Biology 3305: Adaptation and Evolution

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Questions and Answers

What is one reason a trait might persist in a population despite the current selective regime?

  • Genetic drift (correct)
  • Increased competition
  • Migration
  • Natural selection

The adaptationist programme suggests that all traits are adaptations with adaptive significance.

True (A)

What term describes a gene that affects more than one trait?

Pleiotropy

Traits may have been selected for in a past environment that no longer exists, known as ________.

<p>pre-adaptation</p> Signup and view all the answers

Which of the following is a reason traits may persist despite low cost?

<p>Phylogenetic inertia (D)</p> Signup and view all the answers

Match the following terms with their definitions:

<p>Natural selection = The process where organisms better adapted to their environment tend to survive and produce more offspring Genetic drift = Random fluctuation in allele frequencies within a population Exaptation = Traits that were beneficial in a past environment but may not be currently advantageous Preadaptation = A trait that becomes useful in a new context not originally its function</p> Signup and view all the answers

Which of the following methods is NOT used to study adaptation?

<p>Social behaviors of species (D)</p> Signup and view all the answers

What is phenotypic plasticity?

<p>A short-term compensatory change in response to environmental conditions (D)</p> Signup and view all the answers

Vestigial characters are traits that serve a current useful function in an organism.

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

Nucleated red blood cells (RBCs) are characterized by their lack of nuclei.

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

How does the freshwater Mexican cavefish relate to the concepts of adaptation and variation?

<p>It is the same species as the surface-dwelling Mexican tetra but shows significant differences in appearance due to environmental adaptations.</p> Signup and view all the answers

Acclimatization and acclimation are the same processes.

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

What is a character trait that is considered an adaptation in physiology?

<p>hemoglobin</p> Signup and view all the answers

What is one way biologists can directly observe changes in allele frequencies over generations?

<p>By using lab populations followed over many generations.</p> Signup and view all the answers

The relationship between _____ and _____ explains how traits are expressed in organisms.

<p>Phenotype, Genotype</p> Signup and view all the answers

Adaptation through natural selection leads to an organism whose physiology, anatomy, and behavior are matched to the demands of its __________.

<p>environment</p> Signup and view all the answers

Match the following adaptation study methods with their descriptions:

<p>Comparative method = Analyzing differences across species Genetic manipulation = Examining effects of gene alterations Single generation studies = Observing survival based on allele frequency Phylogenetic reconstructions = Inferring evolutionary relationships</p> Signup and view all the answers

Match the terms with their correct definitions:

<p>Acclimation = A short-term change due to experimental exposure to environmental conditions Acclimatization = A persisting change due to prolonged exposure to environmental conditions Adaptation = A trait that evolves due to natural selection over many generations Evolution = A slow process leading to changes in allele frequencies</p> Signup and view all the answers

Which statement best describes the process of evolution?

<p>It leads to changes in allele frequency coding for traits affecting fitness. (A)</p> Signup and view all the answers

Traits evolve because they serve a specific purpose.

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

Explain the difference between acclimation and acclimatization in the context of adaptation.

<p>Acclimation refers to short-term changes due to experimental exposure, while acclimatization refers to persistent changes due to prolonged exposure to environmental conditions.</p> Signup and view all the answers

What does phylogenetic inertia refer to?

<p>The interaction between ancestral traits and natural selection (C)</p> Signup and view all the answers

Adaptation is solely defined as the mechanism by which an organism survives.

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

What is the adaptive significance of hemoglobin?

<p>It allows animals to engage in sustained aerobic activity, increasing their chance of survival.</p> Signup and view all the answers

Evolution is described as a ________, not an engineer.

<p>tinkerer</p> Signup and view all the answers

Why might we not see the best solution to a challenge in evolution?

<p>Because evolution is influenced by ancestral traits (C)</p> Signup and view all the answers

The mechanism of a trait and its adaptive significance are the same concept.

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

Who shared the Nobel Prize in Physiology or Medicine with Francois Jacob?

<p>André Lwoff and Jacques Monod</p> Signup and view all the answers

What distinctive feature does the Mexican cavefish display due to its adaptation to darkness?

<p>Skin growth over useless eyes (C)</p> Signup and view all the answers

Phylogenies can be constructed using only molecular techniques.

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

What is the adaptive significance of traits like the loss of pigmentation in cave-dwelling species?

<p>The loss of pigmentation is an adaptation to survive in darkness and reduce energy expenditure.</p> Signup and view all the answers

A _______ provides the history of the evolution of an organism by showing relationships to other organisms.

<p>phylogeny</p> Signup and view all the answers

Match the following types of red blood cells with their description:

<p>Nucleated RBC = Contains a nucleus Non-nucleated RBC = Lacks a nucleus NN-RBC = Type of red blood cell without a nucleus N-RBC = Type of red blood cell with a nucleus</p> Signup and view all the answers

Which of the following organisms typically has nucleated red blood cells?

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

The comparative method is important for determining if a trait is an adaptation.

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

What may be a reason for the loss of nucleated red blood cells in mammals?

<p>Evolutionary chance or phylogenetic inertia.</p> Signup and view all the answers

The ___________ method provides information about evolutionary history.

<p>comparative</p> Signup and view all the answers

What happens to red blood cells as a result of evolutionary adaptations in certain species?

<p>They can lose their nuclei (D)</p> Signup and view all the answers

Flashcards

Phenotypic Plasticity

The ability of an organism to change its phenotype in response to environmental changes.

Acclimation

A persisting change in a specific function due to prolonged exposure to an environmental condition (e.g., high or low temperature) often induced experimentally.

Acclimatization

The persisting spectrum of changes in an organism due to prolonged exposure to environmental conditions (e.g., high or low temperature).

Adaptation (Evolutionary Adaptation)

The process of evolution through natural selection that results in organisms with physiology, anatomy, and behavior suited to their environment.

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Fitness

The relative ability of an organism to survive and reproduce in a particular environment.

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Trait

A characteristic or feature of an organism.

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Mutation

A random change in the DNA sequence of an organism.

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Natural Selection

The process by which organisms with traits better suited to their environment are more likely to survive and reproduce.

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Adaptationist Programme

The idea that every trait in an organism must have an adaptive function and arose through natural selection.

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Adaptation

A trait that evolved through natural selection to increase an organism's fitness in a specific environment.

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Putative Adaptation

A trait that may be an adaptation, but lacks sufficient evidence to confirm its adaptive significance.

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Genetic Drift

Random changes in gene frequencies within a population, especially in smaller populations.

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Genetic Linkage

The tendency of genes located near each other on a chromosome to be inherited together.

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Pleiotropy

A single gene affecting multiple traits in an organism.

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Phylogenetic Inertia

The persistence of ancestral traits in a lineage, even if they are no longer adaptive in the current environment.

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Exaptation

A trait that evolved for one purpose, but later became adapted to a different function.

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Adaptive Significance

The reason why a trait is advantageous in a particular environment, explaining why it was selected for.

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Evolution: Tinker vs. Engineer

Evolution is a process that builds on existing traits, sometimes leading to non-optimal solutions. It's not about creating perfect designs.

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Hemoglobin: Mechanism vs. Significance

Hemoglobin carries oxygen in blood, but its adaptive significance is the ability to fuel sustained aerobic activity for survival.

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What is the adaptive significance of wings in bats?

Wings enable bats to fly, allowing them to access food sources, escape predators, and migrate efficiently.

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Can a mechanism exist without adaptive significance?

Yes, a trait can exist without being advantageous. It might be a side effect of another trait, or not yet selected for.

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Does adaptive significance always imply mechanism?

No, we might understand why a trait is beneficial, but not the exact biological process involved.

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Comparative Method

A scientific approach that compares different species or groups to understand evolutionary relationships and the functions of traits.

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Phylogeny

A diagram showing the evolutionary history and relationships of organisms.

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Outgroup

A group of organisms outside the group being studied, used to compare and determine evolutionary relationships.

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Character

A feature or trait that can be used to distinguish between different species or groups.

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Nucleated Red Blood Cell (N-RBC)

A red blood cell that contains a nucleus.

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Non-Nucleated Red Blood Cell (NN-RBC)

A red blood cell that does not contain a nucleus.

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Loss of Nuclei in Red Blood Cells

An adaptation found in mammals, where red blood cells have lost their nuclei to increase oxygen carrying capacity.

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Nucleated RBCs

Red blood cells that contain a nucleus. These are found in many vertebrates, including amphibians, reptiles, and fish.

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Loss of Nuclei

The process where red blood cells lose their nucleus during maturation in mammals. This allows for more space for oxygen transport.

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Genetic Studies of Natural Populations

Examining the frequency of alleles in different populations to understand how genetics influences adaptation. It involves tracking allele frequencies in relation to environmental conditions.

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Genetic Manipulation

A method to study adaptation by altering an organism's genes to observe the effects on its structure and function. This allows for direct manipulation of traits and their impact.

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Study Notes

Course Information

  • Course Title: Biology 3305
  • Course Description: Human and Comparative Physiology

Dobzhansky Quote

  • "Nothing in biology makes sense except in the light of evolution" - Theodosius Dobzhansky
  • Dobzhansky was a Russian-American geneticist and evolutionary biologist

Environmental Adaptation

  • Animals are typically matched to their environmental challenges.
  • Animals adapt to their environment via phenotypic plasticity which includes acclimation and acclimatization

Meaning of Adaptation

  • A short-term compensatory change (phenotypic plasticity)
    • Acclimation: A persisting change due to induced exposure to high/low temperature
    • Acclimatization: A persisting change due to environmental exposure
  • A trait
    • Hemoglobin
  • A process
    • Evolution

Evolutionary Adaptation

  • Evolution through natural selection creates a match between an organism's physiology, anatomy, and behavior to their environment
  • The process involves allele frequency changes over generations
  • Evolution is a slow, irreversible process
  • A trait is considered an adaptation only if there is evidence of its selection

Traits and Their Persistence

  • Traits are not always selected for a purpose, traits can appear through mutations
  • Persistence of a trait is due to selection, and the trait's relative benefit to the bearer
  • Phylogenetic inertia: Interaction between ancestral traits and selection in ancestral environments
  • Traits may persist due to no detriment or past adaptive value in a no longer existing environment
  • Preadaptation or exaptation: A trait selected in a past environment that may not necessarily useful for the current environment

Evolution as a Tinkerer

  • "Evolution is a tinkerer, not an engineer" - Francois Jacob
  • Jacob received a Nobel Prize for his work in physiology or medicine

Adaptive Significance

  • An adaptation is a product of natural selection
  • Adaptive significance identifies why a trait or mechanism is beneficial, answering "Why did natural selection favour the trait?"

Adaptive Significance and Mechanism

  • Mechanism does not imply adaptive significance, and adaptive significance does not imply mechanism
  • E.g. Hemoglobin's mechanism is binding oxygen and transporting it to tissues
  • E.g, Hemoglobin's adaptive significance is that animals with hemoglobin can engage in sustained aerobic activity which increases the likelihood of survival

Not All Traits Are Adaptations

  • Not all traits are adaptations
  • The adaptationist programme is a methodology that suggests that the existence of a trait implies its adaptive significance
  • Sometimes a trait may be a product of phylogenetic inertia
  • Evidence of selection is needed to deem a trait an adaptation, also known as putative or possibly an adaptation

Reasons for Trait Persistence (Other than Selection)

  • Genetic drift
  • Genetic linkage and pleiotropy (one gene affects more than one trait)
  • A trait persists due to its no harm (or low cost)
  • A trait may persist despite being maladaptive in the current environment
  • Traits may have been selected in a past environment that no longer exists
  • Preadaptation/exaptation: Traits that are selected in the past can be used in a new way

Exaptation Examples (Preadaptation)

  • Mexican Cavefish: The cavefish is the same species as the surface-dwelling tetra, but the cavefish has lost its pigmentation and grown skin over its eyes because it adapted to living in complete darkness.

Studying Adaptation

  • Biologists cannot directly observe evolution
    • Use the comparative method
      • Use phylogenetic reconstructions
      • Look for independent evolution in different environments
      • Use statistically-sound methods analyzing data from closely related species
    • Use lab populations to observe changes in allele frequency when subjected to stressors
    • Employ single-generation studies of individual genetic variations within a species
    • Observe the frequency of alleles within a population in relation to different environmental conditions
    • Genetic manipulation through methods like gene substitutions, knockouts to determine the effects

Relationship Between Phenotype and Genotype

  • Genotype produces the phenotype
  • Phenotype is influenced by random processes, development, biochemistry, physiology, morphology, behavior and the environment
  • Natural selection acts upon the phenotype, influencing further biological evolution

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