Marcel Holyoak is a Professor and Ecologist at The University of California at Davis. His research program addresses the importance of spatial dynamics to ecological populations and communities, and the maintenance of biodiversity in the face of global change. He is trained in biostatistics, theoretical ecology, experimental design, and natural history. He received his PhD in Population Ecology from Imperial College, University of London (1992) and became a faculty member in the University of California in 2000. He was Editor-in-Chief of leading ecology journal, Ecology Letters and is a co-Editor-in-Chief for a new Wiley Journal Wildlife Letters and is a Senior Editor for Integrative Zoology. He was a founding board member of Dryad.
Climate change, habitat fragmentation and maintaining viable ecological communities and metapopulations
Understanding the effects of weather and changes in climate on interacting species is complex because of the variety of direct and indirect effects, and endogenous and exogenous drivers that can influence dynamics. This situation is made even more complex when we consider spatial dynamics because of the need to quantify population abundances and interactions in multiple locations or habitat types. I report on the source-sink dynamics of a plant-insect herbivore system that is affected by predatory ants and viruses that attack the herbivore. The basic system consists of wet and dry habitat patches for the insect herbivore, with wet patches serving as population sources and dry patches serving as population sinks and regular source to sink migration each year. The sinks sometimes go extinct in dry years and are recolonized from sources in subsequent years. Investigations show greater population densities in wet habitats, likely because of increased plant food availability, whereas dry habitats serve as refuges from ant predation. Over 35 years the system has shifted in the periodicity of rainfall fluctuations (cycles) with an increase after 2004. The increase in rainfall cycle length was associated with changes in the Pacific Decadal Oscillation and produced a change in the period of caterpillar population fluctuations. The changes also produce more frequent droughts that are likely to have implications for the frequency of local extinction of caterpillars and potentially regional distribution. Lastly the study investigated the patterns of movement of the caterpillars among local sites and show dispersal depending on the herbivore adult behavior, through hilltopping mating aggregations. Overall, the results challenge us to understand the changes in spatial dynamics that affect interacting species and to discover whether there are general patterns or whether early studies such as this one are unique in the climate or weather effects they find.
严川，兰州大学生态学院教授，博士毕业于中科院动物研究所。主要从事生态网络、动物种群与群落动态研究。研究成果发表在Ecology Letters、Global Ecology and Biogeography、Oikos等国际生态学经典刊物。主持国家自然科学基金优青、面上项目等。任American Naturalist、Wildlife Letters、兽类学报编委。
自然界物种之间存在多种多样的种间互作关系，从而形成复杂的生态网络。这些种间互作存在可转变性，可体现在：(1) 种间互作因密度或非密度因素发生转变；(2) 物种在种间互作网络中的角色发生转变。报告人围绕生态网络中种间互作的转变，开展了一系列研究：(1) 基于理论模型探讨了不同类型的种间互作转变如何影响生态网络的稳定性；(2) 间接效应对食物网中互作关系的影响；(3) 以鼠类-种子植物互作为例，探究对抗-互惠关系转变的生态机制。