Negative occurrence patterns of two native ant species (Monomorium antarcticum and Prolasius advenus) within beech forests

Rafael Barbieri *1, Julien Grangier 1, Phil Lester 1

1 School of Biological Sciences, Victoria University of Wellington, PO Box 600, Wellington, 6140, NZ

What are the factors that influence species distributions and abundances? Monomorium antarcticum and Prolasius advenus are native, generalist and ubiquitous ant species in New Zealand. Our study examines the spatial distribution of these species, as well as disentangling the mechanisms determining patterns. Two 1 km2 sites were sampled; one in South Island (Nelson Lakes) and one in the North Island (Kaitoke Regional Park). Results indicate that these species present negative co-occurrence patterns. In beech forests Prolasius is very abundant and seem to exclude Monomorium, as this ant is only found in grassy areas or forest edges. However, some Prolasius nests can be found in open areas. Observations in the laboratory highlighted behavioral mechanisms that could explain these patterns. Prolasius is dominant over Monomorium, spraying acid and biting them, indicating that Prolasius may be an aggressive-key species in the ant community. Overall our results suggest that competition may play an important role in determining the ant mosaic in New Zealand beech forests.

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