| Literature DB >> 36188513 |
Sigurd Einum1, Emil R Ullern1, Matthew Walsh2, Tim Burton1,3.
Abstract
Invasive predatory species are frequently observed to cause evolutionary responses in prey phenotypes, which in turn may lead to evolutionary shifts in the population dynamics of prey. Research has provided a link between rates of predation and the evolution of prey population growth in the lab, but studies from natural populations are rare. Here, we tested for evolutionary changes in population dynamics parameters of zooplankton Daphnia pulicaria following invasion by the predator Bythotrephes longimanus into Lake Kegonsa, Wisconsin, US. We used a resurrection ecological approach, whereby clones from pre- and post-invasive periods were hatched from eggs obtained in sediment cores and were used in a 3-month growth experiment. Based on these data, we estimated intrinsic population growth rates (r), the shape of density dependence (θ) and carrying capacities (K) using theta-logistic models. We found that post-invasion Daphnia maintained a higher r and K under these controlled, predation-free laboratory conditions. Evidence for changes in θ was weaker. Whereas previous experimental evolution studies of predator-prey interactions have demonstrated that genotypes that have evolved under predation have inferior competitive ability when the predator is absent, this was not the case for the Daphnia. Given that our study was conducted in a laboratory environment and the possibility for genotype-by-environment interactions, extrapolating these apparent counterintuitive results to the wild should be done with caution. However, barring such complications, we discuss how selection for reduced predator exposure, either temporally or spatially, may have led to the observed changes. This scenario suggests that complexities in ecological interactions represents a challenge when predicting the evolutionary responses of population dynamics to changes in predation pressure in natural systems.Entities:
Keywords: bottom‐up; density‐dependent selection; invasion ecology; predator–prey interactions; top‐down; zooplankton
Year: 2022 PMID: 36188513 PMCID: PMC9487876 DOI: 10.1002/ece3.9348
Source DB: PubMed Journal: Ecol Evol ISSN: 2045-7758 Impact factor: 3.167
AICc comparisons of candidate models explaining variation in observed intrinsic population growth rate (r) carrying capacity (K) and the shape of density dependence (θ) of experimental populations of Daphnia pulicaria originating from Lake Kegonsa. For r, separate linear mixed effects models are fitted to numerical and biomass population growth rate as dependent variables. Full models include effects of invasion history (whether the population originates from a period before or after invasion by the predatory zooplankton species Bythotrephes longimanus), with clone ID as a random effect. For K and θ, separate theta‐logistic models are fitted to numerical population growth rate and biomass population growth rate as dependent variables. Full models include effects of invasion history on K and θ, with clone ID and population (nested within clone ID) included as random effects.
|
| AICC | ΔAICC |
| |
|---|---|---|---|---|
| Numerical, population growth rate | ||||
|
| 4 | −650.61 | 0.00 | 0.61 |
|
| 3 | −649.68 | 0.93 | 0.39 |
| Biomass, population growth rate | ||||
|
| 4 | −598.93 | 0.00 | 0.73 |
|
| 3 | −596.94 | 1.98 | 0.27 |
| Numerical, carrying capacity and theta | ||||
|
| 6 | −3010.67 | 0.00 | 0.56 |
|
| 7 | −3010.00 | 0.67 | 0.40 |
|
| 5 | −3004.93 | 5.73 | 0.03 |
|
| 6 | −3003.48 | 7.19 | 0.02 |
| Biomass, carrying capacity and theta | ||||
|
| 7 | −3314.99 | 0.00 | 0.39 |
|
| 6 | −3314.12 | 0.86 | 0.25 |
|
| 6 | −3314.04 | 0.95 | 0.24 |
|
| 5 | −3312.70 | 2.29 | 0.12 |
Parameter estimates (obtained using REML) of the best fitting models describing the variation in observed intrinsic population growth rate (r) of Daphnia pulicaria originating from Lake Kegonsa (Table 1). Post‐and pre‐invasion populations consist of clones originating from after and before Bythotrephes longimanus invasion, respectively.
| Numerical | Estimate |
|
|
|---|---|---|---|
| Fixed effects | |||
|
| 0.16 | 0.01 | |
|
| −0.03 | 0.02 | .0977 |
| Random effects ( | |||
| Clone ID | 0.04 | ||
| Residual | 0.03 | ||
|
| |||
| Fixed effects | |||
|
| 0.31 | 0.01 | |
|
| −0.04 | 0.02 | .0560 |
| Random effects ( | |||
| Clone ID | 0.04 | ||
| Residual | 0.03 | ||
Parameter estimates (obtained using REML) for K, θ and random effects of K of the best fitting theta‐logistic models describing the population dynamics of Daphnia pulicaria originating from Lake Kegonsa (Table 1). Post‐and pre‐invasion populations consist of clones originating from after and before Bythotrephes longimanus invasion, respectively.
| Numerical | Estimate |
|
|
|---|---|---|---|
| Fixed effects | |||
|
| 50.88 | 2.11 | |
|
| −10.89 | 3.08 | .0004 |
|
| 0.38 | 0.03 | |
| Random effects ( | |||
| Clone ID | 0.0033 | ||
| Population:Clone ID | 0.0011 | ||
| Residual | 0.0763 | ||
|
| |||
| Fixed effects | |||
|
| 2.76 | 0.17 | |
|
| −0.52 | 0.28 | .0619 |
|
| 0.29 | 0.02 | |
|
| −0.04 | 0.02 | .0706 |
| Random effects ( | |||
| Clone ID | 0.5069 | ||
| Population:Clone ID | 0.0001 | ||
| Residual | 0.0672 | ||
FIGURE 1Growth rate in terms of (a) number of individuals and (b) total dry mass for pre‐ and post‐invasion populations of Daphnia pulicaria originating from Lake Kegonsa. Pre‐ and post‐invasion populations consist of clones sourced from before and after Bythotrephes longimanus invasion in 2009, respectively. Regression lines give predictions from theta‐logistic models with parameter estimates from Table 2 (for r) and Table 3 (for K and θ).