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SPECIATION STARTS. "Indiscriminate cell–cell fusions, although they may have generated important novelties during early protoeukaryotic evolution, generate disparate chromosome complements that are toxic to a successful meiosis." https://lnkd.in/ebVhXPf View in LinkedIn

FOUR INNOVATIONS. "At a molecular genetic level, the evolution of meiosis would have entailed the following" four innovations.” http://cshperspectives.cshlp.org/content/6/3/a016154.full View in LinkedIn

PRECONDITION. "In order for haploid products to recapitulate these events, and hence again avail themselves of the advantages of diploidy, they must in turn fuse together to create diploids that are both capable of meiosis and precluded from undergoing additional fusion events." https://lnkd.in/ebVhXPf View in LinkedIn

CHIASMATA ROLE. "Independent assortment produces diversity in the meiotic products of heterozygotes regardless of levels of crossing over, and chiasmata have been shown to play an additional role, aligning homologous chromosomes and providing tension on the spindle for accurate meiosis I segregation." http://cshperspectives.cshlp.org/content/6/3/a016154.full View in LinkedIn

BENEFITS OF HALVING. "Although the initial pressure to develop meiosis may have been to effect ploidy reduction, the process evolved into something far more sophisticated: a mechanism to generate complete chromosome sets during meiosis I and then halve their ploidy during meiosis II." http://cshperspectives.cshlp.org/content/6/3/a016154.full View in LinkedIn

SO ENDS this first of two weekends thinking about what is behind the incredible diversity of flower forms. The comparative anatomy of flowers, which would fill volumes, only makes sense when considered from both an evolutionary and a developmental perspective, and fortunately, the genetics behind flower shape have been greatly illuminating, and surprisingly simple at its base. View in LinkedIn

Europe plans ban on plastic cutlery, straws and more http://money.cnn.com/2018/05/28/news/europe-plastic-ban-proposal/index.html View in LinkedIn

PURGING AND UNMASKING. "That said, haploid meiotic products have the advantage of allowing the “purging” of deleterious alleles and the “unmasking” of potentially adaptive recessive alleles, both clear benefits of the modern version of meiosis." https://lnkd.in/ebVhXPf View in LinkedIn

FALSE PREMISE. "There is no basis to the claim that the original meiotic products were haploid, other than the parsimony argument that because they are so now then they may also have been so when they originated." https://lnkd.in/ebVhXPf View in LinkedIn

PLOIDY TRANSITION. "It is worth noting explicitly that original versions of meiosis may have taken tetraploids to diploids rather than diploids to haploids, or octoploids to tetraploids for that matter because the key metric is ploidy transition rather than absolute ploidy level." https://lnkd.in/ebVhXPf View in LinkedIn