Diversity in motion: the influence of dispersal and metacommunity spatial structure on invertebrate communities in Heliconia phytotelmata
Abstract
A recent trend in community ecology is to investigate the influence of dispersal (a
regional process) on the structure and formation of communities. Dispersal of
individuals is important not only for colonization of habitats, but also for maintenance of
diversity within communities, as dispersal can influence local species interactions.
Herein, I examine the role of dispersal from two viewpoints using a metacommunity of
aquatic invertebrates that inhabit inflorescences of Heliconia imbricata (Zingiberales:
Heliconiaceae).
First, I examined the response of local communities to changes in metacommunity
spatial-structure, including an analysis of the effect on community development. In these
detritus-based communities where positive interactions are dominant and dispersal
limitation is common, spatial isolation decreased local species richness, altered
invertebrate composition, and increased turnover. Additionally, spatial isolation and
community development (succession) had an interactive effect on species richness and
turnover, thus indicating that dispersal has important predictive impacts to succession not
previously documented. These studies were conducted in secondary forest locations
where prior land-use practices have affected forest regeneration and consequently the
spatial structure H. imbricata. Hence, this has relevance to studies of habitat
fragmentation, and demonstrates the usefulness of metacommunity ecology to
conservation biology.
Second, I examined whether dispersal by a single species can impact community
formation (priority effects) leading to development of alternative community states.
Using a combination of mark-recapture techniques and correlational as well as
experimental studies, I tested the effect of a primary consumer, Cephaloleia puncticollis
(Coleoptera: Hispinae), on local community structure and investigated consequences of
dispersal by C. puncticollis on community-level diversity. Results showed that
C. puncticollis larvae, but not adults, affect invertebrate community structure. At the
landscape level, greater C. puncticollis abundance within patches increased invertebrate
species richness and altered composition by increasing predators and detritivores,
resulting in two community types. Overall, invertebrate communities within H.
imbricata inflorescences are affected by the positive interactions of C. puncticollis,
though effects are varied in space and correspond to dispersal of individuals. While
many other factors contribute to patterns of diversity in this system, this study
demonstrates the importance and combined effects of local and regional processes on
ecological communities.
Department
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