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Barnacles,common inhabitants of the rocky intertidal. Joe Connell well known and heavily cited, competition between barnacle species. Exposed to air for more time, middle balanus was only found. Interesting distribution pattern, 2 diff species occupy 2 diff zones. Lower zone neither found. Reciprocal transplant experiment. Clear off area in upper zone and move balanus up there and cleared out bottom and move chthamalus down. If he moved them up even with no competition, balanus
would die out. Can’t handle the factors. Influenced by abiotic factors. Move top to middle by itself, it can tolerate conditions. In the presence of balanus though they quickly die out. When you put them together, balamus will grow underneath shell from chthamalus, they would pry them off. Competition Preventing chthamalus fromliving in middle zone. Transplant both species in lower zone by themselves, they die out because starfish and other predators eat them. Upper zone, balanus scarce and cannot withstand exposure to air. Exclude balanus from middle zone and chthamalus could survive. Desiccation prevents chthamalus from inhabiting higher levels. Competition with balanus excludes chthamalus from middle intertidal zone. Chthamalus is very vulnerable to predation in the lower intertidal zone. Southern pine beetle. Pest consumes live pine trees, cause 100 million dollars in timber loss a year. Use competitors to suppress pine beetle populations. Form a spot or infestation. Spreading offspring to next set of trees and keep eating the trees. 2 species have same resource consume. Pine beetles carry around fungus. Fungus could inhibit population growth of beetles. Caged trees, put same amount of beetles but different fungus. Like 10% of beetles were infected in fungus or 50%. Areas where there is fungal infection, beetles can’t feed. Low infection rate, kits of gallaries (what beetles make) and not much fungus. High, few gallaries and more fungus. At high rates, few beetles. Fungus could control pine beetles.One species drove another one extinct in area. 2 competing species can coexist together. Pine beetle and fungus study is this case. One hasn’t driven the other extinct. Environment determines who the winner is in competition. Distribution of species influenced by competition. Pine beetle density decreased with higher fungusinfection. Built upon logistic model. Model to predict on who wins or if 2 species could co exist.Logistic growth models for 2 species. Competitive outcome: 1. Competitive exclusion (Gauses’s paramecium,Tansley’s bedstraws, Connell’s barnacles, Park’s flour beetles). 2. Coexistence (Hofstetter’s beetles). Outcome depends on environment. Tansley:soil conditions; Park: temperature and humidity; Connell: tidal zones.Distributionof species influenced by competition.