 相似文献
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强烈的人类活动对自然生境的扰动促进了外来植物侵入河岸带,但不同类型的人类活动干扰对外来植物的影响有所不同。按照不同人类活动干扰类型设置了山峡段、平原段和城市段,通过比较河段间河岸带外来植物群落特征的差异,探讨不同人类活动干扰类型对河岸带外来植物群落的影响。结果表明:(1)永定河河岸带共有维管束植物27科72属101种,外来植物13科28属29种。外来种比例高达28.7%,其中82.4%的国外外来种来自美洲和亚洲。(2)不同河段间的外来植物群落的物种构成和优势度呈现出显著性差异。外来种比例由山峡段的20.9%,上升至平原段和城市段的30.2%和25.5%;而优势度由12.1%,分别上升至13.4%和17.5%。(3)不同河段间的外来植物群落生活型结构有显著性差异。多年生草本植物在山峡段比例最高,达到66.7%,在平原段和城市段较低,分别为46.2%和30.8%;而一年生草本植物在城市段比例最高,达到69.2%,在平原段和山峡段较低,分别为53.8%和33.3%。(4)平原段属于农业干扰类型,其河岸带外来植物主要以农业类杂草为主,如禾本科的假稻(Leersia japonica)和菊科的钻叶紫菀(Aster subulatu);城市段是城市干扰类型,外来植物中入侵种比例和优势度较高,典型入侵种为反枝苋(Amaranthus retroflexus)和牛筋草(Eleusine indica)等。北京永定河不同河段河岸带外来植物的种类构成特点,反映了河岸带外来植物受快速城市化、农业活动等不同人类活动干扰的影响呈逐渐扩大的趋势。 相似文献
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Anna Barbara Giles Peter Scanes Adrian Dickson Brian Adam Brendan Kelaher 《Austral ecology》2023,48(2):359-373
Protected areas can be impacted by the presence and proliferation of feral species. Effective management of feral species requires reliable tools to monitor their population size and ecological impacts. Here, we used drone-based image analysis to assess evidence of feral horses and horse-specific ecological impacts on alpine riparian habitat. Valleys with low (0), medium (1–16) and high (>16) horse abundances were chosen for drone imagery analysis based on independent aerial counts of horses. Data collection trips were carried out pre- and post-2019/2020 wildfires, which unexpectedly burnt valleys with low horse presence. Drone-based RGB orthomosaic imagery was sufficient to identify seven indicators of horse presence and determine the severity of feral horse impacts. Despite the impact of fire, drone-derived classifications were able to accurately detect a gradient of horse impacts, showing a significant difference in indicators from low presence valleys compared with medium and high presence valleys, which did not differ significantly from each other. The significance of differences between valleys reveals that regions routinely inhabited by feral horses will display significant environmental impacts. Our results clearly indicated significant differences between valleys with low horse presence compared with either medium or high horse presence regions (0.01 for differences between both low and medium and low and high horse presence). This was evident both before and after the 2019/2020 fires, suggesting that wildfires did not significantly impact horse populations or distribution in the sampled region. Overall, it was evident that feral horses have a clear and definable impact on alpine riparian vegetation, and drone surveying can be used to routinely monitor potential spread and the outcome of management actions. 相似文献
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Abstract Stony downs consist of grassy areas that alternate with areas that have a substantial stone cover. The stone-covered areas are impermeable, and most rain falling on them runs off, substantially increasing the effective rainfall in adjacent grassy areas. As a result, 20–25 mm of rain on stony downs wetted the soil around the grass to a depth of 140–170 mm and allowed sustained grass response. This is much less than the 35–40 mm of rain required for the same response on red clay or grey clay plains. Grasses respond very rapidly after rain. Some have green shoots the day after rain, and all have responded by the second day. Ephemerals dry off in 4–6 weeks, but most tussock grasses still have some green foliage 8–10 weeks after rain. Deeper rooted tussock grasses remain green for so long because most of the moisture that reaches deeper roots after rain remains there. Most moisture loss is through the soil surface and is recognizable as a drying front that descends through the soil profile. Soil above the drying front is nearly air dry (<5% moisture) while soil below the front has substantial moisture (14–16%). By about a month after rain in summer, the drying front is at a depth of about 80–120 mm. This is near the tips of the roots of ephemeral grasses and the ephemerals then dry off rapidly. Only the tips of the leaves of deep rooted grasses like Mitchell grass (Astrebla spp.) dry off. Their leaves continue to remain mostly green during most of the second month after rain and they do not dry off completely until the third month when the drying front reaches the bottom of the main root system. 相似文献
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Archaeological charcoals from Puritjarra rock shelter provide the first direct information about the vegetation of central Australia during the late Pleistocene and early Holocene. During the late Pleistocene there appears to have been a more open vegetation than today with fewer trees and shrubs, though with many of the taxa that are important in the modern central Australian flora. The persistence of species such as Acacia macdonnelliensis, Callitris glaucophylla and Eucalyptus opaca throughout the time of the last glacial maximum and the presence of appreciable quantities of wood charcoal in the archaeological deposits at this time indicate that the region was not a tree-less steppe even during full glacial aridity. From 13,000 B.P. onwards, acacias are strongly represented in the charcoal assemblage both quantitatively and in terms of the number of species present. Acacia aneura is for the first time a major component of the assemblage indicating that it had by this time become a significant element of the local vegetation. These changes coincide with evidence elsewhere in the Australian arid zone for the onset of wetter conditions in the early Holocene. 相似文献
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常绿阔叶林植被分类一直是植被生态学研究中的难题,尤其是基本单位——群丛的分类。该文以地形因子和物种组成数据为变量的多元回归树方法,将浙江古田山24hm2森林监测样地的森林群落分为3个群丛。所得群丛既反映了群落在时间和空间上的相对间断分布,也符合植被分类基本单位的特点,为常绿阔叶林的群丛分类提供了新思路。并首次引入了指示值算法,解决了以往指示种无法量化的难题。最终以优势层优势种为主、下木层指示种为辅的命名原则,将3个群丛命名为:1)石斑木(Raphiolepis indica)+柳叶蜡梅(Chimonanthus salicifolius)-格药柃(Eurya muricata)+赤楠(Syzygium buxifolium)-木荷(Schima superba)+甜槠(Castanopsis eyrei)群丛;2)映山红(Rhododendron simsii)+满山红(Rhododendron mariesii)-短柄枹(Quercus serrata var.brevipetiolata)+灰白蜡瓣花(Corylopsis glandulifera var.hypoglauca)-马尾松(Pinus massoniana)+甜槠群丛;3)短尾越桔(Vaccinium carlesii)+毛花连蕊茶(Camellia fraterna)-杨梅叶蚊母树(Distylium myricoides)+浙江新木姜子(Neolitsea aurata)-木荷+甜槠群丛。 相似文献
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Simone Fattorini Letizia Di Biase Alessandro Chiarucci 《Journal of Biogeography》2019,46(8):1643-1651
Since von Humboldt, recognizing and using elevational subdivisions is at the core of biogeographical and ecological studies in mountain ecosystems. However, despite the large use of vegetational belts, their conceptual definition and practical identification appear to be surprisingly loose and inconsistent. Many authors use variations in climatic conditions to identify elevational belts. These belts are useful to set a framework for ecological studies but cannot be considered a surrogate of vegetational belts, because factors different from climate play a major role in determining the distribution of plant assemblages. Vegetation physiognomy can be used to identify ‘biome‐type’ belts that are useful for comparisons across geographical areas with different floras. However, to properly reflect ecological conditions at local scale, vegetational belts should be based on species composition. One of the most effective statistical approaches for this purpose is the use spatially constrained cluster analysis. The use of indicator species analysis may be also recommended to identify the species that most characterize vegetational belts. This can help researchers to identify belts in the field. Since species identification can be difficult, some authors use plant functional types for belt delimitation. Plant functional types can be helpful to trace the adaptative responses of vegetation along elevational gradients, but cannot be recommended as a standard way to identify belts. In general, criteria to identify vegetational belts can be based on both vegetation structure (namely physiognomy and structural parameters) and/or species composition, depending on the scale and the aim of the analyses, and they should be clearly stated. 相似文献
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选择云丘山景区为研究区域,以该区域的主要植被为研究对象,采用样方法对旅游干扰对云丘山景区内植被的影响进行了研究,共设置了40个乔木样方,并利用TWINSPAN聚类分析以及旅游干扰程度（TDD）对所取样方进行分析。结果表明：TWINSPAN聚类分类将景区内的植物群落划分为5个群系,其中、群系Ⅱ中伴人植物的优势度明显高于其它。干扰程度分析表明,在景区的40个乔木样方中,只有4个样方基本没有受到干扰,有3个样方受到中度干扰,其余的33个样方均为轻度干扰。TWINSPAN聚类分析科学合理地对旅游活动作用下植被景观的类型特征进行了分析。旅游干扰程度（TDD）直观地反映出各个样方所在地植被被干扰的程度,该研究结果可为旅游管理者提供一定的理论依据。 相似文献
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The rarity of parthenogenesis, reproduction without sex, is a major evolutionary puzzle. To understand why sexual genetic systems are so successful in nature, we must understand why parthenogenesis sometimes evolves and persists. Here we use DNA sequence data to test for similarities in the tempo and mode of the evolution of parthenogenesis in a grasshopper and a lizard from the Australian desert. We find spectacular congruence between genetic and geographic patterns of parthenogenesis in these distantly related organisms. In each species, parthenogenesis evolved twice and appears to have expanded in parallel waves across the desert, suggesting a highly general selective force against sex. 相似文献
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Kristina J. Macdonald Don A. Driscoll Kimberley J. Macdonald Bronwyn Hradsky Tim S. Doherty 《Global Change Biology》2023,29(17):4949-4965
Ecosystem disturbance is increasing in extent, severity and frequency across the globe. To date, research has largely focussed on the impacts of disturbance on animal population size, extinction risk and species richness. However, individual responses, such as changes in body condition, can act as more sensitive metrics and may provide early warning signs of reduced fitness and population declines. We conducted the first global systematic review and meta-analysis investigating the impacts of ecosystem disturbance on reptile and amphibian body condition. We collated 384 effect sizes representing 137 species from 133 studies. We tested how disturbance type, species traits, biome and taxon moderate the impacts of disturbance on body condition. We found an overall negative effect of disturbance on herpetofauna body condition (Hedges' g = −0.37, 95% CI: −0.57, −0.18). Disturbance type was an influential predictor of body condition response and all disturbance types had a negative mean effect. Drought, invasive species and agriculture had the largest effects. The impact of disturbance varied in strength and direction across biomes, with the largest negative effects found within Mediterranean and temperate biomes. In contrast, taxon, body size, habitat specialisation and conservation status were not influential predictors of disturbance effects. Our findings reveal the widespread effects of disturbance on herpetofauna body condition and highlight the potential role of individual-level response metrics in enhancing wildlife monitoring. The use of individual response metrics alongside population and community metrics would deepen our understanding of disturbance impacts by revealing both early impacts and chronic effects within affected populations. This could enable early and more informed conservation management. 相似文献
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Cheryl S. Brehme;Philip R. Gould;Denise R. Clark;Robert N. Fisher; 《Conservation Science and Practice》2024,6(3):e13071
For species of conservation concern, long-term monitoring is vital to properly characterize changes in population distribution and abundance over time. In addition, long-term monitoring guides management decisions by informing and evaluating the efficacy of management actions. A long-term monitoring initiative for the federally threatened Stephens' Kangaroo rat (Dipodomys stephensi, SKR) was established in 2005, across 628 hectares within Marine Corps Base Camp Pendleton (MCBCP), San Diego, California, USA. From 2005 to 2018, we tracked trends in area occupied by SKR, trends in relative SKR densities within occupied habitat, and modeled probabilities of SKR occupancy, colonization, extinction, with habitat, climate, and disturbance covariates. Area occupied by SKR increased almost 2-fold from 2005 to 2018 on MCBCP, while density in occupied habitat increased almost 3-fold. Increased area occupied was correlated with increases in estimated density among years, indicating SKR population growth occurs by expansion into suitable habitat patches, as well as increases in numbers within occupied habitat. SKR occupancy was positively associated with gentle slopes (<10%) and moderate open ground (40–80%) and forb cover (>40%). They were more likely to colonize previously unoccupied habitat when there were moderate levels of open ground (40–80%) and low shrub cover (<20%), while more likely to go locally extinct in areas with high slopes (>10%), less open ground (<20%), and increased non-native grass cover (>40%). Additionally, probabilities of SKR occupancy and colonization were higher in areas with moderate levels of disturbance, which was positively associated with open ground and forb cover. We conclude that long-term occupancy and density monitoring is effective in informing status and trends of spatially dynamic species and that moderate habitat-based disturbance is compatible with the management of SKR. 相似文献
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应用双向指示种分析(TWINSPAN)方法对湿地植物群落进行分类,采用除趋势对应分析(DCA)、典范对应分析(CCA)对群落进行排序,以明确博斯腾湖湖滨湿地的主要植物群落类型及影响植被类型变化和分布的主要环境因子。结果表明,博斯腾湖湖滨湿地植被可分为7个主要群丛,分别为长苞香蒲(Ass.Typha angustata)、芦苇+长苞香蒲(Ass.Phragmites australis+Ty.angustata)、芦苇+水烛(Ass.P.australis+Ty.Angustifolia)、多枝柽柳-芦苇(Ass.Tamarix ramosissima-P.australis)、胡杨-多枝柽柳(Ass.Populus euphratica-Ta.ramosissima)、旱柳-多枝柽柳(Ass.Salix matsudana-Ta.ramosissima)和多枝柽柳(Ass.Ta.ramosissima),它们分布于湖滨浅水带、湖滨沼泽带、湖岸乔灌林带和旱生灌丛带;TWINSPAN分类产生的7个主要群丛在DCA排序图上被很好地反映出来。CCA排序与DCA排序结果基本一致,说明土壤含水量和土壤总含盐量是决定该地区植被分布格局的主要环境因子。博斯腾湖湖滨湿地植被种类单一,生态结构简单,水盐动态及其相互作用是影响该地区植被分布的主要因素之一。因此,在对博斯腾湖湖滨湿地进行植被保护与重建过程中,需重点考虑土壤含水量和土壤总含盐量这2个主要环境因子的影响,合理开发、利用水资源,防止土壤盐渍化的发生。 相似文献
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John L. Read Katherine E. Moseby Jason Briffa Adam D. Kilpatrick Andrew Freeman 《Ecological Management & Restoration》2011,12(1):46-53
Summary High densities of the European Rabbit (Oryctolagus cuniculus) were eradicated from 60 km2 of the Arid Recovery Reserve between 1996 and 2001. Eradication was possible due to an initial knockdown caused by rabbit haemorrhagic disease, followed by effective exclusion fencing, broadscale poison baiting, targeted shooting, warren destruction and trapping on rabbit burrows and buckheaps. The efficacy of different broadscale control and intensive rabbit eradication techniques was subsequently estimated in a 26 km2 expansion to the Reserve from 2002 to 2006. Non‐target implications of these control techniques were also assessed where possible. An estimated 8000 rabbits were removed in total from both areas and results suggest that rabbit eradication is possible at a landscape scale. Strategies for eliminating rabbits from confined areas are suggested. 相似文献
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利用巴氏罐诱法,对山西庞泉沟国家自然保护区的不同功能区——核心区（绿色长廊）、缓冲区（八道沟）、远离农田实验区（神尾沟）及靠近农田实验区（八水沟）——林地地表甲虫步甲物种多样性进行了调查和比较,目的在于探明该保护区有代表性林地步甲物种的组成及受不同程度人为干扰下的多样性格局。结果表明：（1）本研究共捕获步甲物种42种,38种是该保护区的新记录种类,其中粗皱步甲Carabus crassesculptus和沟步甲C. canaliculatus 为优势种,与尖角通缘步甲Pterostichus eschscholtzii,强足通缘步甲P. fortipes,罕丽步甲C. manifestus和长叶步甲C. vladimirskyi一起构成研究地的常见种。（2）不同功能区物种组成和数量分布各不相同,多样性各项指标均是靠近农田的实验区最高,核心区最低。（3）各功能区具有特有的指示性种类,其中黄条春步甲Notiophilus reitteri为核心区指示种; 凹唇春步甲N. impressifrons 为缓冲区指示种; 粒步甲C．granulatus,刻翅步甲C．sculptipennis 和中华通缘步甲P．chinensis为实验区指示种。（4）群落相似性分析表明缓冲区与核心区及远离农田实验区之间具有较高的相似性,靠近农田实验区与其他3个地点相似性较低。结果提示适度干扰可提高物种丰富度,但降低人为干扰（如旅游和交通压力）有利于步甲多样性的保护。 相似文献
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该研究基于耐旱藓类连轴藓属5种53条在新疆的地理分布信息和7个气候变量,利用最大熵模型和ArcGIS 10.2软件,分别模拟现代气候和未来气候情景下连轴藓属在新疆的适生分布区,为探讨气候变化对干旱、半干旱区苔藓植物物种分布的影响提供参考。结果表明:(1)Maxent模型预测连轴藓属在新疆适生区的准确性非常高(AUC=0.957)。(2)年降雨量、最干季度降雨量和最暖季度平均气温是影响连轴藓属分布的主要气候因子。(3)连轴藓属在新疆的适生区主要集中在阿尔泰山和天山沿线,在未来(2061~2080年)气候情景下,连轴藓属分布面积将比现代气候下减少10.39%,其绝大部分现有南部适生区将丧失。 相似文献