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Institut Sophia Agrobiotech

UMR INRA - Univ. Nice Sophia Antipolis - Cnrs

http://www.paca.inra.fr/institut-sophia-agrobiotech_eng/

Seasonality causes disruptive selection in plant parasites

Seasonality causes disruptive selection in plant parasites (TEAPEA Team)

Coexistence of closely related plant parasites is widespread. Yet, understanding the ecological determinants of evolutionary divergence in plant parasites remains an issue. Niche differentiation through resource specialization is not sufficient to explain the coexistence of parasites exploiting the same host plant. Most agricultural systems are characterized by a cyclical presence and absence of the crop, due to cropping practices such as harvest and planting. We studied the influence that temporal partitioning can have on co-existence of different parasite strains (specialization for the beginning or the end of crop presence).
We used a semi-discrete epidemiological model* to describe parasite dynamics together with an evolutionary invasion analysis*. Our analysis revealed that the seasonal feature of agrosystems can induce complex plant-parasite dynamics1 and is also an important force promoting evolutionary diversification and coexistence of different strains of the parasite phenotype2. Such a result highlights the major influence of temporal variations of the environment on ecological and evolutionary dynamics of species, through temporal partitioning of the utilization of a time-varying resource.

*Semi-discrete epidemiological model is a modeling framework used to describe processes following continuous-time dynamics most of the time which are perturbed by recurrent discrete-time events (Mailleret and Lemesle, 2009).

*Evolutionary invasion analysis: also known as adaptive dynamics; a set of mathematical techniques for studying long-term phenotypical evolution from population dynamics models.

 

Ecological co-existence of two strains of plant parasites (I1 and I2) through temporal partitioning. Curves are computed from simulations of the seasonal plant epidemic model1,2. Upper panel: epidemiological dynamics over thirty seasons. Lower panel: focus on the stationary solution reached by the epidemic over the last three seasons of the simulation.

Ecological co-existence of two strains of plant parasites (I1 and I2) through temporal partitioning. Curves are computed from simulations of the seasonal plant epidemic model1,2. Upper panel: epidemiological dynamics over thirty seasons. Lower panel: focus on the stationary solution reached by the epidemic over the last three seasons of the simulation.

  • Mailleret L., Castel M., Montarry J. & Hamelin F.M. (2012). From elaborate to compact seasonal plant epidemic models and back: is competitive exclusion in the details? Theoretical Ecology, 5, 311-324

Related

  • Hamelin F.M., Castel M., Poggi S., Andrivon D. & Mailleret L. (2011). Seasonality and the evolutionary divergence of plant parasites.Ecology, 92, 2159-2166