Chapter III —45 — On Areas 



The areas of species of a number of floras (of England — Guppy. 

 1925; Matthews, 1922; of North America — Fernald, 1924; of 

 South Africa — Schonland, 1924; and others) have been studied with 

 the aim of testing Willis's theories, and the investigators came to the 

 conclusion that these theories were not applicable to the cases studied 

 by them. The size of the areas studied depended not so much on their 

 age as on the adaptability of the given species and on whether or not 

 ecological conditions favored dispersal. Species that had migrated at a 

 later period often had larger areas than older species, parts of the areas 

 of which had been destroyed during the Ice Age. The region of greatest 

 concentration of endemics did not coincide with the place of origin of the 

 genera within the limits of the given flora. Moreover, it was shown 

 that Willis entirely ignored those changes in the composition of floras 

 induced by man's activities (Ridley, 1923). Likewise studies of vari- 

 ous families and genera (e.g., Magnoliaceae — Good, 1925; Passerina — 

 Thoday, 1925) also revealed a number of data disagreeing with Willis's 

 theory. On the other hand, several investigators have presented data 

 that agree with the regularities established by him. 



All this indicates that the size of an area does not depend solely 

 on the age of a species. The latter constitutes only one of a combi- 

 nation of factors on which area-formation depends. Nevertheless, the 

 study of age as a factor in plant distribution, the significance of which 

 was first emphasized by Willis, should be continued. 



References: 



Arber, Agnes, 1919: On the law of age and area in relation to the extinction of 

 species (Ann. Bot., Vol. 33, pp. 211-213). 



Arwidsson, Th., 1928: Bizentrische Arten in Skandinavien — eine terminologische 

 Erorterung (Bot. Notiser, No. i). 



Bentham, G., 1873: Note on the classification, history and geographical distribution of 

 the Composiiae (Linn. Soc. Jour., Vol. 13). 



Berry, E. VV., 1917: A note on the age and area hypothesis (Science, Vol. 46, pp. 

 539-40). 



Berry, E. W., 1924: Age and area as viewed by the paleontologist (Amer. Tour. 

 Bot., Vol. II, No. 9). 



Brockman-Jerosch, H., 1913: Der Einfluss des " Klimacharakters " auf die Grenzen 

 der Pflanzenareale (Vierteljahrsschr. Naturf. Ges. Zurich, Vol. 58). 



Brockman-Jerosch, H., 1913: Der Einfluss des "Klimacharakters" auf die Ver- 

 breitung der Pflanzengesellschaften (Engler's Bot. Jahrb., Vol. 49, Suppl. 109). 



Brown, R., 1869: On the geographical distribution of the Coniferae and Gnelaceae 

 (Trans. Bot. Soc, Vol. 10). 



BuNGE, S., 1874: Weite und enge Verbreitungsbezirke einiger Pfianzen (Sitzungsber. 

 Dorp. Naturf. Ges. Jurjey, Vol. n). 



Christ, H., 1913: tjber das Vorkommen des Buchsbaumes (Buxiis sempervirens) in 

 der Schweiz und weiterhin durch Europa und Vorderasien (Verhandl. Naturf. Ges. Basel, 

 Vol. 24). 



Ekxund, O., 1931: tJber die Ursachen der regionalen Verteilung der Scharenflora 

 Sudwest-Finnlands (Acta Bot. Fenn., Vol. 8). 



Eklund, O., 1937: Klimabedingte Artenareale (Acta Soc. pro Fauna et Flora Fennica, 

 Vol. 60). 



Fernald, M., 1924: Isolation and endemism in northeastern America and their 

 relation to the age and area hypothesis (Amer. Jour. Bot., Vol. 11, No. 9). 



Fernald, M., 1926: The antiquity and dispersal of vascular plants (Quart. Rev. 

 Biol., Vol. 1). 



Gams, H., 193 i: Die klimatische Begrenzung der Pflanzenareale (Zeitschr. d. Ges. f. 

 Erdkunde, No. 9/10). 



Gleason, H. a., 1924: Age and area from the viewpoint of phytogeography (Amer. 

 Jour. Bot., Vol. 11). 



Good, R. D'O., 1925: The past and present distribution of the Magnoliae (Ann. Bot., 

 Vol. 39, No. 154). 



