Maintenance of a definite territory has several 

 benefits : a definite breeding location in which the 

 nest can be confidently established and protected is 

 afforded ; it aids the acquisition of mates ; it insures 

 an area of sufficient size to provide food both for the 

 adults and, later, for the young; and it frees the 

 possessor of the onus of despotic interference by 

 other individuals. The extent to which these advan- 

 tages are attained varies with the species ( Nice 1941 ) . 

 Although competition for territory is most keen be- 

 tween individuals of the same species, it also occurs 

 between dififerent species the space requirements of 

 which overlap (Simmons 1951, Sharp 1957). A 

 home range, on the other hand, only provides a 

 breeding location. Possession of territory lessens the 

 pressure of competition during the reproductive pe- 

 riod, particularly for the female, when the entire 

 energy and attention of animals needs to be devoted 

 to the production of offspring. 



SUMMARY 



Beneficial cooperation is evident in division 

 of labor between cells, tissues, and organs within the 

 individual, between individuals in societies, and be- 

 tween species living together in communities. Bene- 

 fits derived from cooperation are physiological and 

 behavioral and may affect survival, reproductive suc- 

 cess, and more efficient use of natural resources. Co- 

 operation between species that is intimate and bene- 



ficial to both participants is called mutualism ; where 

 only one participant benefits, commensalism. These 

 relations may be either facultative or obligative. 

 Where one or more of the participants is harmed 

 there is disoperation, of which parasitism, parasitoid- 

 ism, competition, and predation are the examples. 

 Distinction is made between true parasites, social 

 parasites, and parasitoids. True parasites and their 

 hosts have evolved adaptive interrelations so that 

 coexistence occurs for varying lengths of time. The 

 host is generally weakened, however, and virulent 

 strains of the parasite may cause high mortalities. 

 Causes of mortality or disease among organisms are 

 predators, parasitoids, worm parasites, protozoan 

 parasites, bacteria, viruses, fungi, external parasites, 

 nutritional deficiencies, to.xication, physiological 

 stress, and accidents. 



Competition may be exerted directly through in- 

 terference in the activities of one organism by an- 

 other, or indirectly in the form of excessive ex- 

 ploitation of natural resources. It may be either 

 intraspecific or interspecific. Competition may result 

 in establishment of social hierarchies, establishment 

 of territories, regulation of population size, segrega- 

 tion of species into different niches, or speciation. 

 The over-all effect of competition is to relegate the 

 individual and species to an orderly place in the 

 structure and organization of the community with 

 the result that there is decrease in tension and dis- 

 turbance. 



Ecological processes and dynamics 



