Agents of Evolutionary Change
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Questions and Answers

What does natural selection directly act upon?

  • Ecosystem balance
  • Population size
  • Genetic traits
  • Observable characteristics (correct)

Which scenario best explains the process of natural selection?

  • Giraffes grow longer necks due to stretching in their lifetime.
  • Long-necked giraffes survive better and reproduce more, gradually spreading the trait. (correct)
  • Short-necked giraffes are genetically modified in a lab to have longer necks.
  • Giraffes learn to use tools to reach higher leaves, reducing the need for long necks.

What happens to unfavourable genetic traits in a population over time according to natural selection?

  • They become more common.
  • They become less common. (correct)
  • They remain constant.
  • They alternate in frequency.

Which of the following describes an example of a favourable trait within the giraffe population?

<p>Long necks (A)</p> Signup and view all the answers

According to Lamarck's theory, how would giraffes have developed long necks?

<p>By individually stretching their necks over their lifetimes. (C)</p> Signup and view all the answers

What is gene flow?

<p>Any movement of genes from one population to another (B)</p> Signup and view all the answers

What effect does gene flow have within a single population?

<p>Introduces or reintroduces genes, increasing genetic variation (C)</p> Signup and view all the answers

How does gene flow affect speciation across populations?

<p>Increases genetic similarities, reducing speciation (A)</p> Signup and view all the answers

How would the rate of gene flow typically compare in sedentary organisms versus more mobile organisms?

<p>Lower in sedentary organisms (A)</p> Signup and view all the answers

What is non-random mating?

<p>Mating influenced by human interference (B)</p> Signup and view all the answers

How does non-random mating work against natural selection?

<p>It influences mate choice instead of environmental factors (C)</p> Signup and view all the answers

What happens to a gene once it has been selected for by the environment?

<p>It will increase in frequency over generations. (B)</p> Signup and view all the answers

What is natural selection described as in the provided content?

<p>The mechanism by which evolution may take place in a population. (C)</p> Signup and view all the answers

What did Darwin theorize about the finches in the Galapagos Archipelago?

<p>They all shared a common ancestor. (B)</p> Signup and view all the answers

Which factor selected for the different beak types in Darwin's finches?

<p>Food source (B)</p> Signup and view all the answers

Which example best illustrates an ecological niche based on the provided content?

<p>An anatomical niche where species have different beak shapes for specific food sources. (C)</p> Signup and view all the answers

What role do mutations play in the process observed in Darwin's finches?

<p>Mutations led to genetic variation in beak shapes. (D)</p> Signup and view all the answers

What role does population size play in genetic drift?

<p>Small populations are more prone to genetic drift (B)</p> Signup and view all the answers

What can overshadow natural selection in small populations?

<p>Genetic drift (B)</p> Signup and view all the answers

Which of the following is NOT a cause of mutations?

<p>Natural selection (C)</p> Signup and view all the answers

In the marble analogy, what does the jar represent?

<p>The gene pool of the population (B)</p> Signup and view all the answers

How do favorable mutations affect an organism's likelihood of survival in a population?

<p>They increase the organism's fitness and are passed on to future generations (C)</p> Signup and view all the answers

What is the ultimate outcome of genetic drift in a small population given enough time?

<p>Fixation of one genetic outcome (B)</p> Signup and view all the answers

Most mutations that occur in an organism are:

<p>Minor and do not impact the organism's fitness (C)</p> Signup and view all the answers

During the marble analogy experiment, what does the replacement of each marble represent?

<p>Reproduction of organisms (A)</p> Signup and view all the answers

What happened to the light-colored peppered moths during the Industrial Revolution?

<p>They died off from predation due to loss of camouflage. (A)</p> Signup and view all the answers

Why does genetic drift have less impact on larger populations?

<p>There is a normalizing effect in larger populations (C)</p> Signup and view all the answers

Which of the following was NOT a consequence of the Industrial Revolution on the peppered moths?

<p>Light-colored moths increased in population (B)</p> Signup and view all the answers

Which scenario described best illustrates genetic drift?

<p>A small population where one genetic trait becomes fixed over time (D)</p> Signup and view all the answers

What role do mutations play in evolutionary change?

<p>Act as the primary source of new traits for natural selection (B)</p> Signup and view all the answers

What happens to the less common genetic outcomes in a population undergoing genetic drift?

<p>They are lost over time (D)</p> Signup and view all the answers

What happens to an unfavorable mutation in a population?

<p>It is reduced in frequency (C)</p> Signup and view all the answers

Which term describes changes in the genetic material of an organism?

<p>Mutation (B)</p> Signup and view all the answers

Study Notes

Agents of Evolutionary Change

  • Five agents of evolutionary change: mutation, genetic drift, gene flow, non-random mating, and natural selection

Mutation

  • Changes to the nucleotide sequence in the genetic material of an organism
  • Caused by: errors in DNA replication, exposure to UV or radiation, mutagens, and viruses
  • Creates variation in gene pools
  • Most mutations are minor and do not impact an organism's fitness
  • Mutations are the main provider of new traits for natural selection

Example: The Peppered Moth

  • Evolution of the peppered moth due to pollution during the Industrial Revolution
  • Light-colored moths died off, dark-colored moths flourished due to camouflage

Natural Selection

  • Process by which environmentally favorable genetic traits become more common
  • Acts on observable characteristics of an organism
  • Favourable traits increase in frequency, unfavourable traits decrease

Example: The Giraffe

  • Long-necked giraffes survived and reproduced due to favorable genetic traits
  • Short-necked giraffes died off, leading to the emergence of long-necked giraffes

Evolution

  • Natural selection leads to adaptations and specialization of organisms
  • Can result in the emergence of new species over time

Example: The Finches

  • Finches on the Galapagos Islands adapted to different food sources
  • Different beak shapes emerged due to genetic variations and natural selection

Genetic Drift

  • Random variations in which organisms reproduce, leading to changes in the genetic makeup of a population
  • Depends on small population size
  • Can overshadow natural selection in small populations

Analogy of Genetic Drift

  • Randomly selecting marbles from a jar represents genetic drift
  • Changes in the population's genetic makeup occur due to chance

Gene Flow

  • Movement of genes from one population to another
  • Increases genetic variation in a population
  • Reduces the occurrence of speciation

Effects of Gene Flow on Evolution

  • Introduces or reintroduces genes to a population
  • Makes distant populations genetically similar

Non-Random Mating

  • Mating that does not occur due to chance, but due to human interference
  • Occurs when the possibility of mating is not the same for all possible pairs of individuals
  • Works against natural selection

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Description

Explore the five agents of evolutionary change, including mutation, genetic drift, gene flow, non-random mating, and natural selection in this presentation of notes.

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