DOI: 10.25338/b8jk9q
title: Plasticity and artificial selection for developmental mode in a poecilogonous sea slug

description: The contribution of phenotypically plastic traits to evolution depends on
 the degree of environmental influence on the target of selection (the
 phenotype) as well as the underlying genetic structure of the trait and
 plastic response. Likewise, maternal effects can help or hinder evolution
 through affects to the response to selection. The sacoglossan sea slug
 Alderia willowi exhibits intraspecific variation for developmental mode (=
 poecilogony) that is environmentally modulated with populations producing
 more yolk-feeding (lecithotrophic) larvae during the summer, and more
 planktonic-feeding (planktotrophic) larvae in the winter. I found
 significant family level variation in the reaction norms between 17
 maternal families of A. willowi when reared in a split-brood design in low
 (16 ppt) versus high (32 ppt) salinity; conditions which mimic seasonal
 variation in salinity of natural populations. I documented a significant
 response to selection for lecithotrophic larvae in high and low salinity.
 The slope of the reaction norm was maintained following one generation of
 selection for lecithotrophy. When the maternal environment was controlled
 in the lab, I found significant maternal effects, which reduced the
 response to selection. These results suggest there is standing genetic
 variation for egg-mass type in A. willowi, but the ability of selection to
 act on that variation may depend on the environment in which the phenotype
 is expressed in preceding generations.
description: This paper presents data from two experiments, one designed to
 evaluate the response to selection in high and low salinity, and the other
 to determine the role of maternal effects and effect of selection on
 phenotypic plasticity. For both experiments adult slugs
 were collected from the field. They laid eggs in the lab, the offspring
 from which were reared in low (16ppt) and high (32ppt) salinity. The data
 stored here consists of egg-capule diameter and egg diameter measurements
 from slugs reared in the lab.
description: Raw data and R scripts are included to perform all analyses and
 make all data figures. There are 4 data files which
 contain the raw data, described as follows:
 TomalesBay_capsuledata.csv contains the egg capsule measurements
 for slugs from Tomales Bay reared in low and high salinity. Column headers
 and their descriptions are, date, order, capsule (egg capsule diameter in
 mm), gen (generation), Family, ID (individual slug ID), eggmass (egg mass
 number according to date laid), original (environment)
 EggDiameterMeasurements.csv. contains the egg diameter
 measurements and has columns: date, EggDi (in mm), Family, ID, eggmass,
 original SoCalvNorCal_Data.csv contains the egg capsule
 measurements for slugs from Mill Valley and Long Beach reared in low and
 high salinity. Column headers and their descptions are: date, order,
 capsule, Family, ID, eggmass, original, region.
 F1_capsule_data.csv contains the egg capsule measurements for
 slugs from the F1 treatment evaluating maternal effects and the effect of
 selection to the reaction norm. column headers are: date, order, Capsule,
 mom_id (maternal id), mom_env (maternal environment), off_id (offspring
 id), offspring_env (offspring environment), Family. 
 Scripts in R are provided for each figure in an R markdown
 document which is also presented in a pdf.  Scripts for
 performing the quantitive genetics models are provided in the R file:
 Gibbs_sample_threshold_bays.R