Abstract
Meiotic recombination generates genetic diversity upon which selection can act. Recombination rates are highly variable between species, populations, individuals, sexes, chromosomes, and chromosomal regions. The underlying mechanisms are controlled at the genetic and epigenetic level and show plasticity toward the environment. Environmental plasticity may be divided into short- and long-term responses. We estimated recombination rates in natural populations of wild barley and domesticated landraces using a population genetics approach. We analyzed recombination landscapes in wild barley and domesticated landraces at high resolution. In wild barley, high recombination rates are found in more interstitial chromosome regions in contrast to distal chromosome regions in domesticated barley. Among subpopulations of wild barley, natural variation in effective recombination rate is correlated with temperature, isothermality, and solar radiation in a nonlinear manner. A positive linear correlation was found between effective recombination rate and annual precipitation. We discuss our findings with respect to how the environment might shape effective recombination rates in natural populations. Higher recombination rates in wild barley populations subjected to specific environmental conditions could be a means to maintain fitness in a strictly inbreeding species.
Highlights
Meiotic recombination, the exchange of DNA between homologous chromosomes, and the random segregation of chromosomes into gametes are fundamental to eukaryotic reproduction
Recombination Landscapes Are Highly Conserved between Wild and Domesticated Barley The physical distribution and frequency of recombination events, that is, recombination landscape, play a role in plant adaptation as some genes are more likely to recombine than others
Previous characterizations of the recombination landscape of barley focused on domesticated barley (Kunzel et al 2000; Higgins et al 2012; Phillips et al 2012, 2015; Dreissig et al 2015, 2017), except for cytological studies revealing a slightly higher number of chiasmata in domesticated barley than in wild barley (Ross-Ibarra 2004)
Summary
The exchange of DNA between homologous chromosomes, and the random segregation of chromosomes into gametes are fundamental to eukaryotic reproduction. We used a population genetic approach to estimate effective recombination rates in a strictly inbreeding grass species, H. vulgare, and asked whether natural variation in recombination rates is associated with present (1970–2000) and past (6,000–22,000 years before present [BP]) environmental conditions. We find strong similarities between the recombination landscape of wild and domesticated barley based on population genetic data.
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