This Special Issue includes work from scholars who differ in their perspective, but whose approaches and study systems are complementary. Such integration has not been attempted before and it is our hope that this theme issue will contribute to a comprehensive conceptual framework that will inspire a wider range of theoretical and empirical tests for the evolution of recombination rate—covering the good , the bad and the variable.
We would like to thank Roger Butlin for suggesting we prepare this Theme Issue and greatly appreciate all Helen Eaton's help in preparing the issue. We thank the authors for their great contributions and all of the reviewers for providing valuable and timely feedback.
She is an evolutionary biologist, currently studying how genome structure and organization influence evolutionary processes and adaptation. Her research integrates experimental, genetic and genomic tools in a wide range of study systems, including lizards, birds and plants. She has had a long-standing interest in how and why recombination varies across species and across the genome and how this can influence evolutionary processes, adaptation and speciation.
Philine's research is centred around understanding processes and factors creating and shaping genomic variation and divergence, including recombination. Philine mainly studies fish genome evolution with the aim to link genomic changes to diversity and differentiation at the organismal level.
Her research uses genomic approaches to understand the genetic basis of evolutionary trade-offs in natural populations. Most recently, she has been interested in understanding the evolution of individual recombination rates in wild mammals and birds, and investigating how recombination rates and landscapes evolve under domestication. Anna's current research uses large-scale genomic tools to determine the genetic basis of traits in wild populations, with the aim to understand how these populations will respond to future selection pressures including climate change.
She is currently exploring sex, age and individual differences in recombination rates across a number of species. Anna is also very interested in using genomic information to estimate relatedness between individuals, reconstruct pedigrees and assess population differentiation.
Carole's current research addresses the mechanisms of speciation and adaptation, with a special focus on the factors favouring divergence in the presence of gene flow and the genomics of reproductive isolation.
Her current projects in the house mouse and in the pea aphid tackle the role of sequence, expression and structural divergence at candidate multi-gene families in speciation and the influence of recombination rate variation in shaping patterns of genomic differentiation. National Center for Biotechnology Information , U. Published online Nov 6. Jessica Stapley , 1 Philine G. Feulner , 2, 3 Susan E.
Johnston , 4 Anna W. Santure , 5 and Carole M. Smadja 6. Philine G. Susan E. Anna W. Carole M. Author information Article notes Copyright and License information Disclaimer. Accepted Sep This article has been cited by other articles in PMC.
Abstract Recombination, the process by which DNA strands are broken and repaired, producing new combinations of alleles, occurs in nearly all multicellular organisms and has important implications for many evolutionary processes. Keywords: crossing over, meiosis, genetic linkage, evolution, adaptation, genomics.
Introduction Recombination, the exchange of DNA between maternal and paternal chromosomes during meiosis, is a near universal processes occurring in almost all forms of life and is fundamental for DNA repair and meiotic cell division.
Acknowledgements We would like to thank Roger Butlin for suggesting we prepare this Theme Issue and greatly appreciate all Helen Eaton's help in preparing the issue. Data accessibility This article has no additional data.
Competing interests We declare we have no competing interests. Funding J. References 1. Rice WR. Experimental tests of the adaptive significance of sexual recombination. Felsenstein J. The evolutionary advantage of recombination. Genetics 78 , — Charlesworth B, Barton NH. Recombination load associated with selection for increased recombination. Variation in recombination frequency and distribution across eukaryotes: patterns and processes. B , Are the effects of elevated temperature on meiotic recombination and thermotolerance linked via the axis and synaptonemal complex?
Recombination rate plasticity: revealing mechanisms by design. The impact of recombination on human mutation load and disease. The consequences of sequence erosion in the evolution of recombination hotspots. Otto SP, Lenormand T. Resolving the paradox of sex and recombination. It is responsible for producing genetic combinations not found in earlier generations. Sperm and ova are radically different from somatic cells in the number of chromosomes that they contain. Both male and female sex cells normally get only half of the pair of parent chromosomes 23 for humans.
Which half goes to any one sex cell is a matter of chance. Net effect of the meiosis process in terms of chromosome numbers At conception, a single sperm and an ovum combine their chromosomes to produce a zygote with the normal full set of 46, but with a new combination of chromosomes distinct from either parent. Sperm and ovum combining their chromosomes in a new zygote New combinations of existing genes are produced at the beginning of meiosis when the ends of chromosomes break and reattach , usually on their homologous chromosome.
This crossing-over process results in an unlinking and recombination of parental genes. Why Sex? From an evolutionary perspective, the most important consequence of meiosis and crossing-over is the rearrangement of genetic information. It constantly assures that each generation has significantly new genetic combinations from which nature can select for winners and losers in the competition for survival. The more genetic variation existing in a population, the greater the chance it will survive when there are stressful changes in the environment.
In other words, there will more likely be some individuals who will have a genetic combination that will allow them to survive changes such as major climate shifts or new predators and diseases. Those survivors will be the parents of future generations. This is very likely the reason that sexual reproduction was so successful in the history of evolution on earth. In contrast, organisms that reproduce asexually do not have the advantage of extensively new genetic combinations each generation.
They must rely on periodic mutations to provide their variation. Subsequently, they usually are less responsive to rapid changes in their environments. The short video linked below illustrates this advantage of sex. All rights reserved. Homologous chromosomes separating in the production of sex cells. Genetic linkage continues as homologous chromosomes separate in the formation of sex cells. Crossing-over unlinks alleles of genes as homologous chromosomes separate in the formation of sex cells.
The Red Queen --an explanation of why we have sexual reproduction This link takes you to a video at an external website.
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