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Babies are bacteria-free at birth. The meconium (the first stool) contains no bacteria if secured early enough. Meconium is a sterile mucilaginous material that accumulates in the fetal intestine and is expelled soon after birth. It contains secretions of intestinal glands, gut constituents (proteins, bile acids, fatty acids, and steroids), and ...


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The term you should look up is sperm competition, there is an introductory wikipedia article about it here, where you can get the basic picture and get some references to explore. Simply said, males often compete with other males in the reproductive tract of the female, thus a higher number of sperm will lead to a higher chance of fertilizing the female in ...


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The answer, if you search for a bit, boils down to geometry. It takes X amount of sperm cells to successfully fertilize an egg. If you optimize delivery system (e.g. vagina geometry), you'll need less. In species where one male fertilize number of eggs (aka polygamy) and are able to have progeny from number of females, you need less cells in ejaculate to ...


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If by "simplest" you mean smallest genome, then according to Brock's Biology of Microrganisms (13th ed, p 319) the smallest autotroph is Aquifex aeolicus, a chemolithotroph bacterium. It's genome is 1.5M bases, about 1/3 of that of E.Coli, and was sequenced in 1998 (https://www.ncbi.nlm.nih.gov/pubmed/9537320). The genome is densely packed though and still ...



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