Alpine tundra is found in

Which of the following are examples of short-term adaptation?
$(1)$ Accumulation of melanin in the skin
$(2)$ Utilization of stored fat by animals during hibernation
$(3)$ Seed dormancy
$(4)$ Phototropism of stems and geotropism of roots

Match Column-$I$ with Column-$II$ and choose the correct option.

Column-$I$	Column-$II$
$a.$ Aestivation	$(i)$ Over wintering
$b.$ Hibernation	$(ii)$ Over summer
$c.$ Diapause	$(iii)$ Suspended development in zooplanktons

Ecological equivalents refer to:

Mammals from colder climates generally have shorter ears and limbs to minimize heat loss. This is known as:

$A$ population characteristic of a species susceptible to extinction is