Using an experimental approach, I have elucidated the role of competition among Heliconiinae larvae in Puerto Rico. I used field cages to control predators and parasitoids while otherwise simulating natural conditions. By vegetatively reproducing Passiflora, I controlled for secondary compounds and other genetically influenced traits. To detect negative interactions I measured pupal weights and larval survivorship. Weight is highly correlated with wing length, with no sexual dimorphism for weight. Larval density and food quantity manipulations demonstrated that six or more individuals of Heliconius charitonius L. or Dryas julia Fab. intraspecifically compete when restricted to 600 cm('2) or less of food plant. Interspecific competition occurred at a density of six of each species. Larval development of H. charitonius is faster with a mean of 13.5 days while D. julia takes 21.5 days; consequently, in my cages, H. charitonius was the superior competitor. / One year of observation at two climatically distinct forests, Guanica (dry) and Cambalache (wet), shows variations in the relative density and distribution of heliconians and Passiflora. Guanica's distinct precipitation-induced seasonality is affected by unpredictable tropical storms; consequently abiotic factors are significant determinants of heliconian distribution and abundance. At Guanica, Passifloras are conspicuously clumped while at Cambalache, their densities are higher. Resource partitioning of new and old plant parts was observed only at Cambalache Forest; otherwise no habitat or plant species partitioning was observed. Although 72% of ovipositing females select large enough plants for their larvae to complete development at Cambalache, only 30% did so at Guanica. Even though observed predation and parasitism were low, disappearance of immatures was high, around 65%. / Comparing experimental results to field observations, I found no interspecific competition and insignificant intraspecific competition at Cambalache. At Guanica, where larvae depend on new growth, which occurs in distinct pulses, intra- and interspecific competition occurred in 38% of the observed plants. However, since adults are patchily distributed, island-wide competitive exclusion of any of the species is unlikely. / Source: Dissertation Abstracts International, Volume: 44-06, Section: B, page: 1708. / Thesis (Ph.D.)--The Florida State University, 1983.
| Identifer | oai:union.ndltd.org:fsu.edu/oai:fsu.digital.flvc.org:fsu_75118 |
| Contributors | QUINTERO, HECTOR ENRIQUE., Florida State University |
| Source Sets | Florida State University |
| Detected Language | English |
| Type | Text |
| Format | 194 p. |
| Rights | On campus use only. |
| Relation | Dissertation Abstracts International |
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