Biology SN2 Lecture 2: Evolution Overview
47 Questions
1 Views

Choose a study mode

Play Quiz
Study Flashcards
Spaced Repetition
Chat to Lesson

Podcast

Play an AI-generated podcast conversation about this lesson

Questions and Answers

What does natural selection result in?

  • Sustainable ecosystems
  • Equal distribution of traits
  • Random genetic mutations
  • Adaptive evolution (correct)

    • Which philosopher believed that species were fixed and unchanging?

  • Charles Darwin
  • Carolus Linnaeus
  • Jean-Baptiste Lamarck
  • Aristotle (correct)

    • What is the basic idea of natural selection?

  • Possession of certain traits increases reproductive success (correct)
  • Species are designed with specific traits by God
  • All individuals reproduce at the same rate
  • Fossils do not change over time

    • What did Cuvier propose as the cause for the boundaries between strata in the fossil record?

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

    Which of the following is a key component of Darwin's theory of evolution?

    <p>Different species can share a common ancestor (B)</p> Signup and view all the answers

    What did Carolus Linnaeus contribute to the understanding of species?

    <p>He formulated a system of taxonomy (D)</p> Signup and view all the answers

    What process involves the mixing and reshuffling of genes during reproduction?

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

    Which factor is primarily responsible for natural selection?

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

    What evidence did fossils provide for Darwin's ideas?

    <p>Fossils show a succession of organisms over time (C)</p> Signup and view all the answers

    Which of the following statements is consistent with Darwin's view of evolution?

    <p>Adaptive traits are passed from generation to generation (D)</p> Signup and view all the answers

    Natural selection acts on which type of traits?

    <p>Inherited traits (D)</p> Signup and view all the answers

    What does differential reproductive success refer to?

    <p>Survival of individuals with advantageous traits (A)</p> Signup and view all the answers

    What is a zygote?

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

    How is evolutionary change measured?

    <p>Changes in allele frequencies in a population (B)</p> Signup and view all the answers

    Which of the following describes a characteristic that is favorable in one environment but not in another?

    <p>Context-dependent trait (D)</p> Signup and view all the answers

    What does the term 'environment selects' refer to in natural selection?

    <p>The environment influences evolutionary changes (C)</p> Signup and view all the answers

    What was the primary basis for Darwin's theory of evolution?

    <p>His voyage on the H.M.S. Beagle (C)</p> Signup and view all the answers

    What did Darwin hypothesize about the organisms on the Galapagos Islands?

    <p>They had diversified from mainland species. (A)</p> Signup and view all the answers

    Which factor is NOT a part of natural selection according to Darwin?

    <p>Equal survival among all offspring (C)</p> Signup and view all the answers

    How does sexual reproduction contribute to genetic variation?

    <p>It uses meiosis to produce gametes. (D)</p> Signup and view all the answers

    What happens when a species produces more offspring than the environment can support?

    <p>There is a struggle for existence. (A)</p> Signup and view all the answers

    What is a key characteristic of organisms within a population according to natural selection?

    <p>There are extensive variations in characteristics. (C)</p> Signup and view all the answers

    Which of the following best describes the role of inherited traits in survival?

    <p>Inherited traits can influence survival chances. (A)</p> Signup and view all the answers

    What is a consequence of having limited environmental resources?

    <p>Competition among individuals for survival. (D)</p> Signup and view all the answers

    What is the main mechanism of evolution outlined in the content?

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

    Which of the following is NOT a view held before Darwin?

    <p>Mendel's theory of independent assortment (D)</p> Signup and view all the answers

    What are the two main types of cells discussed in the content?

    <p>Gametes and somatic cells (B)</p> Signup and view all the answers

    What does genotype represent?

    <p>The combination of alleles in an organism (D)</p> Signup and view all the answers

    How is a recessive trait expressed in an individual?

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

    Which term describes the observable traits of an individual?

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

    What role do mutations play in evolution?

    <p>They contribute to genetic diversity. (B)</p> Signup and view all the answers

    What is the genetic composition of sex cells such as eggs and sperm?

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

    How many total chromosomes do humans have in somatic (body) cells?

    <p>46 (C)</p> Signup and view all the answers

    What are homologous chromosomes?

    <p>Chromosomes that may carry different versions of the same gene (B)</p> Signup and view all the answers

    Which term describes alternative versions of a gene?

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

    What is one example of a trait that can have different alleles?

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

    How are offspring's genetic characteristics determined during fertilization?

    <p>They differ genetically from both parents and each other. (A)</p> Signup and view all the answers

    What is one way that genetic variation is increased in sex cells?

    <p>By undergoing mutations during cell division (D)</p> Signup and view all the answers

    What do homologous chromosomes have in common?

    <p>They carry genes for the same trait. (D)</p> Signup and view all the answers

    What is a dominant allele?

    <p>An allele that is always expressed regardless of its partner (A)</p> Signup and view all the answers

    Which of the following combinations represents a heterozygous genotype?

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

    What is the result of sexual reproduction in the context of genetic variation?

    <p>It increases genetic variation (D)</p> Signup and view all the answers

    What does the term 'carrier' refer to in genetic terms?

    <p>An individual that is heterozygous but does not express the recessive trait (A)</p> Signup and view all the answers

    How many major genes are primarily associated with eye color?

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

    Which of the following represents a homozygous recessive genotype?

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

    What is the role of natural selection in genetic variation?

    <p>To choose the fittest organisms (B)</p> Signup and view all the answers

    During what process does reshuffling of genes primarily occur?

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

    Flashcards

    Natural Selection

    The process by which organisms with traits that better suit their environment tend to survive and reproduce more successfully, passing those advantageous traits to their offspring.

    Descent with Modification

    The idea that all living organisms on Earth are descended from a common ancestor, and have evolved over time into the diverse species we see today.

    Paleontology

    The study of fossils, which provides evidence for the history of life on Earth and helps us understand how organisms have changed over time.

    Catastrophism

    A theory that suggests that major changes in Earth's geological history happened suddenly and catastrophically, leading to the extinction of species and the appearance of new ones.

    Signup and view all the flashcards

    Taxonomy

    A hierarchical system used to classify organisms based on their shared characteristics.

    Signup and view all the flashcards

    Scala Naturae

    A ladder-like arrangement of organisms, proposed by Aristotle, where organisms were placed according to their perceived complexity.

    Signup and view all the flashcards

    Fixity of Species

    A theory that species are fixed and unchanging, as opposed to the idea of evolution.

    Signup and view all the flashcards

    Special Creation

    The idea that organisms are created by a divine being and their characteristics are therefore fixed.

    Signup and view all the flashcards

    Overproduction

    The ability of a species to produce more offspring than the environment can support.

    Signup and view all the flashcards

    Limited Resources

    Limited resources such as food, water, and space that organisms compete for in their environment.

    Signup and view all the flashcards

    Variation

    Differences in traits among individuals within a population that can be inherited, like color or size.

    Signup and view all the flashcards

    Fitness

    The adaptations or characteristics that allow an organism to better survive and reproduce in its environment.

    Signup and view all the flashcards

    Speciation

    The process by which new species arise from existing ones, often as a result of natural selection.

    Signup and view all the flashcards

    Evolution

    The study of how life on Earth has changed over time, including the origin and diversification of species.

    Signup and view all the flashcards

    Galapagos Islands

    The islands where Darwin observed distinct variations in finch species, supporting his theory of evolution by natural selection.

    Signup and view all the flashcards

    Haploid

    Sex cells, like sperm and egg, that carry half the number of chromosomes (23) compared to regular body cells.

    Signup and view all the flashcards

    Fertilization

    Process where sex cells (sperm and egg) combine, resulting in an offspring with a unique mix of chromosomes from both parents.

    Signup and view all the flashcards

    Homologous Chromosomes

    Pairs of chromosomes in a body cell, one from the mother and one from the father, carrying similar genes but potentially different versions (alleles).

    Signup and view all the flashcards

    Alleles

    Different versions of the same gene, responsible for variations in traits like hair color or eye color.

    Signup and view all the flashcards

    Meiosis

    The process of sex cells dividing to reduce the number of chromosomes from 46 to 23, creating gametes (sperm and egg).

    Signup and view all the flashcards

    Genetic Variation

    The unique combination of chromosomes in an offspring's sex cells, leading to genetic variation among siblings.

    Signup and view all the flashcards

    Traits

    Features or characteristics determined by genes.

    Signup and view all the flashcards

    Genome

    All the genes and their variations in an individual, determining their physical characteristics and biological functions.

    Signup and view all the flashcards

    Dominant Allele

    An allele that masks the expression of another allele. Always represented with an uppercase letter.

    Signup and view all the flashcards

    Recessive Allele

    An allele whose expression is masked by a dominant allele. Always represented with a lowercase letter.

    Signup and view all the flashcards

    Homozygous

    Having two identical alleles for a given trait.

    Signup and view all the flashcards

    Heterozygous

    Having two different alleles for a given trait.

    Signup and view all the flashcards

    Carrier

    An individual who carries a recessive allele for a trait but does not express it. They have the recessive allele but don't show the trait.

    Signup and view all the flashcards

    Mutation

    Changes in the DNA sequence, creating new alleles and leading to genetic variation.

    Signup and view all the flashcards

    Sexual Reproduction

    The process of mixing and matching alleles during meiosis, leading to unique combinations of genes in offspring.

    Signup and view all the flashcards

    Random Fertilization

    The random fusion of sperm and egg during fertilization.

    Signup and view all the flashcards

    Differential Reproductive Success

    Individuals with traits that make them better suited to their environment have a higher chance of survival and reproduction.

    Signup and view all the flashcards

    Populations Evolve, Not Individuals

    Natural selection acts on individuals, but only populations (groups of individuals) can evolve.

    Signup and view all the flashcards

    Heritable Traits

    Natural selection can only act on traits that can be passed down from parents to offspring.

    Signup and view all the flashcards

    Environment Selects

    Changes in the environment can make a trait that was once beneficial become detrimental, or vice versa.

    Signup and view all the flashcards

    Natural Selection (Negative)

    The process by which organisms with traits that make them less suited to their environment are less likely to survive and reproduce.

    Signup and view all the flashcards

    Natural Selection (Positive)

    The process by which organisms with traits that make them better suited to their environment are more likely to survive and reproduce, passing these traits to their offspring

    Signup and view all the flashcards

    Study Notes

    Biology SN2 Lecture 2: Evolution & Descent with Modification

    • Darwin's theory of evolution posits that species that are more adaptable to change are more likely to survive
    • Species evolve over time through adaptations to their environments. This occurs due to natural selection, where organisms with favorable traits are more likely to survive and reproduce.
    • The evolution of species is closely tied to their environment and related processes
    • Natural selection is a mechanism of evolutionary change. Natural selection leads to adaptive evolution, where populations change over time. Individuals with traits that allow for survival and reproduction in a specific environment are more likely to pass these traits to their offspring
    • Darwin developed his theory based on various factors: Malthus' essay on struggle for existence, Lyell's Principles of Geology, principles of artificial selection, and his observations in the Galapagos.
    • Species are capable of producing more offspring than the environment can support, leading to competition.
    • Populations tend to be stable in size, because environmental resources are limited. Competition for resources, predation, disease, and environmental conditions limit population growth
    • Members within a population vary extensively. No two individuals are exactly alike, and these variations are heritable. Survival often depends on inherited traits.
    • Genetic variation is increased through sexual reproduction and mutation.
    • Differential reproductive success (survival of the fittest) occurs due to variation in inherited traits, which provide advantages in survival and reproduction. This gradual change in traits within a population, which leads to adaptations.

    Before Darwin: Understanding Life

    • Aristotle viewed species as fixed and unchanging, arranging life on a scale of increasing complexity (scala naturae).
    • The Old Testament of the Bible posits that species were individually designed by God
    • Carolus Linnaeus founded taxonomy, grouping similar species into categories. He did not link resemblances to evolutionary kinship
    • Paleontology (the study of fossils) provided evidence of the succession of organisms that populated Earth. Older strata showed greater differences, in comparison to modern life

    Before Darwin: Fossils

    • Fossils are the remains or traces of organisms from the past found in sedimentary rock. Layers (strata) reveal the sequence of events in geological history.
    • Fossils demonstrate the succession of organisms over geological time
    • Cuvier noted that older strata showed greater differences in fossil organisms compared to modern life, he proposed the idea of "catastrophism" to explain these differences
    • Cuvier did not believe in evolution. Instead, he proposed alternative explanations like floods or droughts to explain evolutionary differences.

    Before Darwin: Lamarck

    • Lamarck proposed a theory of evolution based on "use and disuse," arguing that traits acquired during an organism's lifetime could be passed on to offspring.
    • An example is a giraffe's neck stretching to reach higher leaves, resulting in an elongated neck, which is then passed to offspring.
    • Lamarck did not explain the inheritance of acquired traits

    Before Darwin: Hutton and Lyell

    • Hutton proposed the theory of gradualism; profound changes take place over time due to small, continuous geological processes
    • Lyell proposed that changes in Earth's surface result from slow, continuous actions. This suggests that the Earth is much older than previously believed.

    Darwin and Evolution

    • Malthus' essay on the struggle for existence in human populations influenced Darwin.
    • Lyell's principles of geology suggested that the Earth is very old and has been changing gradually.
    • Artificial selection also influenced Darwin; changes in organisms can occur over short periods.
    • Darwin observed various adaptations in plants and animals in the Galapagos as diverse environments.

    Darwin: The Origin of Species (2 Main Ideas):

    • Today's organisms are descendants from ancestor species that differ from modern ones. This illustrates evolutionary history
    • Natural selection is the mechanism for evolutionary change. Natural selection leads to environmental adaptations in a population over time.

    Darwinian Evolution

    • Darwin was fascinated by unusual organisms found in various environments, particularly in the isolated island of Galapagos
    • He hypothesized that these organisms evolved from mainland species, that had then become diversified over time
    • The origin of new species and the adaptation to their environment are related processes. This includes clear differences in the characteristics of the organisms.

    How Does Natural Selection Work?

    • Species can produce more offspring that the environment supports, leading to competition
    • Environmental resources are limited and competition results, with limited resources only a fraction of an organisms offspring survive
    • There are variations in individuals, that are heritable
    • Different reproductive success exists, that leads to traits which give advantages in the environment
    • Populations evolve, individuals do not
    • Natural selection can only act on heritable traits

    Genetic Variation Explained

    • Sexual reproduction mixes alleles during meiosis and fertilization. The offspring inherits a combination of genes from their parents
    • Asexual reproduction creates identical copies, as the offspring inherits all genes from their parent.
    • Mutations (changes in DNA) are the original source of different alleles

    How Does Natural Selection Work? (Important notes)

    • Natural selection only acts on heritable traits, which are passed down between generations
    • Environmental factors vary from time to time and location, so a favorable trait can be non-useful in another environment
    • Natural selection does not create perfect organisms and does not create perfect traits; it instead "edits" existing variations to adapt to the environment
    • Chance and natural selection interact
    • The environment selects for traits based on their fitness in a specific or particular environment

    Evidence for Darwin's Theory

    • Many different sources of evidence support Darwin's theory: Natural selection in action, homology (anatomy, development, and molecular), convergent evolution, biogeography and the fossil record

    Natural Selection in Action (Peppered Moth):

    • In pre-industrial Britain, peppered moths were primarily light colored. These moths blend in with light-colored tree bark. This allowed them to hide from predators.
    • The industrial revolution darkened tree bark due to soot. Dark-colored moths became more prevalent, as they were better camouflaged.

    Natural Selection in Action (Drug Resistance):

    • Use of drugs can select for resistant pathogens. Such resistance can lead to adaptive evolution in pathogens
    • Researchers have developed numerous drugs to combat HIV, for example. But these drugs can select for viruses that are resistant to them.

    Homology: Anatomy

    • Homologous structures are similar in anatomy because of shared ancestry. Even though they have divergent functionalities. Examples include the human arm, cat forelimb, whale flipper and bat wing. These structures exhibit similarities in bone arrangement, muscles, and nerves
    • Vestigial organs are remnants of structures that served functions in an organism's ancestors, but are no longer useful
    • Natural selection will not act on vestigial organs to eliminate them

    Homology: Development

    • Embryos of different vertebrates show similarities in early development. For example, pharyngeal pouches (gill slits) appear in embryos, but develop into different structures in adults (e.g. gills in fish and parts of the ear in mammals). Homologous structures present in the embryos show the common ancestry between organisms.

    Homology: Molecular

    • The universal genetic code is evidence of common ancestry. The same codons in DNA and mRNA translate similar amino acids in diverse organisms.
    • Similarities in proteins (e.g., hemoglobin) between organisms reflect evolutionary relationships and are observed to be inversely proportional to the closeness of kinship between different species

    Convergent Evolution

    • Convergent evolution occurs when organisms with separate ancestors develop similar traits due to similar environmental pressures.
    • For example, similar environments can have independent evolutions like long sharp claws and elongated snouts.

    Biogeography

    • Species tend to be more closely related to other species in the same geographical area, as opposed to species in different geographical locations. This suggests a common ancestor.
    • Continental drift (plate tectonics) and the formation and isolation of populations are related to geographic events and their impact on adaptations

    Fossil Record

    • The fossil record provides a chronicle of life's history, showing a succession of forms. The succession in the fossil record is consistent with other evidence of descent with modification.
    • The fossil record demonstrates that prokaryotes are older than eukaryotes. The oldest fossils are prokaryotes, indicating the precedence of prokaryotic life on earth.

    Natural Selection …Just a Theory?

    • A scientific theory accounts for many observations and data, attempting to explain and integrate these phenomena.
    • Darwin's theory is supported by massive amounts of data from different sources.
    • Neo-Darwinism (Modern synthesis) incorporates Mendelian genetics into Darwin's theory of evolution. Specifically, it states that natural selection influences heritable (genetic) variations and that mutations (especially random copying errors) provide the main source of these genetic variations.

    Lecture 2: Learning Objectives

    • Defines evolution and natural selection
    • Understands pre-Darwinian views of life, which include Aristotle, Old Testament, Linnaeus, fossils, Hutton, Lyell, and Lamarck.
    • Explains how natural selection works
    • Identifies the source of Darwin's ideas (4 main sources)
    • Provides evidence for natural selection for example using convergence, divergence, homology, biogeography, fossils
    • Understands the importance of genes, evolution, and sexual reproduction
    • Know the meaning of scientific terms, such including chromosomes, gametes, somatic cells, homologous chromosomes, alleles, recessive, dominant, genotype, phenotype, zygote, random fertilization

    Summary Slides

    • Asexual reproduction produces offspring identical to the parent, as the parent donates its genes to their offspring. The parent is the only single donor
    • Sexual reproduction produces offspring with unique combinations of genes from two parents, leading to genetic variation.

    Sex Cells (Produced By Meiosis)

    • Meiosis produces haploid sex cells (gametes), with half the number of chromosomes compared to somatic cells. They contain DNA from both parents.
    • The fertilized egg (zygote) contains a complete set of chromosomes (diploid)

    Genotype VS Phenotype

    • Genotype is the genetic makeup, involving the combination of alleles
    • Phenotype is the observable characteristic of an individual determined through the genotype.

    The Behavior of Recessive Alleles

    • Recessively inherited trait/disorders occurs in homozygous recessive individuals.
    • Carriers of recessive alleles are heterozygous for a particular trait, but they do not express the recessive characteristic, and only pass the recessive trait down to their offspring
    • Relatives to carriers can have the same recessive traits

    Principles of Inheritance: Examples

    • Explains different traits inherited through simple mechanisms like genotypes.

    The Evolutionary Significance of Genetic Variability

    • Populations evolve through differential reproductive success
    • Natural selection results in the accumulation of favorable genetic variations
    • Different allele combinations can offer advantages in certain environments, or a variety of specific environments

    Natural Selection in Action (Introduced Species)

    • Soapberry bugs use their beaks to feed on seeds in fruits. Bugs with beaks that match the depth of seeds have a higher reproductive success, as this increases their chances of eating seeds
    • Natural selection impacts beak lengths when food sources change.

    Homology: Anatomy (Vestigial Organs)

    • Vestigial organs are remnants of structures that served a function in the organism's ancestors. An example includes vestigial hind limb bones in snakes and whales

    Studying That Suits You

    Use AI to generate personalized quizzes and flashcards to suit your learning preferences.

    Quiz Team

    Related Documents

    BioSN2Lec2 - Evolution PDF

    Description

    This quiz covers the key concepts of Darwin's theory of evolution, including natural selection and adaptation over time. Explore how species evolve based on their environment and the principles that underpin this transformative process. Test your understanding of the factors influencing evolutionary change as discussed in this lecture.

    More Like This

    Use Quizgecko on...
    Browser
    Open
    Browser
    Browser