Co-occurrence patterns among rocky inter-tidal gastropod community
Student name: Ms Mahi Puri
Guide: Dr Joachim Schmerbeck
Year of completion: 2012
Host Organisation: Centre for Ecological Sciences, Indian Institute of Science, Bangalore
Supervisor (Host Organisation): Dr Kartik Shanker
Abstract: The current study examines co-occurrence patterns in the gastropod community in rocky intertidal
areas along the west coast of India. Over the last four decades, inter-tidal ecology has
evolved from purely descriptive science to experimentation, but at the cost of understanding
generality as many studies have focused on local spatial scales and patch dynamics. We aimed
to assess the generality of co-occurrence patterns at a broader spatial scale, covering over 1000
km by comparing empirical association patterns with random patterns generated by
simulations. We also estimated pair-wise species associations to examine patterns at different
scales. Our results show that at large spatial scales, community structure is non-random and
matches the predictions of Diamond’s assembly rules. Although these analyses show that the
observed co-occurrences are less than expected by chance, they do not confirm the mechanisms
of assembly rules that such deterministic distribution is because of competitive biotic
interactions between species, as the patterns do not emerge at the smallest spatial scales, at
which biotic interactions actually take place. Thus, even though biotic interactions play a vital
role in determining species co-occurrence, dispersal seems to be the most important
determinant of association pattern, when different scales are taken into consideration.
Keywords: Gastropods, rocky inter-tidal, co-occurrence, dispersal
