File:Age and area; a study in geographical distribution and origin of species (1922) (14592023738).jpg

Identifier: ageareastudyinge00will_0 (find matches)
Title: Age and area; a study in geographical distribution and origin of species
Year: 1922 (1920s)
Authors: Willis, J. C. (John Christopher), 1868-1958
Subjects: Biogeography Evolution
Publisher: Cambridge (Eng.) The University press
Contributing Library: Wellesley College Library
Digitizing Sponsor: Boston Library Consortium Member Libraries

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ima with a slight drop between them, but to have onemaximum only is the general rule. One might therefore predict that one would find the endemicspecies of any genus in New Zealand to form such a curve, andthis proved to be the case for every genus in the flora. A fewexamples are here given: Zone in miles 0 100 200 300 400 500 600 700 800 900 to to to to to to to to to to 100 200 300 400 500 600 700 800 900 1000 Ranunculus 2 3 5 7 11 12 18 18 10 Drimys 2 2 2 2 2 3 3 2 1 1 Pittosporum 11 11 11 11 8 7 6 6 5 5 Colobanthus 2 3 3 4 2 Coprosma 12 12 15 16 17 18 18 16 15 12 Metrosideros 8 8 8 8 5 6 6 2 1 1 Ligusticum 1 1 1 2 7 8 9 7 6 Veronica 6 6 10 14 15 39 41 43 38 26 Utricularia 3 3 3 1 1 1 1 1 Pimelea 4 4 5 5 7 8 8 6 5 4 78 AGE AND AREA These curves show many things. The first point that appearsfrom their study is that the maxima are not casually scatteredall over New Zealand, but occur in masses at particular regions,e.g. chiefly at the far north, at a little south of the middle of the
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Soundings in the New Zealand area. Numbers inserted here and theregive the depth in fathoms at those points. (From the Annals of Botany.) 100 fathoms. 1000 fathoms. South Island, and at the north end of the same island. Theselast two groups are so close to one another that they are some-what confused together. Of the examples given above, Pitto-sporum and Metrosideros have northern, Ranunculus and Vero-nica southern, and Drimys and Coprosma central maxima. CH. VIIl) INVASIONS 79 These are bare and unvarnished facts, and though found byaid of the hypothesis of Age and Area do not depend upon it inany way, but may be examined upon their own merits. It isclear from them that the previous distributional history of thesegroups of genera must have been quite different, and it wouldseem to point to the conclusion that the present flora of NewZealand has been the result of at least three distinct invasionsof plants from elsewhere, which probably had their centres atthe points, north, south, a

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