Niche(s) (Continued) 



deliberate evaluation process 

 exercised In by animals, 250 

 diurnation as factor in, 247 

 intricacy of equipment of higher 



animals in, 249 

 shade as consideration in, 247 

 through consideration of physical 

 features by given species, 245 

 competition for: 

 and relationships in as affected 



by geography, 253 

 interspecific, as causing restric- 

 tion of species to optimum 

 niche, 252 

 interspecific, as segregator of 

 species according to Darwin, 

 251-252 

 interspecific, reduced by adapta- 

 tions of related species to 

 climate, 253 

 interspecific, removal of and 



expansion of species, 252 

 most favorable portions of, 222 

 preadaptation as advantage in, 



250-251 

 success in as dependent on 

 parasitoidism, 249 

 concept of as developed by Joseph 



Grinnell, 245 

 concept of in distributional units 

 equivalent to concept of species 

 in taxonomic units, 245 

 correlation of growth rate with 

 environmental resistance in, 

 217 

 defined, 16, 245 

 different, divergence of new 



species into in speciation, 257 

 easy discrimination of by new 



generation, 264 

 economic densities in, 219 

 establishing of segregation in 



during times of stress or crisis, 

 253 

 factors in restriction of species 



to, 245 

 features differentiating micro- 

 habitats in for particular 

 species, 245-247 

 feeding, factors in description of, 



249 

 Cause's rule or "competitive 



exclusion principle," as describ- 

 ing occupation of, 253-254 

 inhabited by garter snakes, and 



kinds of food eaten, 249 

 kinds of cover afforded by, 247 

 measurement of, 27-28 

 nests as, 248 



occupied by species considered 

 ecological equivalents of other 

 species, 256 



Niche(s) (Continued) 

 of parasites, 179 



of soil animals in forest, 130-131 

 ordinary overlapping in clearly 



defined during critical stages 



of life cycle, 253 

 preferences in for certain species 



attributed to appropriate 



behavioral patterns alone, 250 

 requirements in of different 



species and community inter- 

 relations, 16 

 segregation of species into to avoid 



interspecific disturbances, 98 

 similarity of from one community 



to another, 256 

 similarity of in different forest 



types, 137-138 

 special, restriction of parasites 



in body to, 180 

 type of and body water balance, 



97-98 

 variety of downstream and number 



of species, 52 

 Nitrogen Cycle: 

 described, 166-167 

 in aquatic ecosystems, 172 

 Nocturnal Animals: 

 amphibians and reptiles as, 99-100 

 and diurnal predators, 101 

 choice of microhabitat by, 246-247 

 compared to diurnal, 101 

 in deserts, 338 

 in tropical rain forests, 349 

 major period of activity of, 100- 



101 

 mammals in forests as, 99-100 

 physiological adjustments of for 



night activity, 101 

 restriction of body coloration of, 



101 

 North America: 

 amelioration of climate of, and 



northward movement of organ- 

 isms, 291 

 Antarctic— tertiary flora of, 282 

 Arcto- tertiary flora of, 282 

 Asian origin of fauna in, 130-131 

 Basin sagebrush biociation in, 



336-337 

 best developed deciduous forest in, 



293 

 birds in arctic tundra of, 318-319 

 birds in coniferous forests of, 



302-303 

 boreal forest biociation in, 303- 



306 

 building of Appalachian Mountain 



System in, 280, 291-292 

 climate of coniferous forest in, 



301-302 

 climatic changes in 60-70 million 



years ago, 281 



North America (Continued) 

 climatic optimum in, flora and 



fauna during, 289-290 

 coastal plain of Gulf of Mexico 



in, character of, 280 

 Coast ranges of during early 



Tertiary era, 281 

 deciduous forest biociation of, 



animal communities of, 295-297 

 deciduous forest- edge biociation, 



animal communities of, 297-298 

 desert scrub biociation in, 335-336 

 dispersal of Asian species in due 



to Pleistocene glaciation, 318 

 dispersal of isolated fauna of dur- 

 ing interglacial periods, 308 

 distinctiveness of plant community 



in west of Great Plains, 297 

 division of coniferous forest 



refugia in, 308 

 effects of cold climate on dispersal 



of birds in during Pleistocene 



era, 286-288 

 emergence of Gulf of Mexico 



coastal plain in during Tertiary 



era, 280 

 existence of plants of Pleistocene 



era in at present, 285 

 factors in separation of Arcto- 



tertiary forest of into western 



and eastern biociations, 307-308 

 faunistic system of J. A. Allen for, 



272-273 

 flora and fauna of, during xerother- 



mic period of, 290-291 

 flora of during Sub- Atlantic period, 



291 

 forests of during Pleistocene 



period, 285-286 

 formation of Ouachita Mountains 



in, 280-281 

 formation of Ozark ^fountains in, 



280-281 

 fossil and pollen evidence for 



existence of tundra in during 



post-Pleistocene era, 289 

 grassland in: 

 biociation of, 326-327 

 climate of, 324-325 

 extension of, 324 

 in Texas, existence of as possi- 

 ble during Pleistocene era, 286- 



288 

 list of most important genera 



of grasses in, 325 

 plant associations of, 325 

 similarity of to that of rest of 



world, 327-328 

 interior of 60-70 million years ago 



inundated by seas, 280, 291 

 isolation of animal species in 



different refugia of coniferous 



forest of, 308 



430 Index 



