Chp. 36 What impact did BP disaster have on the ocean ecosystem and population?? Reflect on this disaster….

The tale of two fish….population ecology Read scenario p725 Use population ecology to summarize this passage… Read 36.1, 36.2, 36.4, 36.5, 36.6, 36.8, 36.11

36.1 Relate population with boundaries, population ecologist, population dynamics and population growth Example (other than one in the book) of population density Example (other than ones in book) of clumped dispersion, uniform dispersion and random dispersion 36.4 Contrast exponential growth model and logistic growth model. Use per capita, limiting factors and carrying capacity, in discussion

Copyright © 2009 Pearson Education, Inc. Introduction: A Tale of Two Fishes Population ecology is concerned with –Changes in population size –Factors that regulate populations over time It helps explain the biodiversity of an environment

Copyright © 2009 Pearson Education, Inc. Ecologists learn the structure and dynamics of natural populations With this information they are better equipped to –Develop sustainable food sources –Assess the impact of human activities –Balance human needs with the conservation of biodiversity and resources Introduction: A Tale of Two Fishes

Copyright © 2009 Pearson Education, Inc Population ecology is the study of how and why populations change Population –A group of individuals of a single species that occupy the same general area Individuals in a population –Rely on the same resources –Are influenced by the same environmental factors –Are likely to interact and breed with one another

Copyright © 2009 Pearson Education, Inc. A population can be described by the number and distribution of individuals Population dynamics is the interactions between –Biotic and abiotic factors It is the cause of variation in population sizes –A population increases through birth and immigration –Death and emigration out of an area decrease the population 36.1 Population ecology is the study of how and why populations change

Copyright © 2009 Pearson Education, Inc Density and dispersion patterns are important population variables Population density is the number of individuals of a species per unit area or volume Examples of population density –The number of oak trees per square kilometer in a forest –The number of earthworms per cubic meter in forest soil Ecologists use a variety of sampling techniques to estimate population densities

Copyright © 2009 Pearson Education, Inc. Within a population’s geographic range, local densities may vary greatly The dispersion pattern of a population refers to the way individuals are spaced within their area 36.2 Density and dispersion patterns are important population variables

Copyright © 2009 Pearson Education, Inc. The dispersion pattern of a population refers to the way individuals are spaced within their area Dispersion patterns can be –Clumped –Uniform –Random 36.2 Density and dispersion patterns are important population variables

Copyright © 2009 Pearson Education, Inc. In a clumped pattern individuals are grouped in patches Unequal distribution of resources Mating Social behavior Plants and fungi clumped in areas where soil conditions favor germination Flies 36.2 Density and dispersion patterns are important population variables

Copyright © 2009 Pearson Education, Inc. In a uniform pattern individuals are equally spaced in the environment Territorial behavior Interactions between individuals in same population 36.2 Density and dispersion patterns are important population variables

Copyright © 2009 Pearson Education, Inc. In a random pattern of dispersion, the individuals in a population are spaced in an unpredictable way Wind-blown seeds Habits and social interaction make random pattern rare 36.2 Density and dispersion patterns are important population variables

Percentage of maximum life span Percentage of survivors (log scale) III II I

Copyright © 2009 Pearson Education, Inc Idealized models predict patterns of population growth Exponential growth model –The rate of population increases under ideal conditions –Calculated using the equation G = rN –G is the growth rate of the population –N is the population size –r is the per capita rate of increase

Time (months) Population size (N)

Copyright © 2009 Pearson Education, Inc. Logistic growth model –This growth model takes into account limiting factors –Limiting factors are environmental factors that restrict population growth –Formula 36.4 Idealized models predict patterns of population growth

Year Breeding male fur seals (thousands)

Copyright © 2009 Pearson Education, Inc. Idealized models describe two kinds of population growth –Exponential growth –Logistic growth 36.4 Idealized models predict patterns of population growth

Time Number of individuals (N) 0 K G = rN (K – N) K

Test Weds. sections 36.1,2,4,5,6,7 Read 36.5, 36.6, 36.7 and takes notes on these sections. Make sure to include summaries of all figures….

Copyright © 2009 Pearson Education, Inc Multiple factors may limit population growth The logistic growth model –Population growth slows and ceases as population density increases –Increasing population density results in a decrease in birth rate, an increase in death rate, or both

Density of females Clutch size

Copyright © 2009 Pearson Education, Inc. Abiotic factors may reduce population size before other limiting factors become important 36.5 Multiple factors may limit population growth

Apr MayJun Jul AugSepOct Nov Dec Number of aphids Exponential growth Sudden decline

Copyright © 2009 Pearson Education, Inc. Most populations fluctuate in numbers 36.5 Multiple factors may limit population growth

Time (years) Number of females

MalesFemales Experimental transplant of guppies Predator: Killifish; preys mainly on small guppies Guppies: Larger at sexual maturity than those in pike-cichlid pools Pools with killifish, but no guppies prior to transplant Predator: Pike-cichlid preys mainly on large guppies Guppies: Smaller at sexual maturity than those in killifish pools 11 years later Mass of guppies at maturity (mg) Age of guppies at maturity (days) MalesFemales Control: Guppies from pools with pike-cichlids as predators Experimental: Guppies transplanted to pools with killifish as predators

Copyright © 2009 Pearson Education, Inc. THE HUMAN POPULATION

Copyright © 2009 Pearson Education, Inc The human population continues to increase, but the growth rate is slowing Human population is expected to continue increasing for several decades 95% of the increase is in developing nations

1500 Year Population increase Total population size Total population (in billions) Annual increase (in millions)

Year Birth rate Death rate Rate of increase (r) Birth or death rate per 1,000 population

Copyright © 2009 Pearson Education, Inc CONNECTION: An ecological footprint is a measure of resource consumption U.S. Census Bureau projection –8 billion people within the next 20 years –9.5 billion by mid-21st century

Copyright © 2009 Pearson Education, Inc. Ecological footprint helps understand resource availability and usage The United States has a –Big ecological footprint –Large ecological deficit CONNECTION: An ecological footprint is a measure of resource consumption

Copyright © 2009 Pearson Education, Inc. You should now be able to 1.Explain the factors that determine the characteristics of a population 2.Describe exponential growth and the factors that produce logistic growth of a population 3.Explain the limiting factors that influence population growth 4.Distinguish between r- and K-strategies 5.Describe and give examples of the different types of life histories

Copyright © 2009 Pearson Education, Inc. 6.Explain the factors the determine human population growth 7.Describe the concept of ecological footprint You should now be able to

Chp. 37 Communities and Ecosystems I will be able to relate structure and dynamics of ecosystems and communities with how human activities can disrupt the balance

Read p741 Hungry Hippos!!

37.1 Community Define population