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MEIOSIS INNOVATION (3) "Crossovers that occur between homologs and not between sister chromatids." http://cshperspectives.cshlp.org/content/6/3/a016154.full View in LinkedIn

MEIOSIS INNOVATION (2) "DNA replication stimulated at meiosis I and inhibited at meiosis II." http://cshperspectives.cshlp.org/content/6/3/a016154.full View in LinkedIn

SELF RECOGNITION. "The invention of meiosis puts pressure on the development of mechanisms wherein haploid cells first recognize other haploid cells with the same chromosome complement, and then fuse with them selectively." https://lnkd.in/ebVhXPf View in LinkedIn

MEIOSIS INNOVATION (1) "Mechanisms to promote breaks that stimulate meiotic recombination frequencies to higher levels than mitotic recombination frequencies." https://lnkd.in/ebVhXPf View in LinkedIn

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