Các đặc trưng cơ bản của quần thể( MỚI)

Đặc trưng cơ bản của
quần thể
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Bài 25. Các đặc trưng cơ bản của quần thể

TØ lÖ vÒ giíi tÝnh

Nhãm tuæi

Th¸p tuæi d¹ng ph¸t triÓn
EARLY. Each successive
age group (from 0 - 4 to
85 +) is smaller than the
preceding age group. The
working age population
(shown in orange) has to
provide for a mparatively
large population of
children.However,
children can help their
parentsin growing food,
collecting firewood

Th¸p tuæi d¹ng æn ®Þnh
•
INTERMEDIATE.
The age pyramid is dominated
by the working age groups.
Given appropriate conditions
(low
unemployment etc.) the
working age population is
potentially well able to support
the old and the young.
Notice here and in the
followingdiagram the left-right
asymmetry. This is because

women tend to live longer than
men

Th¸p tuæi d¹ng gi¶m sót
•
LATE. Now the
pyramid is almost
rectangular in
shape. The working
age population
needs to support a
large population
of older people