ABSTRACT
Enzyme inhibition is commonly encountered when using molecular biological techniques on museum-prepared animal skin samples, and this problem is exacerbated by a lack of information on how particular skins have been prepared for preservation. This report: (i) demonstrates that while some methods of museum preparation inhibit both proteinase K digestion and the PCR, others do not; (ii) describes a change in buffer conditions that reduces proteinase K enzyme inhibition during tissue digestion: and (iii) uses electron-dispersive X-ray microanalysis (EDXA) to show that the preparation methods for museum-preserved skin are often more complex than the treatment description provided with samples and also suggests that some of these descriptions are incorrect.
Subject(s)
Endopeptidase K/antagonists & inhibitors , Endopeptidase K/metabolism , Enzyme Inhibitors , Museums , Skin , Tissue Preservation/methods , Animals , Biological Evolution , DNA/analysis , Polymerase Chain Reaction , Skin/chemistryABSTRACT
Multiple sources of evidence show that the skuas (Aves:Stercorariidae) are a monophyletic group, closely related to gulls (Laridae. On morphological and behavioural evidence the Stercorariidae are divided into two widely divergent genera, Catharacta and Stercorarius, consistent with observed levels of nuclear and mitochondrial gene divergence. Catharacta skuas are large-bodied and with one exception breed in the Southern Hemisphere. Stercorarius skuas otherwise known as jaegers) are smaller bodied and breed exclusively in the Northern Hemisphere. Evidence from both mitochondrial and nuclear genomes and from ectoparasitic lice (Insecta:Phthiraptera) shows that the Pomarine skua, S. pomarinus, which has been recognized as being somewhat intermediate in certain morphological and behavioural characteristics, is much more closely related to species in the genus Catharacta, especially to the Northern Hemisphere-breeding Great skua, C. skua, than it is to the other two Stercorarius skuas, the Arctic skua, S. parasiticus and the Longtailed skua, S. longicaudus. Three possible explanations that might account for this discordant aspect of skua phylogeny are explored. These involve (i) the segregation of ancestral polymorphism, (ii) convergent evolution of morphology and behaviour or (iii) inter-generic hybridization. The available evidence from both nuclear and mitochondrial genomes does not exclude any of these hypotheses. Thus, resolution of this enigma of skua phylogeny awaits further work.
