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Interactions Biogeography of Eupatorieae (Asteraceae) and its flower head endophages in the Serra da Mantiqueira
Adriana Monteiro de Almeida
Universidade Estadual de Campinas, Instituto de Biologia, Departamento de Zoologia
6109, Campinas, SP, Brazil, CEP 13083-970
email: adrianam@unicamp.br advisor
Thomas Michael Lewinsohn
Universidade Estadual de Campinas, Instituto de Biologia, Departamento de Zoologia
6109, Campinas, SP, Brazil, CEP 13083-970
email: thomasl@unicamp.br keywords
Insect-plant interactions, community ecology, biogeography publication date: 07-19-2002
Abstract
This thesis analysed the influence of regional factors in five local communities composed of endophagous insect species that feed on flower-heads from the tribe Eupatorieae (Asteraceae) in the Mantiqueira range, from 1998 to 1999, within altitudes varying from 760m to 2460m: Ibitipoca (Minas Gerais), Visconde de Mauá (Rio de Janeiro/Minas Gerais), Itatiaia (RJ/MG), Passa Quatro (MG) and Campos do Jordão (São Paulo). It is presented as four independent papers. In the first chapter the Eupatorieae flora (the most diverse Asteraceous tribe in the region) present in the Mantiqueira range was compared to the flora of the Espinhaço range (MG) and Southern mountain ranges (Santa Catarina and Rio Grande do Sul). Only a small fraction of the Eupatorieae species occurs in more than one mountain range, and there is a significant spatial correlation for Espinhaço range and the pool of the three ranges, with adjacent localities being floristically more similar than more distant localities. The second chapter examines the endophagous insects that develop in the Eupatorieae flower-heads in the Mantiqueira range. Endophagous species were divided in three guilds according to the degree of endophagy and relationship to the host plants: Strict endophages, mobile endophages and facultative endophages, and their geographic and host ranges were analysed. We show that strict endophages are more specialized and are more often restricted to a host species, genus or subtribe than the other two guilds. We suggest that different guilds show different responses to environmental pressures. Chapter 3 describes the altitudinal distribution of plant and endophagous species grouped into feeding guilds, and tests the mid-domain hypothesis of Colwell and co-workers against Steven's Rapoport's rule. We observed that in all localities the peak in species richness occurs in mid-altitudes - as predicted by the mid-domain hypothesis - but seldom in the centre of the altitudinal domain, and each guild presented the same pattern of altitudinal richness distribution in each locality. The fact that different guilds respond similarly to the same environmental pressures suggests that ecologically similar species show the same response patterns to the limitations imposed by a harsh environment. This is the first time the mid-domain hypothesis is tested for more than a trophic level and in various localities within a region. The fourth and last chapter presents quantitative trophic webs of the regional and local communities in the Mantiqueira range, using interaction frequency (insect incidence in plant samples) as quantitative measure. With the exception of Itatiaia, both the regional and local webs were divided into compartments according to the endophagous feeding guilds, with interactions within guilds being more intense than among guilds. Regional generalists were also localy generalists, but from 40% to 50% of interactions were directed to only one host species, indicating a clear local preference for a given host.
