Estimation of dispersal distances of the obligately plant‐associated ant Crematogaster decamera

Abstract

Abstract. 1. In obligate symbioses with horizontal transmission, the population dynamics of the partner organisms are highly interdependent. Host population size limits symbiont number, and distribution of partners is restricted by the presence and thus dispersal abilities of their respective partner. The Crematogaster decamera -Macaranga hypoleuca ant-plant symbiosis is obligate for both partners. Host survival depends on colonisation by its ant partner while foundress queens require hosts for colony establishment.2. An experimental approach and population genetic analyses were combined to estimate dispersal distances of foundresses in their natural habitat in a Bornean primary rainforest.3. Colonisation frequency was significantly negatively correlated with distance to potential reproductive colonies. Results were similar for seedlings at natural densities as well as for seedlings brought out in the area experimentally. Population genetic analysis revealed significant population differentiation with an F ST of 0.041 among foundresses (n = 157) located at maximum 2280 m apart. In genetic spatial autocorrelation, genotypes of foundresses were significantly more similar than expected at random below 550 m and less similar above 620 m. Direct estimation of dispersal distances by pedigree analysis yielded an average dispersal distance of 468 m (maximum 1103 m).4. For ants that disperse on the wing, genetic differentiation at such small spatial scales is unusual. The specific nesting requirements of the queens and the necessity for queens to find a host quickly could lead to colonisation of the first suitable seedling encountered, promoting short dispersal distances. Nonetheless, dispersal distances of C. decamera queens may vary with habitat or host spatial distribution.

Differential bait preference and rate of attraction by Argentine ants (Linepithema humileMayr) at freshwater and saltwater marsh sites in southern California

“…Although we did not directly investigate dispersal mechanisms or food resources, C. pilosa likely has the potential to colonize the entire salt marsh but will establish only in areas with adequate resources and habitat. Most ants, including other Crematogaster species, have winged reproductive castes allowing the species to populate new environments (e.g., Türke et al 2010). We found ants on islets within tidal creeks, indicating they have a dispersal strategy allowing them to colonize areas not connected to current populations.…”

Stabilizing Mutualisms Threatened by Exploiters: New Insights from Ant–Plant Research

“…Because plant ants usually swarm at night and find their host over comparably large distances (Türke et al . ), many of them use volatile organic compounds (VOCs) in their host‐finding behavior. The queens of both Azteca and Allomerus ants are attracted to the VOCs emitted by C. nodosa plants, which suggests that they use olfactory cues for the long range detection of their host plants (Edwards et al .…”

Asymmetric Dispersal and Colonization Success of Amazonian Plant-Ants Queens

“…Theory suggests that interspecific differences in the dispersal capability of ant queens play a key role in the maintenance of diversity in these communities, either via tradeoffs between dispersal ability and other life-history traits (e.g., competitive ability, colony fecundity), or from the interaction of dispersal limitation with spatial heterogeneity in host-plant density (reviewed in [3]). Studies in multiple plant-ant systems have demonstrated inequities in the competitive ability of ant queens or colonies [16], [17], plant and colony distribution consistent with habitat partitioning and patch dynamics [18], [19], and patterns of colonization that imply dispersal limitation [8], [12], [20] or interspecific variation in dispersal ability [20], [21]. Nevertheless, drawing general conclusions regarding the importance of dispersal for plant-ant coexistence requires quantitative descriptions of dispersal for multiple ants competing for access to the same host-plants.…”