Ch 50-54: Ecology

1. Ch 50-54: Ecology Study of interactions between organisms and the environment Environmental factors interacting with variation within populations can cause evolutionary change. (Darwin) Abiotic factors- nonliving Temperature, light, pH, nutrients Biotic factors- living Plants, animals, bacteria, fungus, protozoa Population- group of individuals of the same species that live in a geographic area (coyotes in Clayton) Community- all the organisms of ALL species that live in a n area ( all of the populations) (coyotes, jack rabbits, gopher snake, grass, oak tree in Clayton) Ecosystem- community plus abiotic factors (rock quarry, soil, watershed) Biosphere-all of the planet’s ecosystems

2. Biotic vsabiotic

3. Biogeography • Distribution of individual species • Dispersal- movement of individuals away from high population density or origin. • Natural range expansion (cattle egret, sea lamprey? • Species transplants (game animals) • Does behavior play a role in limiting distribution? • -habitat selection • Do biotic factors limit distribution? • Competition, predation, parasitism, disease, pollinators • (zebra mussles) • ***Climate factors (temperature and water) have a major influence on distribution of organisms*** • Proximity of water and topographic features=climate variations (mountains)

4. Climate • Latitudinal variation in sunlight intensity • Seasonal variation in sunlight intensity • Global air circulation/precipitation patterns • Global wind patterns

6. Microclimate-shade and wind effects (forest, city)

7. Aquatic Biomes • Physically and chemically stratified • Photic zone • Aphotic zone • Benthic zone • Thermocline-temperature change • Lakes, wetlands, streams, rivers, estuaries, intertidal zone, ocean pelagic, coral reefs, marine benthic

9. Terrestrial biomes • Climograph- climate distribution of organisms • Biomes determined by annual temperature and rainfall and dominant biota. • Tropical rain forest, desert, savanna, chaparral, temperate grassland, coniferous forest, temperate broadleaf/deciduous forest, tundra

10. Tundra

11. Deciduous forest

12. Ch 51: Behavioral Ecology • Studies how animal behavior is controlled, develops, evolves and contributes to survival and reproductive success. • What is behavior? • everything an animal does and how it does it. • Proximate-focus on environmental stimuli (the triggers) and genetic, physiological and anatomical mechanisms of the behavior. • Ultimate-evolutionary significance of behavior. (why did natural selection favor a behavior?) • What is ethology? (1963) • Studies how animals behave in their natural environment (mechanisms, development, evolutionary history, fitness)

13. What is FAP? • Fixed action pattern-a sequence of unlearned behavioral acts (unchangeable) carried to completion, triggered by a sign stimulus. • Ex. Stickleback fish attack red belly • Imprinting-includes learning and innate behavior (irreversible) with a sensitive period (the only time the behavior can be learned.

14. What is innate behavior? • Behavior that is behaviorally fixed (under strong genetic influence) • Directed movements- animal movements under genetic influence • Kinesis-simple change in activity in response to a stimulus • Ex: pill bugs slow moist conditions • Taxis-automatic oriented movement toward or away from a stimulus • Migration-genetically influenced, move to areas where food is available

15. Communication • Signal- a behavior that causes a change in another animal’s behavior • Communication-the transmission of, reception of, and response to signals. • Pheromones- chemical odors emitted for communication (attract mates, induce fright response) • Auditory communication partly learned as well as genetic.

16. Environment, interacting with an animal’s genetic make up (genotype) influences the development of behaviors. • Diet, social interactions, opportunities for learning • Food eaten by larvae can influence later mate selection • Parental and aggressive behaviors adopted from foster parents • Learning-the modifications of behavior based on specific experiences • Habituation-a loss of responsiveness to stimuli that convey little or no information. • “Cry wolf” • Spatial learning-modification of behavior based on experience with the spatial structure of the environment. • Locations of nest site, hazards, food, prospective mates, landmarks • associative learning-associate one feature on the environment with another (color=bad taste) • Classical conditioning-arbitrary stimulus is associated with a reward or punishment • Operant conditioning-trial and error learning • Cognition- ability of nervous system to perceive, store, process and use information gathered by senses

17. Behavioral variation • Prey selection used as evidence of evolution (garter snake and banana slug) • Aggressive behavior-genetically based and a product of natural selection for different foraging and territorial behavior • Optimal foraging theory-a compromise between benefits of nutrition and costs of obtaining food (energy and risk) • Mate choice- • Promiscuous, monogamous, polygamous • agonistic behavior- ritualized contest • Altruism-selflessness • Behavior that reduces individual fitness but increases fitness for other individuals in the population • Ex. Ground squirrel predator alarm call • Inclusive fitness-total effect on proliferating own genes and enabling close relatives to reproduce (kin selection)

18. Reciprocal altruism • Altruistic behavior toward nonrelative who may return the favor (chimpanzees and humans) • ***altruistic behaviors probably all have the potential to increase fitness in some way*** • What is social learning? • Learning through observing others • Culture is a system of information transfer through social learning/teaching that influences behavior of individuals in the population. • ***changes from social learning are faster than changes from natural selection*** • Mate choice copying (fish and birds) • Alarm calls in monkeys • Sociobiology- study of social behavior based on evolutionary theory

19. Ch 52:Population ecology • Study of populations in relation to the environment • What is a Population? • Group of individuals of the same species living in the same area. • Density-number of individuals per unit area or volume • Dispersion-spacing among individuals • Clumped, uniform, random • Mark and recapture • Immigration- new individuals moving into population • Emigration- movement of individuals out of the population

20. Demography • Study of the vital statistics of a population and how they change over time. • Birth rates and death rates shown in life tables of the cohorts (group) of individuals being studies. • Survivorship curve- plot of living individuals of a cohort

21. Life history traits are products of natural selection • ***Natural selection favors traits that improve an organism’s chances of survival and reproductive success.*** • Life history- traits that affect an organism’s schedule of reproduction and survival .(3 variables) • 1. when reproduction begins • 2. how often organism reproduces • 3. how many offspring are produced • Big bang reproduction-reproduce once (lots of offspring) and then die • Ex. Salmon and agave (century plant) • an adaptation to the environment, large #’s; increases chance of survival. • repeated reproduction-repeat the reproductive act for several years. • Favored in a more stable environment • Trade offs: Organisms have limited resources, large clutch size when infant mortality is high

23. Exponential model of population growth • Population growth in an idealized, unlimited environment. • Studies reveal the capacity of species for increase and needed conditions. • Eventually (in nature) population will stop growing • Limited resources • ΔN/Δt = B-D • B=bN • b= per capita birth rate • Zero population growth (ZPG)- when per capita birth and death rates are equal.

24. Logistic population growth • As population increases, there is a limited number of resources, and a limited number of individuals that can occupy the habitat. • Carrying capacity(K)- the maximum population size that an environment can support. • Varies over time with changes in resources (water, energy, shelter) • Sigmoid shaped growth curve • K-selection- density dependent selection ( K for carrying capacity) • r-selection- density-independent selection (r for rate of increase)

25. Density-dependent population regulation • Negative feedback – at increased density, birth rate decline and/or death rates increase • Stops continual growth • Competition for resources, territoriality, health (transmission of disease), predation, toxic waste, intrinsic factors(physiological) • Population dynamics- fluctuations in population numbers due to the interactions between biotic and abiotic factors • Stability and fluctuation • Metapopulation- a group of populations is linked by immigration and emigration. • Population cycles- boom and bust (snowshoe hare vs lynx)

27. Global Human Population • Ecological Footprint- land and water area appropriated by each nation to produce all resources and absorb all wastes it generates

28. Ch 53- Community Ecology • Community- populations of different species living close enough for interaction. • Interspecific interaction- interactions with other species (competition, predation +/-, herbivory, disease, mutualism +/+, ) • Interspecific competition- different species compete for a resource -/- (weeds and garden plants) • Competitive exclusion – local elimination of one of the species. (zebra mussel and native mussels in fresh water lakes)

29. Ecological niche • Sum total of a species’ use of biotic and abiotic resources in its environment (its job) • ***two species cannot coexist in a community if their niches are identical*** • Fundamental niche- potential niche • Realized niche- the niche actually being occupied • ***evolution by natural selection can result in one of the species using a different set of resources (resource partitioning)*** • Character displacement-characteristic are more divergent in sympatric populations than in allopatric populations (Darwin’s finch study)

30. Predation • One species (predator) kills another species (prey) • ***adaptations of both predators and prey tend to be refined through natural selection*** • Feeding adaptations (claws), behavioral adaptations (hiding), morphological/physiological adaptations (cryptic coloration, aposematic coloration) • Batesian mimicry vsMullerian mimicry

31. Herbivory • Animal eating a plant or alga • Defenses: physical (thorn, spine) and chemical toxins (nicotine, tannins, strychnine) • Parasitism- parasite derives nourishment from a host • Endoparasite-parasite lives inside the host (tapeworm) • Ectoparasite- parasite lives on external surface of host (flea) • Parasitoidism- wasp lays egg on host, larvae consume host, killing it • ***parasites can have a significant effect on the survival an reproduction and density of their host population (directly or indirectly)*** • Pathogens – disease causing agents can limit populations • Mutualism- both species benefit (bacteria in root nodules of legumes) • Commensalism-one species is helped, other species not helped or harmed • ***competition and predation are the key processes driving community dynamics***

32. Species diversity • Variety of organisms that make up the community • 1) Species richness- total number of different species • 2) Relative abundance-the proportion each species represents of the total individuals in the community

33. Trophic structure • Feeding relationships between organisms in a community • Food chain- transfer of food energy up the tropic levels • Food web- food chains are linked • ***10% of the energy stored in the organic matter of each trophic level is converted to organic matter at the next level.***

34. Dominant species • Species that are the most abundant or highest biomass • Keystone species- not necessarily abundant, but exert strong control on community structure (sea otter) • The loss of the sea otter as a keystone species has allowed sea urchin population to increase and destruction of kelp forest. • Bottom up model- from lower to higher • Top down model- from higher to lower (predation controls)

35. Disturbance • An event that changes a community, removes organisms and alters resources (fire, flood, storm, etc…) • Fire adapted populations • Primary succession- lifeless area where soil has not formed yet (lava, retreating glacier) • Secondary succession- community cleared by disturbance but soil is still intact.

36. Biogeographic factors affecting biodiversity • Equatorial-Polar gradient • Area • Island equilibrium model- size of island and distance from mainland

37. Ecosystem • All organisms living in a community and all the abiotic factors. • Primary producers-photosynthesize ( primary production) • Limiting nutrient-element that must be added inorger for production to increase. • Human impact- • Nutrient enrichment, contamination of aquatic ecosystems, acid precipitation, atmospheric carbon dioxide, green house effect, depletion of ozone layer