1. Zoology Chapter 6 Ecology
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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6. 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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7. 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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8. 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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13. 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 <1% 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
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