T H Noel Ellis, Julie M I Hofer, Martin T Swain, Peter J van Dijk
{"title":"Mendel's pea crosses: varieties, traits and statistics.","authors":"T H Noel Ellis, Julie M I Hofer, Martin T Swain, Peter J van Dijk","doi":"10.1186/s41065-019-0111-y","DOIUrl":null,"url":null,"abstract":"<p><p>A controversy arose over Mendel's pea crossing experiments after the statistician R.A. Fisher proposed how these may have been performed and criticised Mendel's interpretation of his data. Here we re-examine Mendel's experiments and investigate Fisher's statistical criticisms of bias. We describe pea varieties available in Mendel's time and show that these could readily provide all the material Mendel needed for his experiments; the characters he chose to follow were clearly described in catalogues at the time. The combination of character states available in these varieties, together with Eichling's report of crosses Mendel performed, suggest that two of his F3 progeny test experiments may have involved the same F2 population, and therefore that these data should not be treated as independent variables in statistical analysis of Mendel's data. A comprehensive re-examination of Mendel's segregation ratios does not support previous suggestions that they differ remarkably from expectation. The χ<sup>2</sup> values for his segregation ratios sum to a value close to the expectation and there is no deficiency of extreme segregation ratios. Overall the χ values for Mendel's segregation ratios deviate slightly from the standard normal distribution; this is probably because of the variance associated with phenotypic rather than genotypic ratios and because Mendel excluded some data sets with small numbers of progeny, where he noted the ratios \"deviate not insignificantly\" from expectation.</p>","PeriodicalId":55057,"journal":{"name":"Hereditas","volume":null,"pages":null},"PeriodicalIF":2.1000,"publicationDate":"2019-10-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1186/s41065-019-0111-y","citationCount":"6","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Hereditas","FirstCategoryId":"99","ListUrlMain":"https://doi.org/10.1186/s41065-019-0111-y","RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"2019/1/1 0:00:00","PubModel":"eCollection","JCR":"Q3","JCRName":"GENETICS & HEREDITY","Score":null,"Total":0}
引用次数: 6
Abstract
A controversy arose over Mendel's pea crossing experiments after the statistician R.A. Fisher proposed how these may have been performed and criticised Mendel's interpretation of his data. Here we re-examine Mendel's experiments and investigate Fisher's statistical criticisms of bias. We describe pea varieties available in Mendel's time and show that these could readily provide all the material Mendel needed for his experiments; the characters he chose to follow were clearly described in catalogues at the time. The combination of character states available in these varieties, together with Eichling's report of crosses Mendel performed, suggest that two of his F3 progeny test experiments may have involved the same F2 population, and therefore that these data should not be treated as independent variables in statistical analysis of Mendel's data. A comprehensive re-examination of Mendel's segregation ratios does not support previous suggestions that they differ remarkably from expectation. The χ2 values for his segregation ratios sum to a value close to the expectation and there is no deficiency of extreme segregation ratios. Overall the χ values for Mendel's segregation ratios deviate slightly from the standard normal distribution; this is probably because of the variance associated with phenotypic rather than genotypic ratios and because Mendel excluded some data sets with small numbers of progeny, where he noted the ratios "deviate not insignificantly" from expectation.
期刊介绍:
For almost a century, Hereditas has published original cutting-edge research and reviews. As the Official journal of the Mendelian Society of Lund, the journal welcomes research from across all areas of genetics and genomics. Topics of interest include human and medical genetics, animal and plant genetics, microbial genetics, agriculture and bioinformatics.