ADAPTATION 



633 



environmental relations, but also upon 

 knowledge of the ecologic relationships of 

 its ancestors. Such paleo-ecologic informa- 

 tion will always be fragmentary, but in the 

 instances in which evidence can be pieced 

 together, it is illuminating. 



An emphasis has been placed illogically 

 upon morphological or mechanical adapta- 

 tion, undoubtedly because of the greater 

 ease of discerning functional associations 

 between visible structures and their envi- 

 ronment. As physiologic and embryologic 

 techniques have developed, biophysical 

 and biochemical functional relations have 

 been discovered. These form a foundation 

 for the modern attitude toward adaptation 

 (Haldane, 1932, Chap. V), without, how- 

 ever, disparaging the many subtle and 

 quantitative processes that may be illus- 

 trated by comparative morphology. 



Adaptational behavior was early recog- 

 nized, but the diflBculties of scientific analy- 

 sis of behavior causation delayed the more 



Fig. 231. A portion of the surface and a 

 cross section of the wall of a termite nest 

 { Apicotermes sp. ), showing a comparatively 

 simple system of ventilation pores. (Redrawn 

 from Hegh. ) 



precise evaluation of psychologic data in 

 relation to the evolution of adaptation. Oc- 

 casionally, morphologic, physiologic, and 

 behavior sequences are so closely correlated 

 that there is Uttle doubt concerning be- 

 havior evolution (Friedmann, 1929; Emer- 

 son, 1938, 1947). 



The evolutionary sequence of behavior 

 is illustrated by the nest structures of the 

 African termite genus, Apicotermes (Des- 

 neux, 1948), All the nests of the species so 

 far known are subterranean and consist of 

 a round structure, about the size of a foot- 

 ball, occupying a cavity under the surface 

 of the ground. Presumably the exchange 

 of gases between the nest and the sur- 



rounding soil is necessary for the existence 

 of these insect colonies, a requirement that 

 is probably more imperative in moist soil. 

 Pores with a small diameter of about \ mm. 

 are molded into the wall of the nest as it 



V" 



Fig. 232. A portion of the surface and a 

 cross section of the wall of a termite nest 

 {Apicotermes lamani), showing funnel-shaped 

 openings exterior to the pores homologous to 

 those shown in Figure 231. (Redrawn from 

 Hegh.) 



is constructed by the worker termites from 

 their claylike excrement. A progressive se- 

 quence in complexity of these pores is ap- 

 parent in three types of nests diagrammed 

 in Figures 231, 232, and 233. This sequence 



Fig. 233. A portion of the surface and a 

 cross section of the wall of a termite nest {Api- 

 cotermes angustatus) , showing openings into 

 circular galleries homologous with the funnels 

 of Figure 232 from which the ventilation pores 

 homologous to those in Figures 231 and 232 

 penetrate to the interior chambers occupied by 

 the termites. (Redrawn from Ilegh. ) 



is in all hkelihood a phylogenetic series. 

 From an examination of the figures it may 

 be seen that behavior evolution parallels 

 morphological evolution in the following 

 attributes; symmetry, replication, homol- 

 ogy, adaptation, population integration, in- 



