Project Description

Photo credit: Bernard Picton

Animal colouration is fascinating and it plays a vital role in communication, reproduction and defence. Defensive colouration is particularly intriguing, with some species showing extensive colour variation across their range in response to predation. Whether this variation arises through adaptation or plasticity remains largely unknown however, especially in marine taxa. Our knowledge of colour variation derives mostly from terrestrial systems (e.g. Johansson & Nilsson-Örtman 2013), but this is problematic since the mechanisms driving these patterns in marine environments may differ given their unique ecological and spectral features.  

Doris pseudoargus is a cryptic nudibranch found in intertidal and shallow subtidal ecosystems across the European Atlantic and Mediterranean and recently introduced to North America. This species varies in colour from red to white in a continuous way, with multiple colour morphs recovered at both small and large spatial scales. This variation has ignited questions about the mechanisms and processes generating and maintaining this phenotypic diversity, and camouflage more specifically. Doris pseudoargus derives a suite of secondary metabolites from its sponge prey, but how diet might mediate colour pattern in this species remains unknown, as do the genetic underpinnings of these patterns. This project will, for the first time, investigate the ecological and evolutionary origins of continuous colour variation in a polymorphic nudibranch mollusc. Nudibranchs are an ideal system to ask questions about colour pattern evolution given their impressive diversity and the prevalence of aposematism, crypsis and mimicry in this group (e.g. Layton et al. 2018, Layton et al. 2020).  

In this PhD, you will collect detailed information about colour pattern and diet in D. pseudoargus through field research, colour pattern analysis and gut content analysis, and you will conduct laboratory experiments in aquaria to determine how diet shapes colour variation. You will also have access to a genomic dataset from populations in the UK and Europe that you will employ for multivariate genome-wide association analyses to determine whether colour varies along environmental gradients and reflects local adaptation. Through this work you will address a key knowledge gap in identifying the drivers of colour variation in this species and in turn improve understanding of how diversity is produced and maintained in the marine environment. We will encourage you to bring your own research interests to this project with the potential to develop the functional genomics, evo-devo or chemical ecology aspects of this work through collaboration within and across schools.   

Essential & desirable candidate skills

You are expected to hold a first-class/upper second Bachelor’s or Master’s degree in a subject relevant to marine biology, zoology or genetics.  

Essential: Marine/coastal fieldwork. Molecular ecology. Basic R skills. 

Desirable: Experimental manipulation of molluscs. Genomic data analysis & bioinformatics. 


Kara Layton

Primary Supervisor:

Profile: Kara Layton
Institution: University of Aberdeen
Department/School: School of Biological Sciences

Sarah Helyar

Secondary Supervisor:

Profile: Sarah Helyar
Institution: Queen's University, Belfast
Department/School: School of Biological Sciences

Lesley Lancaster

Additional Supervisor:

Profile: Lesley Lancaster
Institution: University of Aberdeen
Department/School: School of Biological Sciences


Johansson, F., Nilsson-Örtman, V. Predation and the relative importance of larval colour polymorphisms and colour polyphenism in a damselfly. Evol Ecol 27, 579–591 (2013). 

Layton KKS, Gosliner TM, Wilson NG. Flexible colour patterns obscure identification and mimicry in Indo-Pacific Chromodoris nudibranchs (Gastropoda: Chromodorididae). Mol Phylogenet Evol 124, 27–36 (2018). 

Layton, KKS, Carvajal, JI, Wilson, NG. Mimicry and mitonuclear discordance in nudibranchs: New insights from exon capture phylogenomics. Ecol Evol 10, 11966–11982 (2020). 

Research Methods

You will combine fieldwork, laboratory experiments and genomic data analysis to unveil the environmental and genetic factors shaping continuous colour variation in the European sea lemon (Doris pseudoargus). You will visit suitable sites around the UK and Europe where multiple colour morphs occur, including Ireland, Norway and Denmark, to image individuals in the field for downstream colour pattern analysis and collect gut samples to identify sponge diets. You will also collect slugs from local sites in Aberdeen and maintain these in the University of Aberdeen aquarium facilities to experimentally manipulate diet. In addition, you will have access to a genome-wide, sequence capture dataset to be used for multivariate genotype-phenotype and genotype-environment association analyses. If resources allow, it may be possible to generate additional genome-wide data (i.e. low coverage whole genome sequencing) for this species.  

We will fully support the student’s research interests, within reason. If you have an interest in developing the functional genomics side of this project, you can gain access to high quality reference genomes for both Doris pseudoargus and Doris montereyensis and there exist several candidate genes involved in carotenoid biosynthesis. Alternatively, if you have an interest in chemical or microbial ecology, we can engage with collaborators within and across schools to facilitate this work.  

Expected Training Provision

Through this project you will gain skills in ecological observation, fieldwork, sample collection, husbandry, experimental biology, colour pattern analysis, genomic data analysis, science communication and writing, among other skills. You will receive training from Dr Layton, Dr Lancaster and Dr Helyar and this may be supplemented by students and postdoctoral fellows in the lab. Support for establishing the experimental set-up will be provided by ourselves and collaborators in the US. You will identify and participate in virtual training opportunities in bioinformatics (e.g. EMBL-EBI, NEOF), data visualization and analysis in R (e.g. An Introduction to R, University of Aberdeen), and others. 


This project will generate and deliver new methods and resources that will benefit the academic community and government stakeholders, including a comprehensive collection of specimen images and records from across the UK and Europe. This is especially relevant since this species is one of the most common in UK coastal waters and can serve as an indicator of ecosystem health. Depending on the student’s interest, they can also pursue investigation of chemical diversity in this species, where resulting compounds may be relevant for drug discovery. This project addresses a key knowledge gap in identifying the drivers of colour variation in a marine species distributed across a heterogenous seascape. As climate change continues to alter the seascape, this research may provide insight into how species adapt to new and changing environments. 

Proposed Supervision

You will be supervised by Dr Kara Layton and Dr Lesley Lancaster in the School of Biological Sciences at the University of Aberdeen and by Dr Sarah Helyar in the School of Biological Sciences at Queen’s University Belfast. You will be based at the University of Aberdeen but you will have the opportunity to visit Queen’s University Belfast and the Marine Laboratory in Portaferry. This is in addition to conducting fieldwork across coastal regions in the UK and Europe and establishing a laboratory experiment in world-class aquarium facilities.

Proposed Timetable

Year One: Establish a research plan that will help the student to become familiar with the research topic. Identify suitable collection sites, establish field protocols and begin field observations. Training in bioinformatics to begin synthesizing colour pattern data and genomic data analysis. 

Year Two: Establish protocols and begin laboratory experiments in aquarium facilities. Conduct additional field observations. Finish data collection and finalize colour pattern analysis by end of year two. Student to attend a national conference to promote their research. 

Year Three: Compile field and laboratory results and finalize all data analysis. Continue drafting data chapters for publication. Student to attend an international conference(s) to promote their research. 

Year Four: Publish data chapters and prepare the final thesis for submission. 


  • biodiversity


A potential CASE partnership is under discussion with NatureScot (Forvie National Nature Reserve). An update will be provided in due course.  

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