Genome-wide evolutionary response of European oaks since the Little Ice Age

The pace of tree microevolution during Anthropocene warming is largely unknown. We used a retrospective approach to monitor genomic changes in oak trees since the Little Ice Age (LIA). Allelic frequency changes were assessed from whole-genome pooled sequences for four age-structured cohorts of sessile oak (Quercus petraea) dating back to 1680, in each of three different oak forests in France. The genetic covariances of allelic frequency changes increased between successive time periods, highlighting genome-wide effects of linked selection. We found imprints of convergent linked selection in the three forests during the late LIA, and a shift of selection during more recent time periods. The changes in allelic covariances within and between forests mirrored the documented changes in the occurrence of extreme events (droughts and frosts) over the last three hundred years. The genomic regions with the highest covariances were enriched in genes involved in plant responses to pathogens and abiotic stresses (temperature and drought). These responses are consistent with the reported sequence of frost (or drought) and disease damage ultimately leading to the oak dieback after extreme events. Our results therefore provide evidence of selection operating on long-lived species during recent climatic changes.

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Greenhouses, hot water bottles, cycles and the future of New Zealand climate

Proceedings of the New Zealand Grassland Association ◽

10.33584/jnzg.2009.71.2772 ◽

2009 ◽

pp. 61-67

Author(s):

W.P. De Lange

Keyword(s):

New Zealand ◽

Thermal Energy ◽

Infrared Radiation ◽

Little Ice Age ◽

Hot Water ◽

Ice Age ◽

The Sun ◽

Weather Patterns ◽

Time Periods ◽

Almost All

The Greenhouse Effect acts to slow the escape of infrared radiation to space, and hence warms the atmosphere. The oceans derive almost all of their thermal energy from the sun, and none from infrared radiation in the atmosphere. The thermal energy stored by the oceans is transported globally and released after a range of different time periods. The release of thermal energy from the oceans modifies the behaviour of atmospheric circulation, and hence varies climate. Based on ocean behaviour, New Zealand can expect weather patterns similar to those from 1890-1922 and another Little Ice Age may develop this century.

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Estimating the genome-wide contribution of selection to temporal allele frequency change

10.1101/798595 ◽

2019 ◽

Cited By ~ 1

Author(s):

Vince Buffalo ◽

Graham Coop

Keyword(s):

Allele Frequency ◽

Genetic Drift ◽

Genomic Data ◽

Allele Frequencies ◽

Frequency Change ◽

Standing Variation ◽

Genome Wide ◽

Selection Experiments ◽

Frequency Changes ◽

Linked Selection

AbstractRapid phenotypic adaptation is often observed in natural populations and selection experiments. However, detecting the genome-wide impact of this selection is difficult, since adaptation often proceeds from standing variation and selection on polygenic traits, both of which may leave faint genomic signals indistinguishable from a noisy background of genetic drift. One promising signal comes from the genome-wide covariance between allele frequency changes observable from temporal genomic data, e.g. evolve-and-resequence studies. These temporal covariances reflect how heritable fitness variation in the population leads changes in allele frequencies at one timepoint to be predictive of the changes at later timepoints, as alleles are indirectly selected due to remaining associations with selected alleles. Since genetic drift does not lead to temporal covariance, we can use these covariances to estimate what fraction of the variation in allele frequency change through time is driven by linked selection. Here, we reanalyze three selection experiments to quantify the effects of linked selection over short timescales using covariance among time-points and across replicates. We estimate that at least 17% to 37% of allele frequency change is driven by selection in these experiments. Against this background of positive genome-wide temporal covariances we also identify signals of negative temporal covariance corresponding to reversals in the direction of selection for a reasonable proportion of loci over the time course of a selection experiment. Overall, we find that in the three studies we analyzed, linked selection has a large impact on short-term allele frequency dynamics that is readily distinguishable from genetic drift.Significance StatementA long-standing problem in evolutionary biology is to understand the processes that shape the genetic composition of populations. In a population without migration, the two processes that change allele frequencies are selection, which increases beneficial alleles and removes deleterious ones, and genetic drift which randomly changes frequencies as some parents contribute more or less alleles to the next generation. Previous efforts to disentangle these processes have used genomic samples from a single timepoint and models of how selection affects neighboring sites (linked selection). Here, we use genomic data taken through time to quantify the contributions of selection and drift to genome-wide frequency changes. We show selection acts over short timescales in three evolve-and-resequence studies and has a sizable genome-wide impact.

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Inventory and genesis of glacial lakes in Switzerland since the Little Ice Age

10.5194/egusphere-egu21-12144 ◽

2021 ◽

Author(s):

Nico Mölg ◽

Christian Huggel ◽

Thilo Herold ◽

Florian Storck ◽

Simon Allen ◽

...

Keyword(s):

Little Ice Age ◽

Landscape Planning ◽

Ice Age ◽

Glacial Lakes ◽

Morphological Aspects ◽

Formation Probability ◽

Lake Formation ◽

Morphological Criteria ◽

Time Periods ◽

Existing Data

The deglaciation since the end of the Little Ice Age (LIA, ~1850) has given way to >700km&#178; of &#8220;new&#8221; landscape in Switzerland. Glacial lakes are a conspicuous feature of this new landscape &#8211; with relevance for natural hazards, hydropower and landscape planning. In this study, we compiled an inventory of glacial lakes for Switzerland for the year 2016. Using existing data, we investigated the evolution of glacial lakes in Switzerland for six time periods since the LIA. Additionally, we compiled information constituting a basis for hazard assessment for all ice-contact lakes in 2016 and all lakes >0.5 ha, i.e. surface outflow, dam type and material, and lake freeboard.We found that a total of 1230 lakes formed over the period of ~170 years, 982 still existing in 2016. The largest lakes are >0.4&#160;km&#178; (40&#160;ha) in size, while the majority (>90%) are smaller than 0.01&#160;km&#178;. Annual increase rates in area and number peaked in 1946-1973, decreased towards the end of the 20th century, and reached a new high in the latest period 2006-2016. For a period of 43 years, we compared modelled overdeepenings from previous studies to actual lake genesis. For a better prioritisation of formation probability, we included glacier-morphological criteria such as glacier width and visible crevassing. About 40% of the modelled overdeepened area actually filled with water. The inclusion of morphological aspects clearly aided in linking a lake formation probability to a modelled overdeepening.<img src="https://contentmanager.copernicus.org/fileStorageProxy.php?f=gnp.d3501255f60064578601161/sdaolpUECMynit/12UGE&app=m&a=0&c=a53c560cf096fb15e526d1d230f3d1bf&ct=x&pn=gnp.elif&d=1" alt="" width="381" height="225">Fig. 1: Glacial lake distribution in Switzerland and its evolution over time.&#160;

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Estimating the genome-wide contribution of selection to temporal allele frequency change

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.1919039117 ◽

2020 ◽

Vol 117 (34) ◽

pp. 20672-20680

Author(s):

Vince Buffalo ◽

Graham Coop

Keyword(s):

Allele Frequency ◽

Genetic Drift ◽

Time Course ◽

Frequency Change ◽

Time Points ◽

Standing Variation ◽

Genome Wide ◽

Selection Experiments ◽

Frequency Changes ◽

Linked Selection

Rapid phenotypic adaptation is often observed in natural populations and selection experiments. However, detecting the genome-wide impact of this selection is difficult since adaptation often proceeds from standing variation and selection on polygenic traits, both of which may leave faint genomic signals indistinguishable from a noisy background of genetic drift. One promising signal comes from the genome-wide covariance between allele frequency changes observable from temporal genomic data (e.g., evolve-and-resequence studies). These temporal covariances reflect how heritable fitness variation in the population leads changes in allele frequencies at one time point to be predictive of the changes at later time points, as alleles are indirectly selected due to remaining associations with selected alleles. Since genetic drift does not lead to temporal covariance, we can use these covariances to estimate what fraction of the variation in allele frequency change through time is driven by linked selection. Here, we reanalyze three selection experiments to quantify the effects of linked selection over short timescales using covariance among time points and across replicates. We estimate that at least 17 to 37% of allele frequency change is driven by selection in these experiments. Against this background of positive genome-wide temporal covariances, we also identify signals of negative temporal covariance corresponding to reversals in the direction of selection for a reasonable proportion of loci over the time course of a selection experiment. Overall, we find that in the three studies we analyzed, linked selection has a large impact on short-term allele frequency dynamics that is readily distinguishable from genetic drift.

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Rapid thinning of lake-calving Yakutat Glacier and the collapse of the Yakutat Icefield, southeast Alaska, USA

Journal of Glaciology ◽

10.3189/2013j0g12j081 ◽

2013 ◽

Vol 59 (213) ◽

pp. 149-161 ◽

Cited By ~ 37

Author(s):

Barbara L. Trüssel ◽

Roman J. Motyka ◽

Martin Truffer ◽

Christopher F. Larsen

Keyword(s):

Sea Level ◽

Little Ice Age ◽

Ice Age ◽

Southeast Alaska ◽

Feedback Mechanisms ◽

Climate Conditions ◽

Tidewater Glaciers ◽

Warming Climate ◽

Digital Elevation ◽

Time Periods

AbstractBoth lake-calving Yakutat Glacier (337 km2), Alaska, USA, and its parent icefield (810 km2) are experiencing strong thinning, and under current climate conditions will eventually disappear. Comparison of digital elevation models shows that Yakutat Glacier thinned at area-averaged rates of 4.76 ± 0.06 m w.e.a−1 (2000–07) and 3.66 ± 0.03 m w.e.a−1 (2007–10). Simultaneously, adjacent Yakutat Icefield land-terminating glaciers thinned at lower but still substantial rates (3.79 and 2.94 m w.e.a−1 respectively for the same time periods), indicating lake-calving dynamics helps drive increased mass loss. Yakutat Glacier terminates into Harlequin Lake and for over a decade sustained a ∼3 km long floating tongue, which started to disintegrate into large tabular icebergs in 2010. Such floating tongues are rarely seen on temperate tidewater glaciers. We hypothesize that this difference is likely due to the lack of submarine melting in the case of lake-calving glaciers. Floating-tongue ice losses were evaluated in terms of overall mass balance and contribution to sea-level rise. The post-Little Ice Age collapse of Yakutat Icefield was driven in part by tidewater calving retreats of adjacent glaciers, the lake-calving retreat of Yakutat Glacier, a warming climate and by the positive feedback mechanisms through surface lowering.

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