| Kladothrips | |
|---|---|
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Scientific classification  | |
| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Arthropoda |
| Class: | Insecta |
| Order: | Thysanoptera |
| Family: | Phlaeothripidae |
| Genus: | Kladothrips Froggatt, 1906 |
Kladothrips is a genus of Australian gall thrips. It is notable for including some of the few organisms outside of Hymenoptera that exhibit eusociality.
The following species of Kladothrips are recognized: [1]
Several species of Australian gall thrips from the genus Kladothrips have been discovered to be eusocial. [2] [3] These organisms represent some of the few organisms outside of Hymenoptera (bees, wasps, and ants) and Isoptera (termites) that exhibit eusociality. Eusocial insects are animals that develop large, multigenerational cooperative societies that assist each other in the rearing of young, often at the cost of an individual's life or reproductive ability. Such altruism is explained in that eusocial insects benefit from giving up reproductive ability of many individuals to improve the overall fitness of closely related offspring. In order for an animal to be considered eusocial, it must satisfy the three criteria defined by E. O Wilson. [4] The first criterion is that the species must have reproductive division of labor. Gall thrips have separate castes of reproductive macropterous (fully winged) females, some micropterous reproductive males, and many micropterous non-reproductive females. [2] The second criterion requires that the group has overlapping generations, a phenomenon found in these gall thrips. [5] Finally, gall thrips participate in cooperative brood care by the soldiers who protect the developing larva. This is the final criterion for eusociality. [2]
Macropterous, inseminated females initiate gall formation on the phyllodes of Acacia trees using their mouthparts. What follows is frequent fighting between inseminated females for ownership of the forming gall. The foundress female then lays her eggs and feeds on the phyllodes until her brood hatches and ecloses. Micropterous adults eclose first, with about a 4:1 female to male sex ratio bias. Macropterous larvae, micropterous pupae and eggs are also present. These macropterous larvae, when they eclose, mate and disperse from the gall, though some may breed for a short time into the next generation in the gall where they eclosed. [2] Micropterous individuals are armed with large barbed forelegs for defending against attacking organisms. These individuals, often defined as soldiers, react to ruptures in the gall by swarming the opening, waiting and patrolling the area for some time, until the opening closes. It has been shown that when presented with Koptothrips (a parasitic thrips species) and other variety of extra-specific insects, the micropterous gall thrips will attack and often kill the would-be invader. [2] In gall thrips, brood care is essentially role reversed. Thrips young are not helpless, and can immediately begin to provide for itself and to a certain extent the related individuals around them, while the soldier adults stay busy patrolling the gall for possible incursions. Thus, the brood cares for the adults. [6]
The gall thrips represent a unique organism for studying the evolution and origins of eusociality, given that they are not a member of Hymenoptera or Isoptera. Another useful factor that contributes to the use of these organisms for research into eusociality is a well-defined phylogenetic tree and access to large amounts of genetic data. [7] High relatedness of individuals within a given colony as well as haplodiploidy have been cited as heavy contributing factors to the success of eusocial insects. Gall thrips are in fact haplodiploid, meaning that most offspring (in this case the micropterous offspring) are haploid, where the parent was a diploid organism. This causes a greater-than-expected sister-sister relatedness of 0.75 and has been proposed as a theory for why eusociality has evolved, particularly in Hymenoptera. [8] Gall thrips, however, actually exhibit not only high relatedness between sisters, but also between brother-sister, a departure from the results typical of other haplodiploid eusocial insects. This has been found to be a result of large amounts of inbreeding within a single gall. This inbreeding has been proposed to have reduced the haploidy-induced relatedness symmetries, and also allowed for an explanation of biparental care among thrips, where both males and females participate in defense of the gall. [3] The benefit from altruistic behavior occurs in two ecological modes: "life insurers" as found in social Hymenoptera, and "fortress defenders". [9] The fortress defender model leads to the evolution of eusociality when three criteria are met: food coinciding with shelter, selection for defense against intruders and predators, and the ability to defend such a habitat. [10] Eusocial thrips appear to satisfy these requirements. Gall thrips maintain galls around Acacia phyllodes, a singular and vast resource for them, satisfying the first criterion. The prevalence of other, aggressive, parasitic thrips species (Koptothrips) with known instances of hostile takeover and killing of gall thrips indicates strong selection for defense. [2] The final criterion is satisfied by soldier micropterous thrips with large barbed forelegs that assist them in defending against episodic attacks. [2] [7] Fortress defenders may have developed soldier caste individuals before any other specialization, given the high selective value of protecting the fortress. [9] Perhaps the most compelling evidence, therefore, is the progressive differentiation of soldier caste thrips in Kladothrips, where soldier-to-foundress reproductive allocation corresponds to eusocial life history traits in basal and derived species of a well mapped phylogenetic tree. [11]
In biology, a colony is composed of two or more conspecific individuals living in close association with, or connected to, one another. This association is usually for mutual benefit such as stronger defense or the ability to attack bigger prey.
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Formica exsecta is a species of ant found from Western Europe to Asia.
Thrips are minute, slender insects with fringed wings and unique asymmetrical mouthparts. Entomologists have described approximately 7,700 species. They fly only weakly and their feathery wings are unsuitable for conventional flight; instead, thrips exploit an unusual mechanism, clap and fling, to create lift using an unsteady circulation pattern with transient vortices near the wings.
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Ropalidia marginata is an Old World species of paper wasp. It is primitively eusocial, not showing the same bias in brood care seen in other social insects with greater asymmetry in relatedness. The species employs a variety of colony founding strategies, sometimes with single founders and sometimes in groups of variable number. The queen does not use physical dominance to control workers; there is evidence of pheromones being used to suppress other female workers from overtaking queenship.
Nasutitermes corniger is a species of arboreal termite that is endemic to the neotropics. It is very closely related to Nasutitermes ephratae. The species has been studied relatively intensively, particularly on Barro Colorado Island, Panama. These studies and others have shown that the termite interacts with many different organisms including a bat that roosts in its nest and various species of ants that cohabit with the termite.
Austroplatypus incompertus is a species of ambrosia beetle belonging to the true weevil family, native to Australia, with a verified distribution in New South Wales and Victoria. It forms colonies in the heartwood of Eucalyptus trees and is the first beetle to be recognized as a eusocial insect. Austroplatypus incompertus is considered eusocial because groups contain a single fertilized female that is protected and taken care of by a small number of unfertilized females that also do much of the work. The species likely passed on cultivated fungi to other weevils.
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Polistes metricus is a wasp native to North America. In the United States, it ranges throughout the southern Midwest, the South, and as far northeast as New York, but has recently been spotted in southwest Ontario. A single female specimen has also been reported from Dryden, Maine. Polistes metricus is dark colored, with yellow tarsi and black tibia. Nests of Polistes metricus can be found attached to the sides of buildings, trees, and shrubbery.
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Polistes fuscatus, whose common name is the dark or northern paper wasp, is widely found in eastern North America, from southern Canada through the southern United States. It often nests around human development. However, it greatly prefers areas in which wood is readily available for use as nest material, therefore they are also found near and in woodlands and savannas. P. fuscatus is a social wasp that is part of a complex society based around a single dominant foundress along with other cofoundresses and a dominance hierarchy.
Synalpheus regalis is a species of snapping shrimp that commonly live in sponges in the coral reefs along the tropical West Atlantic. They form a prominent component of the diverse marine cryptofauna of the region. For the span of their entire lives, they live in the internal canals of the host sponge, using it as a food resource and shelter. It has been shown that colonies contain over 300 individuals, but only one reproductive female. Also, larger colony members, most of which apparently never breed, defend the colony against heterospecific intruders. This evidence points towards the first known case of eusociality in a marine animal.
Copidosoma floridanum is a species of wasp in the family Encyrtidae which is primarily a parasitoid of moths in the subfamily Plusiinae. It has the largest recorded brood of any parasitoidal insect, at 3,055 individuals. The life cycle begins when a female oviposits into the eggs of a suitable host species, laying one or two eggs per host. Each egg divides repeatedly and develops into a brood of multiple individuals, a phenomenon called polyembryony. The larvae grow inside their host, breaking free at the end of the host's own larval stage.
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Exoneura robusta is a species of the primitively eusocial allodapine bee, belonging to the genus commonly referred to as "reed bees". Their common name derives from their use of the soft pith of dead fern fronds as a nesting material. They are native to southeastern Australia, living in both montane and heathland habitats. E. robusta do not have a fixed pattern of sociality, but rather they are capable of adapting their social strategy to different environments. While typically univoltine, populations living in warmer habitats are capable of producing two broods per season. This leads to the incidence of sibling rearing and eusocial behavior. E. robusta lack strict morphological castes, thus allowing for their plastic social behavior and dominance hierarchies.
Halictus sexcinctus, commonly referred to as the six-banded furrow bee, is a species of sweat bee found throughout Europe and as far east as Asian Turkey and Iraq. The H. sexcinctus can be easily confused with the closely related species, Halictus scabiosae, due to very similar morphological features. H. sexcinctus show a social polymorphism in which different colonies can exhibit solitary, communal, or eusocial structure. Due to this large variance in social organization, it was suspected that it was not one species at all, but rather multiple, cryptic species. However, genetic analysis was able to confirm these varying populations as one species. H. sexcinctus will forage from multiple flower species, but prefers plant species with wide-open flowers. Their nests can be found dug into the ground in loamy or sandy soil.
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