COMMUNITY INTERACTIONS
Competition Limited resources (food, space, mates, etc) If two organisms want to use the same resource at the same time they must compete between members of the same species between members of different species
Competition Carrying Capacity: max numbers of species that an environment can sustain Results, either Find balance One out competes the other
Carrying Capacity
Aggressive Behaviors Aggressive Behavior: Actual physical struggles or threatening behaviors Tests of strength Actual fighting until one animal wins Symbolic Displays More common Less energy intensive
Dominance Hierarchies Dominance Hierarchies: Rankings within a group of individuals, usually chosen by aggressive behaviors Rankings: Alpha, Beta, Gamma, etc avoid wasting energy, incurring risk Higher ranking=more resources Examples: Baboon aggression Pecking Order
Territorial Behavior defense of particular area (feeding, mating, rearing) Territory: an area individuals defend and from which other members of the same species are excluded Territories vary in size aggression vs. scent-marking, visual, auditory defense requires energy
Courtship Behavior Courtship Ritual: elaborate behavior performed before mating Males compete to have the best Series of displays & movements Confirm that individuals are of the same species, ready to mate and not threats Allow individuals to show off fitness healthy mate=healthy offspring Examples: Three-spined stickleback Bower Bird
Other Interactions Not dealing with competition over resources
Cooperation Cooperation: Individuals working together in a way that is beneficial to the group Examples: Bee Hive Wolves Hunting Ox defensive circle
Altruism behavior that decreases individual fitness, but increases fitness of others How can it make sense? Kin Selection: based on relatedness n your genes in next generation n Ex: honey bees Reciprocal Altruism: based on tit-for-tat n between unrelated individuals n high probability of meeting again n identifying & punishing cheaters n Ex: Vampire Bats and Cleaner Fish
Predation (+/-) Predation involves one species that preys on another, consuming it in the process. Plants can be predators too Broad definitions include parasitism and herbivory Example: Lions preying on wildebeests
Predator-Prey Interactions Defensive traits such as camouflage, mimicry, and warning coloration have evolved in response to predator-prey interactions.
Herbivory Grazing of herbivores on producers Animal eating a green plant Prey are not defenseless!!!
Plant Defenses Physical thorns, spines Chemical Milkweed Poison Ivy Bitter Taste
Animal Physical Defenses Armor of armadillo Quills on porcupine Tufts on caterpillar
Chemical Defense Some animals make their own toxin Poison Dart Frogs Bombardier Beetle Fire Salamander n Squirt Poison from back Some get toxin from food Monarchs Sea Slugs
Camouflage look like something in environment Match color, texture of bark, twigs, leaves Deceptive Markings
Symbiosis Mutualism Commensalism Parasitism
Commensalism Commensalism: one organism lives with, on, or in another without damage to either Can turn into parasitism in extreme cases Example: Orchids Barnacles on whale
Mutualism Mutualism: Both species benefit Examples: Lichen: fungi and algae Nitrogen fixing bacteria Clownfish and Anemone
Mr. Fungus is ready to greet our friend the alga Friend alga cell is prepared to greet Mr. Fungus The Lichen is created between the fungus and the alga
Parasitism Parasitism: one organism lives off another, harming it in the process Examples: leeches, tapeworms, ticks, mosquitos
Summary Interaction Organism A Organism B Competition - - Predation/Parasitism + - Commensalism + 0 Mutualism + +
Review
Name The Relationship Lichens are a sandwich of fungi and algae. The fungus species attaches to the log, rock, or brick wall and absorbs nutrients from the environment. The algae in its turn uses the nutrients absorbed by the fungus and the carbon dioxide produced to photosynthesize.
Name The Relationship Most oak species are susceptible to root and trunk rot by the various species of fungi. Red rot Fungi attach to the roots and cause decay and will cause trees to fall.
Name The Relationship pseudoscorpions disperse by concealing themselves under the wing covers of large beetles. The pseudoscorpions gain the advantage of being dispersed over wide areas while being protected from predators. The beetle is unaffected by the presence of the hitchhikers.
Name The Relationship The Cattle Egret forages in pastures and fields among livestock such as cattle and horses, feeding on the insects stirred up by the movement of the grazing animals. The egrets benefit from the arrangement, but the livestock are neither helped nor harmed.
Name The Relationship Fleas are small dark, reddish-brown, wingless, blood-sucking insects. Their legs are long and well adapted for jumping. The flea body is hard, polished, and covered with many hairs and short spines directed backward. The mouthparts of an adult flea are adapted for sucking blood from a host.
Name The Relationship Many plants disperse their seeds using berries and fruits such as the raspberries in the photograph. The berries or fruits are eaten by birds or mammals. They pass through the digestive system.
Name The Relationship Athlete s foot is a common fungal infection of the skin of your feet. The fungus, tinea pedis, is contracted from public environments. The fungus then grows in the warm and moist environment of your footwear, and can be difficult to eradicate.