Presentations text content in Understanding Populations
Ch8, Section 2: How Species Interact with Each Other
Standards: SEV3e, SEV5a, bSlide2
What is a species’ niche?
Niche- role a species has within an ecosystem.
Species physical homeFactors needed for survivalInteractions with other organismsEx: Bison are grazers & help control tree sapling populations as well as fertilize soil for grassEx: Fungi & bacteria are decomposers, recycling nutrients to soil.Slide3
What is a
Place where a species livesAn organism performs its niche in its habitat.Slide4
How do species interact with each other?
Relationship where individuals or populations share limited resources
Both species are harmed
-/- interaction (“lose/lose”)Intraspecific competition- within the same species.Ex: caterpillars of the same species eating the same leaf.Interspecific competition- between different species
When members of different species compete we say their niches have overlapped.Ex: hyenas compete for kill with lionsSlide6
compete even though they do not come in contact with each other.
Ex: An insect that eats a leaf during the day competes indirectly with an insect that eats the same leaf at night.Ex: Plants compete for pollinators; humans compete with insects for food crop.Slide7
Adaptations to competition-
When 2 species compete for a resource, usually only one will win.
The other species must move to find new resources.This is called competitive exclusion.Slide8
Competitive exclusion can lead to
These species share the same niche & habitat but use a smaller portion of it.Ex: Two barnacle species Chthamalus & Balanusshare the same intertidal zone of a rocky shore lineChthamalus
lives at higher tide line (realized niche)When Balanus is removed, Chthamalus will move further down into the original Balanus habitat. (fundamental niche)
where the species actually lives
where the species could live if given a chance.Slide9
where the species actually lives
where the species could live if given a chance.
Copy this down!Slide10
Predator feeds on prey
Predator benefits, prey is harmed
+/- interaction (win/lose)Some predators are very specific about what they eatCanadian lynx only eat snowshoe haresCreates predator/prey oscillationsMost predators generally eat any prey they can capture
Not all predators are carnivoresSlide11
Animals adapted to avoid predation:
hard to see; blend inEx: some caterpillars; lizardsWarning coloration- alert potential predator that they are dangerousEx: poison dart frogsMimicry- look like something more dangerous even if it isn’t
Ex: some flies have same coloration as beesProtective coverings- too hard for predator to eat.Ex: porcupine, turtle, cactusSlide12
Parasite lives and feeds on host organism.
Parasite benefits, host is harmed
+/- interaction (win/lose)Parasites are different from predators because they do not usually kill their host (what else would they eat if they killed their host?)Parasite can weaken host & make them more susceptible to disease.Ex: ticks, leeches, mistletoe, fleasSlide13
Each species benefits from the relationship
interaction (win/win!)Some species couldn’t live without each otherEx: bacteria in your intestine; acacia tree & ants; insects & flowersSlide14
One species is benefited and the other is neither harmed nor helped.
Ex: orchids in trees; clownfish & anemones; remoras and sharksSlide15
What is Symbiosis
Relationship where two species live in close association
Often one species benefits.
Which of the five species interactions are considered symbiosis?Slide16
What is Coevolution
When species have such close relationships they often coevolve.
These two species would be less likely to survive if one were missing.Ex: bee orchidsThis bee orchid has a dark region with yellow spots that resemble the abdomen of a female bee. Male bees will try to copulate with the orchid and in the process will pollinate the orchids.