Unit 8 Chapter 22 - 23

Chapter 22

Energy Flow Through Ecosystem

  • Endotherms: use thermal energy from their metabolism to maintain body temperature

    • Ex. Mammals and birds

  • Ectotherms: do not have internal mechanisms for maintains body temperature and obtain heat from their environment

    • Must change their behavior in order to regulate their body temperature and obtain heat from their environment

    • Ex. fish

  • Metabolic rate: total amount of energy an organism uses per unit time

    • Smaller organisms have a higher metabolic rate than larger organisms

    • As size increases → metabolic rate decreases

  • Access to energy is key to maintaining the health of an organism

  • A net gain in energy can result in energy storage (fat) or growth

  • A net loss in energy can result to loss of mass or death

  • If energy becomes less available in an ecosystem the producers’ ability to perform photosynthesis will reduce

    • Some will die

  • Leads to massive decreases in the number of species and in population sizes of these species

  • Trophic levels represent steps in the food and energy transfer between organisms in an ecosystem

    • Classified into trophic levels based on their food and energy source

  • Primary consumers: herbivores

  • Secondary, tertiary, quaternary consumers: carnivores and omnivores

  • Food chains show the transfer of energy between these trophic levels

  • Food webs show the interconnection between organisms in different food chains and provide a more complete representation

  • Autotrophs: energy from physical (sunlight) or chemical (small molecules) sources

    • Photoautotrophs: sunlight

    • Chemoautotrophs: small inorganic molecules

  • Heterotrophs: energy from carbon compounds made by others

    • Obtain energy from carbohydrates, lipids, or proteins via breaking down these macromolecules

  • Decomposers: break down dead organic material allowing the nutrients in dead organisms to be recycled through ecosystems

    • Detritivores: obtain energy by consuming the organic waste of dead plants and animals

  • Kleoptoplast: when a heterotroph consumes an autotroph that it uses as food source but removes the chloroplast an incorporates them into its own cells

    • Moves into the sunlight and the chloroplast performs photosynthesis

  • Less energy has you move up trophic levels

  • Bottom - up: regulation of ecosystems; if the population size of the producers decreased there may not be sufficient food or energy for the remaining trophic levels and food web may collapse

  • Top - down: animals at higher trophic levels may help limit the population size at lower levels

    • Ex. Isolated rainforest caused isolation of top predators, without predators plant eating animals grew in higher rate, reducing the number of plants in these area

  • Availability of food and energy affects organisms’ reproductive strategies

  • Organisms that live in unstable environments will produce large number so offspring at a time because the survival rate of the offspring is lower

  • Organisms that live in more stable environments will produce fewer offsprings at a time since the likelihood of survival is higher

Chapter 23

Population Ecology:

  • Population: made of individual organisms that interact with on another and with their environment in complex ways

  • Population growth depends on a number of factors

    • Population size (N)

    • Birth rate (B)

    • Death rate (D)

  • Population growth is calculated based on change in the population size over change in time

  • IF there is no limiting factors a population will experience exponential growth

    • Exponential growth curves are usually J - shaped

  • Some populations will eventually exceed the resources available in their environment, thus their growth will be limited

  • Factors that limit the growth can be either density-dependent factors or density-independent factors

  • These limitations result in logistic growth of a population

  • Carry capacity (K): the maximum population that can be supported by the available resources in an environment

  • Logistic growth curves start with a flat, lag phase, followed by a period of exponential growth or the log phase

K-selected vs r-selected Populations

  • Populations that live in more stable environments and have more energy available tend to have K-selected reproductive strategies

  • K - selected population have stable population sizes at or near the carrying capacity of their environment

    • Invest in parental care in their offspring resulting in a higher survival rate in their offspring

  • Populations that live in environments and have less energy available have r-selected reproductive strategies

    • Reproduce at a younger age and only once in their lifetime

    • Invest little or no parental care in their offspring

  • r - selected populations experience “boom or burst” cycles

    • Period of exponential growth followed by rapid decreases in the population size

Community Ecology and Simpson’s Diversity Index

  • Community: a group of interacting population living in the same habitat

    • Described by their species composition and diversity

    • Species composition is the number os species that line in an area

    • Species diversity reflects the number of species in an area and the number of members of each of those species

  • One way of representing species diversity is the equation for Simpson’s Diversity Index:

Relationships Within Communities

  • Competition: organisms compete for resources

    • Intrespecies: two different species

    • Intraspecies: same species

  • Predator/prey: Predator eat prey

    • Number of prey increase, predator numbers will follow an increase

  • Niche partitioning: competing species amy coexist if they ise the resources aailable in their habitat differently

  • Trophic cascades: far-reaching effects of the reduction of one trophic level in a food web

  • Parasitism: one species benefits from the relationship but the other species is harmed

  • Commensalism: one species benefits and the other neither benefits or is harmed

  • Mutualism: both are benefited

Biodiversity

  • Biodiversity is the variety of living organism in an ecosystem

  • Abiotic (nonliving)

    • climate and water availability

    • Geological events

    • Severe weather

  • Biotic (living)

    • Keystone species have a disproportionally large effect on an ecosystem compared to their numbers

    • When a keystone species is removed the ecosystem may be in danger of collapsing

    • Invasive species are species that are not native to a habitat

    • Human impact

      • Habitat destruction

      • New diseases into the ecosystem

      • Pollution that can make water sources less habitable

  • Adaption are generated by mutations