User:Kamur93/Andricus quercuscalifornicus

Life history of the oak gallwasps
Andricus quercuscalifornicus is a species of gallwasp (Hymenoptera, Cynipidae, Cynipini) capable of cyclical parthenogenesis. According to phylogenetic studies, several species of the genus Andricus have cryptic sexual generations. The cynipid gall-inducer, A. quercuscalifornicus, induces galls of 5-20 cubic centimeters on the twigs of the valley oak (Quercus lobata), an endemic tree in California. Gall growth occurs twice annually, during late spring and mid summer. The abundance and distribution of these galls vary between individual trees, however, there is recorded evidence of trees supporting high densities of galls (50 galls per cubic meter). The native range of these gall wasps spans from most of California (extremes of southern Washington) to northern Mexico.

Adaptive value of gall induction
Andricus quercuscalifornicus is an example of an ecosystem engineer because of its ability to induce gall growth. Several evolutionary hypotheses have been proposed to explain the adaptive nature of plant galls. Many of the benefits of induced galls include nutrition, a refuge from natural enemies, and a consistent environment with controlled abiotic factors. Each of these ecological functions can be described as the "nutrition hypothesis", "enemy-avoidance hypothesis", and "microenvironment hypothesis" respectively. According to recent findings, experimental manipulation of abiotic factors (i.e., relative ambient humidity) indicated that A. quercuscalifornicus larvae modify the internal environments of galls, thereby, supporting the microenvironment hypothesis. Galls have hygrothermal inertia to slow down the rates of abiotic conditions, providing a buffer against desiccation; most apparent in immature galls. Furthermore, support for the microenvironment hypothesis does not supersede both the natural enemies and nutrition hypotheses. The large galls produced by A. quercuscalifornicus may aid in the protection against other parasitoids however, this can also led to increase predation from avian species. The moist conditions created in the internal microclimate of galls can also led to increased chance of fungal infection.

A. quercuscalifornicus insect community
Through modifications of plant tissue, A. quercuscalifornicus is considered a keystone species, facilitating living conditions for a succession of other species. The induced galls are shared with a community of insects including transient occupants, opportunistic foragers, parasitoids, inquilines, and parasitoids of inquilines. These galls are divided into microscale niches allowing for the coexistence of ecologically similar species that exploit similar feeding strategies. Differences in gall morphology, phenology, and location allows for patterns in differential niche uses to arise. It is possible that niche differentiation may account for the diversity of parasitoid species associated with gall wasps. Gall characteristics can also be predictors of community-level species composition.