http://hdl.handle.net/10468/1730 Wed, 18 Oct 2017 12:32:29 GMT 2017-10-18T12:32:29Z http://hdl.handle.net/10468/2311 Where the lake meets the sea: strong reproductive isolation is associated with adaptive divergence between lake resident and anadromous three-spined sticklebacks Ravinet, Mark; Hynes, Rosaleen; Poole, Russell; Cross, Thomas F.; McGinnity, Philip; Harrod, Chris; Prodhl, Paulo A. Contact zones between divergent forms of the same species are often characterised by high levels of phenotypic diversity over small geographic distances. What processes are involved in generating such high phenotypic diversity? One possibility is that introgression and recombination between divergent forms in contact zones results in greater phenotypic and genetic polymorphism. Alternatively, strong reproductive isolation between forms may maintain distinct phenotypes, preventing homogenisation by gene flow. Contact zones between divergent freshwater-resident and anadromous stickleback (Gasterosteus aculeatus L.) forms are numerous and common throughout the species distribution, offering an opportunity to examine these contrasting hypotheses in greater detail. This study reports on an interesting new contact zone located in a tidally influenced lake catchment in western Ireland, characterised by high polymorphism for lateral plate phenotypes. Using neutral and QTL-linked microsatellite markers, we tested whether the high diversity observed in this contact zone arose as a result of introgression or reproductive isolation between divergent forms: we found strong support for the latter hypothesis. Three phenotypic and genetic clusters were identified, consistent with two divergent resident forms and a distinct anadromous completely plated population that migrates in and out of the system. Given the strong neutral differentiation detected between all three morphotypes (mean F-ST = 0.12), we hypothesised that divergent selection between forms maintains reproductive isolation. We found a correlation between neutral genetic and adaptive genetic differentiation that support this. While strong associations between QTL linked markers and phenotypes were also observed in this wild population, our results support the suggestion that such associations may be more complex in some Atlantic populations compared to those in the Pacific. These findings provide an important foundation for future work investigating the dynamics of gene flow and adaptive divergence in this newly discovered stickleback contact zone. Thu, 01 Jan 2015 00:00:00 GMT http://hdl.handle.net/10468/2311 2015-01-01T00:00:00Z http://hdl.handle.net/10468/1726 A health status survey of clams, Mya arenaria and Ensis siliqua, in the Irish Sea Cross, Maud E.; Lynch, Sharon A.; O'Riordan, Ruth M.; Culloty, Sarah C. The soft shell clam, Mya arenaria, and the razor clam, Ensis siliqua, are widely distributed in Irish waters. Though the reproductive biology and other aspects of the physiology of these species has been previously investigated, little or no data are currently available on their health status. As this knowledge is essential for correct management of a species, M. arenaria and E. siliqua were examined to assess their current health status using histological and molecular methods, over a period of sixteen months. No pathogens or disease were observed in M. arenaria, and low incidences of Prokaryote inclusions, trematode parasites, Nematopsis spp. and eosinophilic bodies were recorded in razor clams for the first time in Northern European waters. Mon, 10 Nov 2014 00:00:00 GMT http://hdl.handle.net/10468/1726 2014-11-10T00:00:00Z http://hdl.handle.net/10468/1727 The reproductive biology of the exploited razor clam, Ensis siliqua, in the Irish Sea Cross, Maud E.; O'Riordan, Ruth M.; Culloty, Sarah C. Knowledge of the reproductive cycle of a species is a prerequisite for sustainable management of a fishery. The infaunal marine bivalve, Ensis siliqua, is a commercially important species in Europe, and is exploited in many countries, including Ireland, where it is sold by wet weight. Seasonal variations in the reproductive cycle of subtidal razor clams from the Skerries region of the Irish Sea, an important fisheries area, were examined between June 2010 and September 2011 while monitoring weight. Histological examination revealed that the E. siliqua sex-ratio was not different from parity, and no hermaphrodites were observed in the samples collected. In the summer months of 2010 all female clams were either spent or in early development, with just a small percentage of males still spawning. The gonads of both sexes developed over the autumn and winter months of 2010, with the first spawning individuals recorded in January 2011. Spawning peaked in March 2011, but unlike in 2010, spawning continued through June and July with all animals spent in August 2011. The earlier and longer spawning period found in this species in 2011 compared to 2010 may have been due to the colder than normal temperature observed during the winter of 2010 plus the relatively warmer temperatures of Spring 2011, which could have affected the gametogenic development of E. siliqua in the Irish Sea. It was noted that wet weight dropped in the summer months of both years, immediately after the spawning period which may impact on the practicality of fishing for this species during this period. Timing of development and spawning is compared with other sites in the Irish Sea and elsewhere in Europe, including the Iberian Peninsula. Sat, 01 Feb 2014 00:00:00 GMT http://hdl.handle.net/10468/1727 2014-02-01T00:00:00Z http://hdl.handle.net/10468/2336 Future oceanic warming and acidification alter immune response and disease status in a commercial shellfish species, Mytilus edulis L. Mackenzie, Clara L.; Lynch, Sharon A.; Culloty, Sarah C.; Malham, Shelagh K. Increases in atmospheric carbon dioxide are leading to physical changes in marine environments including parallel decreases in ocean pH and increases in seawater temperature. This study examined the impacts of a six month exposure to combined decreased pH and increased temperature on the immune response and disease status in the blue mussel, Mytilus edulis L. Results provide the first confirmation that exposure to future acidification and warming conditions via aquarium-based simulation may have parallel implications for bivalve health. Collectively, the data suggests that temperature more than pH may be the key driver affecting immune response in M. edulis. Data also suggests that both increases in temperature and/or lowered pH conditions may lead to changes in parasite abundance and diversity, pathological conditions, and bacterial incidence in M. edulis. These results have implications for future management of shellfish under a predicted climate change scenario and future sustainability of shellfisheries. Examination of the combined effects of two stressors over an extended exposure period provides key preliminary data and thus, this work represents a unique and vital contribution to current research efforts towards a collective understanding of expected near-future impacts of climate change on marine environments. Wed, 01 Jan 2014 00:00:00 GMT http://hdl.handle.net/10468/2336 2014-01-01T00:00:00Z