| 1. |
- Günther, Torsten, et al.
(author)
-
Genomic and phenotypic differentiation of Arabidopsis thaliana along altitudinal gradients in the North Italian Alps
- 2016
-
In: Molecular Ecology. - : Wiley. - 0962-1083 .- 1365-294X. ; 25:15, s. 3574-3592
-
Journal article (peer-reviewed)abstract
- Altitudinal gradients in mountain regions are short-range clines of different environmental parameters such as temperature or radiation. We investigated genomic and phenotypic signatures of adaptation to such gradients in five Arabidopsis thaliana populations from the North Italian Alps that originated from 580 to 2350m altitude by resequencing pools of 19-29 individuals from each population. The sample includes two pairs of low- and high-altitude populations from two different valleys. High-altitude populations showed a lower nucleotide diversity and negative Tajima's D values and were more closely related to each other than to low-altitude populations from the same valley. Despite their close geographic proximity, demographic analysis revealed that low- and high-altitude populations split between 260000 and 15000years before present. Single nucleotide polymorphisms whose allele frequencies were highly differentiated between low- and high-altitude populations identified genomic regions of up to 50kb length where patterns of genetic diversity are consistent with signatures of local selective sweeps. These regions harbour multiple genes involved in stress response. Variation among populations in two putative adaptive phenotypic traits, frost tolerance and response to light/UV stress was not correlated with altitude. Taken together, the spatial distribution of genetic diversity reflects a potentially adaptive differentiation between low- and high-altitude populations, whereas the phenotypic differentiation in the two traits investigated does not. It may resemble an interaction between adaptation to the local microhabitat and demographic history influenced by historical glaciation cycles, recent seed dispersal and genetic drift in local populations.
|
|
| 2. |
- Günther, Torsten, et al.
(author)
-
Mutational bias and gene conversion affect the intraspecific nitrogen stoichiometry of the Arabidopsis thaliana transcriptome.
- 2013
-
In: Molecular biology and evolution. - : Oxford University Press (OUP). - 0737-4038 .- 1537-1719. ; 30:3, s. 561-8
-
Journal article (peer-reviewed)abstract
- The transcriptome and proteome of Arabidopsis thaliana are reduced in nitrogen content when compared with other taxa, which may result from ecological nitrogen limitation. We hypothesized that if the A. thaliana transcriptome is selected for a low nitrogen content, nitrogen-reducing derived alleles of single nucleotide polymorphisms (SNPs) should segregate at higher frequencies than nitrogen-increasing alleles. This pattern should be stronger in populations with a larger effective population size (N(e)) if natural selection is more efficient in large than in small populations. We analyzed variation in the nitrogen content in the transcriptome of 80 natural accessions of A. thaliana. In contrast to our expectations, derived alleles increase the nitrogen content in all accessions, and there is a positive correlation between nitrogen difference and derived allele frequency, which is strongest with nonsynonymous SNPs (nsSNPs). Also, there is a positive correlation between nitrogen difference and N(e) that was mainly caused by nsSNPs. These observations led us to reject the hypothesis that the transcriptome of A. thaliana is currently under selection to reduce nitrogen content. Instead, we show that a change in nitrogen content is a side effect of interacting evolutionary factors that influence base composition and include mutational bias, purifying selection of functionally deleterious alleles, and GC-biased gene conversion. We provide strong evidence that GC-biased gene conversion may play an important role for base composition in the highly selfing plant A. thaliana.
|
|
| 3. |
- Santangelo, James S., et al.
(author)
-
Global urban environmental change drives adaptation in white clover
- 2022
-
In: Science. - : American Association for the Advancement of Science (AAAS). - 0036-8075 .- 1095-9203. ; 375
-
Journal article (peer-reviewed)abstract
- Urbanization transforms environments in ways that alter biological evolution. We examined whether urban environmental change drives parallel evolution by sampling 110,019 white clover plants from 6169 populations in 160 cities globally. Plants were assayed for a Mendelian antiherbivore defense that also affects tolerance to abiotic stressors. Urban-rural gradients were associated with the evolution of clines in defense in 47% of cities throughout the world. Variation in the strength of clines was explained by environmental changes in drought stress and vegetation cover that varied among cities. Sequencing 2074 genomes from 26 cities revealed that the evolution of urban-rural dines was best explained by adaptive evolution, but the degree of parallel adaptation varied among cities. Our results demonstrate that urbanization leads to adaptation at a global scale.
|
|
