Biogeografia de interações entre eupatorieae (Asteraceae) e insetos endofagos de capitulos na Serra da Mantiqueira

AUTOR(ES)
DATA DE PUBLICAÇÃO

2001

RESUMO

This thesis analysed the int1uence of regional factors in five local communities composed of endophagous insect species that feed on fiower-heads trom the tribe Eupatorieae (Asteraceae) in the Mantiqueira range, trom 1998 to 1999, within altitudes varying trom 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 fiora (the most diverse Asteraeeous 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 traction of the Eupatorieae species oceurs in more than one mountain range, and there is a signifieant spatial correlation for Espinhaço range and the pool of the three ranges, with adjaeent loealities being floristically more similar than more distant localities. The second ehapter examines the endophagous insects that develop in the Eupatorieae flower-heads in the Mantiqueira range. Endophagous species were divided in three guilds aeeording to the degree of endophagy and relationship to the host plants: Striet endophages, mobile endophages and faeultative 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 environrnental pressures. Chapter 3 deseribes the altitudinal distribution of plant and endophagous species grouped into feeding guilds, and tests the mid-domain hypothesis of Colwell and eo-workers against Steven s Rapoport s rule. We observed that in alI localities the peak in species riehness occurs in mid-altitudes - as predicted by the middomain hypothesis - but seldom in the centre of the altitudinal domain, and eaeh guild presented the same pattern of altitudinal riehness distribution in each loeality. The fact that different guilds respond similarly to the same environrnental pressures suggests that ecologically similar species show the same response patterns to the limitations imposed by a harsh environrnent. This is the first time the mid-domain hypothesis is tested for more than a trophie level and in various localities within a region. The fourth and last ehapter presents quantitative trophie webs of the regional and local eommunities in the Mantiqueira range, using interaetion trequeney (inseet ineidenee in plant samples) as quantitative measure. With the exeeption of Itatiaia, both the regional and local webs were divided into eompartments aecording 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 on1y one host species, indicating a clear local preference for a given host

ASSUNTO(S)

biogeografia relação inseto-planta ecossistema

ACESSO AO ARTIGO

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