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R Ferrière

Publications and source records attributed to R Ferrière.

6 recordsLinked to original sources
PubMed2006

Coevolution of slow-fast populations: evolutionary sliding, evolutionary pseudo-equilibria and complex Red Queen dynamics.

We study the interplay of ecological and evolutionary dynamics in communities composed of populations with contrasting time-scales. In such communities, genetic variation of individual traits can cause population transitions between stationary and cyclic ecological regimes, hence abrupt variations in fitness. Such abrupt variations raise ridges in the adaptive landscape, where the populations are poised between equilibrium and cyclic coexistence and along which evolutionary trajectories can remain sliding for long times or halt at special points called evolutionary pseudo-equilibria. These novel phenomena should be generic to all systems in which ecological interactions cause fitness to vary discontinuously. They are demonstrated by the analysis of a predator-prey community, with one adaptive trait for each population. The eco-evolutionary dynamics of the system show a number of other distinctive features, including evolutionary extinction and two forms of Red Queen dynamics. One of them is characterized by intermittent bouts of cyclic oscillations of the two populations.

Adaptation, Physiological↗
PubMed2001

On mutualists and exploiters: plant-insect coevolution in pollinating seed-parasite systems.

We investigate the coevolution of time of flowering and time of pollinator emergence in an obligate association between a plant and an insect that both pollinates and parasitizes flowers. Numerical analysis shows that the system in general evolves towards a time of flowering different from the time favoured by the abiotic environment. The equilibrium towards which the system evolves is a local fitness maximum (an ESS) with respect to mutational variation in flowering time but, for the insect, it can be a local fitness minimum at which selection on mutational variation in the time of insect emergence is disruptive. A consequence of evolutionary convergence to a fitness minimum is that pollinators having an earlier phenology can coexist with pollinators having a later phenology. Since late emerging insects are more likely to encounter and oviposit within previously pollinated flowers, their effect on the plant is more exploitative, leading them to function as cheaters within the system. Thus, in the long term, pollinators and exploiters are likely to be found in stable coexistence in pollinating seed-parasite systems.

Animals↗
PubMed1993

Chaotic population dynamics can result from natural selection.

The question of whether animal populations display chaotic dynamics has motivated a thriving body of research for two decades. Yet unambiguous evidence for chaos in the wild remains scarce. Accordingly, it has been proposed that evolutionary forces act to preserve populations from chaos as well as oscillations. We have tested for this hypothesis by considering the dynamics associated with evolutionarily stable life histories (including age of maturity, adult survivorship and recruitment to adulthood) in a simple, but general, demographic model. Contrary to expectation, individual selection operating on demographic traits should often lead to oscillatory or chaotic dynamics for species with late feasible ages of maturity and many age classes. Also, the optimality of chaos is more likely whenever trade-offs constrain recruitment to rapidly decrease with increasing adult survival or decreasing age of maturity. Our results bring evolutionary support to the possibility that chaotic population dynamics might be much more widespread than inferred until now from data analyses. Furthermore, these findings provide novel support for the view that chaos could be an optimal regime for several biological systems.

Aging↗
PubMed1992

Evolutionarily stable age at first reproduction in a density-dependent model.

We develop a new model of life history evolution to investigate the evolution of age at first reproduction. Density dependence is taken into account. For a given "species", age of maturity, offspring survival, immature survival, adult survival, fecundity, immature age-classes entering in competition with adults and immature competitive ability are traits adjustable by natural selection, and constitute a particular strategy. On the contrary, the type of intraspecific competition (scramble or contest), strength of competition and inherent net reproductive rate Ro(inh) are fixed (specific) characteristics. As a consequence of fixing Ro(inh), the evolution of any trait will affect trade-offs between others. Evolutionarily stable strategies are determined numerically by using the mathematical concept of Lyapunov exponents. Altogether, we consider 960 different hypothetical "species" (i.e. different combinations of fixed traits). Corresponding ESSs are analyzed with respect to their age at first reproduction, adult survival and immature competitive ability components. They appear to be gathered in three groups. One is intuitive and characterized by a reduction of immature competitive ability and a correlation of age of maturity with adult survival; populations reach mainly equilibria. The two other groups respectively include "species" with low age of maturity but high adult survival, and "species" close to semelparity with delayed maturity; immature competitive ability may not be minimized, and populations possibly exhibit complex dynamics. In conclusion, the hypothesis that the evolution of a demographic parameter modifies trade-offs between others turns out to have important consequences. We argue that life history theory cannot ignore the source and mode-of-operation of density dependence and must regard potential short-term instability as essential.

Animals↗