neoteny


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Related to neoteny: pedomorphism, paedomorphism

neoteny

(nēŏt`ənē), in biology, sexual maturity reached in the larval stage of some animals. Certain environmental conditions can inhibit the completion of metamorphosis; low temperature or lack of available iodine retard the action of the thyroid gland, the larval form may mature sexually, mate, and produce fertile eggs. If environmental conditions improve, neoteny is reversible; i.e., the larvae can complete metamorphosis and attain normal maturity. When neoteny occurs in some salamanders (see axolotlaxolotl
, a salamander, Ambystoma mexicanum, found in certain lakes in the region of Mexico City, which reaches reproductive maturity without losing its larval characteristics.
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), they remain aquatic. In insects, reproduction in the larval stages is known as paedogenesis; it occurs in certain beetles and gall midges. In the midges, the daughter larvae produced within a mother larva consume the mother and escape; the process may continue for several generations.

Neoteny

 

the ability of certain organisms to attain sexual maturity and reproduce during the larval stage or elsewhere in their early ontogeny.

Neoteny is known to occur in some amphibians, arthropods, and worms, and in many plants. The larvae of the caudate salamanders of the genus Ambystoma, or axolotls, are the classic example of neoteny. Axolotls lost the capacity for metamorphosis but are able to reproduce, retaining the form of an aquatic animal with gills, fins, and other larval organs. Neoteny gave rise to the perennibranch caudate amphibians, such as the cave proteus (Necturus maculosus), the blind newt (Typhlomolge rathbun), and sirenians. These are matured “larvae” that maintain an aquatic mode of life.

In the plant world, neoteny is found among bryophytes, club mosses, ferns, gymnosperms, and angiosperms. For example, the simple organization of structures in the duckweed originated as a result of a cessation in development during one of the earliest stages of ontogeny. An interesting example of neoteny is the female gametophyte in angiosperms, the embryo sac.

A. V. IVANOV

neoteny

[′nē·ə‚tē·nē or nē′ät·ən·ē]
(vertebrate zoology)
A phenomenon peculiar to some salamanders, in which large larvae become sexually mature while still retaining gills and other larval features.
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