Data from: Meta‐analysis of chromosome‐scale crossover rate variation in eukaryotes and its significance to evolutionary genomics

Understanding the distribution of crossovers along chromosomes is crucial
to evolutionary genomics because the crossover rate determines how
strongly a genome region is influenced by natural selection. Nevertheless,
generalities in the chromosome-scale distribution of crossovers have not
been investigated formally. We fill this gap by synthesizing joint
information on genetic and physical maps across 62 animal, plant, and
fungal species. Our quantitative analysis reveals a strong and
taxonomically wide-spread reduction of the crossover rate in the center of
chromosomes relative to their peripheries. We demonstrate that this
pattern is poorly explained by the position of the centromere, but find
that the magnitude of the relative reduction in the crossover rate in
chromosome centers increases with chromosome length. That is, long
chromosomes often display a dramatically low crossover rate in their
center whereas short chromosomes exhibit a relatively homogeneous
crossover rate. This observation is compatible with a model in which
crossovers are initiated from the chromosome tips, an idea with
preliminary support from mechanistic investigations of meiotic
recombination. Consequently, we show that organisms achieve a higher
genome-wide crossover rate by evolving smaller chromosomes. Summarizing
theory and providing empirical examples, we finally highlight that
taxonomically wide-spread and systematic heterogeneity in crossover rate
along chromosomes generates predictable broad-scale trends in genetic
diversity and population differentiation by modifying the impact of
natural selection among regions within a genome. We conclude by
emphasizing that chromosome-scale heterogeneity in crossover rate should
urgently be incorporated into analytical tools in evolutionary genomics,
and in the interpretation of emerging patterns.