Living In Ecosystems Chapter 30 Copyright © McGraw-Hill Companies Permission required for reproduction or display Johnson - The Living World: 3rd Ed. - All Rights Reserved - McGraw Hill Companies

Life History Adaptations Population Demography Outline Population Growth Life History Adaptations Population Demography The Niche and Competition Resource Partitioning Symbiotic Relationships Plant and Animal Defenses Predator-Prey Cycles Ecological Succession Johnson - The Living World: 3rd Ed. - All Rights Reserved - McGraw Hill Companies

Population Dispersion Capacity for Growth Population Growth Populations are composed of groups of individuals of the same species living together. Critical Properties Population Size Population Density Population Dispersion Capacity for Growth Johnson - The Living World: 3rd Ed. - All Rights Reserved - McGraw Hill Companies

Exponential Growth Model Population Growth Exponential Growth Model Assumes population growing without limits at its maximal rate. (r = biotic potential) dN/dt=riN N = Number of individuals in population dN/dt = Rate of change in population size over time ri = Intrinsic rate of increase Johnson - The Living World: 3rd Ed. - All Rights Reserved - McGraw Hill Companies

Innate capacity for growth of any population is exponential. Population Growth A population’s actual rate of increase is the difference between birth rate and death rate corrected for migration. Innate capacity for growth of any population is exponential. Even when rate of increase remains constant, the actual increase in the number of individuals accelerates rapidly as the size of the population grows. Johnson - The Living World: 3rd Ed. - All Rights Reserved - McGraw Hill Companies

Number of individuals an area can indefinitely support. Population Growth Carrying Capacity (K) Number of individuals an area can indefinitely support. Logistic Growth Model As population approaches its carrying capacity, its growth rate slows as resources become scarce. dN/dt = rN (K-N/K) Sigmoid Growth Curve Johnson - The Living World: 3rd Ed. - All Rights Reserved - McGraw Hill Companies

Two Models of Population Growth Johnson - The Living World: 3rd Ed. - All Rights Reserved - McGraw Hill Companies

Life History Adaptations Exponential Model Describes species with r-selected adaptations. Favor high rate of increase Logistic Model Describes species with k-selected adaptations. Favor reproduction near carrying capacity. Johnson - The Living World: 3rd Ed. - All Rights Reserved - McGraw Hill Companies

Johnson - The Living World: 3rd Ed Johnson - The Living World: 3rd Ed. - All Rights Reserved - McGraw Hill Companies

Influence of Population Density Density-Dependent Effects Effects are independent of population size and act to regulate growth (weather). Effects are dependent on size of population and act to regulate growth (resource competition). Have increasing effect as population size increases. Johnson - The Living World: 3rd Ed. - All Rights Reserved - McGraw Hill Companies

Population Demography Age Structure Cohort - Group of individuals of same age. Each has a characteristic: Fecundity Rate - Number of offspring produced during a standard time. Mortality Rate - Number of individuals that die during a standard time. Relative number of individuals in each cohort defines population’s age structure. Johnson - The Living World: 3rd Ed. - All Rights Reserved - McGraw Hill Companies

Population Demography Sex Ratio Proportion of males and females in a population. Usually directly related to number of females in the population. Johnson - The Living World: 3rd Ed. - All Rights Reserved - McGraw Hill Companies

Population Demography Survivorship Curves Graphically express age distribution characteristics by plotting percentage of original population that survives to a given age. Type I - Mortality rises in post-reproductive years. Type II - Mortality constant throughout life. Type III - Mortality low after establishment. Johnson - The Living World: 3rd Ed. - All Rights Reserved - McGraw Hill Companies

Survivorship Curves Copyright © McGraw-Hill Companies Permission required for reproduction or display Johnson - The Living World: 3rd Ed. - All Rights Reserved - McGraw Hill Companies

Population Demography Life Tables Indicate chance of survival at any age. Follow cohort from birth to death. Johnson - The Living World: 3rd Ed. - All Rights Reserved - McGraw Hill Companies

The Niche and Competition Niche - Biological role in community. Fundamental - Theoretical role Realized - Actual role Competition - Two or more organisms attempt to use same resource. Interference - Fighting Exploitative - Consuming shared resources Interspecific - Different species Intraspecific - Same species Johnson - The Living World: 3rd Ed. - All Rights Reserved - McGraw Hill Companies

Barnacle Competition Johnson - The Living World: 3rd Ed. - All Rights Reserved - McGraw Hill Companies

Competitive Exclusion Gause - No two species can coexist in the same niche indefinitely. When two species coexist on long-term basis, their niches differ in one or more features. Otherwise, one is eventually driven to extinction. Johnson - The Living World: 3rd Ed. - All Rights Reserved - McGraw Hill Companies

Resource Partitioning Sympatric Species - Occupy same geographical area but avoid competition by utilizing different portions of the habitat. Character Displacement - Differences arise between species due to natural selection. Allopatric Species - Do not occupy same geographical area, thus are not usually in competition. Johnson - The Living World: 3rd Ed. - All Rights Reserved - McGraw Hill Companies

Mutualism - Both species benefit. Symbiosis Symbiotic Relationship - Two or more species of organisms live together, and at least one gains benefit. Commensalism - One species benefits while other neither benefits or is harmed. Mutualism - Both species benefit. Parasitism - One species benefits while the other is harmed. Johnson - The Living World: 3rd Ed. - All Rights Reserved - McGraw Hill Companies

No definite boundary between commensalism and mutualism. Symbiotic relationship that benefits one species and neither hurts or helps the other. Oxpeckers and Rhinos No definite boundary between commensalism and mutualism. Copyright © McGraw-Hill Companies Permission required for reproduction or display Johnson - The Living World: 3rd Ed. - All Rights Reserved - McGraw Hill Companies

Symbiotic relationship among organisms in which both species benefit. Mutualism Symbiotic relationship among organisms in which both species benefit. Ants and Aphids Ants an Acacias Copyright © McGraw-Hill Companies Permission required for reproduction or display Johnson - The Living World: 3rd Ed. - All Rights Reserved - McGraw Hill Companies

Ectoparasites - External parasites. Parasitism Specialized form of symbiosis in which predator is much smaller than prey. Interaction is harmful to prey but beneficial to predators. Ectoparasites - External parasites. Parasitoids - Lay eggs on living hosts. Endoparasites - Internal parasites. Brood Parasitism - Lay eggs in nests of other species. Johnson - The Living World: 3rd Ed. - All Rights Reserved - McGraw Hill Companies

Predator-Prey Interactions Morphological Defenses Plant Defenses Predator-Prey Interactions Morphological Defenses Thorns, spines, plant hairs Chemical Defenses Secondary chemical compounds Evolution of herbivores avoiding plant defense allows access to a new resource without competition from other herbivores. Johnson - The Living World: 3rd Ed. - All Rights Reserved - McGraw Hill Companies

Feeding on plants rich in secondary compounds may have added benefit. Animal Defenses Feeding on plants rich in secondary compounds may have added benefit. Blue Jays and Monarch Butterflies Defensive Coloration Aposomatic Coloration - Advertise poisonous nature with bright coloration. Cryptic Coloration - Camouflage Chemical Defenses Johnson - The Living World: 3rd Ed. - All Rights Reserved - McGraw Hill Companies

Predation is consumption of one organism by another. Predator-Prey Cycles Predation is consumption of one organism by another. Under simple laboratory conditions, predators often exterminate their prey, and then become extinct themselves when they run out of food. If refuges are provided for the prey, a few individuals usually exist, and then repopulate after the predators die out. Johnson - The Living World: 3rd Ed. - All Rights Reserved - McGraw Hill Companies

Snowshoe Hares (Lepus americanus). Food - Willows Predator-Prey Cycles Snowshoe Hares (Lepus americanus). Food - Willows Predators - Canada Lynx (Lynx canadensis) Johnson - The Living World: 3rd Ed. - All Rights Reserved - McGraw Hill Companies

Mimics must be relatively rare. Mimicry Batesian Mimicry - Palatable individuals mimic distasteful or toxic individuals. Mimics must be relatively rare. Mullerian Mimicry - Unrelated but protected (toxic) species come to resemble one another. Copyright © McGraw-Hill Companies Permission required for reproduction or display Johnson - The Living World: 3rd Ed. - All Rights Reserved - McGraw Hill Companies

Ecological Succession Succession - Ecosystem change from simple to more complex plant communities. Secondary Succession - Occurs in areas where an existing community has been disturbed. Primary Succession - Occurs on bare rocks. Climax Community Johnson - The Living World: 3rd Ed. - All Rights Reserved - McGraw Hill Companies

Ecological Succession Three Critical Concepts of Succession Tolerance Facilitation Inhibition Johnson - The Living World: 3rd Ed. - All Rights Reserved - McGraw Hill Companies

Measure of number of different types of species in an area. Biodiversity Measure of number of different types of species in an area. Crucial to ecosystem preservation. Biodiversity Promotion Ecosystem Size Larger ecosystems, usually have higher levels of biodiversity Latitude Length of growing season Climatic stability Johnson - The Living World: 3rd Ed. - All Rights Reserved - McGraw Hill Companies

Latitudinal Cline in Species Richness Johnson - The Living World: 3rd Ed. - All Rights Reserved - McGraw Hill Companies

Island size and distance from mainland play important roles. Island Biogeography Equilibrium Model McArthur and Wilson proposed island species richness is a dynamic equilibrium between colonization and extinction. Island size and distance from mainland play important roles. Johnson - The Living World: 3rd Ed. - All Rights Reserved - McGraw Hill Companies

Equilibrium Model of Island Biogeography Johnson - The Living World: 3rd Ed. - All Rights Reserved - McGraw Hill Companies

Life History Adaptations Population Demography Review Population Growth Life History Adaptations Population Demography The Niche and Competition Resource Partitioning Symbiotic Relationships Plant and Animal Defenses Predator-Prey Cycles Ecological Succession Johnson - The Living World: 3rd Ed. - All Rights Reserved - McGraw Hill Companies

Copyright © McGraw-Hill Companies Permission required for reproduction or display Johnson - The Living World: 3rd Ed. - All Rights Reserved - McGraw Hill Companies