Genetic divergence and aggressiveness within a supercolony of the invasive ant Linepithema humile

Abstract

Biological invasions constitute an opportunity to study the evolutionary processes behind species’ adaptations. The invasive potential of some species, like the Argentine ant (Linepithema humile), has likely been increasing because they show low intraspecific competition. However, multiple introductions over time or genetic divergence could increase the probability of intraspecific competition, constituting barriers for their dispersal and thus, decreasing invasive success. Here, we studied the genetic and behavioural variability of L. humile workers collected at six locations on the NW coast of the Iberian Peninsula, a possible scenario for multiple introductions and population divergence, due to its high level of maritime traffic and complex coastal geography. We analysed behaviours related to spatial navigation (exploration, wall-following), resources acquisition, and competition (inter and intraspecific aggressiveness) through two relevant seasons for the nest ecology: spring and autumn. Genetic analyses using microsatellites indicated that the nests studied belonged to the most spread supercolony in South Europe. However, we identified the existence of two genetically differentiated clusters in Galiza. Lethal interactions were found between workers from different and similar genetic clusters, but a trend suggests higher agonistic behaviours between the two genetic groups. Genetic differences were positively correlated with the geographical distance, but aggressiveness was not correlated with any of them. Ants from each of the tested nests expressed different behaviours with high plasticity through time. Ants from all nests showed more exploration and aggressiveness, less wall-following and faster detection of food in autumn than in spring, with no intraspecific aggressiveness observed in spring. Our findings suggest competition between nests of the same supercolony and behavioural seasonal variability, supporting the hypothesis of divergent evolutionary processes. The results of our work question the assumed unity of supercolonies of this species and offer insights for understanding the future adaptation of L. humile in the introduced areas.

A systematic examination of learning in the invasive antLinepithema humilereveals very rapid development of short and long-term memory

“…It might be that these ants learn better in winter. While this would be surprising, L. humile behaviour has been shown to vary seasonally (Sanmartín-Villar et al 2022). It is important to note, however, that this study was not designed to test any seasonal effect.…”

Unveiling the resistance of native weed communities: insights for managing invasive weed species in disturbed environments

“…These include DNA barcoding or microsatellite analysis to provide information on reproductive strategies, dispersion patterns, and adaptive traits of invasive species. For example, researchers used genetic markers to trace the origin and dispersal of Linepithema humile in different regions (Sanmartín‐Villar et al ., 2022). Modelling and simulation approaches such as population dynamics models and species distribution models are being utilised to forecast the possible spread and effects of invasive species under various environmental conditions (Wisz et al ., 2013; Forester, DeChaine & Bunn, 2013; Briscoe et al ., 2019; Melo‐Merino, Reyes‐Bonilla & Lira‐Noriega, 2020).…”