Low host specificity and broad geographic ranges in a community of parasitic non‐pollinating fig wasps (Sycoryctinae; Chalcidoidea)

Deng, X., Chen, L., Tian, E., Zhang, D., Wattana, T., Yu, H., Kjellberg, F. and Segar, S.T. (2021) Low host specificity and broad geographic ranges in a community of parasitic non‐pollinating fig wasps (Sycoryctinae; Chalcidoidea). Journal of Animal Ecology.

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Plants, phytophagous insects and their parasitoids form the most diverse assemblages of macroscopic organisms on earth. Enclosed assemblages in particular represent a tractable system for studying community assembly and diversification. Communities associated with widespread plant species are especially suitable as they facilitate a comparative approach. Pantropical fig wasp communities represent a remarkably well replicated system, ideal for studying these historical processes. We expect high dispersal ability in non‐pollinating fig wasps to result in lower geographic turnover in comparison to pollinating fig wasps. The ability of non‐pollinating wasps to utilise a number of hosts (low host specificity) is a key determinant of overall geographical range, with intraspecific competition becoming a constraining factor should diet breadth overlap among species. Finally, we expect conserved community structure throughout the host range. We aim to test these expectations, derived from population genetic and community studies, using the multi‐trophic insect community associated with Ficus hirta throughout its 3500 km range across continental and insular Asia. We collect molecular evidence from one coding mitochondrial gene, one non‐coding nuclear gene and multiple microsatellites across 25 geographical sites. Using these data, we establish species boundaries, determine levels of host specificity among non‐pollinating fig wasps and quantify geographical variation in community composition. We find low host specificity in two genera of non‐pollinating fig wasps. Functional community structure is largely conserved across the range of the host fig, despite limited correspondence between the ranges of non‐pollinator and pollinator species. While nine pollinators are associated with Ficus hirta, the two non‐pollinator tribes developing in its figs each contained only four species. Contrary to predictions we find stronger isolation by distance in non‐pollinators than pollinators. Long lived non‐pollinators may disperse more gradually and be less reliant on infrequent long‐distance dispersal by wind currents. Segregation among non‐pollinating species across their range is suggestive of competitive exclusion and we propose that this may be a result of increased levels of local adaptation and moderate, but regular, rates of dispersal. Our findings provide one more example of lack of strict codiversification in the geographic diversification of plant associated insect‐communities.

Item Type: Article
Keywords: Beta‐diversity, community assembly, mutualism, parasitoid, population genetics
Divisions: Agriculture and Environment (from 1.08.20)
Depositing User: Mrs Rachael Harper
Date Deposited: 08 Apr 2021 08:31
Last Modified: 22 Jul 2021 11:30
URI: https://hau.repository.guildhe.ac.uk/id/eprint/17664

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