Exploring abortion rates in hybrid zones between ecotypes of Littorina saxatilis in Sweden
This is a suggestion for a Degree Project for Bachelor's and Master's levels at the Department of Marine Sciences. Degree projects at the Department of Marine Sciences are done independently and must be written and assessed individually.
Subject: Marine Biology
Level: Master's or Bachelor's
Supervisors: Gabriella Malmqvist and Erica Leder
Project Background
Ecological speciation is a process of speciation because of adaptation to different habitats. Adaption potential is key to understand in today’s changing world with higher temperatures, lower ph, and increased precipitation. Since the 1980s, rough periwinkle (Littorina saxatilis) has been studied and has been considered a model species of evolution (Johannesson, 2016).
This small marine snail exists in two distinct ecotypes across several regions, including Sweden, Spain, and the UK. Despite inhabiting the same coastal bays, these ecotypes differ markedly in physical traits and behavior. The larger, more cautious "crab" ecotype is adapted to sheltered bay areas, whereas the smaller, more daring "wave" ecotype thrives in exposed sections of the coastline. This species reproduces via ovoviviparity, with females brooding eggs inside a special pouch and releasing live young.
Crossings between Spanish ecotypes have shown increased abortion rates of embryos, compared with crossings within a Spanish ecotype while a single-time-point assessment of abortion rates in natural populations showed no signs of hybrid incompatibility in Sweden (Johannesson et al., 2020). However, during a student project supervised by Malmqvist in spring 2024, trends of higher abortion rates were observed in early-stage hybrid embryos compared to pure wave and crab ecotypes under controlled rearing conditions. This pattern could suggest postzygotic incompatibilities and indicate early stages of speciation.
Project Description
During this project, we want to further explore and expand this small pilot study to investigate abortion rates of hybrid zones of Littorina saxatilis in Sweden. The project will include sampling, rearing embryos, and following their development.
Contact
Erica Leder
Email: erica.leder@gu.se