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 • decreasingreproduction or by • increasingmortality • - 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

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) Biomes

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 Behavior

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

Unit XI: Ecology and Animal Behavior