As organisms aggregate in a habitat, they neces- 

 sarily estabHsh interrelations of various kinds with 

 one another. Between organisms, coactions that are 

 beneficial to one or more of the participants consti- 

 tute cooperation (Allee et al. 1949, Allee 1951). Co- 

 operation may occur between members of the same 

 species or between different species. Interspecific co- 

 operation includes mutualism, commensalism, and 

 many other sorts of interrelations within the com- 

 munity. As opposed to cooperation, coactions be- 

 tween individuals or species that are harmful to one 

 or more of the participants constitute disoperations. 

 We will consider parasitism, predation, and competi- 

 tion as disoperations. 



INTRASPECIFIC COOPERATION 



12 



Ecological Processes 



and Community 



Dynamics: 



Cooperation and 

 Disoperation 



An early manifestation of cooperation in 

 the evolution of animals is the grouping of free-living 

 protozoans to form colonies, and the further develop- 

 ment of such colonies into multi-cellular metazoans 

 that thereafter behave and respond as unit organisms. 

 Whether the first gathering of protozoan cells to form 

 colonies developed for better protection from some 

 enemy or environmental condition, improved utiliza- 

 tion of food supplies, or more efficient reproduction, it 

 is impossible to say. The colonial form, however, 

 must have had survival value to persist. 



Colonization quickly led to division of labor be- 

 tween somatic and reproductive cells, as occurs in 

 Voh'ox, and later to division of labor between so- 

 matic cells themselves, so that different cells or or- 

 gans became specialized to serve the particular func- 

 tions of digestion, respiration, circulation, and so on. 

 Cooperation between cells, tissues, and organs gave 

 greater metabolic efficiency to the whole individual 

 and resulted in evolution to the highest types of ani- 

 mals. Similarly, the aggregation of individuals must 

 have survival value, because it persists. Hundreds, 

 sometimes thousands, of spotted lady-beetles hiber- 

 nate under leaves at the forest-edge. Mayflies, 

 midges, and mosquitoes swarm for mating purposes. 

 Millions of bats roost together in large caves, notably 

 in the Carlsbad Caverns in New Mexico. The migra- 

 tory locust moves from one locality to another in im- 

 mense hordes, and birds usually migrate in flocks. 

 Highly organized societies are found in such insect 

 groups as termites, ants, bees and wasps, as well as 

 in some breeding colonies of birds and mammals. 



Benefits derived from aggregating are both physi- 

 ological and psychological. Individual honey-bees are 

 poikilothermal, but when hive temperatures drop be- 

 low 14°C (57°F) during the winter, they form 

 clusters and maintain a mass temperature several de- 

 grees above outside temperatures. This is brought 

 about by increased metabolic oxidation of honey in 



174 



