1. Review questions (1 point each): a) What is our definition of a species? b) E
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Question
1. Review questions (1 point each):
a) What is our definition of a species?
b) Explain how phylogenetic analysis can be used to identify species.
c) What do we call pre-zygotic reproductive isolation? Give and explain two examples.
d) Explain the mechanism of Dobzhanski-Muller incompatibility.
e) Some closely related species of plants hybridize easily. What mechanisms can explain that they none-the-less retain their species identity?
f) Briefly explain the parsimony principle and the Maximum Likelihood method of phylogenetic reconstruction. How do the two approaches differ?
Explanation / Answer
A) Species: It encompasses a group of living organisms consisting of similar individuals who are capable of interbreeeding and exchanging their genes. It is one of the principal taxonomic ranks.
B) A phylogenetic analysis is another term for drawing up a phylogenetic tree, which connects various individuals, species, and genera, based on their genome. The more closely related species are placed closer, as opposed to species which have less relation. The tree can thus be used to infer evolutionary background of an unknown species by analysing its genome.
C) Pre-zygotic reproduction isolation is a phenomenon where the fertilization of eggs is prevented , and eventually leads to reproductive isolation. Examples include mechanical isolation ( size difference/ incompatibility of sex organs in plants) , Temporal isolation ( seen in bull mooses), and behavioral isolation ( seen in some bird species).
D) The Dobzhanski-Muller (DM) incompatibility is a model of hybrid incompatibility, It suggests that allele divergence at differenct genetic loci would eventually lead to genetic incompatibility between species.
E) Even though hybrids may be formed, most of times, they are sterile and cannot reproduce further. This ensures that the genetic composition of parent would be more likely to survive, and aid in the continuation of species.
F) The parsimony principle chooses the simplest scientifc explanation among various explanations to explain a problem. With respect to evolution, this translates to a evolutionary tree that is built with the least number of evolutionary changes.Maximum likelihood method uses general statistical tools for analysing unknown parameters of a probability model.
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