Heterochrony is
a. the alteration of the spatial pattern of gene expression.
b. a change in the relative position of a body part.
c. a change in the relative timing of developmental events.
d. a change in a signaling pathway.
Introduction:
Changes in the development, contribute towards the evolution. The species which are closely related differ from each other because of the genetic changes. These genetic changes lead to differences in their developmental pattern, which result in producing different phenotype. The types of these developmental changes include homeosis and heterochrony.
Answer to Problem 1U
Correct answer:
The alterations in the timing of developmental events due to genetic changes are called heterochrony. Therefore, option c. is correct.
Explanation of Solution
Reason for the correct statement:
When the transcription factors are modified during evolution, they bring changes in the gene function. These changes in genes bring alterations in the timing of developmental events. Such modifications are known as heterochrony.
Option c. is given as "a change in the relative timing of developmental events".
As, “in heterochronic mutations, alterations in the timing of developmental events take place as a result of evolutionary changes in the genes”, is the right answer.
Hence, option c. is correct.
Reasons for the incorrect statements:
Option a. is given as “the alteration of the spatial pattern of gene expression”.
The alterations in the spatial pattern of gene expression, is a type of homeosis. So, it is a wrong answer.
Option b. is given as “a change in the relative position of a body part.”
Change in the relative position of a body part is a type of homeotic mutation, which does not produce a phenotype which is viable. So, it is a wrong answer.
Option d. is given as “a change in the signaling pathway”.
Change in the signaling pathway, results in the appearance of a homeotic phenotype. So, it is a wrong answer.
Hence, options a, b and d are incorrect.
A change in the relative timing of developmental events is known as heterochrony.
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Chapter 25 Solutions
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