Below are two possible tree topologies How many clades are d

Below are two possible tree topologies. How many clades are different, in terms of their associated tips? Define exaptation. Give an example of an exaptation. Define polyphenism and give an example. Draw an illustrative isochron plot based upon 87Sr/86Sr and 87Rb/86Sr. Draw lines with different slopes, and indicate which slope corresponds to the more distant moment in time?

Solution

Q5. Answer: The topologies in the trees are different considering the the first tree it has five clades

The B and F have major similllarity hence they have made a clade which is considered as not much variation in the genotype. next comes A and C which has made the clade as they have less variation rest D and E have more variation with other members of the clade as they form the solitary clade.

Comparing first tree with the second thay have common clade A and C where as DB and F had varied lot with respect to clad formation but Clade E has formed solitary clade in both the topological trees.

Q6. Answer : Exaptation is a term used in evolutionary biology to describe a trait that has been co-opted for a use other than the one for which natural selection has built it.

The feathers in birds which are intially used for the heat regulation of the body, which were co-opted for dispaly and flight lateron .

A behavioural example in wolves, licking the mouths of alpha wolves as a sign of submissiveness. (Similarly, dogs, which are wolves who through a long process were domesticated, lick the faces of their human owners.) This trait can be explained as an exaptation of wolf pups licking the faces of adults to encourage them to regurgitate food.

Q7 .A biological mechanism that causes a trait to be polyphenic is called polyphenism. For example, crocodiles possess a sex-determining polyphenism, and therefore their gender is a polyphenic trait.

Polyphenic pigmentation is adaptive for insect species that undergo multiple mating seasons each year. Different pigmentation patterns provide appropriate camouflage throughout the seasons, as well as alter heat retention as temperatures change. Because insects cease growth and development after eclosion, their pigment pattern is invariable in adulthood: thus, a polyphenic pigment adaptation would be less valuable for species whose adult form survives longer than one year