Experimental Studies of Competition
Some of the best evidence for the existence of competition comes from experimental field studies. by setting up experiments in which two species either occur alone or together, scientist can determine whether the presence of one species has a negative effects on a population of a second species. for example, a variety of seed-eating rodents occurs in Chihuahuan Desert of the southwestern part of North America. in 1988, researches set up a series of 50 meter X 50 meters enclosure to investigate the effect of kangaroo rats on other, smaller seed-eating rodents. kangaroo rats were removed from half of the enclosure, but not from the other enclosure. the walls of all of the enclosures had holes in them thatt allowed rodents to come and go, but in the kangaroo rat removal plots, the holes were too small to allow the kangaroo rats to enter. over the course of the next three years, the researchers monitored the number of the other, smaller seed-eating rodents present in the plots. the number of other rodents was substantially higher in the absence of kangaroo rats, indicating that kangaroo rats compete with the other rodents and limit their population sites.
A great number of similar experiments have indicated that interspecific competition occurs between many species of plants and animals. effects of competition can be seen in aspect of population biology other than population size, such as behavior and individual growth rates. for the example, two species of Anolis lizards occur on the island of St. Maarten. when one of the species A. gingivinus, is placed in 12 m x 12 m enclosures without the other species, individual lizard grow faster and perch lower than lizard of the same species do when placed in exclosure in which A. pugus is also present.
Experimental studies can provide strong tests of the hypothesis that interspecific competition occurs, but such studies have limitations. detailed ecological studies are important regardless of wether experiments are conducted
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