Original paper

Relationships within aquatic beetle (Coleoptera) communities in the light of ecological theories

Pakulnicka, Joanna; Górski, Andrzej; Bielecki, Aleksander; Buczyński, Paweł; Tończyk, Grzegorz; Cichocka, Joanna M.

Abstract

Researchers have been attempting to elucidate mechanisms controlling the formation of assemblages of various species in the light of classical niche theories and, more recently, a newer and very controversial approach known as the neutral theory. It remains a difficult task to resolve the question whether the organization of biocenotic communities is a result of stochastic or deterministic processes, particularly because the answer often depends on the scale of available empirical research. In search of an answer to the question as to why do some species occur together in communities, while others tend to avoid each other, we applied neutral theory. We focused on the water beetles, a group of organisms which are favorable for research because of their frequent occurrence and functional and ecological diversity. The study was conducted in 2011?2012 at 12 lakes located in the North-East of Poland, diverse in terms of area, as well as trophic and habitat diversity of the littoral zone. In total, 4418 individuals representing 108 species were collected in 246 samples. The nine most frequently occurring species were used for the analysis which was based on single samples, in which the correlations between pairs of co-occurring species were examined. In accordance with the neutral theory the study did not assume, a priori, the membership of species to any particular guild or synecological group. As a result, 36 possible combinations of pairs of species were evident, while 5 pairs showed no statistically significant correlation and belonged to the same guild. In 12 cases a very high negative correlation was found, indicating avoidance between the two species: high ? in 11, average ? in 6, and weak ? in one pair. Next, using the Principal Component Analysis (PCA) method, the relationship between isolated pairs of species and environmental quality variables was studied. In pairs representing the same species guild this relationship proved strong in some cases, while in others it was weak or average. However, for species belonging to different guilds mutual avoidance is a consequence of a strong relation with environmental conditions and the ecological specialization of species. Our analysis suggests that the co-occurrence of many species is sometimes a consequence of their specialization, but there are cases when the reason seems to be quite the opposite, i.e. an ecological drift.

Keywords

aquatic beetlesco-occurrencecorrelationneutral theoryniche