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ROTIFERS AND CILIATES. "Although meiotic sex was lost in a few multicellular lineages millions of years ago, they constitute rare exceptions. These lineages represent easily amenable multicellular systems, and population genetic analysis showed that they do not suffer from the lack of genetic diversity, which is retained among different clones." https://lnkd.in/deZ8DED View in LinkedIn

CASE STUDY. "If we accept the view that any costly nonadvantageous mechanism is subject to eventual loss, sex retention proves its usefulness, and bdelloid rotifers and ciliates, possibly having done without sex over an extended time period, might enlighten us regarding that use." https://lnkd.in/deZ8DED View in LinkedIn

GENES, CELLS, AND NUCLEI. "In the excitement over the recognition of meiosis-associated genes all over the eukaryotic phylogenetic tree, one might forget that fusion of both cells and nuclei is also critical during the sexual cycle. However, gamete fusion (plasmogamy) and nuclear fusion (karyogamy) have been studied much less than meiosis." https://lnkd.in/deZ8DED View in LinkedIn

EUKS AND MEIOSIS. "In summary, long-term asexuality is rare, and there is growing consensus that meiotic sex was present in the LECA and remains so in all major eukaryotic lineages." (LECA = last eukaryotic common ancestor), https://lnkd.in/deZ8DED View in LinkedIn

THE EXCEPTIONS. "On the other hand, very few examples can be found where genome sequencing has led us to infer a strictly asexual nature of the respective eukaryote." https://lnkd.in/deZ8DED View in LinkedIn

MAINSTREAM DOGMA. "From all of the prior observations we can safely conclude that meiotic sex in eukaryotes is the rule. It is very widespread, old, and clearly of major evolutionary importance." https://lnkd.in/deZ8DED View in LinkedIn

SINGLE EVENT. “Sexual reproduction is a nearly universal feature of eukaryotic organisms. Given its ubiquity and shared core features, sex is thought to have arisen once in the last common ancestor to all eukaryotes.” https://lnkd.in/ebVhXPf View in LinkedIn

SO ENDS this first of two weekends on the gene life cycle. This is at the heart of Darwinian evolution, although even the idea of genes was unknown to Darwin. New genetic material is the engine of diversity and fitness. Nature has found numerous inventive ways to freshen its genetic information content, in order to provide the organism with new phenotypes with which to conquer new niches. And very often, the timeframes involved in new gene generation and fixation are considerable. View in LinkedIn

CO-EVOLUTION. "Maybe we have to recognize eukaryotic evolution as the product of α-proteobacterial endosymbiosis and the momentous, unlikely one-off, it possibly was." https://lnkd.in/deZ8DED View in LinkedIn

HORIZONTAL MECHANISM. "Similar to strict de novo gene origination, horizontal gene transfer, the exchange of genes between genomes from distantly related taxa, can immediately add new genes and functions to a genome. Horizontal gene transfer is a major mechanism for the addition of new genes to prokaryotic genomes, but has also been reported in a number of eukaryotic organisms including plants, insects and fungi." https://lnkd.in/dvpUaYF View in LinkedIn