North America (Contnmed) 

 isolation of bird species in different 



refugia of coniferous forest of, 



308 

 lack of similarity between fauna of 



and that of Europe, 155 

 Laramide orogeny and formation 



of mountains in Rocky system, 



281 

 local glaciers in, 288 

 Madro- tertiary flora of, 283 

 mammals in arctic tundra of, 318 

 mammals in coniferous forests 



of, 302-303 

 mammals once present in, 285 

 montane forest biociation in, 307 

 Neotropical- tertiary flora of, 282 

 origins of breeding bird species in 



forest biociations of, 308 

 physical conditions of during 



Pleistocene age, 284-285 

 plant associations in, 294 

 in coniferous forests, 302 

 in deserts, 333-334 

 in woodland, 311 

 precipitation in arctic regions of, 



315 

 primitive population of bison in, 



328 

 range of time covered by mountain 



formation in, 325 

 refugia of coniferous forest sur- 

 vival during Pleistocene era in, 



286 

 scanty evidence for existence of 



tundra in, 286 

 separation of coniferous forest of 



from Eurasian forest in Tertiary 



era, 284 

 species characteristic of alpine 



tundra in, 321-322 

 South American origin of fauna in, 



155-156 

 southeastern mixed biocies in, 



animal communities of, 298 

 temperate deciduous forest biome 



in: 

 humidity of, 293 

 precipitation in, 293 

 temperature of, 293 

 volcanic action in, 281 

 Western mountains of, zonation of 



vegetation in, 314 

 zonation of communities in, 313- 



314 

 Nutritional Values: 

 and rate of reproduction in animals, 



241 

 awareness by animals of lack of 



in diet, 190 

 effects of deficiencies in of foods, 



181 

 of carbohydrates, 190 



Nutritional Values (Continued) 

 of fats, 190 

 of minerals, 190 

 of non- staple foods, 190 

 of proteins, 190 

 of staple foods, 190 

 of vitamins, 190 

 of water, 190 



Oceanography, early studies in, 6 

 Omnivores: 



adaptations of teeth of for food- 

 getting, 188 



conditions under which animals 

 qualify as, 188 



enzymes of and food palatability, 

 190 



filter- feeders as, 188 



in food chains, 195 



position of in trophic levels, 196 



seasonal variations in food of, 192 

 Optimum: 



defined, for environment, 10 



finding of in population growth 

 curve to determine productivity 

 yield, 207-208 

 Orientation {see also Behavior 

 Patterns): 



of animals to streams, 50 



of organism to changes in environ- 

 ment, 12, 13 



stream organisms' invasion of 

 habitats and need for, 53 



to current, by stream animals, 44, 

 50 

 Outbreaks (see Plagues) 

 Overwintering: 



as characteristic of life- forms of 

 plants, 7 



by forest animals, 300 



in grassland, 330 



of arctic tundra animals, 320 



of cold blooded desert animals, 339 

 Oxidation Debt, 64, 73 

 Oxygen: 



absorption of by aquatic insects, 

 84-85 



absorption of by water organisms 

 and seasonal change, 172 



abundance of in air as compared 

 to water, 99 



and carbon cycle, 167 



as absorber of ultraviolet radia- 

 tion, 243 



availability of seldom critical for 

 land animals, 99 



comparison of amounts of in air 

 and water, 63 



dissolving of by soft- shelled turtle. 



Oxygen (Continued) 

 m lakes, 63-65 

 and measurement of pH changes, 



66 

 classification of lakes according 



to amount of, 64 

 during summer stagnation period, 



71, 73 

 effects of low concentrations of 



on lake organisms, 64 

 factors in reduction of supply 



of, 64 

 of tundra, lack of, 315 

 in ponds: 

 and seasons, 79 

 as varying with photosynthesis, 



79 

 decline of in summer, 87 

 protected from winds, 79 

 variations in content of from day 

 to night, 79 

 in sea: 

 adaptations of marine animals 



for obtaining, 356 

 and compensation point, 354 

 concentration of on surface, 356 

 factors in reduction of concen- 

 trations of, 356 

 high concentration of on shores 



with splashing of waves, 356 

 sources of, 356 

 in soil, 165 



loss of to plants in hot, dry cli- 

 mates, 168-169 

 low pressure of at high altitudes, 

 and mammal adjustment, 323 

 percentage of in dry air, 99 

 reduction of in change of pond to 



marsh, 82-83 

 restriction of fish to water rich in, 



246 

 role of in experiments to determine 

 primary production of energy, 

 203-204 

 saturation of water with, 63-64 

 trapping of in soil during floods, 

 and arthropods, 115 



Pal eo- Ecology: 



of coniferous forests, 307-308 



of deserts, 334-335 



of grassland, 326 



of North American woodland, 311 



of tropical forest biomes, 344-345 

 Parasites {see also Parasitism): 



adaptation of to hosts of one 

 phylum, 180 



adaptations of to living in or on 

 host, 179 



Index 43 



