This thesis aims to study and describe the ancient populations of grey and harp seals in the Baltic Sea, and to present new methodological approaches for general use in ancient DNA studies.
The dissertation is comprised of five studies: a review of the use of paleogenetics in studying ancient human-marine mammal interactions; a method paper investigating patterns of DNA preservation in ancient pinniped samples; a method paper presenting a genetic sex identification method for ancient pinnipeds; a population genomic study of the Baltic grey seal; and a population genomic study of the now extinct Baltic harp seal.
Guidelines for ancient DNA sample selections were deduced from broad-scale statistical modelling of factors influencing DNA preservation in pinniped bones, the most significant of which included type of bone element, collagen content, and whether the bone derive from a cave context. Modern ringed seal samples with known sex were used to test an alternative pinniped sex identification method using the annotated dog genome as a reference for quantification of the relative representation of X chromosome reads. Reliable sex identification was shown to require a minimum of 5,000 total reads mapped to the reference genome. A total of 69 mitochondrial control regions were generated for Baltic grey seals, which revealed that the Mesolithic data largely represent extinct haplotypes, the main of which continued until the Early Neolithic. A population replacement prior to the early Bronze Age introduced mitochondrial variation resembling that of modern Baltic greys seals. The level of genetic differentiation between the Baltic harp seal population and the three contemporary breeding populations, suggests that the White Sea population is the most likely ancestor of the Baltic harp seal breeding population. An increase in genetic diversity, following a hiatus with no Baltic harp seals, combined with the measures of genetic differentiation from this period, further suggests that a second colonization likely occurred from the White Sea during the early Bronze Age.
Open Access: Ancient genomics of Baltic seals
Dissertation:
Maiken Hemme Bro-Jørgensen will defend her thesis Ancient genomics of Baltic seals. Insights on the past Baltic grey seal and harp seal populations, on February 25th, at 13.00-15.00.
To follow the dissertation you have to register in advance:
https://stockholmuniversity.zoom.us/webinar/register/WN_dyEeMTvLTY-4dUaEDUIeTA
Or an H.323/SIP room system:
H.323: 109.105.112.236 or 109.105.112.235
Meeting ID: 614 5032 8475
SIP: 61450328475@109.105.112.236 or 61450328475@109.105.112.235
After registering, you will receive a confirmation email containing information about joining the webinar. Nota bene! You will be able to register and log in from 12.30.
The result will be announced at 15.30 on zoom: https://stockholmuniversity.zoom.us/j/8218373933