Fungal Genetics and Spatial Distribution

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Questions and Answers

If the frequency of the M allele in a population is 0.83, then the frequency of the N allele is approximately ________.

0.17

Assuming Hardy-Weinberg equilibrium, if the frequency of the M allele is 0.83, the frequency of the MM genotype is approximately ________.

0.6889

Which of the following describes gene flow?

  • The accumulation of differences between groups which can lead to the formation of new species.
  • The movement of genes/alleles between populations. (correct)
  • The random change in allele frequencies due to chance events.
  • The process by which new species arise.

Gene flow always increases the genetic differences between populations.

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

What is the most likely effect of increased gene flow between two populations?

<p>Decreased genetic divergence. (B)</p> Signup and view all the answers

In the context of population genetics, what does 'fixation' refer to?

<p>The loss of all alleles except one at a gene locus in a population. (B)</p> Signup and view all the answers

Genetic drift has a more significant impact on large populations than on small populations.

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

Which of the following evolutionary mechanisms is most likely to reduce genetic variation within a population?

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

Match each evolutionary mechanism with its primary effect on genetic variation:

<p>Mutation = Increases genetic variation by introducing new alleles Gene Flow = Can increase or decrease genetic variation depending on the source population Genetic Drift = Reduces genetic variation through random loss of alleles Natural Selection = Can increase or decrease genetic variation depending on the type of selection</p> Signup and view all the answers

In a population of plants, flower color is determined by a single gene with two alleles: red (R) and white (r). If the population consists of 75% red-flowered plants and 25% white-flowered plants, and the red allele is dominant, what can be determined from this information alone?

<p>The frequency of the r allele. (B)</p> Signup and view all the answers

What is the primary difference between the effects of gene flow and natural selection on the genetic diversity of a population?

<p>Gene flow is random, while natural selection is deterministic and based on environmental conditions. (B)</p> Signup and view all the answers

Describe a scenario in which gene flow could prevent two populations from diverging into separate species. Explain how the gene flow counteracts the divergence.

<p>If two populations are beginning to genetically diverge due to different selective pressures, but there is consistent gene flow between them, the introduction of new alleles will homogenize the allele frequencies, preventing the populations from becoming reproductively isolated and eventually forming distinct species.</p> Signup and view all the answers

Oyster mushrooms primarily reproduce asexually. What key observation supports the idea of limited dispersal in Oyster mushrooms?

<p>There is one genetic type per log. (A)</p> Signup and view all the answers

Why does the asexual reproduction strategy of oyster mushrooms imply that their migration and dispersal is limited?

<p>Asexual reproduction produces genetically identical offspring, so spatial clustering indicates limited migration because individuals are not moving far from the parent. (D)</p> Signup and view all the answers

If a population of mushrooms reproduces asexually and has limited dispersal mechanisms, what pattern of genetic diversity would you expect to see in a forest?

<p>I would expect to see high genetic similarity within localized areas, such as individual logs, but significant genetic differences between widely separated logs due to the lack of gene flow.</p> Signup and view all the answers

Why are pollinators of critical importance to the dispersal distances of plants?

<p>Pollinators can carry pollen further. (D)</p> Signup and view all the answers

How did Schmidt's experiment evaluate the connection between bumblebee behavior and gene flow in plant populations?

<p>By tracking the distances flown by bumblebees between plants. (B)</p> Signup and view all the answers

According to the flight distance data of pollinators, which of the following statements is correct between bumblebees and butterflies visiting groundsel?

<p>Butterflies have a greater median flight distance than bumblebees. (B)</p> Signup and view all the answers

A plant is not significantly affected by animals or pollinators.

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

Which is a key factor in studying gene flow among bladder campion populations?

<p>The physical distance between populations. (B)</p> Signup and view all the answers

In a study of bladder campion populations, why would researchers analyze the alleles of multiple individuals from each population?

<p>To assess the genetic variation within and between populations and infer patterns of gene flow. (D)</p> Signup and view all the answers

In studies of bladder campion, what do pie charts representing the geographic location and frequency of mitochondrial allele combinations primarily illustrate?

<p>The extent of gene flow between populations. (B)</p> Signup and view all the answers

Explain the relationship between the genetic similarity of bladder campion populations and their geographic location.

<p>I would expect for geographically closer populations to have more similar allele frequencies due to higher rates of gene flow. Distant populations are expected to show greater genetic differences because of limited dispersal.</p> Signup and view all the answers

Match the following terms with their definitions related to evolutionary biology:

<p>Allele = A variant form of a gene Gene Flow = The transfer of genetic material from one population to another Genetic Drift = Random changes in allele frequencies within a population Population = A group of individuals of the same species living in the same area</p> Signup and view all the answers

What is the most common dispersal patterns observed in juvenile starlings distances?

<p>Most birds demonstrate short-range dispersal. (A)</p> Signup and view all the answers

Why do scientists band juvenile starlings when they are still in the nest?

<p>To understand where the starlings are migrating and dispersing when they are juveniles. (B)</p> Signup and view all the answers

What percentage of birds were dispersed over 300 km?

<p>6.9% (D)</p> Signup and view all the answers

Which of the following statements best describes the genetic structure of starlings across their range?

<p>Starlings have moderate genetic diversity, with localized variations in allele frequencies but overall genetic similarity. (C)</p> Signup and view all the answers

How do patterns of dispersal distances and genetic similarity contribute to an understanding of gene flow/

<p>Dispersal distances provide insights into the potential for gene flow. Short distances might indicate limited gene flow, leading to genetic differences. Long distances may introduce new alleles to distant locations, resulting in more homogenized patterns.</p> Signup and view all the answers

If 16/22 genes have the same one allele in starlings, it suggests that gene flow is high in those starlings.

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

A population of butterflies shows a bimodal distribution of wing colors, with individuals tending to have either very bright or very dull coloration. What type of selection is most likely responsible for this pattern?

<p>Disruptive selection. (B)</p> Signup and view all the answers

A bottleneck event always leads to an increase in genetic diversity.

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

Which type of selection is most likely to maintain a stable intermediate phenotype in a population?

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

Explain how genetic drift can lead to maladaptation in a small population.

<p>Genetic drift results in random changes in allele frequencies, which can cause beneficial alleles to be lost and harmful alleles to become fixed in the population by chance, regardless of their effect on the population's fitness.</p> Signup and view all the answers

What is the most direct effect of non-random mating on allele frequencies in a population?

<p>It changes genotype frequencies but not allele frequencies. (C)</p> Signup and view all the answers

How does mutation contribute to the process of evolution?

<p>Mutation generates the raw material for evolutionary change by introducing new alleles. (D)</p> Signup and view all the answers

Natural selection always results in the evolution of 'perfect' or 'optimal' traits.

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

What is a key contrast in how founder effects and bottleneck effects influence genetic diversity?

<p>Founder effects involve the establishment of a new population by a small number of individuals, while bottleneck effects involve a drastic reduction in population size due to a random event. (B)</p> Signup and view all the answers

Consider a population undergoing strong directional selection for increased body size. What is the most likely outcome for the distribution of body size in future generations?

<p>The distribution will shift towards larger body sizes. (D)</p> Signup and view all the answers

Flashcards

If the freq(M) = 0.83, What is freq(N)?

The frequency of the N allele is 1 - the frequency of the M allele. In this case 1 - 0.83 = 0.17

If the freq(M) = 0.83, What is freq(MM)?

Assuming Hardy-Weinberg equilibrium, the frequency of the MM genotype is p^2, where p is the frequency of the M allele. Thus, 0.83 * 0.83 = 0.6889

If the freq(M) = 0.83, What is freq(MN)?

Assuming Hardy-Weinberg equilibrium, the frequency of the MN genotype is 2pq, where p is the freq of the M allele and q is the frequency of the N allele. Thus 2 * 0.83 * 0.17 = 0.2822

If the freq(N) = 0.17, What is freq(NN)?

Assuming Hardy-Weinberg equilibrium, the frequency of the NN genotype is q^2, where q is the freq of the N allele. Thus 0.17 * 0.17 = 0.0289

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What is a population?

A localized group of individuals capable of interbreeding and producing fertile offspring.

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What is gene flow?

The movement of alleles into or out of a population.

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What does limited dispersal suggest?

Observed spatial clustering suggests limited dispersal.

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What is genetic structure?

Genetic variation clustered within a local area.

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How can genetic variation be evaluated?

Comparing genetic makeup of separated populations.

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Flight differences between bees and butterflies?

Bumblebees generally fly shorter distances and visit more flowers per plant, while butterflies fly longer distances .

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What percentage of birds dispersed > 300 km?

The percentage of birds that dispersed greater than 300 km was only 6.9%.

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Study Notes

  • If the frequency of the M allele is 0.83, then the frequency of the N allele is 0.17
  • If the frequency of the M allele is 0.83, then the frequency of the MM genotype is 0.6889
  • If the frequency of the M allele is 0.83, then the frequency of the MN genotype is 0.2822.
  • If the frequency of the M allele is 0.83, then the frequency of the NN genotype is 0.0289.

Oyster Mushrooms

  • Oyster mushrooms feed on and decompose logs.
  • These mushrooms reproduce asexually.
  • Fruiting bodies release their spores.
  • They have a limited dispersal via wind.

Spatial Structure of Fungus

  • The spatial structure of a fungus population in a forest shows the distribution of distinct genetic types in non-forested areas, downed logs, and streams.
  • Some logs have only one genetic type.
  • The same genetic type is often found on logs near each other.

Distribution of Genetic Types

  • The distribution of genetic types in a fungus inhabiting a rotting log shows groups of genetically similar individuals are circled.

Pollinators

  • Pollinators are key to the dispersal distance of plants.
  • Bumblebees and butterflies consume nectar and disperse pollen.

Schmidtt's Experimental Design

  • Individual bumblebees and butterflies were observed.
  • The number of flowers each pollinator visited per plant was recorded.
  • The distances flown between plants were recorded.
  • The total number of plant visits for each pollinator was recorded.

Flight Distances

  • The median and mean flight distances for bumblebees are very similar (0.5 vs. 0.62).
  • The median and mean flight distances for butterflies are very different (0.96 vs. 3.84).
  • Bumblebees visit more flowers per plant than butterflies.

Bladder Campion

  • In an experiment design on bladder campion there were 18 populations of bladder campions tested.
  • Each population of bladder campion was > 500 meters away from another
  • DNA was extracted from 500 individuals from each population.
  • The alleles of 2 different genes in each individual were determined.
    • An allele is a variation of a gene.
    • A gene is a region of DNA that codes for something, with each mutation in a gene resulting in a new allele of that gene.

Distribution of Allele Combinations

  • A diagram showed the distribution of 13 mitochondrial allele combinations among 18 populations of bladder campion.
  • Each pie chart represents the geographic location and frequency of different mitochondrial allele combinations.
  • Numbers were arbitrarily assigned to each population.

Juvenile Starling Dispersal

  • The frequency histogram of juvenile starling dispersal distances displayed the following:
    • Juvenile starlings banded while still in the nest,
    • The shortest measured dispersal distance was found to be 12 km.
    • The maximum measured dispersal distance for one bird was found to be 2,623 km.
    • 6.9% of birds dispersed > 300 km.
  • Among starlings from CA, CO, VT, and VA:
    • 16/22 genes contained the same one allele.
    • 6/22 genes were found to have >1 allele, but 4 populations had the same percentage of each allele for each gene.
    • 1/22 gene had multiple alleles found in different frequencies among the populations.

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