The Galapagos Islands are home to a unique iguana species that dives for extended periods of time to feed on algae from the sea floor. This makes them the world's only marine lizard. Assume the scales of these iguanas exhibit two phenotypes controlled by a single gene with two alleles: dominant, brown (G) and recessive, green (g). After studying the population for many years, a group of scientists concluded that a mess of 10,000 iguanas was not evolving, and that this mess contained 30% brown alleles and 70% green alleles. a) What is the expected frequency of each genotype for scale color? b) What is the expected number of individuals with each phenotype? Much to the researchers' dismay, one year during an EI Niño cycle, food became scarce and the mess of iguanas was randomly reduced to 100 individuals: 75 brown and 25 green. The researchers then conducted a genetic study on these individuals and found that of the 75 brown individuals, 30 were heterozygous. c) What is the actual frequency of each genotype in the reduced population? d) What is the actual frequency of each allele in the reduced population?
Genetic Variation
Genetic variation refers to the variation in the genome sequences between individual organisms of a species. Individual differences or population differences can both be referred to as genetic variations. It is primarily caused by mutation, but other factors such as genetic drift and sexual reproduction also play a major role.
Quantitative Genetics
Quantitative genetics is the part of genetics that deals with the continuous trait, where the expression of various genes influences the phenotypes. Thus genes are expressed together to produce a trait with continuous variability. This is unlike the classical traits or qualitative traits, where each trait is controlled by the expression of a single or very few genes to produce a discontinuous variation.
![The Galapagos Islands are home to a unique iguana species that dives for extended
periods of time to feed on algae from the sea floor. This makes them the world's only
marine lizard. Assume the scales of these iguanas exhibit two phenotypes controlled by a
single gene with two alleles: dominant, brown (G) and recessive, green (g). After studying
the population for many years, a group of scientists concluded that a mess of 10,000
iguanas was not evolving, and that this mess contained 30% brown alleles and 70%
green alleles.
a) What is the expected frequency of each genotype for scale color?
b) What is the expected number of individuals with each phenotype?
Much to the researchers' dismay, one year during an EI Niño cycle, food became scarce
and the mess of iguanas was randomly reduced to 100 individuals: 75 brown and 25
green. The researchers then conducted a genetic study on these individuals and found
that of the 75 brown individuals, 30 were heterozygous.
c) What is the actual frequency of each genotype in the reduced population?
d) What is the actual frequency of each allele in the reduced population?
To the researchers' delight, the next year saw the end of the El Niño event, and a rebound
in the iguana population size to 300 individuals in the mess: 251 brown and 49 green.
e) What is the expected frequency of each allele in the rebound population?
f) What is the expected number of each genotype in the rebound population?
g) You perform a x? statistical test comparing the original and rebound populations and
get a p = 0.007. Did microevolution occur?
h) Given what you know about the various mechanisms of microevolution, what
mechanism is most likely for any changes in allele frequencies between the original
and rebound populations?](/v2/_next/image?url=https%3A%2F%2Fcontent.bartleby.com%2Fqna-images%2Fquestion%2F6f7ba5f1-b15e-49a0-a32e-9e05862724c4%2F6651bf73-fee8-43dc-9299-8b34798c5625%2F73w9308_processed.jpeg&w=3840&q=75)
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