Cecropia Species Research Articles

Geographic Variation and Community Structure in an Ant-Plant Mutualism: Azteca and Cecropia in Costa Rica

The association between Azteca ants and Cecropia trees is the most conspicuous ant-plant mutualism in the neotropics, yet little is known about the identities or community ecology of the species involved. A survey of ant communities found in Costa Rican Cecropia trees revealed a community of Azteca species obligately associated with Cecropia, and a diverse assemblage of non-obligate ants in a variety of genera. High occupation rates of Cecropia saplings and trees, and presence of many incipient colonies in saplings vs single colonies in trees, suggest that Cecropia are a limiting resource for which ants compete. Obligate Azteca appeared competitively superior to non-obligate ants, since non-obligate ants were never found dominating mature trees. Competitive relationships between obligate Azteca were not clear; local communities contained three to four Azteca species using the same host tree species resource. Two Azteca species had a parapatric distribution, the zone of parapatry co-occurring with a similar zone of parapatry between two Cecropia species. At the boundary, the Azteca species were not host specific. Possible factors influencing the outcome of competition between ants for Cecropia trees include queen and worker behavior, priority effects, partial hostplant specialization, and habitat specialization. Explanation of current distributions may require knowledge of historical factors and stochastic effects. SPECIALIZED MUTUALISMS BETWEEN ANTS AND MYRMECOPHYTES are not isolated pairs of interacting species. They usually involve communities of many species. Myrmecophytes, as used here, are plants that produce cavities (domatia) within which specialized ants nest. Myrmecophytic Acacia trees in Central America are occupied by several Pseudomyrmex species (Janzen 1967, 1973a), at least one of which is a parasite rather than a mutualist (Janzen 1975). Leonardoxa africana in Cameroon is occupied by the mutualist Petalomyrmex phylax and the parasite Cataulacus mckeyi (McKey 1984). New World Triplaris are inhabited by sympatric species of Pseudomyrmex, and Old World Barteria by sympatric species of Tetraponera (P. S. Ward, pers. comm.). Cordia aliodora in Costa Rica is occupied by sympatric populations of Azteca longiceps and Zacryptocerus setulifer (pers. obs.). Examining the structure and spatial variation of these communities may provide insight into how specialized mutualisms evolve and are maintained. Wilson (1987) reported a very rich arboreal fauna occupying single rain forest tree canopies in Peru, and raised questions regarding the mechanisms promoting such high local species richness. Communities of myrmecophytes and their ants provide a microcosm within which to examine the community ecology of arboreal ants. By examining a specialized ant-plant interaction at the community level one can address the following questions. What is the spatial variation in community composition? Do ants exhibit hostplant specificity? Are plants a limiting resource for ants? What factors influence the outcome of competition between ants for plants? Results from a study of an ant-plant community in Peru suggest that a variety of ants do compete for plants, and that specialized inhabitants are competitively superior (Davidson et al., in

Exine structure in Cecropia L. (Moraceae) pollen grains

Devido ao pequeno tamanho dos grãos de pólen de espécies do gênero Cecropia, é elucidada no presente trabalho a estratificação da exina e a ornamentação das superfícies por meio de observações em microscopia eletrônica. As 10 espécies estudadas podem ser separadas em dois grupos segundo a distribuição dos espículos na superfície dos grãos de pólen: distribuição uniforme com espículos acumulados na faixa equatorial, deixando as áreas polares praticamente lisas. A exina é estruturada de fora para dentro por espículos supratectais, de um teto bem desenvolvido atravessado por diminutos canalículos, báculos curtos e delgados, uma nexina 1 descontínua e uma nexina 2 contínua, espessada em volta dos poros. De acordo com estas diferenciações da estrutura da exina, o gênero Cecropia apresenta dentro da família Moraceae um certo grau de evolução que não apoia a sua aproximação à família Urticaceae.

Estimativa da biomassa de raizes de duas espécies de Cecropia e sua relação com a associação ou não das plantas a formigas

Resumo Este trabalho propõe a hipótese de que as formigas associadas com várias espécies do gênero Cecropia, além do outro possível papel como agentes alelopáticos (sensu Janzen, 1969), estariam concentrando nutrientes para as plantas. Esta hipótese foi testada pela comparação do desenvolvimento da biomassa radicular, através da razão peso fresco das raízes/peso fresco do caule, de uma espécie associada a formigas, C. concolor Willdenow, e uma espécie não-associada a formigas, C. sciadophylla Martius. Os resumidos indicam que C. concolor tem uma razão média raízes/caule de 0,27 (n = 5), enquanto em C. sciadophylla a mesma razão é de 0,50 (n = 5), uma diferença significativa ao nível de 5%. Esta tendência, portanto, corrobora a hipótese inicial.

ABSCISSION OF ANTHERS IN CECROPIA LOEFL

Acta Botanica NeerlandicaVolume 26, Issue 5 p. 417-419 Brief Communication ABSCISSION OF ANTHERS IN CECROPIA LOEFL C. C. Berg, C. C. Berg Instituut voor Systematische Plantkunde, UtrechtSearch for more papers by this author C. C. Berg, C. C. Berg Instituut voor Systematische Plantkunde, UtrechtSearch for more papers by this author First published: October 1977 https://doi.org/10.1111/j.1438-8677.1977.tb00255.xCitations: 5AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat Citing Literature Volume26, Issue5October 1977Pages 417-419 RelatedInformation

Gecropia purpurascens, a new species for Brazilian Amazonia

Abstract A new species of Cecropia, C. purpurascens C.C. Berg is described. Although it is common in the vicinity of Manaus, it has been overlooked previously because Cecropia is still a poorly studied genus. This new species is quite distinct from related species and is inhabited by ants of the genus Azteca.