| 1. |
- Dussex, Nicolas, et al.
(författare)
-
Population genomics of the critically endangered kākāpō
- 2021
-
Ingår i: Cell Genomics. - : Elsevier BV. - 2666-979X. ; 1:1
-
Tidskriftsartikel (refereegranskat)abstract
- Summary The kākāpō is a flightless parrot endemic to New Zealand. Once common in the archipelago, only 201 individuals remain today, most of them descending from an isolated island population. We report the first genome-wide analyses of the species, including a high-quality genome assembly for kākāpō, one of the first chromosome-level reference genomes sequenced by the Vertebrate Genomes Project (VGP). We also sequenced and analyzed 35 modern genomes from the sole surviving island population and 14 genomes from the extinct mainland population. While theory suggests that such a small population is likely to have accumulated deleterious mutations through genetic drift, our analyses on the impact of the long-term small population size in kākāpō indicate that present-day island kākāpō have a reduced number of harmful mutations compared to mainland individuals. We hypothesize that this reduced mutational load is due to the island population having been subjected to a combination of genetic drift and purging of deleterious mutations, through increased inbreeding and purifying selection, since its isolation from the mainland ∼10,000 years ago. Our results provide evidence that small populations can survive even when isolated for hundreds of generations. This work provides key insights into kākāpō breeding and recovery and more generally into the application of genetic tools in conservation efforts for endangered species.
|
|
| 2. |
- Kutschera, Verena E., et al.
(författare)
-
GenErode : a bioinformatics pipeline to investigate genome erosion in endangered and extinct species
- 2022
-
Ingår i: BMC Bioinformatics. - : Springer Nature. - 1471-2105. ; 23:1
-
Tidskriftsartikel (refereegranskat)abstract
- Background: Many wild species have suffered drastic population size declines over the past centuries, which have led to 'genomic erosion' processes characterized by reduced genetic diversity, increased inbreeding, and accumulation of harmful mutations. Yet, genomic erosion estimates of modern-day populations often lack concordance with dwindling population sizes and conservation status of threatened species. One way to directly quantify the genomic consequences of population declines is to compare genome-wide data from pre-decline museum samples and modern samples. However, doing so requires computational data processing and analysis tools specifically adapted to comparative analyses of degraded, ancient or historical, DNA data with modern DNA data as well as personnel trained to perform such analyses. Results: Here, we present a highly flexible, scalable, and modular pipeline to compare patterns of genomic erosion using samples from disparate time periods. The GenErode pipeline uses state-of-the-art bioinformatics tools to simultaneously process whole-genome re-sequencing data from ancient/historical and modern samples, and to produce comparable estimates of several genomic erosion indices. No programming knowledge is required to run the pipeline and all bioinformatic steps are well-documented, making the pipeline accessible to users with different backgrounds. GenErode is written in Snakemake and Python3 and uses Conda and Singularity containers to achieve reproducibility on high-performance compute clusters. The source code is freely available on GitHub (https://github.com/NBISweden/GenErode). Conclusions: GenErode is a user-friendly and reproducible pipeline that enables the standardization of genomic erosion indices from temporally sampled whole genome re-sequencing data.
|
|
| 3. |
- Lord, Edana, et al.
(författare)
-
Pre-extinction Demographic Stability and Genomic Signatures of Adaptation in the Woolly Rhinoceros
- 2020
-
Ingår i: Current Biology. - : Elsevier BV. - 0960-9822 .- 1879-0445. ; 30:19
-
Tidskriftsartikel (refereegranskat)abstract
- Ancient DNA has significantly improved our understanding of the evolution and population history of extinct megafauna. However, few studies have used complete ancient genomes to examine species responses to climate change prior to extinction. The woolly rhinoceros (Coelodonta antiquitatis) was a cold-adapted megaherbivore widely distributed across northern Eurasia during the Late Pleistocene and became extinct approximately 14 thousand years before present (ka BP). While humans and climate change have been proposed as potential causes of extinction [1-3], knowledge is limited on how the woolly rhinoceros was impacted by human arrival and climatic fluctuations [2]. Here, we use one complete nuclear genome and 14 mitogenomes to investigate the demographic history of woolly rhinoceros leading up to its extinction. Unlike other northern megafauna, the effective population size of woolly rhinoceros likely increased at 29.7 ka BP and subsequently remained stable until close to the species’ extinction. Analysis of the nuclear genome from a similar to 18.5-ka-old specimen did not indicate any increased inbreeding or reduced genetic diversity, suggesting that the population size remained steady for more than 13 ka following the arrival of humans [4]. The population contraction leading to extinction of the woolly rhinoceros may have thus been sudden and mostly driven by rapid warming in the Bolling-Allerod interstadial. Furthermore, we identify woolly rhinoceros-specific adaptations to arctic climate, similar to those of the woolly mammoth. This study highlights how species respond differently to climatic fluctuations and further illustrates the potential of palaeogenomics to study the evolutionary history of extinct species.
|
|
| 4. |
- Dehasque, Marianne, et al.
(författare)
-
Inference of natural selection from ancient DNA
- 2020
-
Ingår i: Evolution Letters. - : JOHN WILEY & SONS LTD. - 2056-3744. ; 4:2, s. 94-108
-
Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Evolutionary processes, including selection, can be indirectly inferred based on patterns of genomic variation among contemporary populations or species. However, this often requires unrealistic assumptions of ancestral demography and selective regimes. Sequencing ancient DNA from temporally spaced samples can inform about past selection processes, as time series data allow direct quantification of population parameters collected before, during, and after genetic changes driven by selection. In this Comment and Opinion, we advocate for the inclusion of temporal sampling and the generation of paleogenomic datasets in evolutionary biology, and highlight some of the recent advances that have yet to be broadly applied by evolutionary biologists. In doing so, we consider the expected signatures of balancing, purifying, and positive selection in time series data, and detail how this can advance our understanding of the chronology and tempo of genomic change driven by selection. However, we also recognize the limitations of such data, which can suffer from postmortem damage, fragmentation, low coverage, and typically low sample size. We therefore highlight the many assumptions and considerations associated with analyzing paleogenomic data and the assumptions associated with analytical methods.
|
|
| 5. |
- Dussex, Nicolas, et al.
(författare)
-
Integrating multi-taxon palaeogenomes and sedimentary ancient DNA to study past ecosystem dynamics
- 2021
-
Ingår i: Proceedings of the Royal Society of London. Biological Sciences. - : The Royal Society. - 0962-8452 .- 1471-2954. ; 288:1957
-
Forskningsöversikt (refereegranskat)abstract
- Ancient DNA (aDNA) has played a major role in our understanding of the past. Important advances in the sequencing and analysis of aDNA from a range of organisms have enabled a detailed understanding of processes such as past demography, introgression, domestication, adaptation and speciation. However, to date and with the notable exception of microbiomes and sediments, most aDNA studies have focused on single taxa or taxonomic groups, making the study of changes at the community level challenging. This is rather surprising because current sequencing and analytical approaches allow us to obtain and analyse aDNA from multiple source materials. When combined, these data can enable the simultaneous study of multiple taxa through space and time, and could thus provide a more comprehensive understanding of ecosystem-wide changes. It is therefore timely to develop an integrative approach to aDNA studies by combining data from multiple taxa and substrates. In this review, we discuss the various applications, associated challenges and future prospects of such an approach.
|
|
| 6. |
- Feuerborn, Tatiana R., et al.
(författare)
-
Competitive mapping allows for the identification and exclusion of human DNA contamination in ancient faunal genomic datasets
- 2020
-
Ingår i: BMC Genomics. - : Springer Science and Business Media LLC. - 1471-2164. ; 21:1
-
Tidskriftsartikel (refereegranskat)abstract
- Background: After over a decade of developments in field collection, laboratory methods and advances in high-throughput sequencing, contamination remains a key issue in ancient DNA research. Currently, human and microbial contaminant DNA still impose challenges on cost-effective sequencing and accurate interpretation of ancient DNA data.Results: Here we investigate whether human contaminating DNA can be found in ancient faunal sequencing datasets. We identify variable levels of human contamination, which persists even after the sequence reads have been mapped to the faunal reference genomes. This contamination has the potential to affect a range of downstream analyses.Conclusions: We propose a fast and simple method, based on competitive mapping, which allows identifying and removing human contamination from ancient faunal DNA datasets with limited losses of true ancient data. This method could represent an important tool for the ancient DNA field.
|
|
| 7. |
- Jensen, Evelyn L., et al.
(författare)
-
Ancient and historical DNA in conservation policy
- 2022
-
Ingår i: Trends in Ecology & Evolution. - : Elsevier. - 0169-5347 .- 1872-8383. ; 37:5, s. 420-429
-
Forskningsöversikt (refereegranskat)abstract
- Although genetic diversity has been recognized as a key component of biodiversity since the first Convention on Biological Diversity (CBD) in 1993, it has rarely been included in conservation policies and regulations. Even less appreciated is the role that ancient and historical DNA (aDNA and hDNA, respectively) could play in unlocking the temporal dimension of genetic diversity, allowing key conservation issues to be resolved, including setting baselines for intraspecies genetic diversity, estimating changes in effective population size (N-e), and identifying the genealogical continuity of populations. Here, we discuss how genetic information from ancient and historical specimens can play a central role in preserving biodiversity and highlight specific conservation policies that could incorporate such data to help countries meet their CBD obligations.
|
|
| 8. |
- Kurland, Sara, 1989-, et al.
(författare)
-
New indicators for monitoring genetic diversity applied to alpine brown trout populations using whole genome sequence data
- 2024
-
Ingår i: Molecular Ecology. - : John Wiley & Sons. - 0962-1083 .- 1365-294X. ; 33:2
-
Tidskriftsartikel (refereegranskat)abstract
- International policy recently adopted commitments to maintain genetic diversity in wild populations to secure their adaptive potential, including metrics to monitor temporal trends in genetic diversity – so-called indicators. A national programme for assessing trends in genetic diversity was recently initiated in Sweden. Relating to this effort, we systematically assess contemporary genome-wide temporal trends (40 years) in wild populations using the newly adopted indicators and whole genome sequencing (WGS). We use pooled and individual WGS data from brown trout (Salmo trutta) in eight alpine lakes in protected areas. Observed temporal trends in diversity metrics (nucleotide diversity, Watterson's ϴ and heterozygosity) lie within proposed acceptable threshold values for six of the lakes, but with consistently low values in lakes above the tree line and declines observed in these northern-most lakes. Local effective population size is low in all lakes, highlighting the importance of continued protection of interconnected systems to allow genetic connectivity for long-term viability of these populations. Inbreeding (FROH) spans 10%–30% and is mostly represented by ancient (<1 Mb) runs of homozygosity, with observations of little change in mutational load. We also investigate adaptive dynamics over evolutionarily short time frames (a few generations); identifying putative parallel selection across all lakes within a gene pertaining to skin pigmentation as well as candidates of selection unique to specific lakes and lake systems involved in reproduction and immunity. We demonstrate the utility of WGS for systematic monitoring of natural populations, a priority concern if genetic diversity is to be protected.
|
|
| 9. |
|
|
| 10. |
- van der Valk, Tom, et al.
(författare)
-
Historical Genomes Reveal the Genomic Consequences of Recent Population Decline in Eastern Gorillas
- 2019
-
Ingår i: Current Biology. - : Elsevier BV. - 0960-9822 .- 1879-0445. ; 29:1, s. 165-170.e6
-
Tidskriftsartikel (refereegranskat)abstract
- Many endangered species have experienced severe population declines within the last centuries [1, 2]. However, despite concerns about negative fitness effects resulting from increased genetic drift and inbreeding, there is a lack of empirical data on genomic changes in conjunction with such declines [3-7]. Here, we use whole genomes recovered from century-old historical museum specimens to quantify the genomic consequences of small population size in the critically endangered Grauer's and endangered mountain gorillas. We find a reduction of genetic diversity and increase in inbreeding and genetic load in the Grauer's gorilla, which experienced severe population declines in recent decades. In contrast, the small but relatively stable mountain gorilla population has experienced little genomic change during the last century. These results suggest that species histories as well as the rate of demographic change may influence how population declines affect genome diversity.
|
|
