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Wild mallards have more ‘‘goose-like’’ bills than their ancestors: a case of anthropogenic influence?
Kristianstad University, School of Education and Environment, Avdelningen för Naturvetenskap. Kristianstad University, Research environment Man & Biosphere Health (MABH).ORCID iD: 0000-0003-1212-6607
Kristianstad University, School of Education and Environment.
Kristianstad University, School of Education and Environment, Avdelningen för Naturvetenskap. Kristianstad University, Research environment Man & Biosphere Health (MABH).
Office National de la Chasse et de la Faune Sauvage, CNERA Avifaune Migratrice, La Tour du Valat, Le Sambuc, Arles.
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2014 (English)In: PLoS ONE, ISSN 1932-6203, Vol. 9, no 12, e115143Article in journal (Refereed) Published
Abstract [en]

Wild populations of the world’s most common dabbling duck, the mallard (Anas platyrhynchos), run the risk of genetic introgression by farmed conspecifics released for hunting purposes. We tested whether bill morphology of free-living birds has changed since large-scale releases of farmed mallards started. Three groups of mallards from Sweden, Norway and Finland were compared: historical wild (before large-scale releases started), present-day wild, and present-day farmed. Higher density of bill lamellae was observed in historical wild mallards (only males). Farmed mallards had wider bills than present-day and historical wild ones. Present-day wild and farmed mallards also had higher and shorter bills than historical wild mallards. Present-day mallards thus tend to have more “goose-like” bills (wider, higher, and shorter) than their ancestors. Our study suggests that surviving released mallards affect morphological traits in wild population by introgression. We discuss how such anthropogenic impact may lead to a maladapted and genetically compromised wild mallard population. Our study system has bearing on other taxa where large-scale releases of conspecifics with ‘alien genes’ may cause a cryptic invasive process that nevertheless has fitness consequences for individual birds.

Place, publisher, year, edition, pages
2014. Vol. 9, no 12, e115143
National Category
URN: urn:nbn:se:hkr:diva-13321DOI: 10.1371/journal.pone.0115143ISI: 000349146300038PubMedID: 25514789OAI: diva2:774151
Swedish Environmental Protection Agency
Available from: 2014-12-22 Created: 2014-12-22 Last updated: 2016-04-01Bibliographically approved
In thesis
1. Large-scale releases of native species: the mallard as a predictive model system
Open this publication in new window or tab >>Large-scale releases of native species: the mallard as a predictive model system
2015 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Human alteration of natural systems, and its consequences are of great concern and the impact on global ecosystems is one of the biggest threats that biodiversity stands before. Translocations of invasive species, as well as intraspecific contingents with non-native genotypes, whether they are deliberate or unintentional, are one such alteration and its consequences are continuously being assessed. The mallard (Anas platyrhynchos) is the most numerous and widespread duck in the world and a flagship in wetland conservation. It is also an important game species which is heavily restocked for hunting purposes, especially in Europe where over three million ducklings are released every year. Because of its hunted status, its abundance, and the number of released individuals, it can serve as a model species to study effects of releases, both for conservation and restocking for hunting, on wild populations. In this thesis the status of the mallard was assessed in the Nordic countries and the effects of releases on the wild populations were studied by mining historical ringing data, comparing morphology of present-day wild, farmed, and historical mallards, and analyzing phylogeography of wild and farmed mallards in Europe. The status of the mallard population in the Nordic countries are generally good, however, a joint effort of European countries is needed to monitor and manage the population. A significant difference between wild and farmed mallards concerning longevity, migration, bill morphology and genetic structure was also found, together with signs of cryptic introgression of farmed genotypes in the wild population with potential fitness reduction as a result. The effect is however limited by that only a fraction of released farmed mallards reach the breeding season due to low survival. A natural captive environment is crucial to keep individuals wild-like with high survival rates after release. However, with an introgression of potentially maladapted farmed genotypes leading to a reduction in fitness, a low survival of released mallards would favor the wild population. A legislative change regarding obligation to report numbers, provenance, and release sites of farmed mallard should be considered, together with practical solutions of ringing and genetic monitoring of released mallards.

Place, publisher, year, edition, pages
Umeå: Sveriges Lantbruksuniversitet, 2015
, Acta Universitatis agriculturae Sueciae, ISSN 1652-6880 ; 2015:25
National Category
Zoology Fish and Wildlife Management
urn:nbn:se:hkr:diva-13751 (URN)978-91-576-8248-2 (ISBN)978-91-576-8249-9 (ISBN)
Available from: 2015-03-30 Created: 2015-03-30 Last updated: 2016-04-01Bibliographically approved

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Söderquist, PärElmberg, JohanGunnarsson, Gunnar
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