In many organisms, such as insects and flowering plants, morphological traits have been lost insome species due to the evolution of developmental arrest: growth and development cease,eliminating the final trait. The remaining tissuecan be remodeled or resorbed for other use.What does this observation suggest about thenature of mutations and adaptive evolution inthese cases?

In many organisms, such as insects and flowering plants, morphological traits have been lost insome species due to the evolution of developmental arrest: growth and development cease,eliminating the final trait. The remaining tissuecan be remodeled or resorbed for other use.What does this observation suggest about thenature of mutations and adaptive evolution inthese cases?

Human Heredity: Principles and Issues (MindTap Course List)

11th Edition

ISBN:9781305251052

Author:Michael Cummings

Publisher:Michael Cummings

Chapter1: A Perspective On Human Genetics

Section1.3: What Are Genes And How Do They Work?

Problem 1EG: Ancient societies used knowledge that traits are heritable in domesticating animals and developing...

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If mutations such as those of the Ubx gene candrastically change morphology in a single step,why do most evolutionary biologists maintainthat modification of existing traits and the evolution of novel characters have generally proceeded by successive small steps?
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Sympatric speciation by allotetraploidy has been proposed as acommon mechanism for speciation. Let’s suppose you were interestedin the origin of certain grass species in southern California.Experimentally, how would you go about determining if some ofthe grass species are the result of allotetraploidy?
Recent reconstructions of evolutionary history are often dependenton assigning divergence in terms of changes in amino acid ornucleotide sequences. For example, a comparison of cytochromec shows 10 amino acid differences between humans and dogs,24 differences between humans and moths, and 38 differencesbetween humans and yeast. Such data provide no information asto the absolute times of divergence for humans, dogs, moths, andyeast. How might one calibrate the molecular clock to an absolutetime clock? What problems might one encounter in such acalibration?
A case can be made that the sedentary way of life characteristicof many people today is a very recent development in humanhistory, dating from at most a century or so ago. According to thisline of argument, physical exertion was a regular part of daily lifefor most people during most of human evolution. From this pointof view, in what way do recent gene-transcription data suggestthat physical exertion is in fact probably essential for full health?
Wyckoff et al. (2000. Nature 403:304-309) have proposed that some human male reproductive-associated genes have evolved by natural selection and not by neutral evolution. Part of the DNA sequence results of their study is shown below. Which gene(s) did seem to evolve by natural selection? Note: dn = number of substitutions per non-synonymous (replacement) sites and ds = number of substitutions per synonymous (silent) sites. dn ds Acrosin-Trypsin 0.138 0.064 Protamine 1 0.133 0.046 SRY 0.055 0.090 Histone H1 (testicular) 0.055…
Recent studies reveal that certain areas of the DNA are less prone to DNA mutations and that mutations may not be random after all. In a study on Arabidopsis thaliana, important genes that are involved in cell growth and expression have been observed to have low mutation rates. What is a possible implication of this observation in evolution?
Ethion is an insecticide that kills leaf-eating insects such as mites. A species of mite develops a mutation overtime that allows it to survive in the presence of ethion. Is this mutation an example of microevolution? Explainyour answer.
First, concerningthe evolution of development, what have been the changes in developmentalmechanisms that give rise to different phenotypes? A second question, closelyrelated to the first, is how do genetic differences among species map onto phenotypic differences? Third, what is the role of development in either constraining or enhancing evolutionary change in characters? That is, how does development affect “evolvability”? Fourth, how does developmental information help usidentify homologous characters, or even define homology? Finally, can understanding development help us understand the origin of novel characteristics?
In the replica plate experiment, it shows that mutations are random. However, certain environmental stresses (such as high temperature, high salt, and low pH) can increase the mutation rate. QUESTIONS: Does increasing the mutation rate increase the probability that an individual mutation will be adaptive?
Evolutionary biologists often say that evolution “selects for outcomes” not for the particular genetic changes that lead to that adaptive outcome. Given that perspective, is it surprising that different gene mutations might be involved in the evolution of the same trait (such as light skin or adaptation to living in high mountains)? Why or why not?