ECOLOGY AND BEHAVIOR Why study behavior Evolutionary perspective

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 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 = 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 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 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 p. H § 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 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