Publications
NIBIOs employees contribute to several hundred scientific articles and research reports every year. You can browse or search in our collection which contains references and links to these publications as well as other research and dissemination activities. The collection is continously updated with new and historical material.
2020
Abstract
Genetic selection in commercial sheep production has mainly focussed on production traits and to a large extent ignoring behavioural traits, such as response towards predators. The Icelandic leadersheep is a sheep breed selected and known for its special behavioural traits, such as leading the flock and bringing it home from pasture in case of danger. Those traits are also said to be beneficial in areas with a high predator pressure. In this study, it was investigated if there are behavioural differences in sheep flocks with and without a leadersheep present. Behaviour of sheep flocks was observed before, during and after a predator test, in small groups of Icelandic sheep with or without a leadersheep in the group. Eleven groups of Icelandic sheep with six ewes in each group were observed in a test arena while a human, a dog and a drone passed through the pasture. Six of the groups included a leadersheep and the remaining five did not. Groups including a leadersheep spent more time grazing after both the human and dog test, indicating a faster recovering to normal behaviour. They were also located close to the exit during the dog test compared to groups without a leadersheep, fitting well with the assertion that leadersheep bring the flock home in case of danger. During the drone test, groups with a leadersheep however spent more time moving around compared to the other groups. Since the sheep had experienced both humans and dogs before, but not drones, this may indicate that groups with leadersheep recovered quickly from the figurants they had experienced before, but tended to react more in the test which was a new situation. In conclusion, it appears likely that the earlier selection for leader traits in the leadersheep have indeed changed both their own behaviour and also that this has an effect on the behaviour of group members.
Authors
Boris B. Demenou Jérémy Migliore Myriam Heuertz Franck K. Monthe Dario Isidro Ojeda Alayon Jan J. Wieringa Gilles Dauby Laura Albreht Arthur Boom Olivier J. HardyAbstract
Paleo-environmental data show that the distribution of African rain forests was affected by Quaternary climate changes. In particular, the Dahomey Gap (DG) – a 200 km wide savanna corridor currently separating the West African and Central African rain forest blocks and containing relict rain forest fragments – was forested during the mid-Holocene and possibly during previous interglacial periods, whereas it was dominated by open vegetation (savanna) during glacial periods. Genetic signatures of past population fragmentation and demographic changes have been found in some African forest plant species using nuclear markers, but such events appear not to have been synchronous or shared across species. To better understand the colonization history of the DG by rain forest trees through seed dispersal, the plastid genomes of two widespread African forest legume trees, Anthonotha macrophylla and Distemonanthus benthamianus, were sequenced in 47 individuals for each species, providing unprecedented phylogenetic resolution of their maternal lineages (857 and 115 SNPs, respectively). Both species exhibit distinct lineages separating three regions: 1. Upper Guinea (UG, i.e. the West African forest block), 2. the area ranging from the DG to the Cameroon volcanic line (CVL), and 3. Lower Guinea (LG, the western part of the Central African forest block) where three lineages co-occur. In both species, the DG populations (including southern Nigeria west of Cross River) exhibit much lower genetic diversity than UG and LG populations, and their plastid lineages originate from the CVL, confirming the role of the CVL as an ancient forest refuge. Despite the similar phylogeographic structures displayed by A. macrophylla and D. benthamianus, molecular dating indicates very contrasting ages of lineage divergence (UG diverged from LG since c. 7 Ma and 0.7 Ma, respectively) and DG colonization (probably following the Mid Pleistocene Transition and the Last Glacial Maximum, respectively). The stability of forest refuge areas and repeated similar forest shrinking/expanding events during successive glacial periods might explain why similar phylogeographic patterns can be generated over contrasting timescales.
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Authors
Karin Juul Hesselsøe K. Sintorn Koert Donkers N. Dokkuma Yajun Chen Trond Olav Pettersen Wolfgang Prämassing M. Woods D. Cleaver Anne Falk Øgaard Tore Krogstad Trygve S. AamlidAbstract
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Authors
Karin Juul Hesselsøe Pia Heltoft Thomsen Gudni Thorvaldsson Anne mette Dahl jensen Tatsiana Espevig Wendy Marie Waalen Trond Olav Pettersen Jan Tangsveen Per Sørensen Tania Gneist Bjarni Hannesson Trygve S. AamlidAbstract
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