Download ECOLOGY AND BEHAVIOR

ECOLOGY AND
BEHAVIOR
Why study behavior?
● Evolutionary perspective…
o part of phenotype
o acted upon by natural selection
 lead to greater fitness?
 lead to greater survival?
 lead to greater reproductive success?
What is Behavior?
● Behavior =
everything an animal
does & how it does it
● 2 Types:
o innate
o learned
Innate Behaviors
● Fixed action
patterns = sequence
of unlearned acts that
are triggered by a
o sign stimulus
(external cue)
o carried out to
completion
Complex Innate Behaviors
● Use of
environmental cues
to carry out behavior
o Migration,
Hibernation,
Estivation,
Courtship
Innate: Directed Movements
● Taxis = response
movement toward
(positive taxis) or away
from (negative taxis) a
stimulus
Kinesis = random
movement in
response to a stimulus
Plant Behaviors
● Responses to
environment
● Phototaxis –
movement towards
light
● Photoperiodism –
response to different
times of day
Learning
● Imprinting
● Associative
o
o
classical conditioning
operant conditioning
Social Behaviors
● Interactions between
individuals that develop
into evolutionary
adaptations
o
o
o
o
o
communication / language
agonistic behaviors
dominance hierarchy
cooperation
altruistic behavior
Altruistic Behavior
●
reduces individual
fitness but increases
fitness of recipient
o increasing survival of
close relatives
passesfamily genes on
to the next generation –
evolutionary fitness!
Populations
Population
Population = group of individuals of same
species in same area at same time
Factors that affect population size
● Abiotic factors
o sunlight &
temperature
o precipitation / water
o soil / nutrients
● Intrinsic factors
o adaptations
● Biotic factors
o
other living
organisms
 prey (food)
 competitors
 predators,
parasites,
 disease
Characterizing a Population
● Describing a
population
o population range
o pattern of
Dispersion
o Density of
population
Population Dispersion
Population Size
● Changes to
population size
o
o
o
o
birth
death
immigration
emigration
Population Growth Rates
● sex ratio
o how many females vs. males?
● generation time
o at what age do females reproduce?
● age structure
o how females at reproductive age in cohort?
Survivorship Curves
What do these
graphs tell about
survival &
strategy of a
species?
Reproductive Strategies
● K-selected
o late reproduction
o few offspring
o invest a lot in raising offspring
● r-selected
o early reproduction
o many offspring
o little parental care
Growth Rate Models
● Exponential
growth
● Logistic growth
o Rapid growth
o Environmental
constraints
o No constraints
o Limited growth
o J-shaped curve
o S-shaped curve
o Carrying
capacity
Regulation of Population Size
● Limiting Factors
o density dependent
 competition: food, mates, nesting sites
 predators, parasites, pathogens
o density independent
 abiotic factors
Introduced Species
● Non-native species (INVASIVE)
o transplanted populations grow exponentially in new
area
o out-compete native species
o reduce diversity
o examples
 African honeybee
 gypsy moth
 zebra mussel
 purple loosestrife
COMMUNITIES
Introduction
Community = all the organisms that live
together in a place
Community Ecology = study of interactions
among all populations in a common
environment
Niche
● An organism’s niche
is its ecological role
o habitat = address
vs. niche = job
Competitive Exclusion Principle
Resource Partitioning
Community Relationships
● Symbiotic interactions
o competition (-/-)
o predation / parasitism (-/+)
o commensalism (+/0)
o mutualism (+/+)
Predation Drives Evolution
● Predators adaptations
o locate & subdue prey
● Prey adaptations
o elude & defend
● Predation provides a strong selection pressure on
both prey & predator
Anti-predator Adaptations
● Hiding from
predators
o avoid detection
o camouflage
Anti-predator Adaptations
● Warning coloration
o advertise how
undesirable you
are as prey
o Aposematic
coloration
 Batesian mimicry
 Mullerian mimicry
Coevolution in Community
● Predator-prey
relationships
● Parasite-host
relationships
● Flowers &
pollinators
Species Diversity
● Greater biodiversity
offers:
o
o
o
o
more food resources
more habitats
more resilience
in face of
environmental
change
Keystone Species
● Influential
ecological role
o A species that has
a large effect on its
environment
relative to its
abundance
Ecological Succession
● Sequence of community changes
o transition in species composition over
time
Progress of Succession
● Tolerance
o early species are weedy (r-selective)
o tolerant of harsh conditions
● Facilitation & Inhibition
o early species facilitate habitat changes
 change soil pH
 change soil fertility
 change light levels
o allows other species to out-compete
Primary Succession
● Begins with virtually lifeless
area without soil, then…
o
o
o
o
o
bacteria
lichens & mosses
grasses
shrubs
trees
Secondary Succession
● Existing community
cleared, but base
soil is still intact
Climax Community
● Stable plant
community
dominated by trees
● Representing final
stage of natural
succession for a
specific location
ECOSYSTEMS
Ecosystem
● All the organisms in a community plus abiotic
factors
o ecosystems are transformers of energy &
processors of matter
● Ecosystems are self-sustaining
Food Chains
● Trophic levels
o feeding relationships
o start with energy from
the sun
o food chains usually go
up only 4 or 5 levels
 inefficiency of energy
transfer
o all levels connect to
decomposers
Inefficiency of Energy Transfer
● Loss of energy between levels of food chain
o To where is the energy lost? The cost of living!
17%
Growth
33%
Cellular
Respiration
50% Waste
(feces)
Ecological Pyramid
● Loss of energy between levels of food chain
o can feed fewer animals in each level
Productivity
● Primary productivity: Term for the rate which
producers photosynthesize organic compounds in
an ecosystem.
o Gross primary productivity: total amount of
photosynthetic biomass production in an ecosystem
o Net Primary Productivity = GPP – respiration cost