how organisms interact in communities ch. 18 biology ms. haut
TRANSCRIPT
How Organisms Interact in Communities
Ch. 18
Biology
Ms. Haut
Species Evolve in Response to One Another Coevolution—back & forth evolutionary
adjustments between interacting organisms within an ecosystem Interactions between flowers and pollinators
(birds/insects)
Amorphophallus titanum. Collectively known as “Devil’s Tongues,” they are botanically in the Aroid Family (Araceae). Devil’s Tongues have blooms that look and smell like something dead, which delights and attracts the pollinating flies.Its tuber can grow to 6 feet in circumference, and at maturity will weigh 100 pounds! The eventual bloom can measure eight feet tall and four feet across!
Predators and Prey Coevolve Predation—the act of feeding off another
Predators and Prey Coevolve Parasitism—parasite lives on or in another
organism and feeds off of their “host” Do not usually kill host –food source Use host as nursery for offspring
Predators and Prey Coevolve Herbivores—animals
that eat plants Plants have defenses
Thorns, spines, prickles
Toxins—tastes bad or is poisonous
Predators and Prey Coevolve Herbivores have
overcome plant defenses Cabbage butterfly
larvae have enzymes that break down mustard oils (toxic to many insects) Guarantees them a
food source
Animal Defenses Against Predators Behavioral defenses
Alarm cries Distraction displays
Camouflage—coloration/shape Blend in with environment warning coloration
Red/black; yellow/black
Mechanical/chemical defenses Quills, spines, and other similar structures Toxins—distasteful or poisonous
Monarch butterfly stores toxin of milkweed as larvae Poisonous toads secrete toxin
Symbiotic Relationships Symbiosis—2 or more species live together in a
close, long-term association Non-Beneficial
Parasitism—host harmed, not necessarily killed Beneficial
Commensalism—one partner benefits while not harming the other Cattle egrets—egrets eat ectoparasites/cattle are groomed
Mutualism—both partners benefit Lichens-association b/w fungus and algae Nitrogen-fixing bacteria and legumes
Competition in Communities Overproduction of offspring among species
of a community Limited resources in the community—
living space, food, nutrient, water, light, mates
Niches overlap—how an organism lives
Leads to Competition
Niche Restriction Dividing resources
among species Reduces competition
Prothonotary warbler—eastern United States
Species’ Niche Fundamental niche-entire range of
conditions an organism is potentially able to occupy
Realized niche—the part of the fundamental niche that a species actually occupies
Joseph H. Connell Study
Competitive Exclusion Principle Two species cannot coexist in a community if
their niches are identical
Community Structure Predators can moderate competition among its
prey species Keystone species can alter the whole community
Effects of a Keystone Predator:Sea Star (Pisaster)
0
5
10
15
20
25
1963
1964
1965
1966
1967
1968
1969
1970
1971
1972
Year
Num
ber
of S
peci
es
Pre
sent With Pisaster
Without Pisaster