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Questions and Answers
A population of woodpeckers have beak lengths ranging from 2cm-4cm. Woodpeckers with beaks closer to 3cm are better adapted to drilling into trees to find food. The population of woodpeckers now predominantly has beaks closer to 3cm. What type of natural selection is this?
A population of woodpeckers have beak lengths ranging from 2cm-4cm. Woodpeckers with beaks closer to 3cm are better adapted to drilling into trees to find food. The population of woodpeckers now predominantly has beaks closer to 3cm. What type of natural selection is this?
In a population of rabbits, some have brown fur and others have white fur. The white fur rabbits are better camouflaged in the snow, while the brown fur rabbits blend in better with the forest floor. What is likely to happen to the population of rabbits over time?
In a population of rabbits, some have brown fur and others have white fur. The white fur rabbits are better camouflaged in the snow, while the brown fur rabbits blend in better with the forest floor. What is likely to happen to the population of rabbits over time?
A population of birds has a wide range of beak sizes. Some birds have short beaks, some have long beaks, and some have beaks of intermediate length. Due to climate change, the seeds that the birds eat become smaller and harder to crack. Which type of selection would this scenario represent?
A population of birds has a wide range of beak sizes. Some birds have short beaks, some have long beaks, and some have beaks of intermediate length. Due to climate change, the seeds that the birds eat become smaller and harder to crack. Which type of selection would this scenario represent?
Which of the following best describes the process of natural selection?
Which of the following best describes the process of natural selection?
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Which of the following statements is FALSE about disruptive selection?
Which of the following statements is FALSE about disruptive selection?
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A species of fish lives in a lake. The lake is divided into two halves by a rock formation. The fish in the shallow half of the lake are mainly brown, while the fish in the deep half of the lake are mainly black. Which type of natural selection is most likely at play here?
A species of fish lives in a lake. The lake is divided into two halves by a rock formation. The fish in the shallow half of the lake are mainly brown, while the fish in the deep half of the lake are mainly black. Which type of natural selection is most likely at play here?
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A giraffe with a shorter neck is less likely to reach leaves high in trees, compared to a giraffe with a longer neck. This type of selection is called:
A giraffe with a shorter neck is less likely to reach leaves high in trees, compared to a giraffe with a longer neck. This type of selection is called:
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Which of the following statements is TRUE about natural selection?
Which of the following statements is TRUE about natural selection?
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What is the most specific unit of classification for organisms?
What is the most specific unit of classification for organisms?
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What could lead to the evolution of a new species?
What could lead to the evolution of a new species?
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Which concept describes the evolutionary history of related species?
Which concept describes the evolutionary history of related species?
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What is a key reason many species become extinct?
What is a key reason many species become extinct?
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How many species are estimated to become extinct throughout Earth's history?
How many species are estimated to become extinct throughout Earth's history?
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What is the primary concept of evolution as defined in biology?
What is the primary concept of evolution as defined in biology?
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Which evidence supports the theory of common descent?
Which evidence supports the theory of common descent?
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What role did Charles Darwin have on the HMS Beagle?
What role did Charles Darwin have on the HMS Beagle?
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What significant observation did Darwin make regarding species on the Galapagos Islands?
What significant observation did Darwin make regarding species on the Galapagos Islands?
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What is one way the fossil record supports the theory of evolution?
What is one way the fossil record supports the theory of evolution?
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What is the primary result of adaptive radiation?
What is the primary result of adaptive radiation?
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Which of the following best describes convergent evolution?
Which of the following best describes convergent evolution?
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What does the concept of punctuated equilibrium suggest about the process of speciation?
What does the concept of punctuated equilibrium suggest about the process of speciation?
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Which statement about coevolution is accurate?
Which statement about coevolution is accurate?
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What evidence supports both gradualism and punctuated equilibrium as mechanisms of speciation?
What evidence supports both gradualism and punctuated equilibrium as mechanisms of speciation?
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What is the chance for individuals in the Amish community of Lancaster County to express the six fingers and toes mutation?
What is the chance for individuals in the Amish community of Lancaster County to express the six fingers and toes mutation?
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Which factor does NOT contribute to changes in allele frequencies within a population?
Which factor does NOT contribute to changes in allele frequencies within a population?
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What is the condition referred to when allele frequencies remain static over time?
What is the condition referred to when allele frequencies remain static over time?
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Which of the following is NOT a requirement for Hardy-Weinberg Equilibrium?
Which of the following is NOT a requirement for Hardy-Weinberg Equilibrium?
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In the Hardy-Weinberg equation, if $p + q = 1$, what does $p$ represent?
In the Hardy-Weinberg equation, if $p + q = 1$, what does $p$ represent?
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What does the Hardy-Weinberg principle primarily model?
What does the Hardy-Weinberg principle primarily model?
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What does the term 'gene flow' describe?
What does the term 'gene flow' describe?
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Which equation represents the frequencies of genotypes in a population according to the Hardy-Weinberg principle?
Which equation represents the frequencies of genotypes in a population according to the Hardy-Weinberg principle?
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What is the primary mechanism proposed by Charles Darwin to explain how species evolve?
What is the primary mechanism proposed by Charles Darwin to explain how species evolve?
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Which type of adaptation is characterized by a species blending into its surroundings?
Which type of adaptation is characterized by a species blending into its surroundings?
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Which of the following structures is considered vestigial?
Which of the following structures is considered vestigial?
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What principle of natural selection suggests that not all offspring that are produced will survive to adulthood?
What principle of natural selection suggests that not all offspring that are produced will survive to adulthood?
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Which of the following is an example of analogous structures?
Which of the following is an example of analogous structures?
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How does embryology provide evidence for evolution?
How does embryology provide evidence for evolution?
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What process describes how traits that assist survival are passed on to offspring?
What process describes how traits that assist survival are passed on to offspring?
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Which of the following does NOT describe a principle of Darwin's Theory of Natural Selection?
Which of the following does NOT describe a principle of Darwin's Theory of Natural Selection?
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Flashcards
Evolution
Evolution
Change in populations over time; a fundamental concept in biology.
Natural Selection
Natural Selection
Process where organisms better adapted to their environment tend to survive and reproduce more.
Common Descent
Common Descent
Theory that all living organisms share a common ancestor.
Charles Darwin
Charles Darwin
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Fossil Record
Fossil Record
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Adaptation
Adaptation
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Darwin's Theory of Evolution
Darwin's Theory of Evolution
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Homologous Structures
Homologous Structures
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Analogous Structures
Analogous Structures
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Vestigial Structures
Vestigial Structures
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Embryology Evidence
Embryology Evidence
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Principles of Natural Selection
Principles of Natural Selection
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Beak Length Adaptation
Beak Length Adaptation
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Speciation
Speciation
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Phylogeny
Phylogeny
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Extinction Causes
Extinction Causes
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Variation
Variation
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Fossil Evidence
Fossil Evidence
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Stabilizing Selection
Stabilizing Selection
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Directional Selection
Directional Selection
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Disruptive Selection
Disruptive Selection
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Genotypes vs Phenotypes
Genotypes vs Phenotypes
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Populations Evolve, Not Individuals
Populations Evolve, Not Individuals
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Amish Mutation Rate
Amish Mutation Rate
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Gene Flow
Gene Flow
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Genetic Equilibrium
Genetic Equilibrium
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Hardy-Weinberg Principle
Hardy-Weinberg Principle
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Allele Frequencies
Allele Frequencies
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p and q in Alleles
p and q in Alleles
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Genetic Drift
Genetic Drift
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Selection Pressure
Selection Pressure
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Adaptive Radiation
Adaptive Radiation
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Convergent Evolution
Convergent Evolution
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Gradualism
Gradualism
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Punctuated Equilibrium
Punctuated Equilibrium
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Study Notes
Biological Change
- Natural Selection and Evidence for Evolution, a fundamental concept in biology
- Evolution is the change in populations over time
- Charles Darwin was the first to publish ideas on species evolution
What is Evolution?
- The modern theory of evolution is a fundamental concept in biology
- Evolution is defined as the change in populations over time
- Charles Darwin was the first to publish his ideas on how species evolve
Common Descent
- All living organisms on Earth descended from a common ancestor
- DNA and RNA encode structures and functions in all living organisms
- Similarities in amino acid sequences between organisms suggest common descent
- Fossil records show how one type of plant or animal can evolve into different types over time
Charles Darwin
- Began his work in 1831, age 21, as a naturalist on the HMS Beagle
- As a naturalist, he studied and collected biological specimens at each port on his route
- Observed unique species on the Galapagos Islands that were similar to species elsewhere
- Concluded that species can change over time. Spent 22 years to develop an explanation.
- Published On the Origin of Species in 1859, introducing his theory of natural selection to explain species' evolution
- Developed his ideas while sailing on the Beagle
Adaptations: Evidence for Evolution
- Structural adaptations develop over time
- Mimicry: One species resembling another
- Camouflage: A species blending with its surroundings
- Physiological adaptations develop over time
- Antibiotic resistance of bacteria
Other Evidence for Evolution
- Fossils
- Anatomy
- Homologous structures: Similar in anatomy but different functions; share a common evolutionary origin.
- Analogous structures: Similar in function but have different structure; do not share a common evolutionary origin.
- Vestigial structures: Body structures with no function now, but were probably useful to an ancestor.
- Biochemistry
- DNA and RNA
More Evidence For Evolution
- Embryology: Early stages of development in various vertebrate embryos are strikingly similar, indicating a common ancestor.
FETSAL DEVELOPMENT
- Shows detailed stages of growth and development of a fetus from zygote stage.
Principles of Darwin's Theory of Natural Selection
- Variation: Individuals within a population vary
- Heritability: Traits are passed from parent to offspring
- Overproduction: More offspring are produced than can survive
- Reproductive Advantage (Preferential Selection of Traits): Individuals with advantageous traits are more likely to survive and reproduce
Species Change
- Organisms best suited to their environments are more likely to survive and reproduce.
- Adaptations are traits that improve an organism's chance for survival and reproduction.
Adaptation
- Individuals within a species exhibit variation in appearance and function
- Variations are a result of random changes in genetic material during sexual reproduction and mutations
Natural Selection
- Organisms with traits that help them survive and reproduce pass their traits to their offspring
- Helpful traits thrive in a population, while harmful traits disappear over time
- A population can evolve into a new species.
Populations Evolve, Not Individuals
- Variation exists within a population
- Individuals with traits poorly suited to their environment are less likely to survive and reproduce; this, in the long run, affects their genotypes and phenotypes
- Evolution results from changes in a population's genes and their frequencies
Natural Selection Acts on Variation
- Variations can increase or decrease an organism's survival chances in a specific environment
- Stabilizing selection, directional selection, and disruptive selection are three types of natural selection
Types of Natural Selection
- Directional selection: Favors individuals at one extreme of a trait.
- Disruptive selection: Favors individuals at both extremes of a trait.
- Stabilizing selection: Favors the average trait.
Determining the Type of Natural Selection
- Examples of variation in different populations and environmental pressures that affect survival and reproduction are used to determine the type of natural selection.
Classification of Organisms
- Organisms are categorized based on internal and external characteristics
- Species are the most specific unit of classification
The Evolution of Species
- Speciation is the process of the evolution of a new species
- Speciation occurs when members of a population no longer interbreed or produce fertile offspring.
Evolutionary History
- Phylogeny describes the evolutionary history of a group of related species
- All organisms evolved from a single ancestor
- New species evolve from pre-existing species
Fossil Evidence
- Fossil evidence and similarities between ancient and modern species are used to support the theory of evolution
- Physical and molecular similarties between diverse species have been found
Phylogeny of Humans
- Shows the evolutionary relationships among humans and other primates
Extinction
- Organisms try to survive through adaptation in their environments, but many species become extinct
- Extinction can result from environmental changes, human interference or the failure to adapt to new conditions.
Extinction (cont)
-
Extinction is part of evolution.
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999 out of 1000 species that have lived on earth have gone extinct
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The average species survives for 2 to 10 million years.
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Even highly adapted species become extinct
Mass Extinctions
- Many have occurred during Earth's history
- A mass extinction occurs when over 50% of species are wiped out
- Mass extinctions create opportunities for new species to arise/ develop
Changes in Genetic Equilibrium
- Mutations cause genetic changes, frequently influenced by environmental factors (radiation, chemicals)
- Useful mutations persist and add to the gene pool
- Harmful mutations cause death and are removed from the gene pool quickly.
Mutations
- Natural mutations occur at a regular rate
- Differences in genetic material between species estimates how long ago they shared a common ancestor.
Types of Evolution
- Macroevolution refers to the generation of large changes in organisms (speciation)
- Microevolution refers to changes in gene frequencies in a population in the absence of pressure from natural selection
Mechanisms of Evolution
- Populations, not individuals, evolve.
Population Genetics
- Principles of today's modern theory of evolution stem from population genetics and the synthesis of evolution, including genetics
- Darwin developed natural selection without knowledge of genes
Genes and Populations
- Gene pool is the collection of genes within a population
- Genotype is the genetic makeup of an individual at a given locus, taking into consideration the pair of alleles
- Genotype and allele frequencies help understand the genetic makeup of a population.
- Phenotype is the traits of an individual; related to proportion of a given phenotype in a population
Disruption to Genetic Equilibrium
- Genetic drift is the alteration of allelic frequencies by chance events
- Can greatly impact small populations
- Examples include the Amish of Lancaster County, Pennsylvania (6 fingers and toes)
Disruption to Genetic Equilibrium (cont)
- Gene flow is the transfer of genes by migrating individuals
- When an individual enters or leaves a population, it affects the genetic makeup of the population
Alleles and Population Genetics
- Natural selection affects the makeup of a population
- Changes in the gene pool demonstrate changes in allelic frequencies, and evolution is when these allele frequencies are changing.
- A population is in equilibrium when genetic frequencies stay the same over time.
Population Stability
- Dominant alleles are not always the most prevalent in the gene pool; they can change frequently
- Population stability is explained by the Hardy-Weinberg equilibrium
Hardy-Weinberg Principle
- Hardy-Weinberg Equilibrium models conditions required for no change in genetic frequencies over generations. These conditions are: large population size, no migration, random mating, no net mutations, and similar selective value of all genotypes. This rarely happens in nature.
The Ps and Qs of H&W
- Alleles A and a are represented by their frequencies, p and q. p + q = 1
- The frequencies p² + 2pq + q² equal 1, which are the frequencies of the genotypes AA, Aa, and aa, respectively.
- Working out these frequencies can determine if a population is evolving.
H-W: Example
- Example demonstrating how to calculate the frequencies of each allele and genotype in a non-evolving population. The frequencies add up to 1.0 demonstrating the population isn't evolving.
A Fun Experiment in Class
- Tongue rolling as an example of a simple dominant trait to demonstrate genetic equilibrium conditions. Describes steps to determine if a population is evolving based on the frequency of a dominant trait.
5 Factors Upset Genetic Equilibrium
- Mutations, non-random mating, genetic drift, gene flow, and natural selection all disrupt genetic equilibrium.
Population Genetics (cont)
- Populations evolve, not individuals.
- Variations lead to adaptations that help the species thrive, which become more common in a population,.
- Genotype frequency is the proportion of a given genotype in the population.
Reproductive Barriers
- Reproductive barriers limit gene flow (transfer of genes) among populations
- Reproductive isolation results from different barriers (Sexual selection choices, prezygotic isolation (geographic, ecological, behavioral), and postzygotic isolation (hybrid offspring).
Speciation
- Speciation occurs when a population diverges and can no longer interbreed or produce viable offspring, often due to reproductive isolation.
- Allopatric speciation: Physical barrier divides a population, resulting in two reproductively isolated groups
- Sympatric speciation: New species arises without physical isolation (ex: resource utilization or polyploidy).
Patterns of Evolution
- Adaptive radiation (divergent evolution) : A population adapts to different environments, becoming less similar over time, resulting in new species.
- Convergent evolution: Distantly related species occupy similar environments, and evolutionary pressures result in similar traits in both species.
- Coevolution: Evolution of one species affects the evolution of another species (eg. hummingbirds and flowers)
Speciation Can Occur Quickly or Slowly
- Gradualism: Species evolve through gradual change over a long time
- Punctuated equilibrium: A hypothesis that speciation occurs in rapid bursts of changes.
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Description
Test your understanding of natural selection with this quiz. Explore scenarios involving woodpeckers, rabbits, and birds to identify types of selection and the processes involved. Challenge yourself with true or false statements about disruptive selection.
