Anelosimus tungurahua Agnarsson, 2006
Anelosimus studiosus is a subsocial tangle web spider or theridiid spider living in both North America and South America. In 2012, genetic analysis revealed a previously identified species, A. tungurahua, is in fact the same species as A. studiosus.
Anelosimus studiosus is part of the comb-footed spider family, Theridiidae, and can be found throughout much of North and South America, as it is a tropical and temperate spider. A. studiosus exhibit social Polymorphism with two behavioral phenotypes; social spiders that live communally, and asocial solitary spiders. Social spiders not only share the same living space, but also share in the duties of brood care and capturing of prey, while asocial spiders live completely alone and will attack other female spiders that encroach its nesting territory. Populations displaying the social phenotype, generally are not found below 30˚ latitude, and the social phenotype becomes increasingly common moving north. Studies suggest that the correlation between a higher frequency of social phenotypes and colder temperatures is due to decreased survival rates amongst mothers and delayed juvenile development in colder temperatures. In other words, it is believed that sociality developed in A. studiosus in order to mitigate fitness costs for offspring should their mother die before the brood is ready to disperse and survive on their own. Despite drastic differences in behavioral phenotypes, both social and asocial spiders readily interbreed and produce viable offspring. Research on the relatedness of the socially polymorphic spider shows that social spiders in any given nest are more closely related genetically than asocial spiders. These findings suggest that social spiders have a lower dispersal distance than asocial spiders. Spiders that are more closely related genetically and display the social phenotype incur a fitness advantage by staying close to the nest and cooperating with their relatives  Although the emergence of a social phenotype may increase survival rates of offspring in the short term, research suggests it may cause long-term fitness consequences. Development of a social phenotype ultimately leads to a loss of aggression; meaning social spiders are less likely to fight off predators than their asocial counterparts. Social spiders can produce more young in a shorter period of time than asocial spiders, but when predators are introduced, nests of social spiders suffer high predation. This has been suggested to potentially lead to the extinction of large populations of A. studiosus.
- Maxmen, Amy (9 May 2013). "For Spiders, It's Cruel to Be Kind". science.com. Retrieved 9 May 2013.
Take the social spider Anelosimus studiosus, a native of North and South American forests that builds collective webs that house 40 to 100 individuals.
- Agnarsson, Ingi (2012). "A new phylogeny of Anelosimus and the placement and behavior of Anelosimus vierae n. sp. From Uruguay (Araneae: Theridiidae)". Journal of Arachnology. 40 (1): 78–84. doi:10.1636/Ha10-49.1.
- Duncan et. al 2010. Relatedness and genetic structure in a socially polymorphic population of the spider Anelosimus studiosus. Molecular Ecology 19, 810-818.
- Susan E. Reichert and Thomas C. Jones (2008) “Phenotypic variation in the social behavior of the spider Anelosimus studiosus along a latitudinal gradient.” Animal Behavior 75(6): 1893-1902.
- Spiderlab Aarhus University, http://www.spiderlab.dk/social-spiders.html
- Reichert; Jones (2008). "Phenotypic variation in the social behavior of the spider Anelosimus studiosus along a latitudinal gradient" (PDF). Animal Behaviour. doi:10.1016/j.anbehav.2007.10.033. Retrieved 24 October 2014.
- Nearctic Spider Data Base
- News story from Texas
- Community ecology of the Social Spider Anelosimus studiosus
- Bug Guide Web site
- Furey, Robert E (1998). "Two cooperatively social populations of the theridiid spider Anelosimus studiosus in a temperate region". Animal Behaviour. 55 (3): 727–35. doi:10.1006/anbe.1997.0648. PMID 9515053.