Testing Multiple Mechanisms of Species Coexistence in a Guild of African Acacia-ants

0089706. 莫林·斯坦顿。 了解促进物种共存的机制是当代生态学的一个重点领域。 拟议的项目通过研究使四种蚂蚁（它们与肯尼亚的膨胀刺阿卡西亚斯有必然联系）在一种金合欢（Acacia drepanolobium）上共存的因素来解决这些问题。 一系列的替代假设将使用观察，操纵和建模方法进行检查。 第一个假设是，共存的可能性提高到一定程度，即殖民化和竞争能力之间存在权衡。 初步数据表明，两种竞争优势的蚂蚁是有限的殖民者，主要是通过殖民地扩张扩展到新的领域，而殖民的两个竞争劣势的物种是由foundress皇后完成。 拟议的研究将阐明殖民化和当地竞争在决定共存方面的不同作用。 第二个假设是，如果从属蚂蚁物种具有时间优先权所赋予的优势，则共存会得到加强。 计划中的实验将确定持久性带来的好处，这与从属蚂蚁物种对宿主树的修改有关。 第三个假设是，共存是促进，因为竞争优势种是在更大的风险，从天敌比不丰富的从属物种。 初步数据表明，这是不太可能的，因为寄生率和捕食率普遍较低的所有四种蚂蚁。 第四个假设是，在异质环境中有差别地开发零星资源会增加共存的可能性。 初步数据表明，优势种取代从属物种在高质量的斑块，而从属物种更常见于低质量的斑块。 计划的实验将评估竞争性相互作用的结果是否取决于补丁质量。 这些实验的结果将被整合到一个矩阵投影模型中，该模型将评估蚂蚁群落的稳定性以及时空变化在长期群落动态中的作用。

0089706. Maureen Stanton. Understanding the mechanisms, which facilitate the coexistence of species, is a focal area of contemporary ecology. The proposed project addresses such issues by examining the factors that allow four species of ants, which are obligately associated with swollen thorn acacias in Kenya, to co-exist on a single species of acacia, Acacia drepanolobium. A series of alternative hypotheses will be examined using observational, manipulative, and modeling approaches. The first hypothesis is that the likelihood of coexistence is enhanced to the extent that a trade off exists between colonization and competitive ability. Preliminary data suggest that the two competitively dominant species of ants are limited colonizers that principally extend into new areas via colony expansion, whereas colonization by the two competitively inferior species is accomplished by foundress queens. Proposed research will elucidate the differential role of colonization and local competition in determining coexistence. The second hypothesis is that coexistence is enhanced if subordinate ant species have an advantage conferred by temporal priority. Planned experiments will determine the benefit derived from persistence, which is associated with host tree modification by subordinate ant species. The third hypothesis is that coexistence is facilitated because competitively dominant species are at greater risk from natural enemies than are less abundant subordinate species. Preliminary data suggest that this is less likely because rates of parasitism and predation are generally low for all four species of ant. The fourth hypothesis is that differential exploitation of patchy resources in a heterogeneous environment increases the likelihood of coexistence. Preliminary data suggest that dominant species replace subordinant species in high quality patches, whereas subordinant species are more common in low quality patches. Planned experiments will assess whether the outcome of competitive interactions is dependent on patch quality. Results from these experiments will be integrated into a matrix projection model, which will assess the stability of ant communities and the role of spatio-temporal variation in long-term community dynamics.