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SCENARIO 2b. "In a variant of this scenario, early syngamy evolved as a result of ‘manipulation’ by selfish elements (plasmids, transposons) to promote their horizontal transmission." WOW. https://lnkd.in/e2tp_G5 View in LinkedIn

SCENARIO 2. "Proto-meiosis evolved in response to the fusion of two haploid cells (“syngamy”), as in standard modern eukaryotic sexual life cycles. Syngamy may have been favoured because it allows recessive deleterious mutations to be masked in diploids." https://lnkd.in/e2tp_G5 View in LinkedIn

SCENARIO 1. "Diploidy accidentally occurred by replication of the nuclear genome without subsequent cell division (“endoreplication”), and that returning to haploidy was selected for to correct this. Because either haploidy or higher ploidy levels may be favoured in different ecological situations, a variant of this scenario is that a proto-meiosis–endoreplication cycle evolved to switch between ploidy levels." https://lnkd.in/e2tp_G5 View in LinkedIn

MULTIVALENT FORMATION. "In diploids, homologous chromosomes recognise each other and align to form bivalents during Prophase I, but when there are three or more chromosomes with sufficient homology, these chromosomes may all align to varying degrees and form multivalents." https://lnkd.in/e2tp_G5 View in LinkedIn

COMMON DESPITE. "Polyploidy is surprisingly common in eukaryotes given the considerable problems it poses to meiosis." http://biorxiv.org/content/biorxiv/early/2016/04/28/050831.full.pdf View in LinkedIn

LARGELY CONSERVED. "Meiosis is remarkably conserved across eukaryotes. Nevertheless, in many species, variants exist that may offer insights into the evolutionary origins and mechanistic constraints of meiosis." https://lnkd.in/e2tp_G5 View in LinkedIn

GARGANTUAN SMALLNESS. “In a cell or microorganism, the processes that generate mass, energy, information transfer and cell-fate specification are seamlessly integrated through a complex network of cellular constituents and reactions. However, despite the key role of these networks in sustaining cellular functions, their large-scale structure is essentially unknown.” https://lnkd.in/em_2tJm View in LinkedIn

HYPOTHESIS 3. "A third hypothesis posits that a one-step-meiosis is more complex and thus less likely to evolve than a two-step-meiosis." https://lnkd.in/e2tp_G5 View in LinkedIn

SCALE-FREE NETWORKS. “Metabolic, protein, and gene interaction networks have been reported to exhibit scale-free behavior based on the analysis of the distribution of the number of connections of the network nodes.” http://online.liebertpub.com/doi/abs/10.1089/cmb.2006.13.810 View in LinkedIn

TWO STEP HYPOTHESIS 2. "The second hypothesis is that sexual species with one-step-meiosis would be vulnerable to invasion by asexual mutants, and have thus gone disproportionally extinct in the past." http://biorxiv.org/content/biorxiv/early/2016/04/28/050831.full.pdf View in LinkedIn