Chapter 7: Evolution and Adaptation Flashcards
The process of evolution depends on ___________ ___________________
Genetic variation
Can evolution occur without genetic variation?
No
_________________ ________ is a molecule composed of two strands of nucleotides that are wound together into a shape known as a double helix
Deoxyribonucleic acid
________________ are compact structures consisting of long strands of DNA wound around proteins
Chromosomes
In a ___________ _________ or ____________ distribution, there is a symmetrical distribution of values around the mean
Bell curve
Normal distribution
__________________ are alternate forms of a particular gene
Alleles
How do new alleles develop?
Via mutation
________________ refers to a single trait affects by several genes
Polygenic
What is pleiotropy?
When a single gene affects multiple traits
________________ refers to a process wherein the expression of one gene controls that of another gene
Epistasis
What are three examples of epistasis in humans?
(1) Red hair
(2) Albinism
(3) Alzheimer’s disease
________________ refers to an individual who has two different alleles of a particular gene
Heterozygous
_______________ refers to an individual who has two identical alleles of a particular gene
Homozygous
_____________ arises when two alleles both contribute to a third or blended phenotype
Codominance
What’s a common example of codominance?
Pink snapdragons
What is a dominant allele?
An allele that masks the expression of the other allele of a given gene
What is a recessive allele?
An allele whose expression is masked by the presence of another allele
What is a gene pool?
The collection of alleles from all individuals in a population
_____________ _______________ is the combination of alleles of those possessed by the diploid parent in a given gamete
Random assortment
What is a mutation?
A random change in the sequence of nucleotides in regions of DNA that either comprise a gene or control the expression of a gene
__________________ refers to the reshuffling of genes that can occur as DNA is copied during meiosis and chromosomes exchange genetic material
Recombination
Recombination can lead to ____________ _____________, which is required for evolution to occur
Genetic variation
Evolution can occur at _______________ or through _______________
Random
Selection
________________ _____________ is a process that occurs when genetic variation is lost because of random variation in mating, mortality, fecundity, and inheritance
Genetic drift
Genetic drift is also called ______________ ______________
Neutral selection
Does genetic drift act more strongly on a small or large population?
A small population
What is a deme?
A subpopulation, a smaller group within a population, that can freely interbreed
What is the bottleneck effect?
A population bottleneck or genetic bottleneck is a sharp reduction in the size of a population and thus a loss of genetic variation due to environmental events such as famines, earthquakes, floods, fires, disease, and droughts or human activities such as genocide and human population planning.
What are two ways in which genetic drift may occur?
Bottleneck effect
Founder effect
The ____________ _____________ is the loss of genetic variation that occurs when a new population is established by a very small number of individuals from a larger population
Founder effect
What plant discussed in class spread in the United States as a result of the founder effect?
Eichhornia crassipes
The water hyacinth
