Comparative study of anemones from distinct thermal habitats: Highlighting the impact of geographic isolation in promoting evolution of thermal resistant genotypes

Project Rationale:

Acquisition of phototrophic endosymbionts constitutes a key ecological innovation in the evolution of corals, permitting these animals to flourish in oligotrophic waters. Due to recent global environmental changes the coral reefs are declining worldwide, associated with loss of endosymbiotic relations known as coral bleaching [1]. Corals have different thermal tolerances related to their local environmental conditions [2], while anemones like Anemonia viridis and Aiptasia mutabilis have a broad geographical distribution with extremely different temperature conditions. Anemones in the Mediterranean Sea (27°C) are known for enhanced thermal tolerance when compared to counterparts from mild temperature habitats like coastal regions of the United Kingdom (15°C - 20°C). Phenotypic plasticity and genotype selection by environment interactions are key elements in defining the survival success of a species in broad ecological niches. These anemones possibility evolved with novel adaptations enabling survival in higher stress environments and these adaptations support for evolution of thermal resistant genotypes. We aim to understand the genetic factors that underlie adaptations of anemone strains to thermal stress conditions by comparison of anemones from geographically distinct locations with different thermal tolerance. This study will enable us to understand the influence of environmental conditions on genotype.

Methodology:

Anemone samples (Anemonia viridis and Aiptasia mutabilis) will be collected in the United Kingdom and Mediterranean Sea regions. Acclimatization is vital for a species to thrive in broad environmental conditions, hence we will test whether anemone strains from the lower thermal stress conditions can acclimatize to the higher thermal stress. To identify the thermal tolerance limits of anemone strains collected from distinct geographical regions, we will conduct heat stress experiments [2]. The anemone samples will be subjected to transcriptome analyses to identify the genes responsible for thermal tolerance. The upstream regulatory regions of the differentially expressed genes will be analysed to identify genomic changes. From this experiment, we aim to question whether environmental interactions can shape the genotype to face thermal stress. We will assess the Symbiodinium density and diversity in anemone strains from different geographical sites, to study if association with distinct clades of Symbiodinium are related to local environments [2]. Recent reports suggest that in stony corals after bleaching events, the thermal sensitive Symbiodinium are displaced by more resilient Symbiodinium clades [3]. We aim to explore whether anemones have a similar trade-off with Symbiodinium from broad environmental conditions.

Training:

The INSPIRE DTP programme provides comprehensive personal and professional development training alongside extensive opportunities for students to expand their multi-disciplinary outlook through interactions with a wide network of academic, research and industrial/policy partners. The student will be registered at the University of Southampton and hosted at the Marine Biological Association, Cell and Molecular Biology.

Specific training will include:
I) Working with coral animals (Anemonia viridis and Aiptasia mutabilis), carrying out physiological measurements and genetic identification of Symbiodinium. II) Learning molecular biology tools, advanced microscopy including fluorescent and confocal microscopes. III) RNA library preparation. IV) Learn RNA-Seq data analysis using a variety of bioinformatic tools and for de novo assembly Trinity. V) Performing phylogenetic analysis using PhyML and RAxML. Analyzing the rate of gene evolution using OrthoMCL, HMMER, parsimony analysis (Dollo and Wagner).

The project will provide an opportunity for the student to carry out anemones collection from the field sites, for example, North-West Scotland and the United Kingdom, the Mediterranean Sea regions (Thermaic Gulf, Greece). This will enhance fieldwork experience.