In this thesis I take a multi-disciplinary approach to identify and characterise ‘Evolutionary Significant Units’ (ESUs) and ‘Management Units’ (MUs) of killer whale in the eastern North Atlantic. Several markers and traits including mitochondrial DNA control region, 15N stable isotope values, tooth wear, tooth count, total body length and pigmentation pattern indicated sympatric lineages could be categorized in to two ecologically & morphologically disparate types, which should be considered as distinct ESUs. One type (type 2) appears to be a specialist and may predate cetaceans. The other type (type 1) appears to be a generalist, although the total niche width of the population appears to be more dependent upon between-individual variation than within-individual variation in dietary composition. However, the other indicator of long-term diet, apical tooth wear, was found in all type 1 individuals, suggesting some overlap in the components of the diet. There are shallow genetic differences between the two types based on mtDNA control region, however analysis of bi-parentally inherited nuclear DNA markers are needed to see if the two types are reproductively isolated. The data above on diet is further supported by observational data of individuals moving between the Icelandic herring grounds to the seal pupping haul-outs around the Northern Isles, Scotland. However, large scale movement of individuals is mostly correlated with the movement of large predictable prey stocks such as the Icelandic and Norwegian stocks of Atlantic herring. Therefore there is the potential for prey choice to cause intrinsic isolation through temporal or spatial isolation even when the prey type is similar, e.g. mackerel, Icelandic herring or Norwegian herring. The microsatellite data are consistent with this pattern and taken together the genetic and mark-recapture data identify four demographically independent MUs of type 1 killer whales. We only identify one community or MU of type 2 killer whales, which is small (10 individuals) and appears to be suffering from demographic stochasticity. Our results suggest intrinsic isolation through temporal and spatial isolation as the most parsimonious mechanism for reducing gene flow between populations of the same type. Further work is needed to determine if there is gene flow between types or if adaptive divergence feeds back to reduce gene flow through mate choice.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:531859 |
| Date | January 2010 |
| Creators | Foote, Andrew D. |
| Publisher | University of Aberdeen |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | http://digitool.abdn.ac.uk:80/webclient/DeliveryManager?pid=158398 |
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