DOI: 10.5061/dryad.wwpzgmsj1
title: Multiple modes of selection can influence the role of phenotypic plasticity in species’ invasions: Evidence from a manipulative field experiment

description: 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.
description: 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
 <i>Plantago lanceolata </i>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.
description: There are two files, the "Read Me" file and the .xlsx
 data file.