Insects (Continued) 

 in grassland communities, 124 

 in rock seres, 104-105 

 in soil of forest communities, 130, 



131-132, 132-134, 134, 134-135, 



135 

 intra- specific cooperation in 



societies of, 175-176 

 mimicry as protective device 



among, 194 

 multiple population peaks of, 137 

 pond, life-histories of, 88-89 

 populations of, and weather levels 



of conditions, 230 

 social, as domesticators of other 



species, 177 

 soil, censusing of, 38-39 

 stream, life- histories of, 53-54 

 structural adaptations of for living 



in grasslands, 125 

 terrestrial, in pond- marsh biocies, 



83-84 

 use of dung by as microhabitat, 125 

 variations in populations of in 



streams, 55-56 

 Insight learning, 15-16 

 Instinct: 

 as cause of invariable responses 



to environmental factors, 12- 



13, 13 

 defined, 13 



migratory behavior as, 158 

 Irruptions (see Plagues) 

 Invertebrates: 

 adjustment to winter by, 99 

 as affected by flooding, 115 

 as asexual and self-fertilizing 



forms, 264 

 as found in chaparral, 313 

 as grazing animals, 126-127 

 development of in alpine tundra 



and temperature, 322 

 inactive condition of during winter 



in grassland, 330 

 in antarctic, 319 

 in burned coniferous forest: 



in coniferous forest as resem- 

 bling those of deciduous forest, 30 

 increase in, with advance of clay 



sere, 112-113 

 in desert sagebrush biociation, 337 

 in desert scrub biociation, 336 

 in forest soil, 130-135 

 in grassland communities, 124-125 

 in North American deciduous 



forests, 296-297 

 in secondary communities of 



oceanic plankton and nekton 



biome of sea, 359-360 

 in woodland, 311-312 

 marine: 

 adaptations of for feeding on 



detritus, 188 



Invertebrates (Continued) 

 as feeders on undissolved 



organic matter, 360-361, 361 

 catastrophes and populations of, 



236-237 

 number of eggs laid by and parental 



care, 211 

 overwintering of in arctic tundra, 



320 

 population cycles among, 237 

 populations in coniferous forests, 



310 

 species of in arctic tundra, 319 

 terrestrial, species of in marshes, 



85 

 variations in clutch size of and 



weather, 211 

 variation of between diurnal and 



nocturnal, 100-101 

 Islands: 

 competition among species of, 



155 

 dispersal to from mainland by 



means of land bridges, 155 

 Hawaiian, adaptive radiation on, 



266 

 inbreeding of animals on and loss 



of adaptability, 155 

 large, fauna of compared to that 



of small islands, 155 

 long survival of animals on due 



to lack of competitors and 



predators, 155 

 low resistance of species of to 



invasion of mainland forms, 



155 

 near continents, similarity of 



fauna on to that of mainland, 



155 

 oceanic, unbalanced fauna of, 155 

 of East Indies, receipt of fauna by 



through land connections, 272 

 Isolation of Populations {see also 



Niches): 

 and dispersal during interglacial 



periods, 308 

 biotic factors listed which function 

 ) as mechanisms for of sympatric 



species, 258 

 during Pleistocene era into differ- 

 ent refugia of coniferous forests 



of North America, 308 

 ethological: 

 and development of characteris- 

 tics which prevent interbreed- 

 ing in re- contact of species, 



262 

 breakdown in during disturbance 



of natural conditions, 259 

 correct performance of court- 

 ship behavior and, 258-259 

 failure to find breeding partners 



and, 258-259 



Isolation of Populations (Continued) 

 occurrence of in ecologically 

 isolated budworms when mating 

 periods overlap, 259 

 recognition of sex of individuals 

 through clues or sign stimuli 

 and, 258-259 

 genetic, conditions of occurrence 



of, 259 

 geographic: 

 and summary of speciation 



process, 260 

 as a necessary factor in differen- 

 tiation into distinct species, 260 

 circumstances of possible occur- 

 rence of, 259 

 importance of intermediate 



species in, 259-260 

 partial effectiveness of barriers 

 in and nature of differentiations, 

 259 

 slow rate of gene flow in and 

 possible speciation, 259-260 

 in North American montane 



forest biociation, 307 

 mechanical, through differences 

 in structure of copulatory 

 organs, 257 

 occurrence of during split of 

 Arcto- tertiary forest into 

 western and eastern sections, 

 307-308 

 of arctic tundra due to Pleistocene 



glaciation, 318 

 reduction of gamete wastage in 

 hybrids and reinforcement of 

 mechanisms causing, 264 



Kineses, defined, 12 

 Kinesthetics, as cause of stimuli, 



13-14 

 Kruniholz, occurrence of in alpine 



tundra, 317 



Lake Management: 

 as form of applied ecology, 77 

 control of erosion as job in, 77 

 dangers of silting and necessity 



for control in, 77 

 improvement of habitats in, 77 

 increasing fish productivity in, 77 

 problem of pollution in, 77 

 varieties of tasks in, 77 



Lakes {see also Biocies, Lake; 

 Littoral Zone of Lakes): 

 adaptations of organisms to, 60 



424 



Index 



