Dennis J. O'Dowd

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In second growth forest in lowland Costa Rica, ants forage at the foliar nectaries of juvenile Ochroma pyramidale. The relationship between leaf development, foliar nectar production and ant visitation indicates that nectar secretion and ant maintenance are greatest following rapid leaf expansion. Nectar measurements in the glasshouse corroborate field(More)
Associations between mites and leaf domatia have been widely reported, but little is known about their consequences for either plants or mites. By excising domatia from leaves of the laureltinus, Viburnum tinus L. (Caprifoliaceae), in the garden and laboratory, we showed that domatia alter the abundance, distribution, and reproduction of potential plant(More)
In a study of the biochemical basis of seed dispersal by ants, elaiosomes of Acacia myrtifolia and Tetratheca stenocarpa induced seed collection: intact diaspores and elaiosomes were taken rapidly by ants while most seeds remained on the forest floor. Extracts of elaiosomes (non-polar lipids, polar lipids, and aqueous fractions) were differentially(More)
Plant populations are regulated by a diverse assortment of abiotic and biotic factors that influence seed dispersal and viability, and seedling establishment and growth at the microsite. Rarely does one animal guild exert as significant an influence on different plant assemblages as land crabs. We review three tropical coastal ecosystems-mangroves, island(More)
Associations between mites and leaf domatia are widespread, abundant and probably ancient. Recent research has shown that mites commonly shelter, develop and reproduce within domatia on plants in many geographic regions, from the tropics to the temperate zone, and most of these mites belong to predaceous or fungivorous taxa. Of hypotheses offered to explain(More)
Optimal plant defense should incorporate any mechanisms that influence the feeding behavior of potential pests. From a diverse collection of examples suggesting that the defense of a plant may be improved in the company of specific neighbors, we discuss a framework of operational mechanisms that begin to clarify some aspects of the recognized influence of(More)
In multiply invaded ecosystems, introduced species should interact with each other as well as with native species. Invader-invader interactions may affect the success of further invaders by altering attributes of recipient communities and propagule pressure. The invasional meltdown hypothesis (IMH) posits that positive interactions among invaders initiate(More)
Biological invaders can reconfigure ecological networks in communities, which changes community structure, composition, and ecosystem function. We investigated whether impacts caused by the introduced yellow crazy ant (Anoplolepis gracilipes), a pantropical invader rapidly expanding its range, extend to higher-order consumers by comparing counts, behaviors,(More)
Experiments have promise in determining mechanisms by which communities resist invasion. Growth and survivorship of transplanted seedlings of introduced tree species (Leucaena leucocephala, Muntingia calabura, Adenanthera pavonia, and Clausena excavata) were used to assess abiotic (light regime) and biotic resistance (herbivory) to invasion of rainforest on(More)
Characterstics of Australian endemic Helichrysum bracteratum and H. viscosum suggest that foraging ants act as “guards” of developing flowerheads, protecting capitula from seed predators: (1) extrafloral nectar is secreted from leaves subtending the capitula and from bracts encircling the floral disc during pre- to post-flowering periods; (2) capitula are(More)