''Platythyrea'' is a

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial nom ...

of predaceous

ant Ants are eusocial insects of the family Formicidae and, along with the related wasps and bees, belong to the order Hymenoptera. Ants evolved from vespoid wasp ancestors in the Cretaceous period. More than 13,800 of an estimated total of ...

s in the subfamily

Ponerinae Ponerinae is a subfamily of ants in the Poneromorph subfamilies group, with about 1,600 species in 47 extant genera, including '' Dinoponera gigantea'' - one of the world's largest species of ant. Mated workers have replaced the queen as the ...

and the sole member of the

tribe The term tribe is used in many different contexts to refer to a category of human social group. The predominant worldwide usage of the term in English is in the discipline of anthropology. This definition is contested, in part due to confli ...

Platythyreini.

Distribution

The genus has a worldwide distribution, and is found in the

tropics The tropics are the regions of Earth surrounding the Equator. They are defined in latitude by the Tropic of Cancer in the Northern Hemisphere at N and the Tropic of Capricorn in the Southern Hemisphere at S. The tropics are also referr ...

and subtropics of the world.

Description

Workers are small to very large in size (4–20 mm). Gamergates (reproductive female workers) are known from all studied species except one, ''P. conradti'', which have

ergatoid An ergatoid (from Greek '' ergat-'', "worker" + ''-oid'', "like") is a permanently wingless reproductive adult ant or termite. The similar but somewhat ambiguous term ergatogyne refers to any intermediate form between workers and standard gynes. E ...

queens (wingless reproductive ants, intermediate in form between workers and winged queens). Some species with gamergates also have

alate Alate (Latin ''ālātus'', from ''āla'' (“wing”)) is an adjective and noun used in entomology and botany to refer to something that has wings or winglike structures. In entomology In entomology, "alate" usually refers to the winged form o ...

queens, which are similar to the workers but winged. Central fusion and terminal fusion automixis

Parthenogenesis

Parthenogenesis is a natural form of reproduction in which growth and development of embryos occur without fertilisation.

Thelytoky Thelytoky (from the Greek ''thēlys'' "female" and ''tokos'' "birth") is a type of parthenogenesis in which females are produced from unfertilized eggs, as for example in aphids. Thelytokous parthenogenesis is rare among animals and reported in a ...

is a particular form of parthenogenesis in which the development of a female individual occurs from an unfertilized egg. Automixis is a form of thelytoky, but there are different kinds of automixis. The kind of automixis relevant here is one in which two haploid products from the same

meiosis Meiosis (; , since it is a reductional division) is a special type of cell division of germ cells in sexually-reproducing organisms that produces the gametes, such as sperm or egg cells. It involves two rounds of division that ultimately r ...

combine to form a diploid

zygote A zygote (, ) is a eukaryotic cell formed by a fertilization event between two gametes. The zygote's genome is a combination of the DNA in each gamete, and contains all of the genetic information of a new individual organism. In multicell ...

(see diagram). Colonies of ''Platythyrea punctata'' from Florida and the Caribbean Islands produce offspring almost exclusively by automictic thelytoky. Automixis appears to involve central fusion of two of the haploid products of meiosis (see diagram). This form of automixis tends to maintain

heterozygosity Zygosity (the noun, zygote, is from the Greek "yoked," from "yoke") () is the degree to which both copies of a chromosome or gene have the same genetic sequence. In other words, it is the degree of similarity of the alleles in an organism. Mo ...

in transmission of the genome from mother to offspring, and to minimize

inbreeding depression Inbreeding depression is the reduced biological fitness which has the potential to result from inbreeding (the breeding of related individuals). Biological fitness refers to an organism's ability to survive and perpetuate its genetic material. ...

. Furthermore, crossover recombination occurs at a greatly reduced rate during

, which likely restrains the transition from heterozygosity to homozygosity.

Species

References

External links

* Ponerinae Ant genera {{Ponerinae-stub