Life History Strategies and Phenotypic Plasticity
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Questions and Answers

What does an organism's life history record include?

  • Growth, development, reproduction, and survival (correct)
  • Development, habitat preference, and survival
  • Growth, reproduction, and geographic distribution
  • Reproduction, size, and environmental adaptation

    • What is primarily involved in defining a complex life cycle?

  • Multiple life stages with different body forms (correct)
  • Morphological changes that occur gradually
  • Constant form throughout life stages
  • Single life stage in a specific habitat

    • Which of the following best describes r-selection?

  • Selection for rapid reproduction in unstable environments (correct)
  • Selection favoring parental care for offspring
  • Selection resulting in longer lifespans
  • Selection for larger size with fewer offspring

    • Which of the following is an example of a morph?

    <p>Spadefoot toad tadpoles with omnivore and carnivore forms</p> Signup and view all the answers

    What defines the transition in metamorphosis?

    <p>Abrupt transformation from larval to juvenile stage</p> Signup and view all the answers

    What is a key characteristic of K-selected species?

    <p>Large size and slower development</p> Signup and view all the answers

    In alternation of generations, what does the sporophyte phase produce?

    <p>Spores through meiosis</p> Signup and view all the answers

    What is a trade-off in biological terms?

    <p>Allocation of energy or resources to one function at the expense of another</p> Signup and view all the answers

    What is the primary reason females are described as 'choosy' in reproductive strategies?

    <p>Females produce a limited number of eggs.</p> Signup and view all the answers

    How is paternity certainty affected in species with internal fertilization?

    <p>Paternity certainty is low due to timing differences.</p> Signup and view all the answers

    What does the operational sex ratio refer to?

    <p>The ratio of males to females who are capable of reproducing at a given time.</p> Signup and view all the answers

    Which of the following best describes abundance in a population?

    <p>The total number of individuals in a specific area.</p> Signup and view all the answers

    Which factor is NOT considered an abiotic factor affecting population distribution?

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

    What is an example of an ecological disturbance?

    <p>A severe drought affecting water availability.</p> Signup and view all the answers

    What defines geographic range?

    <p>The entire geographic region a species occupies.</p> Signup and view all the answers

    Why might a species exhibit patchy distribution?

    <p>Because not all habitat within the range is suitable.</p> Signup and view all the answers

    What is meant by the term 'fecundity' in a life table?

    <p>Average number of offspring a female will have at a specific age</p> Signup and view all the answers

    Which of the following best describes a cohort life table?

    <p>Monitors the survival of individuals born at the same time</p> Signup and view all the answers

    How does Type II survivorship curve differ from Type I and Type III curves?

    <p>Constant chance of survival throughout life</p> Signup and view all the answers

    What relationship exists between survivorship curves and r- and K-selection?

    <p>K-selected species usually have Type I curves with high survival rates</p> Signup and view all the answers

    What is 'carrying capacity' in the context of logistic growth?

    <p>Maximum population size that can be supported indefinitely</p> Signup and view all the answers

    Which type of growth is associated with r-selection?

    <p>Exponential growth with overlapping generations</p> Signup and view all the answers

    What differentiates logistic growth from exponential growth?

    <p>Logistic growth stabilizes at the carrying capacity</p> Signup and view all the answers

    Which of the following factors is classified as density-independent?

    <p>Natural disasters impacting habitats</p> Signup and view all the answers

    What is a defining characteristic of predators that aids in hunting?

    <p>High speed for pursuit</p> Signup and view all the answers

    What is a consequence of the removal of a top predator from an ecosystem?

    <p>Explosion of herbivore populations</p> Signup and view all the answers

    Which term accurately describes organisms that live in or on other organisms?

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

    What is a characteristic of density-dependent factors?

    <p>They change with the population density.</p> Signup and view all the answers

    What best describes ectoparasitism?

    <p>Feed on the host's blood</p> Signup and view all the answers

    Why can no population grow indefinitely?

    <p>Each environment has a limited carrying capacity.</p> Signup and view all the answers

    What defines the feeding strategy of a herbivore?

    <p>It consumes the tissues or fluids of living plants.</p> Signup and view all the answers

    What function do 'memory cells' serve in the vertebrate immune system?

    <p>Recognize previously encountered microparasites</p> Signup and view all the answers

    Which organism exemplifies a hyperparasite?

    <p>A parasite that infects another parasite</p> Signup and view all the answers

    Which adaptive strategy does camouflage represent in prey species?

    <p>A method to blend into the environment and avoid detection.</p> Signup and view all the answers

    What is meant by the term 'exploitation' in ecological relationships?

    <p>One organism benefits at the expense of another.</p> Signup and view all the answers

    What is a distinguishing feature of endoparasitism?

    <p>Live within the host's body</p> Signup and view all the answers

    Which of the following is NOT a defense against parasites utilized by organisms?

    <p>Producing chemicals to attract other organisms</p> Signup and view all the answers

    How do tobacco plants defend themselves against herbivory?

    <p>Through toxic secondary compounds that deter herbivores.</p> Signup and view all the answers

    What is a characteristic of anti-predator behavior?

    <p>It includes mechanisms developed through evolution to survive.</p> Signup and view all the answers

    What is compensation in response to herbivory in plants?

    <p>The ability to regrow or produce new biomass after damage.</p> Signup and view all the answers

    Study Notes

    Life History

    • A record of events related to an organism's growth, development, reproduction, and survival.
    • Defines how an organism allocates its energy and resources over its lifespan.
    • Includes factors such as:
      • Age and size at sexual maturity.
      • Amount and timing of reproduction.
      • Survival and mortality rates.

    Life History Strategy

    • The overall pattern of life history events within a species.
    • Takes into account the average timing and characteristics of life history events, like reproduction and survival.

    Phenotypic Plasticity

    • The ability of an organism to alter its phenotype (observable characteristics) in response to changes in the environment.
    • Example: Spadefoot toad tadpoles can develop into two different morphs (omnivore or carnivore) based on the available resources and conditions in the pond.

    Morph

    • A distinct form or variation within a species, often due to phenotypic plasticity.
    • Example: Spadefoot toad tadpoles have two morphs: omnivore and carnivore, determined by the environment.

    Complex Life Cycles

    • Involve multiple distinct stages with different body forms and habitats.
    • Example: Frogs undergo metamorphosis, transforming from tadpole larvae to adult frogs.

    Metamorphosis

    • An abrupt transition in form from the larval to the juvenile stage.
    • Occurs in amphibians (frogs), insects (butterflies), and some other organisms.

    Direct Development

    • Young hatch or are born resembling a smaller version of the adult form.
    • Example: Humans, cats, and dogs.
    • More common in nature than complex life cycles.

    Alternation of Generations

    • A life cycle where a multicellular diploid sporophyte alternates with a multicellular haploid gametophyte.
    • Found in plants and some algae.

    Sporophyte

    • The diploid phase of a plant's life cycle that produces spores through meiosis.

    Gametophyte

    • The haploid phase of a plant's life cycle that produces gametes (sex cells) through mitosis.

    r-selection

    • Favors rapid population growth, usually in unstable or unpredictable environments.
    • Traits:
      • Small size
      • Fast development
      • Short lifespan
      • Many offspring
      • Little or no parental care
    • Example: Rabbits, fish, insects, and frogs.

    K-selection

    • Favors slower population growth, usually in stable or predictable environments.
    • Traits:
      • Large size
      • Slow development
      • Long lifespan
      • Reproduction later in life
      • More parental care
    • Example: Humans, elephants, and whales.

    Trade-off

    • Organisms allocate limited energy and resources to one function at the expense of another.
    • Example: The trade-off between the size and number of offspring.

    Anisogamy

    • The difference in size between male and female gametes (sperm and egg).
    • Explains the differences in reproductive strategies between males and females.
    • Females invest significantly more energy in producing eggs than males in producing sperm.

    Operational Sex Ratio (OSR)

    • The ratio of males to females that are capable of reproducing at a given time.
    • Influences the intensity of sexual selection.
    • When OSR is skewed towards males, competition for mates is intensified.

    Distribution

    • The geographical area where a species can be found.

    Abundance

    • The number of individuals of a species in a particular area.

    Population

    • A group of individuals of the same species that live within a particular area and interact with one another.

    Population Density

    • The number of individuals per unit area.
    • Calculated by dividing the number of individuals by the area.

    Abiotic Factors

    • Non-living factors that influence population distribution.
    • Examples:
      • Moisture
      • Temperature
      • pH
      • Sunlight
      • Nutrients

    Biotic Factors

    • Living factors that influence population distribution.
    • Examples:
      • Herbivores
      • Predators
      • Competitors
      • Parasites
      • Pathogens

    Ecological Disturbance

    • Events that kill or damage individuals, creating opportunities for other individuals to grow and reproduce.
    • Examples:
      • Fires
      • Floods
      • Storms
      • Insect/pest outbreaks
      • Landslides
      • Invasive species

    Geographic Range

    • The entire geographical region where a species is found.

    Patchy Distribution

    • Species are not found evenly across their range.
    • Occurs because not all habitats within the range are suitable.

    Dispersion

    • The spatial arrangement of individuals within a population.
    • Examples:
      • Random: Individuals are positioned without a predictable pattern.
      • Clumped: Individuals are grouped together in specific areas.
      • Uniform: Individuals are evenly spaced apart.

    Life Table

    • A summary of survival and reproduction rates for individuals of different ages within a population.

    Survival Rate

    • The probability that an individual of age x will survive to age x+1.

    Survivorship

    • The proportion of individuals that survive from birth to age x.

    Fecundity

    • The average number of offspring a female will have at age x.

    Cohort Life Table

    • Follows the fate of a group of individuals born at the same time (a cohort).
    • Tracks survival and reproduction across the entire lifespan of the cohort.

    Static Life Table

    • Studies survival and reproduction of individuals of different ages during a single time period.
    • Provides a snapshot of the population at a specific time.

    Survivorship Curves

    • Visual representations of how survival rates vary with age.

    • Three main types:

      • Type I: Most individuals survive to old age.
      • Example: Humans, large mammals like elephants.
      • Type II: The chance of surviving remains constant throughout the lifetime.
      • Example: Birds, some reptiles.
      • Type III: High death rates for young; those that reach adulthood survive well.
      • Example: Many fish, plants, insects.

    Exponential Growth

    • Population increases rapidly, at a constant rate.
    • Occurs when resources are abundant and there are no limiting factors.
    • Associated with r-selection.
    • Example: A rapidly growing population of mice in a new environment with plentiful resources.

    Logistic Growth

    • Population increases rapidly, then stabilizes at the carrying capacity.
    • Occurs as resources become limited.
    • Associated with K-selection.
    • Example: Elephants, which have a long lifespan, low reproduction rate, and are limited by the environment's carrying capacity for resources.

    Carrying Capacity (K)

    • The maximum population size that can be supported indefinitely by the environment.
    • Determined by the availability of resources such as food, water, and shelter.

    Density-independent Factors

    • Factors that affect birth and death rates independent of the number of individuals in the population.
    • Examples:
      • Weather conditions (temperature, precipitation)
      • Catastrophes (floods, hurricanes)

    Density-dependent Factors

    • Factors that affect birth, death, and dispersal rates based on the density of the population.
    • Examples:
      • Competition for resources
      • Toxic wastes
      • Predation

    Exploitation

    • A relationship where one organism benefits by feeding on and harming another.
    • Examples: Predators and prey, herbivores and plants, parasites and hosts.

    Herbivore

    • An organism that eats the tissue or internal fluids of living plants or algae.

    Predator

    • An organism that kills and eats other organisms (prey).

    Parasite

    • An organism that lives in or on another organism (host), feeding on parts of it.
    • May not always kill the host.
    • Some parasites (pathogens) cause diseases.

    Prey Adaptations

    • Adaptations that help prey avoid being captured by predators.

    • Examples:

      • Camouflage: Blending in with the environment to avoid detection.
      • Startle: Sudden, surprising movements to deter a predator.
      • Warn: Bright colors or markings to signal that the prey is poisonous or unpalatable.
      • Disrupt: Patterns or movements that confuse the predator during escape.

    Plant Adaptations to Herbivory

    • Adaptations that help plants defend themselves against herbivores.

    • Examples:

      • Toxic secondary compounds: Chemicals that deter herbivores directly.
      • Compounds that attract predators and parasitoids: Attract natural enemies of herbivores.
      • Sticky resins: Stored in canals and released to repel or kill insects.

    Anti-predator Behavior

    • Behaviors that help prey avoid being captured by predators.
    • Examples:
      • Hiding
      • Running away
      • Forming groups
      • Making alarm calls.

    Compensation in Response to Herbivory

    • The ability of a plant to regrow or produce new biomass after being partially eaten by herbivores.

    Predator Adaptations

    • Adaptations that help predators capture and consume prey.
    • Examples:
      • Sharp teeth and claws
      • Enhanced senses (sight, smell, hearing)
      • Camouflage
      • High speed
      • Specialized hunting strategies
      • Venom or toxins to subdue prey.

    Effects of Predation and Herbivory on a Community

    • Predation and herbivory can regulate population sizes, influence distribution, and shape the overall structure of an ecosystem.
    • Example: The removal of a top predator can lead to a trophic cascade, where herbivore populations increase dramatically and reduce plant biomass, impacting the entire community.

    Symbiont

    • An organism that lives in or on another organism.

    Parasite

    • An organism that has an intimate relationship with its host at some point in its life cycle and may harm the host.

    Pathogen

    • A parasite that causes diseases.

    Parasitoid

    • An organism whose larvae feed on a single host, almost always killing it.

    Host Specificity

    • Most parasites feed on only one or a few specific types of host organisms.

    Hyperparasitism

    • The phenomenon where parasites themselves are infected by other parasites.

    Ectoparasitism

    • Parasites that live on the outer body surface of the host.
    • Example: Ticks, fleas, lice.

    Endoparasitism

    • Parasites that live within the host.
    • Example: Tapeworms, intestinal worms.

    Advantages and Disadvantages of Ectoparasitism and Endoparasitism

    • Ectoparasitism:
      • Advantages:
        • Easy access to food and a host's external environment
        • Relatively safe from host's immune system.
      • Disadvantages:
        • Exposure to predators and parasites
        • More susceptible to environmental changes on the host's surface.
    • Endoparasitism:
      • Advantages:
        • Protected from predators and environmental changes
        • Easy access to food and nutrients.
      • Disadvantages:
        • Difficult to find a new host
        • More vulnerable to host's immune system.

    Defenses Against Parasites

    • Plants:
      • Protective outer coverings (bark, thorns, waxy coatings)
      • Production of toxic compounds.
    • Animals:
      • Protective outer coverings (skin, exoskeletons)
      • Vertebrate immune systems:
        • Specialized “memory cells” for recognizing and attacking parasites.
        • Immune system cells (macrophages) that engulf and destroy parasites or mark them for destruction.

    Counterdefenses by Parasites

    • Parasites have evolved strategies to evade host defenses.
    • Example: Plasmodium, the parasite that causes malaria, can change its surface proteins to avoid detection by the host's immune system.

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    Test 2 Study Guide PDF

    Description

    Explore the complex concepts of life history strategies and phenotypic plasticity in organisms. This quiz covers how organisms allocate resources, reproductive timing, and survival patterns. Delve into examples like spadefoot toad tadpoles and their adaptive morphs.

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