Transcript Unit XI: Ecology and Animal Behavior

Unit XI: Ecology and Animal
Behavior
Ecological interactions affect how
organisms evolve, and evolutionary
change in turn affects ecological
relationships.
Ecology
Ecology
• the study of the relationships between organisms and their environment
+ two types of interactions
- biotic (living)
- abiotic (nonliving)
+ levels of study
- population, community, ecosystem, biosphere
• Population Ecology
+ population: group of individuals all of the same species living in
the same area
- describing abundance/distribution of populations
+ size (total number of individuals = N)
+ density (total number of individuals per area/volume)
+ dispersion (clumped, uniform, random)
Age Structure
Sweden- relatively stable population growth
Mexico- rapidly growing population
United States- relatively stable population growth
Survivorship Curves
Type I: most individuals die old
Type II: length of survivorship is random
Type III: most individuals die young
Population Growth
Biotic potential
• maximum growth rate of population under ideal conditions
+ bacteria divide every 20 minutes
+ elephants require 2 year gestation period
- factors
+ age at reproductive maturity
+ clutch size
+ frequency of reproduction
+ reproductive lifetime
+ survivorship of offspring to maturity
Carrying Capacity (K)
• maximum number of individuals a population can sustain
+ limiting factors
- elements that prevent a population from attaining
its biotic potential
Density-dependent Factors
Density-dependent factor
• intensifies as population increases
+ reduce the population growth by
decreasing reproduction or by
increasing mortality
- parasites/disease, competition,
predation, stress
Density-independent Factors
Density-independent factor
• occurs independently of population; unrelated to population size
+ natural disasters and extremes of climate
Calculating Growth Rate
r = births - deaths
N
r = reproductive/growth rate
births - deaths = net increase of individuals
N • r = births - deaths
ΔN = r • N
Δt
represents the change in the number of individuals over a given time
When r is…
positive (rmax = intrinsic rate) population size will increase
negative, population size will decrease
zero, population size remains constant (ZPG)
Exponential Growth
J-shaped curve
Logistic Growth
Logistic Growth
• occurs when limiting
factors restrict the size
of the population to
the carrying capacity (K)
ΔN = r • N (K - N)
Δt
K
• as population increases,
r decreases until N = K,
and r = 0
S-shaped/sigmoid curve
Life-history Strategies
k selected and r selected species
• k selected (prudent or equilibrial populations)
+ produce small numbers of young; lots of parental care
- long life expectancy strategy
+ consequences
- increased probability of long term survival
- slow to recuperate numbers when population is reduced
• r selected (prodigal or opportunistic populations)
+ produce many young; very little parental care
- short life expectancy strategy
+ consequences
- can recuperate numbers quickly following population crash
- lead risky lives
Generation Time and Body Size
Which organisms are…
r selected?
k selected?
What about in the plant kingdom?
Community Ecology
Community Ecology
• looking at the interactions between populations
+ interspecific/intraspecific interactions
- interactions between populations of different/same species
- positive (+), negative (-), or neutral (0)
+ types
- Competition
- Predation
- Symbiosis
Competition
Competition (-/-)
• interaction between individual organisms that use the same resources
present in limited supply
- niche: set of resources/conditions necessary for survival
+ organism’s role/job in the community
- intraspecific/interspecific competition
+ same/different species
- types
+ Interference Competition
- animals: overt fighting; plants: secretion of toxins
+ Exploitative Competition
- removal of a resource
- Competitive Exclusion Principle- G.F. Gause, Russian biologist
Predation
Predation (+/-)
• eating of live or freshly killed organisms
+ predators eat prey
+ parasitism
- specialized predators do not actually kill prey (host)
+ Three hypotheses
- When prey population decreases, predator population decreases;
When predator population decreases, prey population increases
- Prey populations may undergo a regular cycle
- Predator populations may undergo a regular cycle
+ Defense against Predators
- cryptic coloration (camouflage)
- aposematic coloration (warning coloration)
- mimicry
+ Batesian (harmless species mimics harmful model)
+ Mullerian (harmful species resemble each other)
Symbiosis
Symbiosis
• close and long term association between organisms of two species
+ Mutualism (+/+)
- both organisms benefit from the interaction
+ mycorrhizae, lichens
+ Commensalism (+/0)
- one species benefits, but other is unaffected
+ remora-shark relationship
Community Composition and the
Question of Stability
Disturbances
• events, such as storms, fire, floods, droughts, overgrazing, etc.
+ damage community, remove organisms, alter resource availability
- communities are usually in a state of recovery
Ecological Succession
• change in the composition of species over time
+ climax community
- final successional stage of constant species composition
+ changes that induce succession
- substrate texture
- soil pH
- soil water potential
- light availability
- crowding
Primary Succession
Primary Succession
• occurs on substrates that never
previously supported living things
+ succession on rock or lava
- lichens
- bacteria, protists, mosses
- insects, other arthropods
- r-selected species of plants
- k-selected species of plants
Secondary Succession
Secondary Succession
• begins in habitats where communities were destroyed by disturbances
+ abandoned cropland
Ecosystems
Trophic Levels
• Primary producers
+ autotrophs (plants, protists,
cyanobacteria, chemosynthetic
bacteria)
• Primary consumers
+ herbivores
• Secondary consumers
+ primary carnivores
• Tertiary consumers
+ secondary carnivores
• Detritivores
+ decomposers (fungi, bacteria,
earthworms, insects,
scavengers)
Pyramid of Energy
Pyramid of Biomass
Pyramid of Numbers
Ecological Efficiency
Ecological Efficiency
• proportion of energy
represented at one trophic level
that is transferred to the next
+ average efficiency=10%
- only 10% of productivity
is transferred to next level
- remaining 90% is
consumed by metabolism
Food Chains and Food Webs
Food Chain
• linear flow chart of who eats whom
grass --> zebra --> lion --> vulture
Food Webs
• expanded, more complete
Biogeochemical Cycles
Biogeochemical Cycles
• flow of essential elements from the environment to living things and
back to the environment
+ reservoirs
- major storage locations
+ assimilation
- processes through which element incorporates into
terrestrial plants and animals
+ release
- processes through which element returns to the environment
Hydrologic Cycle (water cycle)
Reservoirs: oceans, air, groundwater, glaciers
Assimilation: plants absorb from soil; animals eat/drink
Release: plants transpire; animals/plants decompose
Carbon Cycle
Reservoirs: atmosphere (CO2), fossil fuels, peat, cellulose
Assimilation: plants via photosynthesis; consumers
Release: respiration and decomposition; burn fossil fuels
Nitrogen Cycle
Reservoirs: atmosphere (N2); soil (ammonium, ammonia, nitrite, nitrate)
Assimilation: plants absorb from soil; animals consume plants/animals
Release: denitrifying and detrivorous bacteria; animal excretion
Phosphorous Cycle
Reservoirs: rocks
Assimilation: plants absorb from soil (phosphate); consumers
Release: decomposition; excretion in waste products
Biomes
Biome
• region of biosphere characteristized by vegetation and
adaptations of organisms inhabiting the environment
+ Tropical rain forest (high temp., heavy rainfall)
+ Savannahs (grassland with scattered trees)
- tropical, but receive less rainfall than rain forest
+ Temperate grasslands (North American prairie)
- receive less water/lower temp. than savannahs
+ Temperate deciduous forests (warm summer/cold winters)
+ Deserts (hot and dry)
+ Taigas (coniferous forests)
- precipitation in the form of snow
+ Tundras (Lambau Field)
- permafrost
+ Fresh water biomes (ponds, lakes, streams, rivers)
+ Marine biomes (estuaries, intertidal zones, continental shelves,
coral reefs, pelagic oceans)
Animal Behavior
Ethology
• the study of animal behavior
• nature versus nurture… both?
+ kinds of animal behavior
- Innate Behavior
+ instinct
+ fixed action patterns or FAP (Niko Tinbergen)
+ imprinting* (Konrad Lorenz)
- Learned Behavior
+ associative learning
- classical conditioning (Ivan Pavlov)
- operant conditioning (B.F. Skinner)
+ habituation
+ observational learning
+ insight
Animal Movement
Kinesis
• undirected change in speed of movement in response to stimulus
+ speed up in unfavorable; slow down in favorable
- light, touch, air temp., etc.
+ Avon bug in the bathroom tub
Taxis
• directed movement in response to stimulus
+ toward/away from stimulus
- phototaxis, chemotaxis
+ mosquitos and CO2
Migration
• long-distance, seasonal movement
+ availability of food, degradation of environment
- whales, birds, elks, insects, bats
Communication in Animals
Why do animals communicate? How do animals communicate?
Chemical
• pheromones
+ releaser pheromones cause immediate/specific behavioral changes
+ primer pheromones cause physiological changes
- marking your territory
Visual
• agonistic behavior
+ displays of aggression
• courtship behavior
+ announce participants as non-threatening/potential mates
Auditory
• sounds
+ whales, crickets, birds
Tactile
• touching
Social Behavior
Agonistic Behavior
• aggression/submission
+ competition for food, mates, territory
+ ritualized; reduces injury/energy
Dominance Hierarchies
• power and status relationships among groups
+ minimize fighting for food/mates
Territoriality
• possession/defense of territory
+ insures adequate food/space
Altruistic Behavior
• unselfish behavior that appears to reduce fitness
+ increases inclusive fitness
- ground squirrels