Evolution of Wings and Archosaurs
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Questions and Answers

Which condition is NOT required for allele frequencies to remain in equilibrium?

  • Population size is infinite
  • No migration
  • Presence of fitness variation (correct)
  • No mutation

    • What does the equation $p + q = 1.0$ represent in population genetics?

  • The expected genotype frequencies in Hardy-Weinberg equilibrium
  • The relationship between dominant and recessive phenotype frequencies
  • The total frequency of all alleles in a population (correct)
  • The combined frequency of all alleles in a diploid population

    • Which of the following factors can disrupt Hardy-Weinberg equilibrium?

  • Random mating
  • No migration
  • Genetic drift in small populations (correct)
  • Equal fitness among genotypes

    • What is the purpose of using the Chi-squared test in population genetics?

    <p>To compare observed genotype frequencies to expected frequencies</p> Signup and view all the answers

    Under what scenario would recessive alleles potentially be overrun by dominant alleles?

    <p>There is migration introducing new alleles</p> Signup and view all the answers

    What is one indication that wings likely evolved from gills?

    <p>Wings are made of a stiff membrane</p> Signup and view all the answers

    What adaptation aids birds in efficient flight?

    <p>System of air sacs for oxygen extraction</p> Signup and view all the answers

    Which structural change is NOT associated with the transition from quadruped to biped?

    <p>Thickening of the arms for better support</p> Signup and view all the answers

    Which of the following factors contribute to the fossilization process?

    <p>Being quickly covered after death</p> Signup and view all the answers

    What method is NOT part of relative dating for fossils?

    <p>Radiometric dating</p> Signup and view all the answers

    The evolution of mammals included adaptations that allowed them to do what?

    <p>Walk upright with an erect stance</p> Signup and view all the answers

    Which feature is characteristic of birds that aids in flight adaptations?

    <p>Presence of feathers for lift</p> Signup and view all the answers

    In terms of stance, which animals have femurs that sit outward to the side?

    <p>Lizards and crocodiles</p> Signup and view all the answers

    What is a primary factor in the process of natural selection?

    <p>Phenotypes suited to the environment</p> Signup and view all the answers

    Which of the following statements accurately describes macroevolution?

    <p>Major evolutionary changes occurring over long time spans</p> Signup and view all the answers

    What role do DNA variants play in adaptation?

    <p>They must be passed down from parents to offspring.</p> Signup and view all the answers

    What type of evidence supports the idea that Galapagos finches evolved from a common ancestor?

    <p>Diversity in their beak shapes and sizes</p> Signup and view all the answers

    How is microevolution best described?

    <p>Evolution within a single species or population</p> Signup and view all the answers

    What is the definition of species in the context of evolution?

    <p>A group of interbreeding natural populations that are reproductively isolated</p> Signup and view all the answers

    Which of the following best distinguishes natural selection from evolution?

    <p>Natural selection is the driving force of evolution based on phenotypic advantages.</p> Signup and view all the answers

    What adaptation have flightless cormorants developed for survival?

    <p>The ability to swim efficiently for catching fish</p> Signup and view all the answers

    What is the effect of natural selection on traits that enhance reproductive success?

    <p>It can increase their frequency in the population.</p> Signup and view all the answers

    Which type of selection favors individuals at one end of the distribution of phenotypes?

    <p>Directional selection</p> Signup and view all the answers

    In the case of the Galapagos medium ground finch, what characteristic is primarily selected during a drought?

    <p>Beak size</p> Signup and view all the answers

    How does natural selection typically act on dominant alleles compared to recessive alleles?

    <p>It acts faster on dominant alleles.</p> Signup and view all the answers

    What occurs during stabilizing selection?

    <p>Average traits become more common.</p> Signup and view all the answers

    What is the selection differential?

    <p>The difference between selected mean and population mean.</p> Signup and view all the answers

    In the scenario of industrial melanism, which phenotype had a selective advantage post-industrial revolution?

    <p>Darker colored moths</p> Signup and view all the answers

    What is the primary role of variation in the process of natural selection?

    <p>To provide a basis for selection based on traits.</p> Signup and view all the answers

    How does receptor-ligand specificity influence physiological responses?

    <p>Only specific receptors produce a specific response when the ligand binds.</p> Signup and view all the answers

    What primary role does noradrenaline play in the body?

    <p>Evoking responses related to fear and the 'fight or flight' mechanism.</p> Signup and view all the answers

    Which of the following methods of heat exchange does NOT involve a physical medium?

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

    How does shivering thermogenesis primarily contribute to body temperature regulation?

    <p>Through muscular activity generating heat.</p> Signup and view all the answers

    What triggers a fever in the human body?

    <p>Release of pyrogens activating an immune response.</p> Signup and view all the answers

    What is the relationship between core body temperature and subjective alertness?

    <p>Low core body temperature relates to feelings of tiredness.</p> Signup and view all the answers

    What effect does adrenaline have on the body's physiological responses?

    <p>Increases energy expenditure leading to heat production.</p> Signup and view all the answers

    What characterizes the circadian rhythm's effect on core body temperature?

    <p>Core body temperature oscillates in sync with hormone levels.</p> Signup and view all the answers

    What is the primary function of the bronchial system in respiration?

    <p>Conducting air to the alveoli for gas exchange.</p> Signup and view all the answers

    What can excess high temperature during sepsis lead to?

    <p>Organ damage due to uncontrolled inflammatory response.</p> Signup and view all the answers

    Study Notes

    Evolution of Wings

    • Wings evolved from structures that could have helped with gliding
    • Stoneflies use their early wings to aid locomotion across water
    • Wings are stiff membranes strengthened by veins
    • Likely evolved from gills

    Archosaurs

    • Birds evolved from dinosaurs
    • A fossil that was initially believed to be a dinosaur was discovered to have feathers and wings
    • Reptiles evolved from amphibians
    • Archosaurs survived adaptations to avoid needing water

    Adaptations for Flight

    • Birds have less dense bones
    • Birds possess larger chest muscles for flight
    • Feathers increase surface area and maintain lift
    • Birds have a system of air sacs that connect to lungs to extract more oxygen per breath

    Evolution of Mammals

    • Mammals have an erect stance with pressure on the pelvis
    • The femur sits underneath the pelvis
    • Dinosaurs are from the same lineage as crocodiles
    • Mammals evolved from reptiles but walk upright
    • Lizards and crocodiles have a sprawling stance

    Changes from Quadruped to Biped

    • Humans walk upright
    • Big toe is reduced
    • The pelvis is shortened and more bowl-like to support the spine
    • The femur bends inwards, the knee straightens, and the patella is central to the joint
    • The spinal column connects to the underside of the skull
    • The arms are less robust

    Fossils

    • Fossils can be preserved remains or traces of once-living organisms
    • Organisms with bones or hard structures are more likely to fossilize
    • Organisms that are quickly covered after death are more likely to fossilize
    • Fossils are more likely to be preserved in anoxic environments to prevent decomposition
    • Fossils are more likely to be preserved if the chemistry of the environment does not dissolve the organism

    How to Date Fossils

    • Relative dating is based on layers of rock, where older layers are lower and newer layers are higher in a particular location
    • Index fossils have a known date and are used to date unknown fossils when found together
    • Radiometric dating uses the decay of certain elements
    • Different elements have different half-lives and are used for different timescales

    Galapagos Islands

    • Diverse ecosystems allow the study of adaptations
    • Short-necked tortoises with round shells are found on Santa Cruz Island, where food is found on the ground
    • Longer-necked tortoises are found on Isabela Island, and food is found at higher levels in plants

    Adaptation

    • Environments are constantly changing
    • Genetic variation is essential for adaptation
    • Species must survive long enough to adapt to changing environments
    • DNA variants need to be passed on
    • Changes in environment can lead to adaptations
    • Flightless Cormorant: evolved to swim for fish
    • Prickly cactus: developed bark to protect itself from being eaten
    • Marine Iguana: Has a blunt snout, powerful tail, special glands for being underwater, and can reduce body size when resources are scarce

    Galapagos Finches

    • Galapagos finches have radiated into many species
    • All Galapagos finches share a common ancestor
    • Natural selection favors individuals that are suited to their environment
    • Different islands and habitats lead to different adaptations

    Natural Selection vs Evolution

    • Natural selection favors those with phenotypes best suited to their environment, who are more likely to reproduce with the same phenotypes
    • Natural selection is the driver of evolution
    • Natural selection acts on heritable variation
    • Evolution is the cumulative change of a species over time

    Macroevolution vs Microevolution

    • Macroevolution refers to changes that occur among large taxonomic groups
    • Microevolution studies the agents of change that shape the genome of a species
    • Macroevolution involves major evolutionary changes over long periods
    • Macroevolution occurs at the species level or above
    • Microevolution is evolution within a single species or population

    Species

    • Species are the fundamental unit of evolution
    • A species is a group of interbreeding, natural populations that are reproductively isolated
    • Difficult to define

    Microevolution: Agents of Change

    • Microevolution is caused by genetic changes that alter the frequency of alleles within a population
    • Dominant alleles do not overrun recessive alleles due to several factors
    • Allele frequencies remain in equilibrium if five conditions are met:
      • No migration
      • No mutations
      • Equal fitness and no selection
      • Infinite population size
      • Mating is random
    • Allele frequencies are calculated by counting the number of alleles in a population

    Disequilibrium

    • Migration, mutations, selection, fintie population sizes, and non-random mating all cause deviations from Hardy-Weinberg equilibrium
    • Genotype frequencies not in Hardy-Weinberg equilibrium may indicate a population is under selection
    • Observed frequencies are compared to expected frequencies to determine if there is significant variation
    • A chi-squared test can determine if observed frequencies differ significantly from expected frequencies
    • A chi-squared value greater than the critical value indicates a significant difference

    Natural Selection

    • Variations in traits exist within a population that are influenced by heredity
    • Natural selection occurs when environmental conditions favor certain traits
    • Those with traits that increase reproductive success are more likely to survive and reproduce
    • Selection can act in different ways:
      • Directional: Favors individuals on one end of the distribution.
      • Stabilizing: Favors individuals in the middle
      • Disruptive: Favors individuals at either end of the distribution

    Examples of Natural Selection

    • Industrial melanism is an example of directional selection
    • Pale moths had a selective advantage on light-colored trees and vice versa
    • During the industrial revolution, trees darkened, making pale moths easier for predators to see.

    Receptors and Ligands

    • Ligands are signaling molecules
    • Receptors are specific for a particular ligand
    • Ligands trigger a specific response when bound to their receptor

    Neurotransmitters vs Hormones

    • Neurotransmitters
      • released in small packets at the synapse - the connection between neurons
      • Actions are discreet; restricted to receptors at the synapse
    • Endocrine hormones
      • Released into the circulatory system
      • Action happens on any cell in the body with a receptor for the ligand
    • Key Neurotransmitters and Hormones for Thermoregulation
      • Neurotransmitters
        • Noradrenaline
          • Released by the sympathetic nervous system, evokes fear, flight, and fight
          • Activates adrenergic receptors
      • Hormones
        • Adrenaline
          • Secreted by adrenal glands, activates adrenergic receptors
        • Thyroid
          • Secreted by the thyroid gland, regulates energy expenditure and heat production

    Circadian Rhythm

    • Circadian rhythms are 24-hour cycles, part of the body's internal clock.
    • Core body temperature oscillates throughout the day
    • Sleep cycle: Decline in core body temperature
    • Wake cycle: Arousal; increase in core body temperature
    • Alertness is linked to core body temperature oscillations
    • Low body temperatures are linked to tiredness

    Thermoregulation

    • How We Exchange Heat With the Environment
    • Radiation: Heat from the sun
    • Evaporation: Heat transfer when water evaporates
    • Convection: Heat exchange with surrounding air or water
    • Conduction: Heat exchange with another object
    • Circulation helps us use these systems
    • Physiological Thermoregulation Responses
      • Metabolism
        • Nonshivering thermogenesis: Increase in heat production by the sympathetic nervous system and endocrine system via increased metabolic activity
        • Shivering thermogenesis: Increases heat production by the somatic nervous system and endocrine system via muscle activity
      • Skin Blood Flow: Increased blood flow from sympathetic system (vasodilation); decreased blood flow from sympathetic system (vasoconstriction).
      • Sweating: Increase in sweating from sympathetic system

    Fever

    • Fever is an altered temperature set point
    • Infectious agents activate the immune response to release pyrogens
    • Pyrogens cause fever by releasing inflammatory mediators
    • Inflammatory mediators stimulate production of prostaglandins
    • Prostaglandins alter neuronal activity in the hypothalamus - leading to a higher set point
    • Changes in set point cause:
      • Increase in heat production (shivering)
      • Decrease in heat loss (shunting blood away from skin)
      • Rise in core body temperature
    • Benefits of Fever
      • Bacteria and viruses operate more efficiently at normal human body temperature
      • Higher temperatures reduce the efficiency of bacterial and viral activity
      • Proteins function better at higher temperatures -** Sepsis:**
      • An uncontrolled inflammatory response that can lead to organ damage
      • High temperature reduces cell function

    Respiratory System

    • The respiratory system is responsible for transferring oxygen from the environment to red blood cells
    • The respiratory system is also responsible for transferring CO2 from the blood to air.
    • The respiratory system regulates acid-base balance
    • The bronchial system is the airway conducting system that transmits air to the alveoli
    • Asthma is a chronic inflammatory disease of the airways

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    Exploring Biomed Lecture Notes PDF

    Description

    Explore the fascinating evolution of wings and the adaptations for flight in birds, along with the evolutionary link between birds, reptiles, and mammals. Discover how these creatures adapted to their environments over time, including the development of features that enhance their survival. Test your knowledge on the evolutionary journey from amphibians to archosaurs.

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