DOI: 10.5061/dryad.1g1jwsv35
title: Data from: Functional trait plasticity diverges between sexes in African cichlids: a contribution toward ecological sexual dimorphism?

description: Phenotypic plasticity enables development to produce multiple phenotypes
 in response to environmental conditions. Plasticity driven variation has
 been suggested to play a key role in adaptive divergence, and plasticity
 itself can evolve. However, the interaction of plasticity with the
 multiple levels involved with adaptive divergence is less understood. For
 example, sexual dimorphism can contribute to adaptive variation through
 ecological sexual dimorphism (ESD), but the contribution of plasticity to
 this phenomenon is unknown. Therefore, to determine the potential
 contribution of plasticity to ESD, we used the adaptive radiation of
 Malawi cichlids. Two mouthbrooding species (Labeotropheus fuelleborni and
 Tropheops “Red Cheek”, hereafter LF and TRC respectively) with differences
 in foraging tactics underwent foraging experiments using benthic and
 limnetic treatments while accounting for sex. Plasticity in craniofacial
 shape and three functionally important traits were measured. Plasticity
 was shown, but without any sex-based differences in shape. However, for
 mechanical advantage traits of the mandible sex by diet interactions were
 found. This suggests that ESD, may be influenced by phenotypic plasticity
 that diverges between sexes. Given the involvement of the mandible in
 parental care in cichlids this may indicate that sexual divergence in
 plasticity may trade-off against maternal care tactics.
description: Stock cichlids were obtained from the wild and purchased through
 the pet trade. At the University of Glasgow, they were kept in 100L
 aquariums and monitored for breeding and egg holding. Cichlid broods were
 collected for LF and TRC from females at 3 days post fertilisation
 (dpf). A total of 101 fish from ten broods were collected for TRC, and 115
 fish from four broods were collected for LF. Each brood was raised
 separately in a 1L conical flask with 1-2 drops of methylene blue to
 prevent fungus growth and the embryos were kept aerated. At around
 20 dpf the yolk was nearly fully absorbed, and each brood was moved into a
 separate 25L tank to feed independently. After a further 4-6 weeks, the
 broods were divided and moved into larger (~125L) tanks as part of a mixed
 family group. In total there were four treatment tanks for each species;
 two for the benthic treatment and two for the limnetic. Each
 tank contained the same enrichment and used the same water supply. To
 limit potential effects from density, each family was
 divided approximately equally into four treatment tanks containing between
 22-26 fish.   <em><strong>Diet treatment
 experiment</strong></em> To test the impact
 of different foraging and biomechanical demands on morphology, treatment
 groups were fed either limnetic or benthic food based on previous methods.
 The nutritional content of food was kept similar to limit the possibility
 of nutritional effects on morphological plasticity. The limnetic
 treatment, given to half of the groups, consisted of a ground mixture of
 flake food, algae wafer, and freeze-dried daphnia which was then sprinkled
 into the water column to elicit suction feeding. The benthic treatment,
 given to the other half of treatment groups was the same mixture but air
 dried o to lava rocks. During feeding these rocks were placed at the
 bottom of the tank to elicit a biting mode of feeding. Each treatment tank
 was fed twice daily until satiation (morning and afternoon feeds) for
 approximately 6-7 months until fish were within the size range of a mature
 cichlid (approximately 4-8 cm standard length (SL)) and sexual dimorphism
 in colouration and spawning activity had begun. Smaller fish were excluded
 from downstream analysis as they were difficult to dissect (n = 4). All
 fish were euthanised following UK Home Office Schedule 1 guidelines,
 labelled, and fixed in 10% neutral buffered formalin (NBF). Fish were
 sexed using colouration and venting. Dissection of internal anatomy was
 also conducted to confirm sex.
 <em><strong>Morphometrics</strong></em> Following fixation, the craniofacial region was dissected to reveal musculature and allow landmarks to be collected for geometric morphometrics. Craniofacial landmarks were selected based on previous work to ensure that they were relevant to the evolution and functional anatomy of cichlids. Fish were secured to a wax dish with a scale and ID tag and photographed laterally from a fixed distance, with their mouth closed, using a mounted Canon EOS 1100D camera (Canon (UK), Surrey). For landmark digitisation, the tps suite of software was used (available at: http://life.bio.sunysb.edu/ee/rohlf/software.html). Firstly, a tps file linking photographs was created from all photographs using tpsUtil. Prior to digitisation and to reduce intra-observer variability, the ID tags were removed from the images and the photographs were randomised using tpsUtil. Digitisation of landmarks was conducted using tpsDig2 with a scale factor measured for each image. Following digitisation, the tps files were analysed in R version 4.0.4 using the geomorph package unless stated otherwise. Before any analysis could take place, the landmarks were subjected to a Procrustes superimposition that translated, rotated and scaled specimens to a common centroid size using gpagen in the geomorph R package. Procrustes coordinates were then used for all downstream analyses.
description: # Data from: Functional trait plasticity diverges between sexes in African
 cichlids: a contribution toward ecological sexual dimorphism?
 [https://doi.org/10.5061/dryad.1g1jwsv35](https://doi.org/10.5061/dryad.1g1jwsv35) ## Description of the data and file structure The data comprises three files including a set of functional measures on the cichlid craniofacial region and 2d morphometric data. 1. The functional measures are in the form of univariate measures within the .csv file entitled ‘FuncTrait\_Names\_Factors.csv’. This file is comprised of 10 named columns with the following interpretations: * Fish.list- this column provides an image file name that was assigned when photographing took place, it is unique to each fish used in the study * TPS- This column contains a number for each fish that was assigned within each TPS file (provided separately). This number identifies the order each fish picture appears within each TPS file. * Species- this column refers to the species being used with LF denoting *Labeotropheus fuelleborni*, and TRC denoting *Tropheops* ‘red cheek’ * Tank – This column contains an identifier for each tank a given fish was reared within. * Treatment – this column denotes the foraging treatment a fish experienced including Limnetic and Benthic treatments * SL\_mm – This column provides the standard length for each fish in mm * Sex- the sex of each fish is denoted as an M for males, and F for females * RA – This column provides the measures for the retroarticular in mm * IOP- This column provides the measures for the inner opercular in mm * Fixed – This column provides the measures for the fixed link in mm 2. Dimensional Morphometric Data This data consists of x,y landmark coordinates in the .tps format which is standard for geometric morphometrics. There are 15 landmarks for each specimen in the study, along with an image name (matching FuncTrait\_Names\_Factors.csv’) and a scale factor which was collected from each photo. There are two files provided: * TRC.tps * LF.tps The ‘TRC.tps’ file contains the landmark data for the species Tropheops ‘red cheek’, while the ‘LF.tps’ file contains the landmark data for the species Labeotropheus fuelleborni. These .tps file were used in the study by appending them together before performing all analyses. These files can be opened directly within the geomorph package in the R statistical language. ## Sharing/Access information Data can also be accessed from a server at the University of Glasgow: http://kevpar66.quickconnect.to/d/s/vmASNlYaO5ZIJcqHCNWtd9bRF22CahNq/VGFAoExaEpBOVLWuKT5Zi-1GKLA-giqV-srsAVxuw2go ## Code/Software All data were collected in tpsDig2 available at: http://life.bio.sunysb.edu/ee/rohlf/software.html. Data were analysed in R version 4.04 using standard functions in the geomorph package