DOI: 10.5061/dryad.b5mkkwhr2
title: Plasticity in Daphnia eye size is determined by intra-generational environmental conditions

description: Variation in structure and size of the eye in relation to light
 environments is well-documented across animal taxa. However, the long-term
 effects of ultraviolet radiation (UVR) on eye size across generations
 remain understudied, despite natural fluctuations in UVR being common in
 aquatic habitats. Here, we used Daphnia magna to test whether an
 evolutionary history of UVR threat modifies plasticity and
 transgenerational responses in eye size. We conducted a reciprocal
 split-brood experiment across three parthenogenetic generations using two
 groups maintained under either UVR or non-UVR conditions for over 150
 generations, enabling the potential accumulation of adaptive responses and
 the establishment of distinct evolutionary lineages for comparison. We
 found strong plasticity in eye size, primarily shaped by current
 environmental conditions rather than transgenerational effects. Smaller
 eyes developed in response to UVR but rapidly reverted to larger
 dimensions in its absence. Furthermore, changes in relative eye size were
 associated with fitness-related traits, including swimming behaviour and
 reproductive output, although these relationships varied in strength and
 direction between UVR-exposed and unexposed individuals. Our study
 highlights the role of environmental stressors and evolutionary history in
 shaping sensory adaptations, providing conceptual advances on how sensory
 traits among aquatic invertebrates may rapidly evolve under changing
 environmental conditions.
description: # Plasticity in *Daphnia* eye size is determined by intra-generational
 environmental conditions Dataset DOI:
 [10.5061/dryad.b5mkkwhr2](10.5061/dryad.b5mkkwhr2) ## Description of the
 data and file structure This dataset includes all necessary data and code
 to replicate the analyses and visualizations presented in the manuscript
 titled "Plasticity in *Daphnia* eye size is determined by
 intra-generational environmental conditions". The file labelled
 "Eyesize.csv" contains eye size measurements of *D. magna*
 reared under non-UVR and UVR conditions across three parthenogenetic
 generations, as well as additional data on swimming speed, mean depth, age
 at maturation and the number of offspring produced in the first four
 clutches. The data file comprises 21 columns and the description of each
 column is provided below. ### Files and variables #### File: Eyesize.csv
 **Description:** Data used in the analysis. ##### Variables *
 Generation: Indicates the generation of experiment, G1=the first
 experimental generation, G2=the second experimental generation, G3=the
 third experimental generation. * Past.environmental.history: The
 evolutionary history of stressors in the ancestral generations,
 C=individuals have been reared under non-UVR for more than 150
 generations; U=individuals have been reared under UVR for more than 150
 generations. * Grandparental: Treatment in the grandparental generation:
 C=Non-UVR exposure; U=UVR exposure. * Parental: Treatment in the parental
 generation: C=Non-UVR exposure; U=UVR exposure. * Offspring: Treatment in
 the offspring: C=Non-UVR exposure; U=UVR exposure. * JARID: Jar identity
 that held the initial stock populations. * ID: ID code of each
 investigated individual. * Treatment: Different treatment combinations of
 the past and current light conditions: C=Non-UVR exposure; U=UVR exposure.
 * Sub.line: Indicate the maternal line. * Age.at.Maturation: Age at
 maturation in days. * Clutch1: Number of offspring born from the first
 clutch. * Clutch2: Number of offspring born from the second clutch. *
 Clutch3: Number of offspring born from the third clutch. * Clutch4: Number
 of offspring born from the fourth clutch. * Total_offspring: Total number
 of offspring born from the first four clutches. * Body.length: Individual
 body length measured from the top of the head to the origin of the tail
 spine (mm). * Absolute.eye.size: Absolute eye size measured at the widest
 distance between ommatidium representing the largest dimension of the eye
 (mm). * Relative.eye.size: Indicate the ratio between absolute eye size
 and body length. * Swimming.speed: The mean swimming speed during UVR
 exposure (mm/s). * Mean.depth: The mean values of depth position in the
 water column during the exposure to UVR (mm). * std.resid: The
 standardized residuals from the linear regression between absolute eye
 size and body length for each group. #### File: Rscript.R
 **Description:** R code used for statistical analyses and figure
 generation. ## Code/software R environment version 4.4.2