Ecology: Part 2Ecology: Part 2

Chapter 4 Population Biology

4.1: Population Dynamics Section Objectives:Section Objectives: Relate the reproductive patterns of different Relate the reproductive patterns of different

populations of organisms to models of populations of organisms to models of population growthpopulation growth

Predict effects of environmental factors on Predict effects of environmental factors on population growth.population growth.

Principles of Population Growth

A A population population is a group of organisms, all of the is a group of organisms, all of the same species, that live in a specific area.same species, that live in a specific area.

A healthy population will grow and die at a A healthy population will grow and die at a steady rate unless it runs out of food or space, steady rate unless it runs out of food or space, or is attacked in some way by disease or or is attacked in some way by disease or predators.predators.

What can limit growth?

Limiting factors, such as availability of food, Limiting factors, such as availability of food, disease, predators, or lack of space, will cause disease, predators, or lack of space, will cause population growth to slowpopulation growth to slow

Carrying capacity

The number of organisms The number of organisms of one species that an of one species that an environment can support environment can support indefinitelyindefinitely

When a population When a population overshoots the overshoots the carrying carrying capacity, capacity, then limiting then limiting factors may come into factors may come into effect.effect.

Deaths begin to exceed Deaths begin to exceed births and the population births and the population falls below falls below carrying carrying capacitycapacity

Carrying capacity

Density factors and population growth

How organisms are dispersed can be important.How organisms are dispersed can be important.

two kinds of limiting factors that are related to two kinds of limiting factors that are related to dispersal: dispersal: density-dependent and density-independent density-dependent and density-independent factors.factors.

Density-dependent factorsDensity-dependent factors include disease, include disease, competition, predators, parasites, and food.competition, predators, parasites, and food.

Density-independent factorsDensity-independent factors can affect all populations, can affect all populations, regardless of their density.regardless of their density. Most density-independent factors are abiotic factors, such as Most density-independent factors are abiotic factors, such as

temperature, storms, floods, drought, and major habitat temperature, storms, floods, drought, and major habitat disruption.disruption.

Organism Interactions Limit Population Size

1.Predation affects population size

Populations of predators Populations of predators the Lynx and their prey the the Lynx and their prey the Snowhare are known to Snowhare are known to experience cycles or experience cycles or changes in their numbers changes in their numbers over periods of timeover periods of time

LynxHare

Organism Interactions Limit Population Size II

2. Competition within a population When only a few individuals compete for When only a few individuals compete for

resources, no problem arises.resources, no problem arises.

When a population increases to the point at When a population increases to the point at which demand for resources exceeds the which demand for resources exceeds the supply, the population size decreases.supply, the population size decreases.

Organism Interactions Limit Population Size III

The effects of crowding and stress

These include aggression, decrease in These include aggression, decrease in parental care, decreased fertility, and parental care, decreased fertility, and decreased resistance to diseasedecreased resistance to disease

become limiting factors for growth and keep become limiting factors for growth and keep populations below carrying capacity.populations below carrying capacity.

Chapter 5: Biological Diversity and Conservation

What You’ll Learn

You will explain the importance of biological diversity

You will distinguish environmental changes that may result in the loss of species

You will describe the work of conservation biologists

5.1: Vanishing Species

Section Objectives:Section Objectives:

Explain biodiversity and its importance.Explain biodiversity and its importance.

Relate various threats to the loss of Relate various threats to the loss of biodiversity.biodiversity.

Biological Diversity BiodiversityBiodiversity refers to refers to

the variety of species the variety of species in a specific area.in a specific area.

The simplest and most The simplest and most common measure of common measure of biodiversity is the biodiversity is the number of different number of different species that live in a species that live in a certain area.certain area.

Areas around the Areas around the world differ in world differ in biodiversitybiodiversity

..

Where is biodiversity found?

Biodiversity increases as Biodiversity increases as you move toward the you move toward the equator.equator.

Tropical regions contain Tropical regions contain two-thirds of all land two-thirds of all land species on Earth.species on Earth.

Importance to nature

Living things are interdependentLiving things are interdependent Living things can be niches for other living Living things can be niches for other living

things.things.

Populations are adapted to live together in Populations are adapted to live together in communities.communities.

Scientists do know that if a species is lost from Scientists do know that if a species is lost from an ecosystem, the loss may have an ecosystem, the loss may have consequences for other living things in the consequences for other living things in the area.area.

Importance to people

Biodiversity provides Biodiversity provides humans with food, humans with food, clothing, shelter, oxygen, clothing, shelter, oxygen, soil fertility, etc.soil fertility, etc.

Biodiversity could help Biodiversity could help breeders produce additional breeders produce additional food crops.food crops.

can be used to improve can be used to improve people’s health- some of people’s health- some of which may provide future which may provide future drugs.drugs.

Penicillium

Loss of Biodiversity ExtinctionExtinction is the is the

disappearance of a species disappearance of a species when the last of its when the last of its members dies.members dies.

Extinction is a natural Extinction is a natural process and Earth has process and Earth has experienced several mass experienced several mass extinctions during its extinctions during its history.history.

However, the current rate However, the current rate of extinction is very highof extinction is very high

OverexploitationOverexploitation of of wildlife also threatens wildlife also threatens many speciesmany species

Loss of Biodiversity II OverexploitationOverexploitation of wildlife also of wildlife also

threatens many speciesthreatens many species A species is considered A species is considered

to be an to be an endangered endangered speciesspecies when its when its numbers become so low numbers become so low that extinction is that extinction is possible.possible.

When the population of a When the population of a species is likely to species is likely to become endangered, it become endangered, it is said to be a is said to be a threatened speciesthreatened species..

Threats to Biodiversity

1. Habitat loss

The loss of tropical rain forests The loss of tropical rain forests and marine habitats are and marine habitats are especially devastatingespecially devastating

2. Habitat fragmentation

the separation of wilderness the separation of wilderness areas from other wilderness areas from other wilderness areasareas

Threats to BiodiversityII

3. Habitat degradation:

the damage to a habitat by pollution.the damage to a habitat by pollution.

Three types of pollution are air, water, and land Three types of pollution are air, water, and land pollution.pollution.

Air pollutionAir pollution

Pollutants enter the Pollutants enter the atmosphere in many atmosphere in many ways—including volcanic ways—including volcanic eruptions and forest eruptions and forest fires.fires.

Air pollution IIAir pollution II Rapid global warming could alter the Rapid global warming could alter the

entire biosphereentire biosphere Burning fossil fuels is Burning fossil fuels is

increasing the amount of COincreasing the amount of CO2 2

and other greenhouse gases and other greenhouse gases in the air whichin the air which increase increase global temperature global temperature negative effects:negative effects: Change in climate Change in climate

patterns patterns Melting of polar ice Melting of polar ice Flooding of coastal Flooding of coastal

regionsregions Increase in the rate of Increase in the rate of

species lossspecies loss

Air pollution IIIAir pollution III Acid precipitationAcid precipitation—has been —has been

linked to the deterioration of linked to the deterioration of some forests and lakes.some forests and lakes.

Destruction of the Destruction of the ozone layer ozone layer hashas increased the ultraviolet increased the ultraviolet radiation reaching Earth’s radiation reaching Earth’s surface.surface.

probably results from the accumulation probably results from the accumulation of chlorofluorocarbons -chemicals used of chlorofluorocarbons -chemicals used in refrigeration andin refrigeration and aerosol cans, and aerosol cans, and in certain manufacturing processesin certain manufacturing processes..

Water pollution

Excess fertilizers and animal Excess fertilizers and animal wastes are often carried by rain wastes are often carried by rain into streams and lakes.into streams and lakes.

The sudden availability of nutrients The sudden availability of nutrients causes algal blooms, the causes algal blooms, the excessive growth of algae. ->excessive growth of algae. ->

Detergents, heavy metals, and Detergents, heavy metals, and industrial chemicals in runoff can industrial chemicals in runoff can cause death in aquatic organisms.cause death in aquatic organisms.

Oil spills ->Oil spills ->

Abandoned drift nets in oceans Abandoned drift nets in oceans have been known to entangle and have been known to entangle and kill dolphins, whales, and other sea kill dolphins, whales, and other sea life.life.

Land pollution

Trash, or solid wasteTrash, or solid waste

The use of pesticides and The use of pesticides and other chemicalsother chemicals Chemical pesticides are Chemical pesticides are

concentrated in food concentrated in food chains by biological chains by biological magnificationmagnification

Exotic species People sometimes People sometimes

introduce a new species introduce a new species into an ecosystem, either into an ecosystem, either intentionally or intentionally or unintentionally.unintentionally.

These species can cause These species can cause problems for the native problems for the native speciesspecies

these species can grow at these species can grow at an exponential rate due to an exponential rate due to the fact that they are not the fact that they are not immediately as vulnerable immediately as vulnerable to local competitors or to local competitors or predators as are the predators as are the established native species.established native species.

• Section ObjectiveSection Objective

• Describe strategies used in conservation biology.

• Conservation biology is the study and implementation of methods to protect biodiversity.

• Natural resources are those parts of the environment that are useful or necessary for living organisms.~ include sunlight, water, air, and plant and animal resources.

5.2: Conservation of Biodiversity

Conservation Biology

Legal protections of species

• the U.S. Endangered Species Act became law in 1973.

Preserving habitats

the creation of natural preserves

and parks.

Conservation Biology

Working with people• The philosophy of

sustainable use strives to enable people to use natural resources in ways that will benefit them and maintain the ecosystem.

Reintroduction and species preservation programs

Conservation Biology

BioremediationBioremediation is the is the use of living use of living organisms to detoxify organisms to detoxify polluted ecosystemspolluted ecosystems

–These lichens are concentrating mining

wastes