生境破碎化对动物种群存活的影响

生境破碎是生物多样性下降的主要原因之一。通常以岛屿生物地理学、异质种群生物学和景观生态学的理论来解释不同空间尺度中生境破碎化的生态学效应。生境破碎化引起面积效应、隔离效应和边缘效应。这些效应通过影响动物种群的绝灭阈值、分布和多度、种间关系以及生态系统过程,最终影响动物种群的存活。野外研究表明,破碎化对动物的影响,因物种、生境类型和地理区域不同而有所变化,因此,预测物种在破碎生境中的存活比较困难。研究热点集中于：确定生境面积损失和生境斑块的空间格局对破碎景观中物种绝灭的相对影响,破碎景观中物种的适宜生境比例和绝灭阈值,异质种群动态以及生态系统的生态过程。随着3S技术的发展,生境破碎化模型趋于复杂,而发展有效的模型和验证模型将成为一项富有挑战性的任务。     

蜣螂的生态价值和保护意义

蜣螂通常以粪便或腐殖质为食,在生态系统平衡中具有重要的作用。文章系统介绍蜣螂的生态价值,包括转将运粪便到地下、对种子二次传播的作用、传粉作用、对有害生物的控制作用和寄生虫的中间宿主,以及广阔的开发应用前景、重要仿生学意义和重大理论意义;并进一步提出蜣螂保护的迫切性和重要意义。     

Establishment of exotic dung beetles in Queensland: the role of habitat specificity

Between 1968 and 1983, 22 species of dung beetles from southern Africa were released into pastoral regions of Queensland in northern Australia. Seven species have become widespread and abundant and the others either occur in isolated patches, are rare or have failed to establish self perpetuating populations. These species all occur in the Hluhluwe district in southern Africa which has a climate similar to that of coastal central and southern Queensland. The numberical abundance and habitat associations of the 22 speices were examined at Hluhluwe to seek an explanation for their performance in Australia. It was concluded that habitat specificity and the adequacy with which habitat was matched in Australia were critical factors. Species which established in Australia were relatively common in cattle dung in Africa where they showed a preference for grassland on clay-loam soils.      

Rethinking species' ability to cope with rapid climate change

Ongoing climate change is assumed to be exceptional because of its unprecedented velocity. However, new geophysical research suggests that dramatic climatic changes during the Late Pleistocene occurred extremely rapid, over just a few years. These abrupt climatic changes may have been even faster than contemporary ones, but relatively few continent‐wide extinctions of species have been documented for these periods. This raises questions about the ability of extant species to adapt to ongoing climate change. We propose that the advances in geophysical research challenge current views about species' ability to cope with climate change, and that lessons must be learned for modelling future impacts of climate change on species.     

Habitat fragmentation and extinction thresholds on fractal landscapes

Habitat fragmentation is a potentially critical factor in determining population persistence. In this paper, we explore the effect of fragmentation when the fragmentation follows a fractal pattern. The habitat is divided into patches, each of which is suitable or unsuitable. Suitable patches are either occupied or unoccupied, and change state depending on rates of colonization and local extinction. We compare the behaviour of two models: a spatially implicit patch-occupancy (PO) model and a spatially explicit cellular automaton (CA) model. The PO model has two fixed points: extinction, and a stable equilibrium with a fixed proportion of occupied patches. Global extinction results when habitat destruction reduces the proportion of suitable patches below a critical threshold. The PO model successfully recreates the extinction patterns found in other models. We translated the PO model into a stochastic cellular automaton. Fractal arrangements of suitable and unsuitable patches were used to simulate habitat fragmentation. We found that: (i) a population on a fractal landscape can tolerate more habitat destruction than predicted by the patch-occupancy model, and (ii) the extinction threshold decreases as the fractal dimension of the landscape decreases. These effects cannot be seen in spatially implicit models. Landscape struc-ture plays a vital role in mediating the effects of habitat fragmentation on persistence.     

A new pollination system: dung-beetle pollination discovered in Orchidantha inouei (Lowiaceae, Zingiberales) in Sarawak, Malaysia

Lowiaceae, a family of the Zingiberales, comprise 11 species in the single genus Orchidantha. Here we present the first report on the pollination of Lowiaceae and describe a new system of dung-beetle pollination from Sarawak, Borneo. Orchidantha inouei has a zygomorphic flower located just above the ground. Observations revealed that the plant is visited frequently and is pollinated by scarabaeid dung beetles, mainly members of the genus Onthophagus. All four species of Onthophagus collected on O. inouei have also been caught using traps baited with dung or carrion in Borneo. Onthophagus was presumably attracted to the dung-like odor of the flower. Pollination of O. inouei is different from other examples of beetle pollination in that its flower provides neither reward nor protected space. Dung beetles are excellent at following a particular dung scent. Orchidantha is the only genus that includes species lacking floral nectar. It is interesting that this deception pollination using dung beetles was found in Zingiberales, in which all known species have mutual and specialized relationships with their long-distance, but costly, pollinators-bees, birds, and bats.     

海南北部蔬菜生境天敌瓢虫多样性研究

为了解海南北部主要蔬菜作物生境天敌瓢虫的群落结构和物种多样性,本文利用黄板诱集法于2019年对茄子、豇豆和辣椒生境的天敌瓢虫种类和数量进行了调查研究。结果表明,3种作物生境共采集获得瓢虫标本4 993头,隶属于16个属28种,其群落多样性从高到低依次为茄子、辣椒和豇豆生境,其中茄子生境拥有28种,辣椒和豇豆生境分别为10种和11种。茄子生境的多样性指数、丰富度指数、优势度指数和均匀度指数均为最高,分别为1.58、3.40、0.27和0.47,明显高于豇豆和辣椒生境。无论哪种生境,六斑月瓢虫Cheilomenes sexmaculata (Fabricius)和龟纹瓢虫Propylae japonica (Thunberg)均是优势种类,分别占整个瓢虫数量相对多度的45.26%和19.67%。两种优势瓢虫时序变化特征表明,瓢虫数量呈多峰型分布,5月中下旬至7月上旬这一时段总体发生数量较低。研究结果可为海南北部蔬菜作物生境天敌瓢虫保护和利用提供理论依据。     

Rodents on tropical land-bridge islands

The results are reported of a survey of rodents on 10 forested land-bridge islands ranging in size from 0.2 to 350 ha in the state of Bolívar, Venezuela. The islands were contained within a lake formed c. 12 years before the study by the damming of the Caroni River for hydroelectric power. Rodents were sampled on each island by live-trapping along transects that sampled all available habitat types on each island, and microhabitat structure was measured at each trap station. A total of 674 captures of 359 individuals of six species of rodents was recorded. Species composition changed from the largest to the smallest islands, and small and medium islands (0.2–11 ha) displayed the typical effects of insularity, with fewer species and increased abundances and biomass. The largest island (350 ha) seemed to function more like a mainland. Most species were associated with a suite of microhabitat variables. It is suggested that release from top-down control by predators was responsible for higher abundances and biomass on the smaller islands and that predators moving between large islands and other nearby landmasses help maintain a mainland community structure on large islands. However, changes in species composition on smaller islands may be the result of patchy occurrences of some species before isolation, changes in microhabitat structure following isolation, and species-specific microhabitat requirements.