Logo: to the web site of Uppsala University

uu.sePublications from Uppsala University
Change search
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association
  • 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
  • rtf
From high masked to high realized genetic load in inbred Scandinavian wolves
Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Evolutionary Biology.ORCID iD: 0000-0002-8415-9259
Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Evolutionary Biology.ORCID iD: 0000-0002-5035-1736
2023 (English)In: Molecular Ecology, ISSN 0962-1083, E-ISSN 1365-294X, Vol. 32, no 7, p. 1567-1580Article in journal (Refereed) Published
Abstract [en]

When new mutations arise at functional sites they are more likely to impair than improve fitness. If not removed by purifying selection, such deleterious mutations will generate a genetic load that can have negative fitness effects in small populations and increase the risk of extinction. This is relevant for the highly inbred Scandinavian wolf (Canis lupus) population, founded by only three wolves in the 1980s and suffering from inbreeding depression. We used functional annotation and evolutionary conservation scores to study deleterious variation in a total of 209 genomes from both the Scandinavian and neighbouring wolf populations in northern Europe. The masked load (deleterious mutations in heterozygote state) was highest in Russia and Finland with deleterious alleles segregating at lower frequency than neutral variation. Genetic drift in the Scandinavian population led to the loss of ancestral alleles, fixation of deleterious variants and a significant increase in the per-individual realized load (deleterious mutations in homozygote state; an increase by 45% in protein-coding genes) over five generations of inbreeding. Arrival of immigrants gave a temporary genetic rescue effect with ancestral alleles re-entering the population and thereby shifting deleterious alleles from homozygous into heterozygote genotypes. However, in the absence of permanent connectivity to Finnish and Russian populations, inbreeding has then again led to the exposure of deleterious mutations. These observations provide genome-wide insight into the magnitude of genetic load and genetic rescue at the molecular level, and in relation to population history. They emphasize the importance of securing gene flow in the management of endangered populations.

Place, publisher, year, edition, pages
John Wiley & Sons, 2023. Vol. 32, no 7, p. 1567-1580
Keywords [en]
conservation genetics, deleterious mutations, genetic load
National Category
Evolutionary Biology Genetics
Identifiers
URN: urn:nbn:se:uu:diva-501377DOI: 10.1111/mec.16802ISI: 000897947900001PubMedID: 36458895OAI: oai:DiVA.org:uu-501377DiVA, id: diva2:1755777
Funder
Knut and Alice Wallenberg Foundation, 2014-0044Swedish Research Council, 2013-8271Available from: 2023-05-09 Created: 2023-05-09 Last updated: 2023-12-15Bibliographically approved
In thesis
1. Conservation genomics in inbred Scandinavian wolves using bioinformatic methods
Open this publication in new window or tab >>Conservation genomics in inbred Scandinavian wolves using bioinformatic methods
2024 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

With the recent and unprecedented progress in retrieving DNA sequence information from a large number of individuals of any species, conservation genetic research has entered a new phase. Specifically, it has become possible to study how genomes of endangered species respond to reductions in population size. Using genomic and bioinformatic approaches, in this thesis I investigate the contemporary Scandinavian wolf population founded 40 years ago by only three individuals, after the original population had been extirpated some decades earlier. The origin of the founders has been the subject of controversy, so I aimed to trace their origin using first male-specific Y chromosome sequences, and then whole-genome sequence data. I compared Scandinavian wolves to wolves from the nearby Finnish-Russian population as well as to publicly available wolf and dog samples from around the northern hemisphere, and found that the Scandinavian founders shared Y-haplotypes only with Finnish wolves. Consistent with this observation, when assessing population structure on the genomic scale, founders clustered with Finnish and Russian wolves, and an admixture analysis showed no other ancestries, nor traces of introgression from dogs. 

Small populations tend to have less genetic variation than larger populations, which might reduce their adaptive potential and increase the risk for extinction. A common measure used to investigate the genetic health of small populations is the genetic load, which is the fitness reduction of individuals due to accumulation of deleterious variants. I assessed the genetic load in Scandinavian wolves, divided into the components masked load (comprised of deleterious mutations in heterozygous state) and realized load (comprised of deleterious mutations in homozygous state), using both putatively deleterious single nucleotides and structural variants. I found that the realized load increased with every generation of inbreeding but was alleviated after genetic rescue events when new immigrants entered the population. Finally, I searched for the genetic basis of cryptorchidism, a testis condition that results in lowered fertility and is thought to be related to inbreeding depression. The trait is likely highly polygenic and the fact that only one significant association (to a region on the X chromosome) was found can be explained by that the number of available samples was very low, as is inevitable for small populations. 

In conclusion, this thesis explores the origin and the genetic health status of a small and recently founded natural population, and gives insights into how patterns of genetic load are affected by inbreeding and genetic rescue.  

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2024. p. 65
Series
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, ISSN 1651-6214 ; 2351
Keywords
conservation genomics, Canis lupus, bioinformatics, Y chromosome, admixture, genetic load, structural variation, GWAS
National Category
Evolutionary Biology
Research subject
Biology with specialization in Evolutionary Genetics
Identifiers
urn:nbn:se:uu:diva-517653 (URN)978-91-513-1998-8 (ISBN)
Public defence
2024-02-16, Zootissalen, EBC, Villavägen 9, Uppsala, 10:00 (English)
Opponent
Supervisors
Available from: 2024-01-24 Created: 2023-12-15 Last updated: 2024-01-24

Open Access in DiVA

fulltext(4445 kB)219 downloads
File information
File name FULLTEXT01.pdfFile size 4445 kBChecksum SHA-512
ea6b78e1a3ed60df4dbd046a80a3eb5a8bf4d5261156d290afbab69c551d0b73debd3c1e0f9d2a29ad7d47e572f983a03fee64f8e5b0d48c35a842ca48123ed5
Type fulltextMimetype application/pdf

Other links

Publisher's full textPubMed

Authority records

Smeds, LinnéaEllegren, Hans

Search in DiVA

By author/editor
Smeds, LinnéaEllegren, Hans
By organisation
Evolutionary Biology
In the same journal
Molecular Ecology
Evolutionary BiologyGenetics

Search outside of DiVA

GoogleGoogle Scholar
Total: 219 downloads
The number of downloads is the sum of all downloads of full texts. It may include eg previous versions that are now no longer available

doi
pubmed
urn-nbn

Altmetric score

doi
pubmed
urn-nbn
Total: 81 hits
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association
  • 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
  • rtf