2019/09/17 108-1 跨領域環境議題座談 Does omnivory alter the effects of consumer diversity on the consumption of prey?

時間:9月27日 (五) 12:30~14:00
舉辦單位: 全球變遷研究中心,氣候變遷及永續發展國際學位學程
講者:張峰勳– 博士後研究員 臺灣大學海洋研究所
講題:Does omnivory alter the effects of consumer diversity on the consumption of prey?

The efficiency by which plants and animals utilize limited resource drives numerous ecological processes that are beneficial to society. For example, the efficiency by which plants assimilate nutrients and water controls rates of plant biomass production that lead to yield of food crops, and production of wood. The efficiency by which animals consume their prey controls pest and disease populations, as well as pollination. It is, therefore, important to understand what ecological factors regulate the efficiency by which limited resources are used. After two decades of studies on plants communities, scientists have reached a consensus that consumption of abiotic resources by plants is positively associated with the plant diversity, i.e., the variety of plant species, genes and functional groups coexisting in an ecosystem. The positive effects of plant diversity are believed to result from the partitioning of limited resources in space or time. Similar to plants, diversity of animal consumers can increase prey consumption when consumers partition their resource use. However, unlike plants, consumers exhibit more complex forms of interspecific interactions like omnivory, which have potential to reduce the efficiency by which animals consume prey. In this study, I test the general hypothesis that omnivory tends to reduce the association between consumer diversity and resource prey consumption. To address this hypothesis, I first built a mathematical model and conducted well-controlled laboratory experiments to show that the simplest case of omnivory, intra-guild predation (IGP), can have either positive or negative impacts on resource prey consumption. I then analyzed data from an extensive biogeographic dataset and performed in situ incubation experiments to investigate whether omnivory defined more broadly influenced the association between consumer diversity and the consumption of resource prey. In these more natural settings, I did not find any significant impact of omnivory on the relationship between consumer diversity and resource prey consumption. Instead, I found that omnivory is driven mostly by shifts in the composition of the dominant animal consumers. While my research gives contradictory support for the original hypothesis (e.g., support in models and controlled lab experiment, rejection in more natural field conditions), it paves the way for further studies to resolve the impacts of omnivory on the diversity-function relationship.