Ecology The scientific study of interactions between organisms
Ecology The scientific study of interactions between organisms and their environment
THE NATURE OF ECOLOGY • Ecology is a study of connections in nature. • How organisms interact with one another and with their nonliving environment. Figure 3 -2
Symbiosis • Species can interact through competition, predation, parasitism, mutualism, and commensalism. • Some species evolve adaptations that allow them to reduce or avoid competition for resources with other species (resource partitioning).
SPECIES INTERACTIONS: COMPETITION AND PREDATION • Species called predators feed on other species called prey. • Organisms use their senses to locate objects and prey and to attract pollinators and mates. • Some predators are fast enough to catch their prey, some hide and lie in wait, and some inject chemicals to paralyze their prey.
Predator-prey Balance: Wolves and Moose
PREDATION • Some prey escape their predators or have outer protection, some are camouflaged, and some use chemicals to repel predators. Figure 7 -8
SPECIES INTERACTIONS: PARASITISM, MUTUALISM, AND COMMENSALIM • Parasitism (+and -) occurs when one species feeds on part of another organism. • In mutualism (+ and +), two species interact in a way that benefits both. • Commensalism (+ and o) is an interaction that benefits one species but has little, if any, effect on the other species.
Mutualism (+ and +): Win-Win Relationship • Two species can interact in ways that benefit both of them. Figure 7 -9
(a) Oxpeckers and black rhinoceros Fig. 7 -9 a, p. 154
(b) Clownfish and sea anemone Fig. 7 -9 b, p. 154
Commensalism (+ and o): Using without Harming • Some species interact in a way that helps one species but has little or no effect on the other. Figure 7 -10
Competition (- and -) • In competition they both theoretically loose. A community interaction where there is a fight for food, territory, or mates. Energy is lost by both in the struggle. Interspecific and Intraspecific competition.
Competition Reduction Strategy: Resource Partitioning • Each species minimizes competition with the others for food by spending at least half its feeding time in a distinct portion of the spruce tree and by consuming somewhat different insect species.
Niche Specialization • Niches become separated to avoid competition for resources. Figure 7 -6
Specialized Feeding Niches • Resource partitioning reduces competition and allows sharing of limited resources. Figure 4 -8
POPULATION DYNAMICS AND CARRYING CAPACITY • Most populations live in clumps although other patterns occur based on resource distribution. Figure 8 -2
Exponential and Logistic Population Growth: J-Curves and S-Curves • Populations grow rapidly with ample resources, but as resources become limited, its growth rate slows and levels off. Figure 8 -4
Reproductive Patterns • r-selected species tend to be opportunists (generalist) while K-selected species tend to be competitors (specialist). Figure 8 -10
Reproductive Patterns: Opportunists and Competitors • Large number of smaller offspring with little parental care (r-selected species). • Fewer, larger offspring with higher invested parental care (K-selected species). Figure 8 -9
Succession • The process where plants & animals of a particular area are replaced by other more complex species over time.
Succession
Succession and Disturbance • Ecological succession: the orderly and progressive replacement of one community type by another until a climax stage is reached. • Primary - no previous biotic community • Secondary - previously occupied by a community • Aquatic - transition from pond or lake to terrestrial community
Primary vs. Secondary • Primary begins with a lifeless area where there is no soil (ex. bare rock). Soil formation begins with lichens or moss.
Secondary begins in an area where the natural community has been disturbed, removed, or destroyed, but soil or bottom sediments remain.
Pioneer Communities • Lichens and moss.
Climax Communities • The area dominated by a few, longlived plant species.
Water – bare bottom small/few underwater vegetation temporary pond and prairie forest and swamp
Aquatic Succession
Habitat Islands-any habitat surrounded by a different one.
Deforestation – clearing of a large amount of trees for the land.
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