Local adaptation in a phoretic mite-burying beetle symbiosis
Ecology and Biodiversity of Animals and Ecosystems, Organismic Interactions
Final Report Abstract
All life is interconnected. Most if not all species regularly interact with others to the extent that their fitnesses are in one way or another affecting each other. Such reciprocal selection that two species pose on each other can lead to coevolution, where one species adapts to the other, and the other species then adapts to the adaptive changes in the first. Coevolution between species has led to many of the major transitions in evolution, can speed up evolution, and is contributing to and maintaining biodiversity. Since the ecological conditions vary across different habitats, the species interactions might be different in different locations. We studied the symbiosis of a phoretic mite with burying beetles to test whether different microevolutionary trends may lead to these so-called “geographic mosaics of coevolution”, with strong local adaptation and symbiont specialisation in some habitats, but relaxed coevolution with generalist symbionts in others. We found that indeed bites and beetles locally adapted to the environment, specifically the temperature. We found evidence for so-called countergradient variation, which means that development in populations is sped up in cold-adapted populations to counteract the fact that low temperatures directly slow down physiological processes. Both mites and beetles reacted similarly to changes in temperature, indicating that their temperature reaction norms are similar. This is important because for optimal mite fitness, mite and beetle development need to be synchronised. We further found evidence for a geographic mosaic of coevolution. While some populations of mites and beetles were locally adapted to their symbionts (i.e. their fitness was higher with local symbionts than with those from other regions), the opposite was the case in other populations. This indicates that there may be close coevolution, potentially with fluctuating red queen dynamics, within each habitat. Beetle and mite traits vary over time: sometimes the mites fare better, and sometimes the beetles, depending on how well the traits of the two species match. However, low mite fitness did not necessarily lead to high beetle fitness and vice versa, which indicates that one consequence of close coevolution may sometimes be reduced virulence, so that the fitness of both symbionts can increase over time.
Publications
- (2017) Phoretic Poecilochirus mites specialise on their burying beetle hosts. Ecol. Evol. 7: 10743–10751
Nehring, V., Müller, J.K., Steinmetz, N.
(See online at https://doi.org/10.1002/ece3.3591) - (2018) Rapid adaptation in phoretic mite development time. Sci. Rep. 8: 16460
Schedwill, P., Geiler, A.M., Nehring, V.
(See online at https://doi.org/10.1038/s41598-018-34798-6) - (2019) Dose-independent virulence in phoretic mites that parasitize burying beetles. Int. J. Parasitol. 49:759-767
Nehring, V., Teubner, H., König, S.
(See online at https://doi.org/10.1016/j.ijpara.2019.05.011) - (2020) From the host’s point of view: Effects of variation in burying beetle brood care and brood size on the interaction with parasitic mites. Plos ONE 15: e0228047
Schedwill, P., Paschkewitz, S., Teubner, H., Steinmetz, N., Nehring, V.
(See online at https://doi.org/10.1371/journal.pone.0228047) - (2021): Cryptic diversity within the Poecilochirus carabi mite species complex phoretic on Nicrophorus burying beetles: phylogeny, biogeography, and host specificity
Canitz, J., Sikes, D.S., Knee, W., Baumann, J., Haftaro, P., Steinmetz, N., Nave, M., Eggert, A.-K., Hwang, W., Nehring, V.
(See online at https://doi.org/10.1101/2021.05.20.443311)
