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Hit and Miss: The Complexity of Admixture
Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science. (Evolutionär ekologi)
2014 (English)Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
Abstract [en]

With massive population declines all over the world, conservationists are faced with a serious threat of extinctions with a need to explore possibilities of translocations and interbreeding programs. While admixture, mixing of separate gene pools, can have beneficial effects, scientists have become aware of the risk of outbreeding depression. The aim of the present study was to investigate the symmetry in outcome in interbreeding population pairs and examine if there are any general patterns. A systematic review was conducted on 28 experimental studies about interbreeding and admixture in plants and animals with comparisons between purebred groups and hybrid groups. Three main types of traits were investigated, chosen to represent quantity, quality and body size of offspring. Overall, symmetrical outcomes were most frequent (62.8 ± 2.6 %), most commonly with a neutral outcome (i.e. none of the populations significantly affected by admixture) in both populations (40.6  ± 3.9 % of all outcome possibilities), which even might be an underestimate because of potential publication bias. Positive and negative outcomes were similar in frequency (11.5 and 11.2 %, respectively, in symmetrical outcomes; 18.1 and 14.4 % in asymmetrical outcomes). The results indicate that consequences of admixture differed between experiments conducted in the laboratory versus semi-natural or natural conditions, between plants and animals, and between the three types of traits. The effects of admixture depended on whether the response was measured in first, second, third generation hybrids, or backcrosses. However, there was no difference in outcome between first and second generation hybrids, which is not in agreement with theory where a more frequent and/or severe negative outcome is expected in later generations. The cause of positive or negative admixture could not be identified, although the heterogenous outcome might indicate that interactions in population pairs are unique. Accordingly, no translocation should be carried out into endangered populations before cautious investigation of possible admixture outcomes. Future research should aim to disentangle the cause and effect of admixture and, preferably, use genetic divergence as an explanatory variable.

Place, publisher, year, edition, pages
2014. , 21 p.
Keyword [en]
Interbreeding, populations, admixture, outbreeding depression, inbreeding depression, hybridization, fitness, systematic review
National Category
Evolutionary Biology
Identifiers
URN: urn:nbn:se:lnu:diva-36201OAI: oai:DiVA.org:lnu-36201DiVA: diva2:735409
Subject / course
Biology
Educational program
Biology Programme, 180 credits
Supervisors
Examiners
Available from: 2014-08-05 Created: 2014-07-27 Last updated: 2014-08-05Bibliographically approved

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CiteExportLink to record
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Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
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