In plants we find the same phenomenon prevalent. Distinct species of
columbine are found in Central Europe (Aguilegia vulgaris), in Eastern
Europe, and Siberia (A. glandulosa), in the Alps (A. Alpina), in the
Pyrenees (A. pyrenaiea), in the Greek mountains (A. ottonis), and in
Corsica (A. Bernardi), but rarely are two species found in the same
area. So, each part of the world has its own peculiar forms of pines,
firs, and cedars, but the closely allied species or varieties are in
almost every case inhabitants of distinct areas. Examples are the deodar
of the Himalayas, the cedar of Lebanon, and that of North Africa, all
very closely allied but confined to distinct areas; and the numerous
closely allied species of true pine (genus Pinus), which almost always
inhabit different countries or occupy different stations. We will now
consider some other modes in which natural selection will act, to adapt
organisms to changed conditions.
_Adaptation to Conditions at Various Periods of Life._
It is found, that, in domestic animals and cultivated plants, variations
occurring at any one period of life reappear in the offspring at the
same period, and can be perpetuated and increased by selection without
modifying other parts of the organisation.
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