Ecology and Behavior

Ecology and Behavior EOC GOALS for this unit: • Develop an understanding of ecological relationships among organisms • Develop an understanding of the behavior of organisms, resulting from a combination of heredity and environment

Interrelationships in Ecology • Population • Community • Ecosystem • Biosphere

Population • Members of the same species in a given area. • Population growth and characteristics are the study of population ecologists • Three Key Features of PopulationsA population’s future survival is determined by its size, density, and dispersion.

Exponential Growth • Growth Rate The rate of population growth is the difference between the birthrate and the death rate. • Exponential Growth Curve A J-shaped graph in which the rate of population growth stays the same is known as an exponential growth curve. (increasing) • Rapidly Growing Populations R-strategists grow exponentially when environmental conditions allow them to reproduce and this often results in temporarily large populations.

Exponential Growth in an r-selected species.

Logistic Growth • Leveling off at carrying capacity • K = carrying capacity – the number of organisms a population can sustain. • Slowly Growing Populations = K-strategists grow slowly, have small population sizes, and their population density are near the carrying capacity.

Logistic Growth of a K-selected Species initial carrying capacity (or K)

Community • All the populations that live together in a given area • Community interactions involve things like predator-prey, symbiosis, and competition • Every organism in a community has the following: • habitat: place where an organisms lives • niche: an organism’s job; all the resources that an organism uses • Type of habitat shapes a community’s structure

Niche • Sum of activities and relationships in which a species engages to secure and use resources necessary for survival and reproduction

Species Interactions • Most interactions are neutral; have no effect on either species • Interspecific competition has a negative effect on both species • Predation and parasitism both benefit one species at a cost to another

Symbiosis - Living together for at least some part of the life cycle • Commensalism, mutualism, and parasitism are forms of symbiosis • Commensalism helps one species and has no effect on the other • Mutualism helps both species • Parasitism helps the parasite at the cost of the host

Parasitism • Parasites drain nutrients from their hosts and live on or in their bodies • Natural selection favors parasites that do not kill their host too quickly

Predation • Predators are animals that feed on other living organisms • Predators are free-living; they do not take up residence on their prey

Ecosystem An association of organisms and their physical environment, interconnected by ongoing flow of energy and a cycling of materials

Matter (Biogeochemical) Cycling • The flow of a nutrient from the environment to living organisms and back to the environment • Main reservoir for the nutrient is in the environment

Three Categories • Hydrologic cycle • Water • Atmospheric cycles • Nitrogen and carbon • Sedimentary cycles • Phosphorus and sulfur

Water (Hydrologic) Cycle Atmosphere precipitation onto land 111,000 wind-driven water vapor 40,000 evaporation from land plants (evapotranspiration) 71,000 evaporation from ocean 425,000 precipitation into ocean 385,000 surface and groundwater flow 40,000 Land Ocean Figure 48.14 Page 876

Carbon Cycle • Carbon moves through the atmosphere and food webs on its way to and from the ocean, sediments, and rocks • Sediments and rocks are the main reservoir

Carbon Cycle - Land atmosphere combustion of fossil fuels volcanic action aerobic respiration combustion of wood photosynthesis terrestrial rocks sedimentation weathering land food webs soil water peat, fossil fuels death, burial, compaction over geologic time leaching, runoff Figure 48.16 Page 878

Nitrogen Cycle • Nitrogen is used in amino acids and nucleic acids • Main reservoir is nitrogen gas in the atmosphere

Nitrogen Cycle gaseous nitrogen (N2) in atmosphere nitrogen fixation by industry food webs on land uptake by autotrophs excretion, death, decomposition uptake by autotrophs fertilizers nitrogenous wastes, remains NO3- in soil nitrogen fixation dentrification ammonification 2. Nitrification NH3-,NH4+ in soil NO2- in soil 1. Nitrification leaching leaching Figure 48.21 Page 882

Nitrogen Fixation • Plants cannot use nitrogen gas • Nitrogen-fixing bacteria convert nitrogen gas into ammonia (NH3) • Ammonia and ammonium can be taken up by plants

Human Effects • Humans increase rate of nitrogen loss by clearing forests and grasslands • Humans increase nitrogen in water and air by using fertilizers and by burning fossil fuels • Too much or too little nitrogen can compromise plant health

Energy Flow in Ecosystems energy input from sun PHOTOAUTOTROPHS (plants, other producers) nutrient cycling HETEROTROPHS (consumers, decomposers) energy output (mainly heat)

SPRING Consumers • Herbivores-plants • Carnivores-meat • Parasites • Omnivores-meat/plants • Decomposers • Detritivores fruits insects rodents, rabbits birds fruits rodents, rabbits insects SUMMER birds Seasonal variation in the diet of an omnivore (red fox)

Trophic Levels • All the organisms at a trophic level are the same number of steps away from the energy input into the system • Producers are closest to the energy input and are the first trophic level

Trophic Levels in Prairie Fourth-level consumers (heterotrophs): 5th Top carnivores, parasites, detritivores, decomposers Third-level consumers (heterotrophs): 4th Carnivores, parasites, detritivores, decomposers Second-level consumers (heterotrophs): 3rd Carnivores, parasites, detritivores, decomposers First-level consumers (heterotrophs): 2nd Herbivores, parasites, detritivores, decomposers Primary producers (autotrophs): 1st Photoautotrophs, chemoautotrophs

Food Chain marsh hawk • A straight-line sequence of who eats whom • Simple food chains are rare in nature upland sandpiper garter snake cutworm plants

Tall-Grass Prairie Food Web marsh hawk sandpiper crow snake frog coyote weasel badger spider sparrow pocket gopher ground squirrel vole earthworms, insects grasses, composites

Ecological Succession • Change in the composition of species over time • Classical model describes a predictable sequence with a stable climax community

Types of Succession • Primary succession - new environments • Secondary succession - communities were destroyed or displaced

Pioneer Species • Species that colonize barren habitats • Lichens, small plants with brief life cycles • Improve conditions for other species who then replace them

Climax Community • Stable array of species that persists relatively unchanged over time • Succession does not always move predictably toward a specific climax community; other stable communities may persist

Cyclic Changes • Cyclic, nondirectional changes also shape community structure • Tree falls cause local patchiness in tropical forests • Fires periodically destroy underbrush in sequoia forests

Human Activities/Impacts on Environment • Global Warming • Human Population Growth • Pesticide Use • Species Effects

Carbon in Atmosphere • Atmospheric carbon is mainly carbon dioxide • Carbon dioxide is added to atmosphere • Aerobic respiration, volcanic action, burning fossil fuels • Removed by photosynthesis

Greenhouse Effect • Greenhouse gases impede the escape of heat from Earth’s surface Figure 48.18, Page 880

Global Warming Long-term increase in the temperature of Earth’s lower atmosphere Figure 48.19, Page 881

Carbon Dioxide Increase • Carbon dioxide levels fluctuate seasonally • The average level is steadily increasing • Burning of fossil fuels and deforestation are contributing to the increase

Human Population Growth 1999 1975 beginning of industrial, scientific revolutions domestication of plants, animals 9000 B.C. (about 11,000 years ago) agriculturally based urban societies

DDT in Food Webs • Synthetic pesticide banned in United States since the 1970s • Birds that are carnivores accumulate DDT in their tissues, produce brittle egg shells

DDT in an Estuary (1967) – Rachel Carson’s Silent Spring DDT Residues (ppm wet weight of whole live organism) Ring-billed gull fledgling (Larus delawarensis) Herring gull (Larus argentatus) Osprey (Pandion haliaetus) Green heron (Butorides virescens) Atlantic needlefish (Strongylira marina) Summer flounder (Paralychthys dentatus) Sheepshead minnow (Cyprinodon variegatus) Hard clam (Mercenaria mercenaria) Marsh grass shoots (Spartina patens) Flying insects (mostly flies) Mud snail (Nassarius obsoletus) Shrimps (composite of several samples) Green alga (Cladophora gracilis) Plankton (mostly zooplankton) Water 75.5 18.5 13.8 3.57 2.07 1.28 0.94 0.42 0.33 0.30 0.26 0.16 0.083 0.040 0.00005

Keystone Species • A species that can dictate community structure • Removal of a keystone species can cause drastic changes in a community; can increase or decrease diversity

Exotic Species • Species that has left its home range and become established elsewhere • Becomes part of its new community • Can have beneficial, neutral, or harmful effects on a community

Endangered Species • A species that is extremely vulnerable to extinction • Close to 70 percent of endangered species have been negatively affected by exotic competitors

Adaptive Responses to Environmental Pressures • Prey Defenses • Camouflage • Warning coloration • Mimicry • Parental behaviors • Feeding strategies • Behavioral responses

Plant Tropisms and other Responses • Phototropism – plants grow towards a light source • Geo/gravitropism – stems grow away from gravity; roots grow towards gravity

Types of Animal Behaviors • Taxis • Reflexes • Instincts • Learned behaviors

Complex Innate Behaviors Waggle dance signals food >100 meters from hive Orientation of straight run shows direction to food

Biological Clocks and Rhythmic Behaviors • Circadian rhythms-internal “biological” clocks • Migration-movement during seasonal changes • Estivation • hibernation

Ecology and Behavior