Eco-Evolutionary Dynamics in Cold Blood
Eco-evolutionary dynamics occur when ecological change influences evolutionary change (eco-to-evo) and when evolutionary change influences ecological change (evo-to-eco), both on contemporary time scales. Fishes, amphibians, and reptiles have played important roles as study animals in the empirical study and exploration of these dynamics. We suggest that this primacy stems in part from the sweet-spot that many species of fishes, amphibians, and reptiles occupy on the continuum from experimental convenience to ecological importance, as well as on the particular organismal properties that they share, including indeterminate growth and ectothermy. Yet our overall understanding of eco-evolutionary dynamics remains very limited. In the hope of reducing this information gap, the present symposium proceedings include 12 contributions that speak directly to three critical topics in eco-evolutionary dynamics: the role of human influences, constraints and alternatives, and the context dependence of eco-evolutionary dynamics in nature.
An example of phenotypic plasticity in the context of evolutionary change. In the top panel, a population may express differing ranges of phenotypes depending on different environmental conditions. The distributions of these phenotypes (normal curves) vary but remain within the limits (dashed lines) of what is genetically possible. In the lower panel, an evolutionary change in the genetic structure of the population has shifted the range of possible phenotypes along the fitness landscape. The evolution of the population may be masked by phenotypic plasticity and appear to be unchanged (gray-filled curves) depending on conditions.
Common garden vs. common gardening experiments in eco-evolutionary dynamics. A common garden experiment (top panel) raises different phenotypes, usually taken from nature, under identical conditions to test if the variation is due to genetic differences or due to phenotypic plasticity. A common gardening experiment (bottom panel) places different phenotypes (which can be from a common garden experiment) into identical environments and then monitors how the environment changes.
Fryxell and Palkovacs (this volume, 2017) used experimental ponds to test whether thermal context influenced predator intra-specific effects. Warming (warmed relative to unwarmed mesocosms) enhanced top-down fish effects on zooplankton biomass and strengthened ecological effects differences between two recently (<100 years) diverged source populations of mosquitofish. The cool-source population reduced zooplankton biomass more than did the warm-source population in warmed, but not in unwarmed, mesocosms.
Urban et al. (this volume, 2017) found that Wood Frog tadpoles display adaptive reaction norms in response to Marbled Salamander predation. The survival of Wood Frog tadpoles depended on whether populations came from high-risk sites (solid line) or low-risk sites (dotted line), as well as whether they were raised in high-predation risk or low-predation risk environments.
Brady and Goedert (this volume, 2017) documented family-level variation in larval Wood Frog survival across the interaction of population type by environment. Black lines represent roadside populations and gray lines represent woodland populations. Adaptive genotypic variation is present among the roadside populations despite the average pattern of maladaptive survival they exhibit.
Kindsvater and Palkovacs (this volume, 2017) used models to show how demography and adaptation could interact to shape the abundance, body size distribution, and trophic role of Atlantic Cod.
Fitzpatrick et al. (this volume, 2017) explored multivariate trait responses to gene flow in female guppies. Shown are results of discriminant analysis of principal components (DAPC) ordination and 95% confidence ellipses. Two recipient pre-gene flow populations (light fill, small-dashed ellipses) received gene flow from a divergent source population (dark fill). Traits were measured in post-gene flow populations (no fill, large-dashed ellipses) approximately ten generations after gene flow. All traits were measured on second-generation lab-reared guppies in a common environment.
Simon et al. (this volume, 2017) explored the effects of guppy ecotypes on ecosystems in nature. Shown are least square means (±1 standard error) for algal biomass in streams with locally adapted low-predation (LP) guppies or introduced high-predation (HP) guppies. The authors found a significant interaction between fish community type and guppy ecotype for algal biomass, indicating that the effects of guppies depend on the phenotype of the population.
Contributor Notes
From “Eco-Evolutionary Dynamics in Cold Blood,” an ASIH-sponsored symposium at the 2016 Joint Meeting of Ichthyologists and Herpetologists in New Orleans, Louisiana.