Game Theory & Biodiversity
Source Article: https://phys.org/news/2018-08-tackling-great-paradox-biodiversity-game.html
This article delves into the use of game theory as an explanation of unexpected interplay between biodiversity and available resources, known as “the paradox of the plankton.” This paradox revolves around a conflict between the existence of a large amount plankton species and the competitive exclusion principle. Essentially, the competitive exclusion principle states that in a conflict between two species for the same limited resource, only one species will survive while the other will fall to extinction. However, stable populations of diverse phytoplanktonic organisms are observed in ecosystems in which these species compete for the same subset of finite resources. Though named specifically for the phenomenon studied in plankton populations, this paradox extends to other ecosystems as well.
A 2 x 2 symmetric game between hawks and doves forms the basis for a game theory-driven explanation of this paradox. doves are assumed to be pacifistic, and will either split resources when confronted by another dove or run away when cornered by an aggressive hawk. Hawks are assumed to be militant and always willing to put up a fight for resources.
| Dove | Hawk | |
| Dove | 1,1 | 0,2 |
| Hawk | 2,0 | -1,-1 |
Should a dove encounter a dove, the two split resources. If a hawk encounters a dove, the hawk will scare off the dove and gain all the available resources. Should a hawk encounter another hawk, a physical altercation will occur which harms both hawks involved. In this example, neither species has a dominant strategy and no pure nash equilibrium exists, suggesting that the two species coexist to a degree. When expanded to a larger game consisting of more species and more resources, a large degree of diversity in combinations, and as a result a large amount of mixed strategies, emerged. This suggests that a large number of potential species can coexist despite direct conflict for shared-need resources. According to the article, many real ecosystems reflect the outcomes predicted by the proposed games. Though the mechanisms of competition prescribed by game theory have not yet been verified to accurately mirror species’ behavior, researchers believe these models hold promise in explaining seemingly paradoxical biodiversity.