Evolutionary Ecology - EE

Adaptation in heterogeneous environments

The group ‘adaptation in heterogeneous environments’ is composed of 2 senior researchers, 1 FCT investigator and 1 post-doctoral fellow, and 2 PhD students and 1 grant holder.

Our research lies at the intersection between Ecology and Evolution. We aim at addressing the short-term evolutionary changes in populations, using ecologically-relevant scenarios. As a research model, we use spider mites, tiny spider-like arthropods that cause severe damage to several crop plants (tomato, bean, cucumber, citrus, strawberry, etc). Whenever it is possible, we use Experimental Evolution, which allows following the evolutionary trajectories of populations in real time.

Currently, we are focusing on:

1. Host-parasite interactions

(a) Plant-mite interactions: We use three spider-mite species, Tetranychus urticae, T. ludeni  (endemic crop pests) and T. evansi (an invasive species), which are plant parasites (i.e., herbivores) with different strategies to cope with plant defenses. This system is ideal to address parasite evolution in single and multiple infection scenarios and the consequences of invasions. We are testing (i) the interactions between mites and plant defences, and the direct (e.g. reproductive interference) and indirect (e.g., via the plant), interactions among different mite species.

(b) Mite-pathogen interactions: How spider mites cope with their microbial parasites remains to be elucidated. We are addressing this using functional, ecological and evolutionary approaches. This knowledge is relevant to control mite populations, with a potential economic impact.

(c) Mite-endosymbiont interactions: Wolbachia are arguably the most common sex-ratio distorting endosymbiotic bacteria. We are addressing how they interact with sex allocation and mate choice of their host, and whether they are involved in mite-plant interactions

2. Sex allocation

Spider mites produce a female-biased sex ratio, which has been attributed to the fact that their population structure favours local mate competition. Indeed, populations of spider mites are usually founded by one or few related females. Under those circumstances, it is predicted that females will produce few males, to avoid competition among related males. We have used experimental evolution to show that the adjustment of sex ratio to population structure varies with the evolutionary history of the mites. We are pursuing this research line, analyzing the populations that have evolved under different population structures.

Sex allocation may also interact with the mating strategies of spider mites, which are yet to be completely understood. Indeed, only the first male is able to fertilize females but still, spider mites often remate. We are trying to unravel this puzzle using several approaches.

3. mating strategies

In spider mites, the first male sires most of the offspring. However, males still mate with mated females. We are investigating this paradox from several angles, from the mechanistic basis of mate recognition to the eco-evolutionary implications of first male precedence.