Zoology Chapter 6 Ecology

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Zoology Chapter 6Ecology

• Ms. K. Cox

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Introduction

• Ecology is the study of organisms and their
  relationships to each other, as well as the
  components of their environment. The habitat of
  an organism includes all biotic and abiotic
  characteristics of the area that it inhabits.

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Energy

• Organisms gain and use energy in different ways.
  There are two main energy sources
• autotrophs are typically photosynthetic
• heterotrophs eat autotrophs or other heterotrophs.

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How is Energy Used

• The energy budgets of organisms also vary
• Habitat ranges and metabolic rates are different
  for endotherms and ectotherms.
• Torpor, hibernation, and winter sleep may act to
  conserve energy during colder periods.
• Aestivation occurs during periods of heat and
  drying.

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• A population is a group of organisms of one
  species that occupy the same area at a given
  time. Population size is influenced by birth and
  death rates and dispersal rates. Survivorship
  curves illustrate mortality patterns as a
  function of age there are 3 main types of
  survivorship curves pg 82

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Logistic population growth

• . Populations with abundant resources may exhibit
  exponential growth for a period, but they
  typically reach a carrying capacity, the maximum
  population size that can be supported
  indefinitely.

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Interactions between different populations
structure the community

• herbivores include animals that eat plant parts
• predators feed on other organisms, so predator
  and their prey populations are intricately tied
  together.

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Interactions between different populations
structure the community

• Another form of interaction between populations
  is interspecific competition it may result in
  competitive exclusion, the local extinction of
  one species, or coexistence.

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Interactions

• In coevolution, the two species evolve in
  response to each other, as illustrated by insects
  and the plants they pollinate.
• In symbiosis, an intimate relationship develops
  between two different species coevolution is
  also common among symbionts. Symbiosis includes
  parasitism, commensalisms, and mutalism.

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Interactions

• In parasitism, one organism lives in or on
  another organism, called the host. The
  definitive host is the host that harbors the
  sexually reproductive stage of the parasite.
• Commensalisms is a relationship in which one
  organism benefits and the other is neither harmed
  nor helped.
• In mutualism, both species benefit by their
  symbiosis.

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Interactions

• Camouflage occurs when body color patterns are
  used to hide the animal cryptic coloration that
  is a type of camouflage that occurs when the
  animal blends in with the environment.
• Countershading occurs when animals are dark on
  top, but light on the bottom and therefore less
  visible to predators looking upward to see them.
• Aposematic coloration is a warning coloration.
• Mimicry occurs when a prey species resembles
  another inedible or distasteful species.

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Energy Flow

• An ecosystem is composed of both communities and
  the environment in which they live.
• Ecosystems may be best understood by analyzing
  energy transfers with them. The passage of
  energy through the populations of organisms may
  be depicted as a food chain, or more
  realistically as a food web. The food web has 3
  main trophic levels

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Three main trophic levels

• 1. Producers are typically autotrophs
  (photosynthetic plants).
• 2. Consumers may be described as herbivores,
  carnivores, or scavengers.
• 3. Decomposers clean up left over plant
  material, dead organisms, and excrement.
• The efficiency of energy transfers across trophic
  levels varies from lt1 for herbivorous endotherms
  to 35 for carnivorous ectotherms.

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Humans

• Global human population may have already exceeded
  the carrying capacity of our planet, but carrying
  capacity depends on the standard of living for
  all people and on the way in which resources are
  distributed