What is diapause and what is its significance?

The wide variety of natural habitats is based on which of the following?

Two or more species occupying identical or overlapping areas are known as

$I.$ Biochemical adaptations are seen in organisms living at great depths of the ocean to face crushing pressure.
$II.$ Allen's rule explains adaptations in mammals living in colder climates.
$III.$ Altitude sickness is caused because the body does not get enough oxygen due to low atmospheric pressure at high altitudes.
$IV.$ Desert lizards lack behavioural means to manage their body temperature.
Choose the correct option for the above statements.

Many tribes live in the high altitude of the Himalayas. What physiological adaptation do they exhibit?

In which of the following is a thick layer of fat (blubber) found under the skin?