CHAPTER 5

Cards (41)

  • Southern Sea Otter
    • Live in giant kelp forests on Pacific coast
    • Hunted almost to extinction by early 1900s
    • Partial recovery since listed as endangered in 1977
  • Reasons to care about sea otters
  • Five types of species interactions
    • Interspecific competition
    • Predation
    • Parasitism
    • Mutualism
    • Commensalism
  • Interspecific competition

    Competition between different species to use the same limited resources
  • Competitive exclusion principle
    Two species cannot occupy the same niche
  • Resource partitioning
    Different species evolve specialized traits that allow them to share the same resources
  • Predation
    • Predator feeds directly on all or part of a member of another species (prey)
    • Strong effect on population sizes and other factors in ecosystems
  • Methods of predation
    • Herbivores walk, swim, or fly to plants
    • Carnivores use speed, flight, and senses to locate prey
    • Predators adapt camouflage and chemical warfare
    • Prey adapt protective shells, bark, spines, and thorns
  • Prey species adaptations
    • Camouflage
    • Chemical warfare
    • Warning coloration
    • Mimicry
    • Behavioral strategies
    • Giant kelp anchored to ocean floor and grow toward surface
    • Fast growing
    • Resistant to storm and wave damage
    • Support many marine plants and animals
  • Sea urchins prey on kelp plants
    Southern sea otter helps control sea urchin population
  • Coevolution
    Changes in the gene pool of one species can cause changes in the gene pool of the other
  • Coevolution example
    • Bats and moths
    • Echolocation of bats and sensitive hearing of moths
  • Parasitism
    • One species (parasite) lives on another organism
    • Parasites harm but rarely kill the host
  • Parasitism examples
    • Tapeworms
    • Sea lampreys
    • Fleas
    • Ticks
  • Mutualism
    • Interaction that benefits both species
    • Nutrition and protective relationship
    • Not cooperation—mutual exploitation
  • Mutualism example
    • Clownfish live within sea anemones
    • Gain protection and feed on waste matter left by anemones' meals
    • Clownfish protect anemones from some predators and parasites
  • Commensalism
    Benefits one species and has little effect on the other
  • Commensalism examples
    • Epiphytes (air plants) attach themselves to trees
    • Birds nest in trees
  • Primary ecological succession
    • Involves gradual establishment of communities in lifeless areas
    • Need to build up fertile soil or aquatic sediments to support plant community
    • Pioneer species such as lichens or mosses
  • Secondary ecological succession
    • Series of terrestrial communities or ecosystems develop in places with soil or sediment
    • Examples: abandoned farmland, burned or cut forests, and flooded land
  • Factors affecting rate of secondary succession
    • Facilitation of area by one species for another
    • Inhibition hinders growth
    • Tolerance occurs when organisms are not in direct competition
  • Traditional view of ecological succession
    • Proceeds to stable climax communities
    • Equilibrium called balance of nature
  • Current view of ecological succession
    • Leads to a more complex, diverse, and resilient ecosystem
    • Can withstand changes if not too large or too sudden
  • Ecological inertia or persistence
    Ability of a living system to survive moderate disturbances
  • Resilience
    Ability of a living system to be restored through secondary succession after a moderate disturbance
  • Population
    Group of interbreeding individuals of the same species
  • Variables that govern changes in population size
    • Births
    • Deaths
    • Immigration
    • Emigration
  • Age structure
    • Pre-reproductive stage
    • Reproductive stage
    • Post-reproductive stage
  • Limiting factors
    • Precipitation (on land)
    • Water temperature, depth, clarity, and other factors (in aquatic environments)
    • Population density
    • Density-dependent factors
    1. shaped growth curve
    • Some species can reproduce exponentially
    • Reproduce at an early age
    • Have many offspring each time they reproduce
    • Short intervals in between reproductive cycles
  • Environmental resistance
    Sum of all factors that limit population growth
  • Carrying capacity
    Maximum population of a given species that a particular habitat can sustain indefinitely
    1. selected species
    • Species with capacity for a high rate of population growth
    • May go through irregular and unstable cycles in population sizes
    • Tend to be opportunists
    1. selected species
    • Species that reproduce later in life
    • Have few offspring
    • Have long life spans
    • Can be vulnerable to extinction
    • 1900: deer habitat destruction and uncontrolled hunting
    • 1920s–1930s: laws to protect deer
    • Current deer population explosion in suburban areas
    • Increased deer-vehicle collisions and Lyme disease
    • Factors in declining sea otter population
    • Increased predation by orcas
    • Toxic algae and pollutants released into the ocean
    • Low reproductive rate
    • Rising mortality rate
    • Other threats: oil spills and fishing traps
    • Otter population rising in last several years
  • Survivorship curve
    • Shows the percentages of members of population surviving at different ages
    • Late loss (K-selected species)
    • Early loss (r-selected species)
    • Constant loss (many songbirds)
  • Mature white oak (Quercus alba) produces thousands of acorns per year, which serve as an important food source for many animals. Mature trees have an average lifespan of 300 years.
  • Technological, social, and cultural changes have expanded earth's carrying capacity for the human species today