Stress response of native and invasive populations of intertidal invertebrates from the North Atlantic: an intraspecific comparison

• Main Author: Schubert, Sophia
• Format: Thesis
• Language: English
• Published: 2011
• Subjects: North Atlantic
• Online Access: https://oceanrep.geomar.de/id/eprint/12090/; https://oceanrep.geomar.de/id/eprint/12090/1/SophiaSchubert.pdf

Bioinvasions are amongst the aspects of global change. Continual ship traffic, in particular increasing during the past 250 years, caused an exponential increase in the number of species introductions into new environments. However, not all transported species become successful invaders. Unfavorable transport conditions in particular kill high proportions of species in transit. Species comprising the ability to maintain fitness under adverse conditions may survive the transport more likely than species lacking this ability. Hence, stress robust species may become successful invaders more frequently. In fact, stress tolerance has been shown to be different between native and invasive species. However, the reason why invasive species are more robust than natives against stress has yet not been investigated. Possibly, the higher stress tolerance is caused by evolutionary changes which made certain species in general more tolerant to abiotic stress than species remaining in their native ranges. Also possible is that the conditions during the invasion process select for genotypes with a high robustness to abiotic stress. As a consequence, invasive populations comprise a higher mean stress tolerance to their physical environment than native populations. Therefore, I looked at tolerances to physical stress of an invasive population of Crepidula fornicata and a native population of Ciona intestinalis, in the Irish Sea. Comparable experiments were conducted with a native and a second invasive population of C. fornicata, originated at the east and west coasts of North America, and one invasive population of C. intestinalis, sampled in Japan. I applied two different stresses in an experiment with two sequential stress phases. An intermediate recovery phase should assure that individuals entering the second stress phase comprise only individuals with a high stress tolerance. This approach addresses a putative pre-selection for genotypes with a high robustness to stress. In small pilot studies individuals of both species ...