Unit XI: Ecology and Animal Behavior

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Unit XI Ecology and Animal Behavior

• Ecological interactions affect how organisms
  evolve, and evolutionary change in turn affects
  ecological relationships.

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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)

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Age Structure
Sweden- relatively stable population
growth Mexico- rapidly growing population United
States- relatively stable population growth
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Survivorship Curves
Type I most individuals die old Type II
length of survivorship is random Type III most
individuals die young
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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

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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

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Density-independent Factors

• Density-independent factor
• occurs independently of population unrelated
  to population size
• natural disasters and extremes of climate

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Calculating Growth Rate

• r births - deaths
• N
• r reproductive/growth rate
• births - deaths net increase of individuals
• N r births - deaths
• ?N r N
• ?t
• 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)

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Exponential Growth
J-shaped curve
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Logistic Growth

• Logistic Growth
• occurs when limiting
• factors restrict the size
• of the population to
• the carrying capacity (K)
• ?N r N (K - N)
• ?t K
• as population increases,
• r decreases until N K,
• and r 0

S-shaped/sigmoid curve
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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

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Generation Time and Body Size
Which organisms are r selected? k
selected? What about in the plant kingdom?
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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

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Competition

• Competition (-/-)
• interaction between individual organisms that
  use the same resources
• present in limited supply
• - niche set of resources/conditions necessary
  for survival
• organisms 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

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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)

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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

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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

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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

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Secondary Succession

• Secondary Succession
• begins in habitats where communities were
  destroyed by disturbances
• abandoned cropland

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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)

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Pyramid of Energy
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Pyramid of Biomass
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Pyramid of Numbers
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Ecological Efficiency

• Ecological Efficiency
• proportion of energy
• represented at one trophic level
• that is transferred to the next
• average efficiency10
• - only 10 of productivity
• is transferred to next level
• - remaining 90 is
• consumed by metabolism

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Food Chains and Food Webs

• Food Chain
• linear flow chart of who eats whom
• grass --gt zebra --gt lion --gt vulture
• Food Webs
• expanded, more complete

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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

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Hydrologic Cycle (water cycle)
Reservoirs oceans, air, groundwater,
glaciers Assimilation plants absorb from soil
animals eat/drink Release plants transpire
animals/plants decompose
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Carbon Cycle
Reservoirs atmosphere (CO2), fossil fuels,
peat, cellulose Assimilation plants via
photosynthesis consumers Release respiration
and decomposition burn fossil fuels
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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
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Phosphorous Cycle
Reservoirs rocks Assimilation plants absorb
from soil (phosphate) consumers Release
decomposition excretion in waste products
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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)

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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

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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

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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

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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