Exploring Fennoscandian agricultural history through genetic analysis of aged crop materials

Abstract

Crop plants have undergone a multitude of genetic changes during and following their domestication. The spread of agriculture brought the crops to new geographic regions exposing them to new environments and selection pressures along the way. This gave rise to many local variants with traits favoured both by agricultural practices and the environment. Agriculture was introduced in Fennoscandia (Norway, Sweden, Finland and Denmark) around 4000 BC. The composition of the archaeobotanical record gives some clues as to which species were cultivated, but macroscale analyses rarely reach beyond that. Therefore, methods like genetic analysis are necessary to expand our knowledge about the history of crop cultivation. Under optimal conditions, DNA can survive in biological samples for several hundred thousand years. The preservation of plant specimens in the Fennoscandian climate has, however, rarely been explored. This thesis therefore attempts to dive deeper into the Fennoscandian cultivation history through genetic analyses of aged plant materials from both museum collections and archaeological sources. Cereal grains from a range of preservation conditions were evaluated to find which ones might be of interest for genetic investigations. Desiccated materials gave the highest success rates, in agreement with previous studies. Waterlogged materials appeared to contain small amounts of endogenous DNA, whereas genetic analysis of charred cereals failed completely in all samples. Population structure was investigated in 17-19 th century materials of both barley and rye from Sweden and Finland. Northern and southern populations of Finnish six-row barley were distinct from one another. In southern Sweden, genetic analysis suggested conserved population structure extending over 200 years. The genetic composition of rye also seemed mostly conserved, but rye did not show geographic population structure across the investigated region in Sweden and Finland. A long-standing question in Fennoscandian crop history has been the interpretation of historical written records mentioning Brassica (cole crops, turnips and mustards), as well as the species identity of archaeobotanical finds of Brassica seeds. Thus, Next Generation Sequencing (NGS) was applied to identify which Brassica types that were cultivated in 17 th century Kalmar, Sweden. The analysis corroborated morphological species classification in two of the investigated subfossil seeds, whereas no conclusions could be drawn from the remaining samples. The genome coverages were too low to allow subspecies identification. Wheat has been cultivated in Fennoscandia since the introduction of agriculture but has increased dramatically in importance over the last century. The functional allele of the wheat nutrition gene NAM-B1 was found to be particularly prominent in Fennoscandian wheats, likely associated with its effect on grain maturation time. Here the evolutionary history of NAM-B1 was investigated to see if it could truly be considered a domestication gene as suggested in a pr...

Dog behaviour : Intricate picture of genetics, epigenetics, and human-dog relations

“…Pointing is a commonly used referential gesture in humans. It is used across cultures and both practised and understood by infants (53). Studies have shown that dogs readily and reliably use several human referential cues to find hidden food (see 3, for review, eg.…”