Understanding the Genetic Basis of Variation in Meiotic Recombination: Past, Present, and Future

Meiotic recombination is a fundamental feature of sexually reproducing species. It is often required for proper chromosome segregation and plays important role in adaptation and the maintenance of genetic diversity. The molecular mechanisms of recombination are remarkably conserved across eukaryotes, yet meiotic genes and proteins show substantial variation in their sequence and function, even between closely related species. Furthermore, the rate and distribution of recombination shows a huge diversity within and between chromosomes, individuals, sexes, populations, and species. This variation has implications for many molecular and evolutionary processes, yet how and why this diversity has evolved is not well understood. A key step in understanding trait evolution is to determine its genetic basis—that is, the number, effect sizes, and distribution of loci underpinning variation. In this perspective, I discuss past and current knowledge on the genetic basis of variation in recombination rate and distribution, explore its evolutionary implications, and present open questions for future research

A genomic region containing <i>REC8</i> and <i>RNF212B</i> is associated with individual recombination rate variation in a wild population of red deer (<i>Cervus elaphus</i>)

Recombination is a fundamental feature of sexual reproduction, ensuring proper disjunction, preventing mutation accumulation and generating new allelic combinations upon which selection can act. However it is also mutagenic, and breaks up favorable allelic combinations previously built up by selection. Identifying the genetic drivers of recombination rate variation is a key step in understanding the causes and consequences of this variation, how loci associated with recombination are evolving and how they affect the potential of a population to respond to selection. However, to date, few studies have examined the genetic architecture of recombination rate variation in natural populations. Here, we use pedigree data from ∼ 2,600 individuals genotyped at ∼ 38,000 SNPs to investigate the genetic architecture of individual autosomal recombination rate in a wild population of red deer (Cervus elaphus). Female red deer exhibited a higher mean and phenotypic variance in autosomal crossover counts (ACC). Animal models fitting genomic relatedness matrices showed that ACC was heritable in females (h2 = 0.12) but not in males. A regional heritability mapping approach showed that almost all heritable variation in female ACC was explained by a genomic region on deer linkage group 12 containing the candidate loci REC8 and RNF212B, with an additional region on linkage group 32 containing TOP2B approaching genome-wide significance. The REC8/RNF212B region and its paralogue RNF212 have been associated with recombination in cattle, mice, humans and sheep. Our findings suggest that mammalian recombination rates have a relatively conserved genetic architecture in both domesticated and wild systems, and provide a foundation for understanding the association between recombination loci and individual fitness within this population

Taking Quantitative Genomics into the Wild

A key goal in studies of ecology and evolution is understanding the causes of phenotypic diversity in nature. Most traits of interest, such as those relating to morphology, life-history, immunity and behaviour are quantitative, and phenotypic variation is driven by the cumulative effects of genetic and environmental variation. The field of quantitative genetics aims to quantify the additive genetic component of this trait variance (i.e. the "heritability"), often with the underlying assumption that trait variance is driven by many loci of infinitesimal effects throughout the genome. This approach allows us to understand the evolutionary potential of natural populations and can be extended to examine the genetic covariation with fitness to predict responses to selection. Therefore, quantitative genetic studies are fundamental to understanding evolution in the wild. Over the last two decades, there has been a wealth of studies investigating trait heritabilities and genetic correlations, but these were initially limited to long-term studies of pedigreed populations or common-garden experiments. However, genomic technologies have since allowed quantitative genetic studies in a more diverse range of wild systems and has increased the opportunities for addressing outstanding questions in ecology and evolution. In particular, genomic studies can uncover the genetic basis of fitness-related quantitative traits, allowing a better understanding of their evolutionary dynamics. We organised this special issue to highlight new work and review recent advances at the cutting edge of "Wild Quantitative Genomics". In this Editorial, we will present some history of wild quantitative genetic and genomic studies, before discussing the main themes in the papers published in this special issue and highlighting the future outlook of this dynamic field.Comment: 17 page (plus references) Editorial for a special issue of Proceedings of the Royal Society B: Biological Sciences. Revised submissio

Recombination rates in pigs differ between breeds, sexes and individuals, and are associated with the RNF212, SYCP2, PRDM7, MEI1 and MSH4 loci

publishedVersio

Developing coaches for mathematical resilience

The construct ‘Mathematical Resilience’ [1] has been developed to describe a positive stance towards mathematics that enables learners to develop approaches to mathematical learning which enable them to overcome the barriers and setbacks that can be part of learning mathematics for many people. A resilient stance towards mathematics can be engineered by a strategic and explicit focus on the culture of learning mathematics within both formal and informal learning environments. As part of that cultural engineering, we have developed the notion of coaches specifically to support emergent resilience. The work described here is focused on developing coaches who can work beside learners, helping them to think about and use resilient learning ideas when facing difficulties in mathematics. Coaches develop a culture of ‘can do’ mathematics which works to counter the prevalent culture of mathematics helplessness and mathematics anxiety in the general population when faced with mathematical ideas. The coaches are not required to know the answer but rather to know ways that might yield an understanding of the mathematical ideas involved and thus lead to an answer. This paper discusses the outcomes of a pilot course (April to June 2013) designed to develop ‘coaches for mathematical resilience’. The course recruited 11 participants who regularly work with apprentices, both young and more mature, in a work-based environment and who are required to learn and use mathematics as part of their on-going training. They became part of the course due to recognition of their own lack of knowledge about how to overcome deep seated antipathy to mathematics in themselves and in those with whom they work. The data confirms that in order to become an effective coach, an individual first needs to develop their own personal mathematical resilience, work through their own anxieties and negative stance towards mathematics in a safe and collaborative environment, before they can coach a learner to develop as a resilient learner of mathematics. An environment that enables an individual to learn to be a mathematics resilience coach will need to expose the learners to mathematical ideas in order to enable participants to consider and manage their own reactions to mathematical ideas and reflect on how to help someone else find the resources to overcome their own barriers to learning mathematics

Inside Hollins (1942)

https://digitalcommons.hollins.edu/insideh/1002/thumbnail.jp