Ch. 51 Review

Matching:A. Classical conditioningB. Operant conditioningC. HabituationD. Fixed action patternE. Imprinting

1.Birds exposed to a full song in a critical period cause development of the same song2.Prairie dogs who live near hiking trails do not give alarm calls every time a person walks by3.Your dog learns to shake hands with you when you hold out your hand after being rewarded with treats4.A rat learns how to get through a maze when it is rewarded with a treat, but never obtains food if it makes a mistake5.A baby duck runs for cover when an object is thrown over its head, but stops running after many trials

Ch. 53 Warm-Up

1. Sketch an exponential population growth curve and a logistic population growth curve.

2. What is an ecological footprint?

3. What are ways that you can reduce your ecological footprint?

POPULATION ECOLOGYChapter 53

You Must Know:

• How density, dispersion, and demographics can describe a population.

• The differences between exponential and logistic models of population growth.

• How density-dependent and density-independent factors can control population growth.

• Population = group of individuals of a single species living in same general area

• Rely on the same resources, Interact, and Interbreed

Introduction

Characterizing aPopulation

• Population Size -

changes to the # of

organisms in a

population• Involves adding &

removing individuals• Birth rate

• Death rate

• Immigration

• Emigration

Characterizing a Population

• Density - # of individuals per unit of area or volume• Count the # of individuals

• Mark-Recapture Method

• Also affected by birth rates, death

• rates, immigration, and emigration

density

Characterizing a Population

• Dispersion- spacing patterns within a population

Provides insight into theenvironmental associations& social interactions ofindividuals in population

Clumped Pattern (most common)

Uniform

• May result from

direct interactions

between individuals

in the population

• territoriality

Random

• Unpredictable patterns –

no strong attraction or

repulsion between the

individuals

Patterns of Dispersal:

1. Clumped – most common; near required resource

2. Uniform – usually antagonistic interactions

3. Random – not common in nature

Characterizing a Population

• Population Range - geographical limitations of a population

• Abiotic & biotic factors such as temperature, rainfall, food, predators, etc.

• Organisms have adaptations specific to their habitat

adaptations topolar biome

adaptations torainforest biome

Changes in Range

• Range expansions & contractions

• changing environment

At Risk Populations

• Endangered species are greatly affected by changes in range

• The more limited their range / habitat the more at risk the organisms are to extinction

Iriomote cat

New GuineatreekangarooNorthern white rhinoceros

SocorroisopodCatalina

Islandmahoganytree

IiwiHawaiianbird

Devil’s holepupfish

• Additions occur through birth, and subtractions occur through death.

• Life table : age-specific summary of the survival pattern of a population

• Represent data with a survivorship curve.

• Plot # of individuals in a cohort still alive at each age.

Demography: the study of vital statistics that affect population size

Life Table

Population Growth Rates

• Survivorship Curves - graphic representation of life table

• The relatively straight lines of the plots indicate relatively constant rates of death; however, males have a lower survival rate overall than females.

Survivorship Curves:

• Type I curve: low death rate early in life (humans)

• Type II curve: constant death rate over lifespan (squirrels)

• Type III curve: high death rate early in life (oysters)

Population Growth Rates

• Factors that affect population growth rates:• sex ratio

• how many females vs. males?• generation time

• at what age do females reproduce?• age structure

• How many cohorts (groups that are the same age) of females are able to reproduce?

Trade-offs: Survival vs. Reproduction• Reproduction has a cost…

• increase reproduction may decrease survival

• investment per offspring (how many offspring are produced and how much parental care is necessary)

• reproductive events per lifetime (how often they reproduce)

• when reproduction begins - age at first reproduction or at maturity Natural selection

favors a lifehistory thatmaximizes lifetimereproductivesuccess

Parental Survival

Kestrel Falcons:The cost of largerbroods to both male& female parents

Reproductive Strategies

Semelparity

•Big-bang reproduction

•Many offspring produced at once

•Individual often dies afterwards

•Less stable environments

•Selected by organisms rate of growth r-selected

•Fish, bugs and plants Agave Plant

Reproductive Strategies

Iteroparity

•Repeated reproduction

•Few, but large offspring

•More stable environments

•Selected by carrying capacity k-selected

•Mammals, birds, etc

Lizard

Critical factors: survival rate of offspring and repeated reproduction when resources are limited

• K-selection: pop. close to carrying capacity

• r-selection: maximize reproductive success

K-selection r-selectionLive around K Exponential growth

High prenatal care Little or no care

Low birth numbers High birth numbers

Good survival of young

Poor survival of young

Density-dependent Density independent

ie. Humans ie. cockroaches

N/t = B-D

N = population size

t = time

Change in Population Size

Change in population size

during time interval

Births during time interval

Deaths during time interval= -

• Zero population growth: B = D

• Exponential population growth: ideal conditions, population grows rapidly

• Unlimited resources are rare

• Logistic model: incorporates carrying capacity (K)

• K = maximum stable population which can be sustained by environment

• dN/dt = rmax((K-N)/K)

• S-shaped curve

Laboratory Populations

Factors that limit population growth:• Density-Dependent factors: population

matters

• i.e. Predation, disease, competition, territoriality, waste accumulation, physiological factors

• Density-Independent factors: population not a factor

• i.e. Natural disasters: fire, flood, weather

• Populations fluctuate due to biotic and abiotic factors

1975-1980: peak in wolf numbers1995: harsh winter weather (deep snow)

What do you notice about the population cycles of the showshoe hare and lynx?

Boom-and-bust cycles

• Predator-prey interactions

• Eg. lynx and snowshoe hare on 10-year cycle

Introduced Species• Non-native species

• transplanted populations grow exponentially in new area

• out-compete native species

• loss of natural controls

• lack of predators, parasites, competitors

• reduce diversity

• Ex.

• African honeybee

• gypsy moth

• water hyacinth

• zebra mussel

• purple loosestrife

kudzu

gypsy moth

Human Population Growth

• 2 configurations for a stable human population (zero population growth):

A. High birth / high death

B. Low birth / low death

• Demographic transition: occurs when population goes from A B

Population Growth Rates

• Age Structure – the relative number of individuals of each age

• Used to predict a populations growth trends and bring to light social conditions such as war, immigration, emigration, poor health care, etc.

What does the data imply about population growth inthese countries?

Global Carrying Capacity

• UN predicts: 7.8 to 10.8 billion people by the year 2050

• 2012 = 7 billion

• Estimated carrying capacity = 10-15 billion?

• Ecological footprint: total land + water area needed for all the resources a person consumes in a pop.

• 1.7 hectares (ha)/person is sustainable

• U.S.: 10 ha/person over K??

Limitations? Consequences? Solutions?

Human Population Growth

• 1650500 millionWhat factors havecontributed to thisexponential growthpattern?

1650500 million

Industrial Revolution

Significant advancesin medicine throughscience and technology

20056 billion

adding 82 million/yearPopulation of…China: 1.3 billionIndia: 1.1 billion

Map of ecological footprint of countries in the world

(proportional sizes shown)

Concept Check Questions

1. Define population.

2. What are the three types of dispersion?

3. What 4 things affect population size and density?

4. This relies on kin selection and reduces individual fitness but increases fitness of recipient.

5. This is the loss of response to stimulus