Abundance–occupancy relationships

1.  The abundance and distribution of species tend to be linked, such that species declining in abundance often tend also to show declines in the number of sites they occupy, while species increasing in abundance tend also to be increasing in occupancy. Therefore, intraspecific abundance–occupancy relationships are commonly positive.
2.  The intraspecific pattern is mirrored by more general positive interspecific abundance–occupancy relationships: widespread species tend to be abundant, and narrowly distributed species rare.
3.  Here, we review recent research on these patterns based on the flora and fauna of the British Isles. We assess their generality, describe what is currently known about their structure, and summarize the results of tests of the several hypotheses proposed to explain their existence.
4.  The positive form generally exhibited by abundance–occupancy relationships, intraspecific or interspecific, has consequences for several areas of applied ecology, including conservation, harvesting, biological invasions and biodiversity inventorying. These implications are discussed briefly.     

Food webs in space: On the interplay of dynamic instability and spatial processes

Ecologists increasingly recognize that a consideration of spatial dynamics is essential for resolving many classical problems in community ecology. In the present paper, I argue that understanding how trophic interactions influence population stability can have important implications for the expression of spatial processes. I use two examples to illustrate this point. The first example has to do with spatial determinants of food chain length. Prior theoretical and empirical work has suggested that colonization–extinction dynamics can influence food chain length, at least for specialist consumers. I briefly review evidence and prior theory that food chain length is sensitive to area. A metacommunity scenario, in which each of various patches can have a food chain varying in length (but in which a consumer is not present on a patch unless its required resource is also present), shows that alternative landscape states are possible. This possibility arises if top predators moderate unstable interactions between intermediate predators and basal resources. The second example has to do with the impact of recurrent immigration on the stability of persistent populations. Immigration can either stabilize or destabilize local population dynamics. Moreover, an increase in immigration can decrease average population size for unstable populations with direct density-dependence, or in predator–prey systems with saturating functional responses. These theoretical models suggest that the interplay of temporal variation and spatial fluxes can lead to novel qualitative phenomena.     

中国两栖动物物种丰富度省级地理分布格局及其与气候因子的关系

: 物种丰富度分布格局及其形成机制的研究对于生物多样性保护具有重要意义。为了解中国两栖动物物种丰富度分布格局,本文利用中国省级尺度两栖动物物种分布数据和环境信息,结合GIS和数理统计方法,探讨两栖动物物种丰富度的地理分布格局与环境因子之间的关系。研究结果表明:(1)物种丰富度随纬度增加呈逐渐递减趋势,但缺乏显著的经度梯度。丰富度最高的地区主要集中在南方,我国北方、西北干旱区和青藏高原北部地区丰富度较低;(2)最优模型由年均温、最冷月均温、净初级生产力、年降水量变化范围、月均降水量标准差组成,多层次方差分解表明,最冷月均温的独立解释能力(17.6%)高于年均温(11.5%);(3)方差分解表明,季节性因子的独立解释能力(5.6%)低于热量因子(6.1%),但高于水分因子(4.5%),因此我们认为季节性因子也是限制中国两栖动物分布的重要因素。     

Island biology: looking towards the future

Oceanic islands are renowned for the profound scientific insights that their fascinating biotas have provided to biologists during the past two centuries. Research presented at Island Biology 2014—an international conference, held in Honolulu, Hawaii (7–11 July 2014), which attracted 253 presenters and 430 participants from at least 35 countries¹—demonstrated that islands are reclaiming a leading role in ecology and evolution, especially for synthetic studies at the intersections of macroecology, evolution, community ecology and applied ecology. New dynamics in island biology are stimulated by four major developments. We are experiencing the emergence of a truly global and comprehensive island research community incorporating previously neglected islands and taxa. Macroecology and big-data analyses yield a wealth of global-scale synthetic studies and detailed multi-island comparisons, while other modern research approaches such as genomics, phylogenetic and functional ecology, and palaeoecology, are also dispersing to islands. And, increasingly tight collaborations between basic research and conservation management make islands places where new conservation solutions for the twenty-first century are being tested. Islands are home to a disproportionate share of the world''s rare (and extinct) species, and there is an urgent need to develop increasingly collaborative and innovative research to address their conservation requirements.