Unit 4 Flashcards
Sea Otter Case Study
- Live in giant kelp forests on Pacific coast
- Hunted almost to extinction by early 1900s
- Partial recovery since listed as endangered in 1977
Reasons to care about sea otters:
- Keystone species
- Ethics
- Tourism dollars
Five Types of Species interactions
- Competition
- Predation
- Parasitism
- Mutualism
- Commensalism
Competition
- Most common interaction is competition
Interspecific competition
- Competition between different species to use the same limited resources
Resource partitioning
- Occurs when different species evolve specialized traits that allow them to share the same resources
- Species may use only parts of resource
- At different times
In different ways
Interspecific competition
- Competition between different species to use the same limited resources
Resource partitioning
- Occurs when different species evolve specialized traits that allow them to share the same resources
- Species may use only parts of resource
- At different times
In different ways
Predation
- Predator feeds directly on all or part of a member of another species (prey)
- Strong effect on population sizes and other factors in ecosystems
Methods of Predation
- Walk, swim, or fly
- Camouflage
- Chemical warfare
Ways that prey avoid predators
- Camouflage
- Chemical warfare
- Warning coloration
- Mimicry
- Behavioral strategies
Coevolution
- Changes in the gene pool of one species can cause changes in the gene pool of the other
- Example: bats and moths
- Echolocation of bats and sensitive hearing of moths
Predation + Natural Selection
Animals with better defenses against predation tend to leave more offspring
Parasitism
- One species (parasite) lives on another organism
- Parasites harm but rarely kill the host
- Examples: tapeworms, sea lampreys, fleas, and ticks
Mutualism
- Interaction that benefits both species
- Nutrition and protective relationship
- Not cooperation—mutual exploitation
- Example: clownfish live within sea anemones
- Gain protection and feed on waste matter left by anemones’ meals
Clownfish protect anemones from some predators and parasites
Commensalism
- Benefits one species and has little effect on the other
- Examples:
- Epiphytes (air plants) attach themselves to trees
- Birds nest in trees
Ecological succession
- Normally gradual change in structure and species composition in a given system
Primary ecological succession
- Involves gradual establishment of communities in lifeless areas
- Need to build up fertile soil or aquatic sediments to support plant community
- Pioneer species such as lichens or mosses
Secondary ecological succession
- Series of terrestrial communities or ecosystems develop in places with soil or sediment
- Examples: abandoned farmland, burned or cut forests, and flooded land
Factors affecting secondary ecological succession rate
Facilitation of area by one species for another
Inhibition hinders growth
Intertia
Ability of a living system to survive moderate disturbances
Resilience
Ability of a living system to be restored through secondary succession after a moderate disturbance
Population
Group of interbreeding individuals of the same species
Population size
- May increase, decrease, or remain the same in response to changing environmental conditions
- Scientists use sampling techniques to estimate
Variables that govern changes in population size:
- Births, deaths, immigration, and emigration
Population distribution
- Most populations live together in clumps or groups
- Organisms cluster for resources
- Protection from predators
Age structure
- Distribution of individuals among various age groups
- Pre-reproductive, reproductive, and post-reproductive stages