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 22,000 species have been classified. They are easily identified by their geniculate (elbowed) antennae and the distinctive node-like structure that forms their slender waists.
Atta is a genus of New World ants of the subfamily Myrmicinae. It contains at least 17 known species.
Leafcutter ants, a non-generic name, are any of 47 species of leaf-chewing ants belonging to the two genera Atta and Acromyrmex. These species of tropical, fungus-growing ants are all endemic to South and Central America, Mexico, and parts of the southern United States. Leafcutter ants can carry twenty times their body weight and cut and process fresh vegetation to serve as the nutritional substrate for their fungal cultivates.
Fungus-growing ants comprise all the known fungus-growing ant species participating in ant–fungus mutualism. They are known for cutting grasses and leaves, carrying them to their colonies' nests, and using them to grow fungus on which they later feed.
In biology, two related species or populations are considered sympatric when they exist in the same geographic area and thus frequently encounter one another. An initially interbreeding population that splits into two or more distinct species sharing a common range exemplifies sympatric speciation. Such speciation may be a product of reproductive isolation – which prevents hybrid offspring from being viable or able to reproduce, thereby reducing gene flow – that results in genetic divergence. Sympatric speciation may, but need not, arise through secondary contact, which refers to speciation or divergence in allopatry followed by range expansions leading to an area of sympatry. Sympatric species or taxa in secondary contact may or may not interbreed.
The name army ant (or legionary ant or marabunta) is applied to over 200 ant species in different lineages. Because of their aggressive predatory foraging groups, known as "raids", a huge number of ants forage simultaneously over a limited area.
The ant–fungus mutualism is a symbiosis seen between certain ant and fungal species, in which ants actively cultivate fungus much like humans farm crops as a food source. There is only evidence of two instances in which this form of agriculture evolved in ants resulting in a dependence on fungi for food. These instances were the attine ants and some ants that are part of the Megalomyrmex genus. In some species, the ants and fungi are dependent on each other for survival. This type of codependency is prevalent among herbivores who rely on plant material for nutrition. The fungus’ ability to convert the plant material into a food source accessible to their host makes them the ideal partner. The leafcutter ant is a well-known example of this symbiosis. Leafcutter ants species can be found in southern South America up to the United States. However, ants are not the only ground-dwelling arthropods which have developed symbioses with fungi. A similar mutualism with fungi is also noted in termites within the subfamily Macrotermitinae which are widely distributed throughout the Old World tropics with the highest diversity in Africa.
Parthenogenesis is a natural form of asexual reproduction in which growth and development of embryos occur in a gamete without combining with another gamete. In animals, parthenogenesis means development of an embryo from an unfertilized egg cell. In plants, parthenogenesis is a component process of apomixis. In algae, parthenogenesis can mean the development of an embryo from either an individual sperm or an individual egg.
Acromyrmex is a genus of New World ants of the subfamily Myrmicinae. This genus is found in South America and parts of Central America and the Caribbean Islands, and contains 33 known species. Commonly known as "leafcutter ants" they comprise one of the two genera of advanced attines within the tribe Attini, along with Atta.
Eusociality, the highest level of organization of sociality, is defined by the following characteristics: cooperative brood care, overlapping generations within a colony of adults, and a division of labor into reproductive and non-reproductive groups. The division of labor creates specialized behavioral groups within an animal society which are sometimes referred to as 'castes'. Eusociality is distinguished from all other social systems because individuals of at least one caste usually lose the ability to perform at least one behavior characteristic of individuals in another caste. Eusocial colonies can be viewed as superorganisms.
Atta colombica is one of 47 species of leafcutter ants. This species is part of the Attini tribe.
Acromyrmex insinuator is a social parasite of the closely related Acromyrmex echinatior. This specific parasite is of particular interest as it is an opportunity to study the development of social parasitism in the Attini tribe, and provides further evidence for Emery's rule, which theorizes social parasites among insects tend to be parasites of species or genera to which they are closely related to.
Acromyrmex versicolor is known as the desert leafcutter ant. A. versicolor is found during the summer months in the Colorado and Sonoran deserts when there is precipitation. They form large, distinctive nest craters that are covered with leaf fragments. Living and dead leaves are collected by workers and used to cultivate fungus gardens. Each colony can have multiple queens, if they do this is a practice called polygyny, and each queen has her own batch of “starter” fungus. This species does not sting.
A gamergate is a mated worker ant that can reproduce sexually, i.e., lay fertilized eggs that will develop as females. In the vast majority of ant species, workers are sterile and gamergates are restricted to taxa where the workers have a functional sperm reservoir ('spermatheca'). In some species, gamergates reproduce in addition to winged queens, while in other species the queen caste has been completely replaced by gamergates. In gamergate species, all workers in a colony have similar reproductive potentials, but as a result of physical interactions, a dominance hierarchy is formed and only one or a few top-ranking workers can mate and produce eggs. Subsequently however, aggression is no longer needed as gamergates secrete chemical signals that inform the other workers of their reproductive status in the colony.
Worker policing is a behavior seen in colonies of social hymenopterans whereby worker females eat or remove eggs that have been laid by other workers rather than those laid by a queen. Worker policing ensures that the offspring of the queen will predominate in the group. In certain species of bees, ants and wasps, workers or the queen may also act aggressively towards fertile workers. Worker policing has been suggested as a form of coercion to promote the evolution of altruistic behavior in eusocial insect societies.
Leptothorax acervorum is a small brown to yellow ant in the subfamily Myrmicinae. It was first described by Johan Christian Fabricius in 1793. L. acervorum is vastly distributed across the globe, most commonly found in the coniferous forests of Central, Western and Northern Europe. The morphology of L. acervorum is extremely similar to that of other Leptothorax ants. The difference arises in the two-toned appearance of L. acervorum, with the head and metasoma being darker than the mesosoma segment of the body, and hair across its body. Following Bergmann's rule—unusually, for ectothermic animals—body size increases with latitude.
Megalopta genalis is a species of the family Halictidae, otherwise known as the sweat bees. The bee is native to Central and South America. Its eyes have anatomical adaptations that make them 27 times more sensitive to light than diurnal bees, giving it the ability to be nocturnal. However, its eyes are not completely different from other diurnal bees, but are still apposition compound eyes. The difference therefore lies purely in adaptations to become nocturnal, increasing the success of foraging and minimizing the danger of doing so from predation. This species has served as a model organism in studies of social behavior and night vision in bees.
In behavioral ecology, polyandry is a class of mating system where one female mates with several males in a breeding season. Polyandry is often compared to the polygyny system based on the cost and benefits incurred by members of each sex. Polygyny is where one male mates with several females in a breeding season . A common example of polyandrous mating can be found in the field cricket of the invertebrate order Orthoptera. Polyandrous behavior is also prominent in many other insect species, including the red flour beetle and the species of spider Stegodyphus lineatus. Polyandry also occurs in some primates such as marmosets, mammal groups, the marsupial genus' Antechinus and bandicoots, around 1% of all bird species, such as jacanas and dunnocks, insects such as honeybees, and fish such as pipefish.
This is a glossary of terms used in the descriptions of ants.
Leucoagaricus gongylophorus is a fungus in the family Agaricaceae which is cultivated by certain leafcutter ants. Like other species of fungi cultivated by ants, L. gongylophorus produces gongylidia, nutrient-rich hyphal swellings upon which the ants feed. Production of mushrooms occurs only once ants abandon the nest. L. gongylophorus is farmed by leaf cutter ant species belonging to the genera Atta and Acromyrmex, amongst others.
