Question

A phylogeny in which the branch lengths are given as measures of change in the data type used to infer the phylogeny (e.g., gene sequence divergence) is known by which term?

	A.	Majority rule consensus tree
	B.	Strict consensus tree
	C.	Cladogram
	D.	Chronogram
	E.	Phylogram

Two closely related skunk species with overlapping distributions sometimes breed, but the resulting hybrids are sterile. The barrier separating these species is:

	A.	prezygotic
	B.	postzygotic
	C.	monozygotic
	D.	a Dobzhansky-Muller incompatibility.

Answer 1

Ans 1) Phylogeny in which the branch lengths are given as measures of change in data type used to infer the phylogeny (e.g gene sequence divergence) is known by which term ------------ such trees are called Phylogram.

phylogram --- it is a tree which shows relation between Biological species on the basis of their genetic characters similarities and differences. The lines in tree are the lengths and shows time.

While in cladogram --- hypothetical relationship is shown by following comparison between organisms and their common ancestor. The lines used in it have no meaning and are used for representing the common ancestor or etc.

Correct answer Option C, Cladogram

Ans 2) Two closely related skunk species with overlapping distributions sometimes breed, but the resulting hybrids are sterile. The barrier separating these species is -------- Postzygotic .

There are different kinds of barriers that helps in maintaining reproductive isolation between organisms and this isolation helps in maintaining the characteristic of an oranism, species, genus, etc. In given question the 2 species overlap that means occupying same area of living and mate sometimes but their offspring or hybrid is Sterile. This is due to Postzygotic barrier. Postzygotic barrier acts when 2 species are able to mate but can't produce a fertile progeny. Post = afte; zygotic = after formation of zygote.

In prezygotic = the progeny can't develop. The species can mate but can't form a zygote.

Dobzhansky-Muller incompatibility --- according to it species were living in a common area but one get isolated due to different factors and just live there for long time and hence get evolve and specify and when it mates with already compatible species fails to produce offsprings and it is due geographical barriers.

Correct answer Option B, Postzygotic.