Some organisms have a large geographic range. For example, the Norway rat lives on every
continent except Antarctica.
A population of Norway rats is the number of rats
in one particular area. Do you think it's
scientifically possible for a population of Norway
rats in North America to carry different genetic
mutations than a population of Norway rats in
Africa? Do you think it's possible that they carry
some of the same mutations? What types of
information can scientists learn by studying the
genomes of these two populations of rats?

a unit of heredity that is transferred from a parent to offspring and is held to determine some characteristic of the offspring.

the glands which are associated with each description is given below:

the oldest known insects are believed to live around 400 millions ago as suggested by the fossil records.   some plants having woody stems also evolved during this time.

after the evolution of insects the first four legged species or the tetrapods evolved in shallow freshwater habitats from the intermediate species approximately 397 million years ago. the tetrapods went on conquering the land giving rise to amphibians, reptiles, mammals and birds.

the major split in tetrapods first occurred 340 million years ago branching off from amphibians.

363 million years ago when the carboniferous period began the insects started roaming on land and taking flights, following which the four limbed tetrapods adapted in the terrestrial habitat.