The role of geography in the evolution of gamete incompatibility in hybridizing blue mussels
- UNCW Author/Contributor (non-UNCW co-authors, if there are any, appear on document)
- Christin T. Slaughter (Creator)
- Institution
- The University of North Carolina Wilmington (UNCW )
- Web Site: http://library.uncw.edu/
- Advisor
- Mike McCartney
Abstract: The examination of natural hybridization and hybrid zones are useful tools to examine
the evolution of prezygotic and post zygotic mechanisms through which reproductive isolation
develops in marine environments that typically lack the absolute physical barriers that are
requisite for traditional allopatric models of genetic differentiation thought to lead to species
formation. For blue mussels species that readily hybridize in areas of sympatry, post zygotic
mechanisms have been the focus of the majority of investigations addressing isolating
mechanisms. However, for free-spawning marine invertebrates, gametic incompatibility can
facilitate the evolution of “complete” reproductive isolation in sympatric species through the
strengthening of prezygotic isolating traits as a result of selection against hybrids and
hybridization (i.e. reinforcement).
The reinforcement of pre-mating isolation, as evidenced by a pattern of reproductive
character displacement, was investigated in the hybridizing blue mussels, Mytilus edulis and M.
trossulus within the Gulf of Maine. Using in vitro fertilization experiments, a simple comparison
was made evaluating levels of heterospecific gamete compatibility, in allopatric, M. edulis
females, compared to M. edulis females from a sympatric, hybridizing, population. Partial
compatibility of M. edulis females in heterospecific crosses was observed in both sympatric and
allopatric populations, however in a pattern opposite to that expected under a theory of
reinforcement. Mytilus edulis females from allopatric populations were more strongly blocked to
heterospecific fertilization than M. edulis females from sympatric populations.
The absence of a signal of reproductive character displacement consistent with the
process of reinforcement suggests that the “atypically” compatible female found in sympatric
populations may be a product of introgression, with highly introgressed individuals undetected at the current level of resolution available. The absence of reproductive character displacement
should not, however, eliminate the role that reinforcement may play in the pattern of
interbreeding, and non-fusion, in these hybridizing species. A comparison of patterns in
heterospecific gamete incompatibility between western and northeastern Atlantic hybrid zones
may prove to be valuable for studying the process of reinforcement, as well as lead to a greater
understanding of the role of hybridization in species formation.
The role of geography in the evolution of gamete incompatibility in hybridizing blue mussels
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Additional Information
- Publication
- Thesis
- A Thesis Submitted to the University of North Carolina at Wilmington in Partial Fulfillment Of the Requirements for the Degree of Master of Science
- Language: English
- Date: 2009
- Keywords
- Mussels--Effect of environment on, Mussels--Reproduction, Mutation (Biology), Mytilidae--Effect of environment on, Mytilidae--Reproduction
- Subjects
- Mussels -- Effect of environment on
- Mussels -- Reproduction
- Mutation (Biology)
- Mytilidae -- Effect of environment on
- Mytilidae -- Reproduction