19 research outputs found
Stochastic dynamics of adaptive trait and neutral marker driven by eco-evolutionary feedbacks
How the neutral diversity is affected by selection and adaptation is
investigated in an eco-evolutionary framework. In our model, we study a finite
population in continuous time, where each individual is characterized by a
trait under selection and a completely linked neutral marker. Population
dynamics are driven by births and deaths, mutations at birth, and competition
between individuals. Trait values influence ecological processes (demographic
events, competition), and competition generates selection on trait variation,
thus closing the eco-evolutionary feedback loop. The demographic effects of the
trait are also expected to influence the generation and maintenance of neutral
variation. We consider a large population limit with rare mutation, under the
assumption that the neutral marker mutates faster than the trait under
selection. We prove the convergence of the stochastic individual-based process
to a new measure-valued diffusive process with jumps that we call Substitution
Fleming-Viot Process (SFVP). When restricted to the trait space this process is
the Trait Substitution Sequence first introduced by Metz et al. (1996). During
the invasion of a favorable mutation, a genetical bottleneck occurs and the
marker associated with this favorable mutant is hitchhiked. By rigorously
analysing the hitchhiking effect and how the neutral diversity is restored
afterwards, we obtain the condition for a time-scale separation; under this
condition, we show that the marker distribution is approximated by a
Fleming-Viot distribution between two trait substitutions. We discuss the
implications of the SFVP for our understanding of the dynamics of neutral
variation under eco-evolutionary feedbacks and illustrate the main phenomena
with simulations. Our results highlight the joint importance of mutations,
ecological parameters, and trait values in the restoration of neutral diversity
after a selective sweep.Comment: 29 page
Biotic soil-plant interaction processes explain most of hysteretic soil CO2 efux response to temperature in cross-factorial mesocosm experiment
Ecosystem carbon fux partitioning is strongly infuenced by poorly constrained soil CO2 efux (Fsoil).
Simple model applications (Arrhenius and Q10) do not account for observed diel hysteresis between
Fsoil and soil temperature. How this hysteresis emerges and how it will respond to variation in
vegetation or soil moisture remains unknown. We used an ecosystem-level experimental system to
independently control potential abiotic and biotic drivers of the Fsoil-T hysteresis. We hypothesized
a principally biological cause for the hysteresis. Alternatively, Fsoil hysteresis is primarily driven by
thermal convection through the soil profle. We conducted experiments under normal, fuctuating
diurnal soil temperatures and under conditions where we held soil temperature near constant. We
found (i) signifcant and nearly equal amplitudes of hysteresis regardless of soil temperature regime,
and (ii) the amplitude of hysteresis was most closely tied to baseline rates of Fsoil, which were mostly
driven by photosynthetic rates. Together, these fndings suggest a more biologically-driven mechanism
associated with photosynthate transport in yielding the observed patterns of soil CO2 efux being out
of sync with soil temperature. These fndings should be considered on future partitioning models of
ecosystem respiration.French governmentFrench National Research Agency (ANR)
ANR-10-IDEX-0001-02 PSL
ANR-11-INBS-0001ENSUniversity of Arizona (UofA)Philecology Foundation (Fort Worth, Texas, USA)Thomas R. Brown Family FoundationRegion Ile-de-France
I-05-098/R
2011-11017735European Union (EU)National Science Foundation (NSF)
1417101
1331408European Union (EU)
625988UofA Office of Global InitiativesOffice of the Vice President of Research at the UofAUMI iGLOBES program at the Uof
Clade diversification dynamics and the biotic and abiotic controls of speciation and extinction rates
The history and patterns of species diversity are shaped by a variety of ecological and evolutionary factors. Here, the authors develop a computational model to predict clade diversification dynamics and rates of speciation and extinction under the influences of resource competition, genetic differentiation, and random landscape fluctuation
Data from: Direct and indirect ecosystem effects of evolutionary adaptation in the Trinidadian guppy (Poecilia reticulata)
Ecological and evolutionary processes may interact on the same timescale, but we are just beginning to understand how. Several studies have examined the net effects of adaptive evolution on ecosystem properties. However, we do not know if the these effects are confined to direct interactions or if they propagate further through indirect ecological pathways. Even less well understood is how the combination of direct and indirect ecological effects of the phenotype promotes or inhibits evolutionary change. We coupled mesocosm experiments and ecosystem modeling to evaluate the ecological effects of local adaptation in Trinidadian guppies (Poecilia reticulata). The experiments show that guppies adapted to life with and without predators alter the ecosystem directly through differences in diet. The ecosystem model reveals that the small total indirect effect of the phenotype observed in the experiments is likely a combination of several large indirect effects which act in opposing directions. The model further suggests that these indirect effects can reverse the direction of selection that direct effects alone exert back on phenotypic variation. We conclude that phenotypic divergence can have major effects deep in the web of indirect ecological interactions and even small total indirect effects can radically change the dynamics of adaptation