Podcast
Questions and Answers
Which of the following best defines non-adaptive evolution?
Which of the following best defines non-adaptive evolution?
- Evolution resulting from migration and gene flow between populations.
- Evolution driven by natural selection leading to beneficial traits.
- Evolution of a population due to random changes in the genome. (correct)
- Evolution caused by mutations that provide a survival advantage.
Non-adaptive evolution always leads to a decrease in the fitness of a population.
Non-adaptive evolution always leads to a decrease in the fitness of a population.
False (B)
Name the evolutionary process in which allele frequencies change due to chance events, especially in small populations?
Name the evolutionary process in which allele frequencies change due to chance events, especially in small populations?
genetic drift
A drastic reduction in population size due to a natural disaster is an example of a genetic ________ effect.
A drastic reduction in population size due to a natural disaster is an example of a genetic ________ effect.
Which condition is NOT a requirement for Hardy-Weinberg equilibrium?
Which condition is NOT a requirement for Hardy-Weinberg equilibrium?
In the Hardy-Weinberg equation, what does the term $2pq$ represent?
In the Hardy-Weinberg equation, what does the term $2pq$ represent?
Genetic drift has a more significant impact on large populations than on small populations.
Genetic drift has a more significant impact on large populations than on small populations.
What is the term for the establishment of a new population by a small number of individuals carrying only a fraction of the original population's genetic variation?
What is the term for the establishment of a new population by a small number of individuals carrying only a fraction of the original population's genetic variation?
A population of butterflies with two color forms experiences a volcanic eruption that kills most of the individuals randomly. This is an example of which evolutionary mechanism?
A population of butterflies with two color forms experiences a volcanic eruption that kills most of the individuals randomly. This is an example of which evolutionary mechanism?
Gene flow always increases the genetic differences between populations.
Gene flow always increases the genetic differences between populations.
The migration of fertile individuals between populations is known as __________.
The migration of fertile individuals between populations is known as __________.
Which of the following statements best describes the expected change in genetic similarity between two isolated populations over time?
Which of the following statements best describes the expected change in genetic similarity between two isolated populations over time?
Populations of the same species that are geographically closer to each other are expected to have lower genetic distances compared to those that are farther apart.
Populations of the same species that are geographically closer to each other are expected to have lower genetic distances compared to those that are farther apart.
What is the term for the measure of genetic differences between populations, which often increases with geographical distance?
What is the term for the measure of genetic differences between populations, which often increases with geographical distance?
What do the graphs relating geographic and genetic distance in Swiss Alps plant populations (Alpine willowherb, Rose-like plant, Yellow bellflower) show?
What do the graphs relating geographic and genetic distance in Swiss Alps plant populations (Alpine willowherb, Rose-like plant, Yellow bellflower) show?
A population bottleneck results in a loss of __________ __________, which reduces a population’s ability to adapt to changing environmental conditions.
A population bottleneck results in a loss of __________ __________, which reduces a population’s ability to adapt to changing environmental conditions.
Insect-pollinated plants are more likely to exhibit high gene flow across fragmented populations compared to wind-pollinated plants.
Insect-pollinated plants are more likely to exhibit high gene flow across fragmented populations compared to wind-pollinated plants.
What type of population distribution is typically associated with high levels of genetic diversity within subpopulations?
What type of population distribution is typically associated with high levels of genetic diversity within subpopulations?
How does a decrease in population size affect genetic diversity?
How does a decrease in population size affect genetic diversity?
The black grouse population in the Netherlands experienced an increase in genetic diversity due to migration from other populations.
The black grouse population in the Netherlands experienced an increase in genetic diversity due to migration from other populations.
The _______ ______ in the black grouse population in the Netherlands led to reduced numbers and loss of genetic diversity.
The _______ ______ in the black grouse population in the Netherlands led to reduced numbers and loss of genetic diversity.
Which term describes the increased chance of mating between closely related individuals in a small population?
Which term describes the increased chance of mating between closely related individuals in a small population?
Why was it useful to analyze the DNA of stuffed black grouse from a Netherlands museum?
Why was it useful to analyze the DNA of stuffed black grouse from a Netherlands museum?
Match the term to its definition:
Match the term to its definition:
Which of the following is an effect of genetic drift on small populations?
Which of the following is an effect of genetic drift on small populations?
Migration, or gene flow, always results in better adaptation of the recipient population to its environment.
Migration, or gene flow, always results in better adaptation of the recipient population to its environment.
Name the effect that occurs when a few individuals colonize a new habitat, and their allele frequencies are significantly different from the larger source population.
Name the effect that occurs when a few individuals colonize a new habitat, and their allele frequencies are significantly different from the larger source population.
The Hardy-Weinberg equilibrium serves as a __________ __________ to determine whether evolution is occurring in a population.
The Hardy-Weinberg equilibrium serves as a __________ __________ to determine whether evolution is occurring in a population.
What is the frequency of the homozygous recessive genotype in a population where the frequency of the recessive allele, $q$, is 0.3?
What is the frequency of the homozygous recessive genotype in a population where the frequency of the recessive allele, $q$, is 0.3?
Inbreeding increases the proportion of heterozygotes in a population.
Inbreeding increases the proportion of heterozygotes in a population.
What two conditions increase the likelyhood of a loss of genetic diversity in small populations?
What two conditions increase the likelyhood of a loss of genetic diversity in small populations?
Loss of genetic diversity can have consequences that are neither ________ nor _________ to the population.
Loss of genetic diversity can have consequences that are neither ________ nor _________ to the population.
Which outcome is likely from population isolation?
Which outcome is likely from population isolation?
Isolation in a population will always result in decreased heterozygosity.
Isolation in a population will always result in decreased heterozygosity.
Besides for the analysis of genetic diversity, what other reason was there to sequence DNA from different populations?
Besides for the analysis of genetic diversity, what other reason was there to sequence DNA from different populations?
Flashcards
Non-adaptive Evolution
Non-adaptive Evolution
Evolution of a population caused by random changes in the genome. These changes are neither beneficial nor harmful.
Hardy-Weinberg Equilibrium
Hardy-Weinberg Equilibrium
States that genetic variation in a population will remain constant from one generation to the next if certain conditions are met.
Genetic Drift
Genetic Drift
Changes in allele frequencies due to chance events, especially in small populations.
Bottleneck Effect
Bottleneck Effect
Signup and view all the flashcards
Founder Effect
Founder Effect
Signup and view all the flashcards
Genetic Drift: Founder Effect
Genetic Drift: Founder Effect
Signup and view all the flashcards
Genetic Drift: Bottleneck Effect
Genetic Drift: Bottleneck Effect
Signup and view all the flashcards
Bottleneck Effect
Bottleneck Effect
Signup and view all the flashcards
Study Notes
- Chapter 19 focuses on the mechanisms of evolution
- Section 19.4 addresses the question: Do populations evolve in the absence of natural selection?
Biology Learning Objectives
- Assess gene flow and genetic drift regarding their effects on populations and variation.
- Determine how a population's structure impacts its evolution and the strength of gene flow and genetic drift.
- Describe how non-adaptive evolution, like genetic drift, changes the genome of a population over time.
- Determine how speciation needs time and genetic isolation.
Non-adaptive Evolution
- Evolution caused by random changes in the genome of a population.
- These changes are neither beneficial nor harmful.
Hardy-Weinberg Equilibrium
- Genetic variation remains constant from one generation to the next if specific conditions are met.
- The conditions include:
- The population is very large.
- There is no natural selection.
- There is no migration (gene flow).
- There is no mutation.
- There is random mating (no inbreeding).
- If any of these conditions are unmet, evolution occurs.
- It serves as the null hypothesis.
- p + q = 1 (allele frequencies)
- p² + 2pq + q² = 1 (genotype frequencies)
- p² = percentage of homozygous dominant.
- 2pq = percentage of heterozygotes.
- q² = percentage of recessive homozygous.
Genetic Drift
- Violations to Hardy-Weinberg (HW) equilibrium.
- Changes in frequencies occur due to chance events associated with small population sizes.
- Genetic distances have increased for isolated populations over time.
- Formula: Increased genetic distance
Genetic Drift: Bottleneck and Founder Effects
- Changes in frequencies occur due to chance events associated with small population sizes.
- Original population goes through a bottlenecking event resulting in a surviving, smaller population
- Some species moved from the continent to an isolated island and started a new "founder" population
Population Isolation and Genetic Diversity
- Studied using RAPD (randomly amplified regions of DNA) to separate DNA fragments by size.
- A study observed plants in the Swiss Alps:
- Three plant species were studied.
- Populations were separated by 5 to 30 kilometers.
- The species were insect-pollinated with wind dispersed seeds.
- Researchers questioned whether these scattered populations were truly isolated.
- Heterozygosity and multiple alleles observed in Swiss Alp plant populations.
- Diversity detected even in isolated populations.
- Genetic and geographic distance between plant populations compared
Genetic Distance vs Geographic Distance
- Graphs showed genetic distance for pairs of Alpine willowherb, Rose-like plant, and Yellow bellflower populations
- R = 0.57, P<0.001 correlation between genetic and geographic distance in Alpine willowherb populations
- R = 0.81, P<0.001 correlation between genetic and geographic distance in “rose-like” plant populations
- R = 0.317, P=0.007 correlation between genetic and geographic distance in Yellow bellflower populations
- Show a clumped or random distribution.
- The correlation between the genetic and geographic distance varied for the species.
Black Grouse Case Study
- Black grouse (Lyrurus tetrix) experienced declines in European populations leading to genetic diversity loss.
- The Dutch population is more than 200 kilometers away from populations in Belgium and Germany.
- Grouse dispersal range is 30 kilometers for hens (females).
- Graphs showed over time there was a reduction in # of displaying black grouse cocks in the Netherlands and reduction of occupied breeding areas
- DNA was sequenced from different populations and museum specimens in the Netherlands
- The main cause for the diversity decrease appears to be the bottleneck effect.
- Bottleneck Effect is a drop in numbers in an isolated population that leads to loss of genetic diversity
- The decrease is caused from the Black Grouse going to one isolated breeding area
- Loss of genetic diversity occurs in small populations from the random genetic drift and high potential for inbreeding.
- Random genetic drift and the high potential for inbreeding lowers the genetic diversity.
Studying That Suits You
Use AI to generate personalized quizzes and flashcards to suit your learning preferences.
