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Multiple modes of selection can influence the role of phenotypic plasticity in species’ invasions: Evidence from a manipulative field experiment

Citation

Lacey, Elizabeth; Herrera, Freddy; Richter, Scott (2022), Multiple modes of selection can influence the role of phenotypic plasticity in species’ invasions: Evidence from a manipulative field experiment, Dryad, Dataset, https://doi.org/10.5061/dryad.wwpzgmsj1

Abstract

In exploring the roles of phenotypic plasticity in the establishment and early evolution of invading species, little empirical attention has been given to the importance of correlational selection acting upon suites of functionally related plastic traits in nature. We illustrate how this lack of attention has limited our ability to evaluate plasticity's role during invasion and also, the costs and benefits of plasticity. We addressed these issues by transplanting clones of European-derived Plantago lanceolata L. genotypes into two temporally variable habitats in the species’ introduced range in North America. Phenotypic selection analyses were performed for each habitat to estimate linear, quadratic, and correlational selection on phenotypic trait values and plasticities in the reproductive traits: flowering onset, spike and scape lengths. Also, we measured pairwise genetic correlations for our “colonists”. Results showed that 1) correlational selection acted on trait plasticity after transplantation, 2) selection favored certain combinations of genetically correlated and uncorrelated trait values and plasticities, 3) Using signed, instead of absolute, values of plasticity in analyses facilitated the detection of correlational selection on trait value-plasticity combinations and their adaptive value. Based on our results, we urge future studies on species invasions to: 1) measure correlational selection and 2) retain signed values of plasticity in order to better discriminate between adaptive and maladaptive plasticity.

Methods

We conducted an experiment that assessed the fitness effects of trait value and plasticity in reproductive traits in two temporally variable habitats in nature. Clones of 50 native European Plantago lanceolata genotypes were transplanted into two habitats within the species' introduced range in North America. In summer 2011, we recorded and marked biweekly spike production per clone. As spikes matured, we collected the spikes and recorded scape and spike lengths. From these data, we determined flowering duration and median flowering week for each clone. Our first goal was to determine which reproductive traits showed genetic variation in plasticity. We defined plasticity as a property of a genotype and as the ability, or flexibility, to modify its phenotype in response to environmental change. Spike length, scape length, and onset of flowering showed statistically significant genotype by site interactions. Therefore, for these traits, we addressed the following questions for our European genotypes at each transplant site: 1) What are the genetic correlations between trait values and plasticities? 2) What is the most appropriate statistical model (e.g., linear, quadratic, correlational) for assessing selection on plasticities and trait values, given our data? 3) What modes of selection are acting on trait values and plasticities? Here we looked for evidence of directional, quadratic (i.e., curvilinear), and correlational selection. 4) How are genetic correlations expected to affect the responses to selection? 5) What are the effects of using signed values of plasticity versus using absolute values to estimate costs and benefits of plasticity?

Data were entered in an excel file with missing values indicated by a ".". For statistical analyses with PROCEDURES CORR, MIXED, AND TPSPLINE (SAS version 9.4), we used the 34 genotypes that flowered at both sites.

Usage Notes

There are two files, the "Read Me" file and the .xlsx data file.

Funding

National Science Foundation, Award: NSF DEB 0236526 to EPL

University of North Carolina at Greensboro