Evolutionary ecology of the Crematogaster-Macaranga mutualism and an ant's eye view to Southeast Asian rain forest history.

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題名:
Evolutionary ecology of the Crematogaster-Macaranga mutualism and an ant's eye view to Southeast Asian rain forest history.
著者: Swee Peck. Quek
Harvard University.
主題: Biology, Entomology; Biology, Ecology
所屬期刊: Dissertation Abstracts International 65-10B.
描述: In the forests of Malaya, Sumatra and Borneo, 25 species of Macaranga trees are inhabited by mutualistic ants that occupy hollow stem domatia and defend their host plants against vines and herbivores. The ants harvest foodbodies secreted by the plants, and tend scale insects for honeydew within the hollow stems. Using phylogenetic tools, I investigate the evolution of host association among the Crematogaster (subgenus Decacrema) ant and coccid scale insect inhabitants of Macaranga trees, and infer time frames for their evolutionary diversifications. The Decacrema from Macaranga form a strongly monophyletic group comprising eleven well-defined clades showing a surprising degree of host specificity. A correlated succession of Macaranga stem texture traits is seen in the ant and plant phylogenies and indicates a history of codiversification between the mutualists. Based on a molecular clock analysis and on the age of rain forests in Southeast Asia, the ant-plant mutualism is estimated to be 12--20 million years old.
The association of the coccids with the ants and with the plants appears to be unspecific, in contrast to the specialized association between the ants and plants. However, the coccids and ants show similar levels of genetic divergence and parallel biogeographic scenarios, suggesting that most of their evolutionary histories have been contemporaneous. The Macaranga symbiotic system thus represents an ancient coevolved threesome dating to the mid-to-early Miocene.
Using population genetic and phylogenetic analyses, I investigate the biogeographic and demographic history of the ants as a proxy to understanding rain forest history in Southeast Asia. The major diversification of Decacrema occurred in Borneo, with greatest endemism and taxonomic and genetic diversity in the northwest. In Malaya and Sumatra, taxonomic diversity, genetic diversity, and old, stable populations are associated with mountain ranges while the lowlands are occupied by younger populations that expanded in the Pleistocene. Thus northwest Borneo and Malayo-Sumatran mountain ranges may have harbored rain forest refugia during the more arid Pleistocene phases. The expansion dates suggest an earlier recovery of lowland rain forests in Borneo than in Malayo-Sumatra. Most of the migrations across the South China sea were inferred to have occurred during the Pliocene.
Despite the high taxonomic diversity of Decacrema in Lambir Hills National Park (Sarawak, Malaysia), the five Decacrema taxa there show impoverished genetic diversities within Lambir. Three were inferred to be the result of single and recent Pleistocene colonizations, and all five populations there have undergone historical bottlenecks. These findings are consistent with Lambir's young history as a terrestrial basin, having emerged from the sea only in Pliocene times. They further suggest that much of Lambir's biota may represent recent colonizations, as opposed to endogenous origins.
出版者: Thesis (Ph.D.)--Harvard University, 2004.
建立日期: 2004
格式: 142 p..
語言: 英文
識別號: ISBN0496094475
資源來源: NUTN ALEPH

連結

Evolutionary ecology of the Crematogaster-Macaranga mutualism and an ant's eye view to Southeast Asian rain forest history.

Swee Peck. Quek Harvard University. 2004

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