Analysis of avian communities in Lake Guri, Venezuela, using multiple assembly rule models

Abstract

This study analyzed the distribution of resident, forest-interior bird species nesting on islands in Lake Guri, Venezuela using several different community assembly rule models. The models that were tested included Diamond's Assembly Rules, Size Structure, Guild Proportionality, Favored States, and Nestedness. It was determined that the species composition of the study communities was only weakly influenced by competition, but that competition did appear to limit the size similarity which is permissible for co-occurring species. There was no tendency for the relative proportion of species within guilds (i.e. insectivore, omnivore, nectivore and frugivore) to remain stable among the islands. When only the insectivorous and omnivorous species were analyzed (using feeding strata as the functional groups) there was some support for the guild proportionality hypothesis. This study found no support for Fox's Favored State hypothesis, possibly due to the overrepresentation of insectivores and omnivores in the species pool. The island communities exhibit a highly nested structure. This high degree of nestedness supports the hypothesis that the assemblages are more strongly determined by differential extinction vulnerability and selective species loss than by interspecific or inter-guild competition. Understanding patterns of community assembly and their underlying forces has important implications for conservation ecology and reserve design.

Species interactions regulate the collapse of biodiversity and ecosystem function in tropical forest fragments

“…Some studies argue that fragmentation reduces interspecific competition by generating new niche axes (Buchmann et al 2013) or limiting the scope for monopolization, thus allowing more species to co-occur (e.g., Levin 1974, Atkinson andShorrocks 1981). Other studies provide evidence that competition is elevated in smaller fragments (Feeley 2003, Bennett et al 2014, which seems plausible if the overall pool of resources declines in parallel with fragment size, increasing the likelihood of resource limitation and competitive exclusion. However, these alternative hypotheses have rarely been tested directly, with most studies focusing on the extent to which local extinction is mediated by species traits rather than species interactions (e.g., Robinson et al 1992, McKinney and Lockwood 1999, Smith and Knapp 2003, Banks-Leite et al 2012, Senior et al 2013).…”

Pattern in the Co-occurrence of Fishes Inhabiting the Coral Reefs of Bonaire, Netherlands Antilles

“…In order to explore the relationships of species in each cluster group based on functional roles, we assigned a trophic guild (i.e., herbivore, planktivore, browser, microinvertivore, macroinvertivore, piscivore; Table 1) to each species based on summaries of trophic status in Bohnsack (2002) and Randall (1967). To test the hypothesis that each cluster group contained constant proportions of species within trophic guilds, we compared the differences in guild representation between groups by using v 2 goodness-of-fit tests (Wilson 1989, Feeley 2003. Species that were originally assigned to multiple trophic guilds were subsequently assigned to a single major group (except we combined micro-and macro-invertivores), based on prey preferences of adults, to avoid violating assumptions of the goodness-of-fit test due to zeros in the data matrix .…”

Patrones de coocurrencia y conducta alimentaria a escala local de Phlebotominae (Diptera: Psychodidae) del estado Falcón, Venezuela

“…Los gremios ecológicos son grupos de especies dentro de una comunidad que comparten recursos que les son comunes: es más probable que especies dentro de un mismo gremio interactúen o compitan por recursos que las de diferentes gremios (Gotelli 2000;Gotelli & Entsminger 2003). Asimismo, se realizó la prueba de la hipótesis de los estados favorecidos (Fox 1987), y que no es más que una variante más estricta del modelo de gremios (Feeley 2003). Un estado favorecido correspondería si la distribución de las especies entre los gremios es uniforme dentro de las comunidades (Feeley 2003, Gotelli & Entsminger 2003.…”

“…Uno de los tópicos que ecología de comunidades presta a más atención es la identificación de los mecanismos generales que gobiernan la estructura de las comunidades biológicas ("reglas de ensamble"), y aunque se han propuesto varias reglas se le ha dado mayor relevancia a las interacciones interespecíficas (competencia, mutualismo) (Vilchis 2000, Chase 2003, Feeley 2003. Sin embargo, es necesario indicar que la coexistencia entre las especies puede estar gobernada por fuerzas competitivas y no competitivas (Gordon 2000).…”