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Others reproduce quickly; but, under normal circumstances, most offspring do not survive to adulthood. For example, a rabbit (mature after 8 months) can produce 10–30 offspring per year, and a fruit fly (mature after 10–14 days) can produce up to 900 offspring per year.
Many protists reproduce sexually, as do many multicellular plants, animals, and fungi. In the eukaryotic fossil record, sexual reproduction first appeared about 2.0 billion years ago in the Proterozoic Eon, [63] [64] although a later date, 1.2 billion years ago, has also been presented.
In order to reproduce sexually, both males and females need to find a mate. Generally in animals mate choice is made by females while males compete to be chosen. This can lead organisms to extreme efforts in order to reproduce, such as combat and display, or produce extreme features caused by a positive feedback known as a Fisherian runaway.
Meiosis is ubiquitous among eukaryotes. It occurs in single-celled organisms such as yeast, as well as in multicellular organisms, such as humans. Eukaryotes arose from prokaryotes more than 2.2 billion years ago [1] and the earliest eukaryotes were likely single-celled organisms. To understand sex in eukaryotes, it is necessary to understand ...
Evolution is an inevitable result of imperfectly copying, self-replicating organisms reproducing over billions of years under the selective pressure of the environment. The outcome of evolution is not a perfectly designed organism. The end products of natural selection are organisms that are adapted to their present environments.
This is an accepted version of this page This is the latest accepted revision, reviewed on 27 November 2024. Procreative biological processes of humanity Part of a series on Sex Biological terms Sexual dimorphism Sexual differentiation Feminization Virilization Sex-determination system XY XO ZW ZO Temperature-dependent Haplodiploidy Heterogametic sex Homogametic sex Sex chromosome X chromosome ...
Peter Debye derives the T-cubed law for the low temperature heat capacity of a nonmetallic solid.; Casimir Funk introduces the concept of vitamins. [2]J. J. Thomson finds the first evidence for multiple isotopes of a stable (non-radioactive) element as part of his exploration into the composition of canal rays (positive ions).
The term life history is often used, particularly for organisms such as the red algae which have three multicellular stages (or more), rather than two. [ 3 ] Life cycles that include sexual reproduction involve alternating haploid ( n ) and diploid (2 n ) stages, i.e., a change of ploidy is involved.