Biodiversity, Species Interactions, and Population

Control

Biodiversity, Species Interactions, and Population

Control

Ch. 5, part 2

Miller & Spoolman, 16th ed.

Ch. 5, part 2

Miller & Spoolman, 16th ed.

Big Idea #2Big Idea #2Populations cannot grow indefinitely

because resource are limited and there is competition for those resources

Populations cannot grow indefinitely because resource are limited and there is competition for those resources

Population DynamicsPopulation DynamicsThe study of how

Distribution Age structurePopulation SizePopulation Density

These things change in response to changes in the environment

The study of how Distribution Age structurePopulation SizePopulation Density

These things change in response to changes in the environment

Some species count more than othersSome species count more than othersChanges in the growth rate of

Invasive speciesKeystone speciesEcosystem engineers

Has a greater impact on the biodiversity of an area than other species

Changes in the growth rate of Invasive speciesKeystone speciesEcosystem engineers

Has a greater impact on the biodiversity of an area than other species

DistributionDistribution

Population DynamicsPopulation DynamicsFor example:

How disease affects a populationHow the introduction of a nonnative species affects a

populationHow the presence of chemicals like pesticides affect

populations

Studying these things helps us identify keystone species

For example: How disease affects a populationHow the introduction of a nonnative species affects a

populationHow the presence of chemicals like pesticides affect

populations

Studying these things helps us identify keystone species

Population DistributionPopulation Distribution3 basic patterns:

ClumpedUniformRandom

3 basic patterns:ClumpedUniformRandom

Clumped DistributionClumped DistributionMost common in both plants and

animals

Most common in both plants and animals

Why clump?Why clump?1. Cluster where there are resources

2. More likely to find resources if they work together

3. Protection from predators

4. Teamwork to catch prey

5. Mating group and/or help raising young

1. Cluster where there are resources

2. More likely to find resources if they work together

3. Protection from predators

4. Teamwork to catch prey

5. Mating group and/or help raising young

UniformUniformEspecially in plantsSecrete chemicals that prevent others

from growing nearbyIncreases chances of getting the water and

soil nutrients it needs

Especially in plantsSecrete chemicals that prevent others

from growing nearbyIncreases chances of getting the water and

soil nutrients it needs

RandomRandomPretty rareOccurs when there is no good reason for

the other types

Pretty rareOccurs when there is no good reason for

the other types

Random, uniform, clumped? Why? Random, uniform, clumped? Why?

Population SizePopulation Size

Population SizePopulation Size4 variables

Birth rate (natality) +Death rate (mortality) -Immigration rate +Emigration rate -

Let’s try some math!

4 variablesBirth rate (natality) +Death rate (mortality) -Immigration rate +Emigration rate -

Let’s try some math!

Biotic PotentialBiotic PotentialA population’s capacity for growth

under ideal conditionsGeneral rule of thumb:

Big things have low biotic potentialLittle things have high biotic potential

A population’s capacity for growth under ideal conditions

General rule of thumb:Big things have low biotic potentialLittle things have high biotic potential

Blue whale & calf

ants

E. O. Wilson studied ants mostly

Give an example of an

organism with low biotic

potential and an organism

with high biotic potential

Intrinsic Rate of Increase (r)Intrinsic Rate of Increase (r)The rate at which a population

would grow if it had unlimited resource

Species with high “r” usually:Reproduce early in lifeHave short generationsCan reproduce oftenHave lots of offspring each time

The rate at which a population would grow if it had unlimited resource

Species with high “r” usually:Reproduce early in lifeHave short generationsCan reproduce oftenHave lots of offspring each time

So what’s the difference between biotic potential and intrinsic rate of increase?

Reproductive StrategiesReproductive Strategiesr-selected species

High biotic potentialLots of offspringLittle or no parental careUsually opportunist species

r-selected speciesHigh biotic potentialLots of offspringLittle or no parental careUsually opportunist species

Reproductive StrategiesReproductive StrategiesK-selected species

Low biotic potentialFew offspringLots of parental careUsually competitive species

K-selected speciesLow biotic potentialFew offspringLots of parental careUsually competitive species

22 mo. Gestation, 5 22 mo. Gestation, 5 years between birthsyears between births

9 mo. Gestation, 9 mo. Gestation, 8 years between 8 years between birthsbirths

Most fall somewhere in the middleMost fall somewhere in the middle

Species can’t keep growing and growing…Species can’t keep growing and growing…There are limiting factors that prevent

thisCompetition for resourcesPredatorsDisease

There are limiting factors that prevent thisCompetition for resourcesPredatorsDisease

How do you feel about what you are learning? How do you feel about what you are learning? A. Happy

B. Frustrated

C. Suspicious

D. Love-struck

E. Confused

F. Overwhelmed

G. Other? _________________

A. Happy

B. Frustrated

C. Suspicious

D. Love-struck

E. Confused

F. Overwhelmed

G. Other? _________________

Check all that apply

Population DensityPopulation Density

Population DensityPopulation DensityThe number of individuals in

a given volume

The number of individuals in a given volume

Density-Dependent ControlsDensity-Dependent Controls

• Competition for resources

• Predation

• Parasitism

• Disease

• Poisoning

• Human Harvesting

• Competition for resources

• Predation

• Parasitism

• Disease

• Poisoning

• Human Harvesting

Density-Independent ControlsDensity-Independent Controls

• Natural disasters

• Global warming

• Ozone depletion

• Natural disasters

• Global warming

• Ozone depletion

Environmental ResistanceEnvironmental ResistanceThe combination of all the factors that limit the

growth of a populationTogether these factors determine the carrying

capacity (K) of the populationThe maximum number of a species that can survive in a

given area

The combination of all the factors that limit the growth of a population

Together these factors determine the carrying capacity (K) of the populationThe maximum number of a species that can survive in a

given area

Alphabet SoupAlphabet Soup

What are the letter symbols we’ve learned and what do they stand for?

What are the letter symbols we’ve learned and what do they stand for?

Genetics and Population Dynamics

Genetics and Population Dynamics

Genetic DiversityGenetic Diversity

Difference in genes among members of a population

A very important factor in the long term health and survival of a population

Difference in genes among members of a population

A very important factor in the long term health and survival of a population

The Founder EffectThe Founder Effect

Founder Effect - a small group of individuals becomes separated from the larger population.

They may have less genetic diversity than the larger population

Founder Effect - a small group of individuals becomes separated from the larger population.

They may have less genetic diversity than the larger population

The Bottleneck EffectThe Bottleneck EffectWhen only a small

group survives some change in the environment

Lack of variation means less adaptability

Humans sometimes create bottlenecks in other species

When only a small group survives some change in the environment

Lack of variation means less adaptability

Humans sometimes create bottlenecks in other species

Small populations may experience genetic driftSmall populations may experience genetic drift

Fluctuations in gene frequencies in a small population from one generation to the nextThe smaller the size of the population, the

more likely there is to be a major shift in allele frequencies

Fluctuations in gene frequencies in a small population from one generation to the nextThe smaller the size of the population, the

more likely there is to be a major shift in allele frequencies

ExampleExampleIf I flip a penny 100 times, how

many heads should I get?If I flip a penny 10 times,

would it seem really weird that I got 7 heads and only 3 tails?

Why not?

If I flip a penny 100 times, how many heads should I get?

If I flip a penny 10 times, would it seem really weird that I got 7 heads and only 3 tails?

Why not?

InbreedingInbreeding

Individuals in a small population mate with each other

Increase the frequency of defective genes

Individuals in a small population mate with each other

Increase the frequency of defective genes

Minimum viable population Minimum viable population The minimum number of individuals

needed to maintain a species for the long term (so no inbreeding!)

The minimum number of individuals needed to maintain a species for the long term (so no inbreeding!)

How do you feel about your knowledge of genetics and population dynamics at this point?

How do you feel about your knowledge of genetics and population dynamics at this point?

0 – not even with prompting can I explain this topic

1 – with some prompting I could explain some of it

2 - I get the basics

3 – I understand it beyond just basic info without help

4 – I can apply what I know to a test question

0 – not even with prompting can I explain this topic

1 – with some prompting I could explain some of it

2 - I get the basics

3 – I understand it beyond just basic info without help

4 – I can apply what I know to a test question

Population Growth PatternsPopulation Growth Patterns

StableStableFluctuates a little above and below

carrying capacityFound in stable ecosystems like rain

forests

Fluctuates a little above and below carrying capacity

Found in stable ecosystems like rain forests

Irruptive Irruptive Population explodes,

then stabilized at a lower level; often tied to the seasons

Population explodes, then stabilized at a lower level; often tied to the seasons

CyclicCyclicBoom and bust; like lynx and hare -

every few years/generations

Boom and bust; like lynx and hare - every few years/generations

LE 52-18

1960

Year

Mo

ose

po

pu

lati

on

siz

e

2,500

Steady decline probably caused largely by wolf predation

2,000

1,500

1,000

500

01970 1980 1990 2000

Dramatic collapse caused by severe winter weather and food shortage, leading to starvation of more than 75% of the population

Irregular

Age StructureAge Structure

Age StructureAge Structure

Quick ThinkQuick ThinkWhat are the pros and cons of:Rapid population growth?No population growth?Declining population?

What are the pros and cons of:Rapid population growth?No population growth?Declining population?

EconomicSocialEnvironmental

Choose 1:Choose 1:Would you rather…Sleep in a bed of rats.Catch a porcupine thrown from a 2nd story

window.Be sprayed by a skunk.Let a rattle snake slither across your body.Let bumble bees cover you from head to feet.Let a tarantula walk across your face. Give a speech to the student body with only

your underwear onShave off your head hair and eyebrows for

the rest of the semester

Would you rather…Sleep in a bed of rats.Catch a porcupine thrown from a 2nd story

window.Be sprayed by a skunk.Let a rattle snake slither across your body.Let bumble bees cover you from head to feet.Let a tarantula walk across your face. Give a speech to the student body with only

your underwear onShave off your head hair and eyebrows for

the rest of the semester

Stump the class• Work in teams of 2-3• Each person write one multiple choice or short

answer question on your index cards from Ch. 4 or 5

• Question on one side, answer on the other• Share your questions with your team and

revise if necessary• Give your cards to Beck to share with the class