Data and code from: Climate and parasite pressure jointly shape traits mediating the coevolution between an ant social parasite and its host

Host-parasite relationships are often shaped by coevolutionary arms races.
While abiotic influences on these dynamics are well documented, a combined
analysis of abiotic and biotic factors is essential for understanding
coevolution, particularly under climate change. In this study, we analysed
the interactions of the obligate social parasite Temnothorax americanus, a
dulotic ant, and its primary host, the ant Temnothorax longispinosus,
focusing on behavioural and cuticular hydrocarbon (CHCs) traits that
govern parasite invasion and host defence. We studied the link between
these traits and local climate as well as parasite prevalence. Our results
revealed that behavioural interactions were more strongly associated with
climate than parasite prevalence. Hosts from warmer, drier regions
exhibited reduced aggression during parasite encounters, opting to pick up
the brood and flee, while parasites from these regions exhibited greater
aggression and activity. CHCs mediating enemy recognition in these ants
were linked to local climate and parasite prevalence in both species. As
all colonies were maintained under standardised conditions for a year, we
attribute the observed phenotypic traits to evolutionary adaptation rather
than phenotypic plasticity. Our findings suggest that both abiotic and
biotic factors play critical roles in shaping co-evolving traits,
sometimes leading to unexpected patterns that would potentially be
overlooked when considering only a single factor. These insights provide a
framework for understanding how climate influences coevolution of
interacting species.