envi sci lecture 4

8/8/2019 ENVI SCI Lecture 4

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ENVIRONMENTAL SCIENCE 13e

CHAPTER 4:Biodiversity andEvolution

4-1 What Is Biodiversity andWhy Is It Important?

Concept 4-1 The biodiversity found in

genes, species, ecosystems, andecosystem processes is vital tosustaining life on earth.

Biodiversity (1)

Species diversity

A set of individuals that can mate andproduce fertile offspring

8-100 million species total; likely 10-14 million

2 million species identified

~50% in endangered tropicalrainforests

CLASSIFICATION OF LIVING

ORGANISM

Classification multilevel grouping ofindividuals

Organisms are first classified byAristotle

Classification scheme of the middle

ages (Polynomial) was replaced withBINOMIAL SYSTEM by Linnaeus

TAXONOMY.....

DESCRIPTION

IDENTIFICATION

NOMENCLATURE

CLASSIFICATION

ROOTLESS, STEMLESS, LEAFLESS

PLANT, PARASITIC, BROWNISH

SCALELIKE LEAVE, FOUL SMELLINGFLOWERS

RAFFLESSIA

Rafflessia arnoldii

FAMILY

RAFFLESIACEAE


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Species NamesFirst word of binomial name is Genus andis always capitalized

Second word refers to specific epithet and

is not capitalized

Together form scientific name, written initalics

A complete scientific name (BotanicalName) includes the authors name

Nepenthes madagascariensisPoir

Carl Linnaeus (1707-1778)

Father of Taxonomy

His system of

naming, ranking,and classifyingorganism is still inwide use today.

Before 1969, life was

classified into 2

kingdoms; the Plant

Kingdom and the Animal

Kingdom.

From 1969-1990, life was

classified into 5

kingdoms; Monera,

Protista, Fungi, Plants,

and Animal and some

accept the 6 kingdom

classification: Eubacteria,Archaeobacteria, Protista,

Fungi, Plantae and

Animalia.

1990 Life was classified into 3 Domains( by Carl Woese, 1990):

Domain 1. Archaea oldest known organisms appearing on a fossilrecord

over 3.6 million years ago.

Domain 2. Bacteria

Domain 3. Eucaryota


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Philippine Biodiversity:

Plant Diversity:

The flora of the Philippines iscomposed of at least 13,500

species that is 5% of the worldsflora:

- 8,000 flowering plant species (ofthese, 3200 endemic to thePhilippines)

- 3 gymnosperms (18 % endemic)

- 1,011 ferns and fern allies (30 %endemic)

- 806 mosses (23% endemic)

- 790 fungi

- Lichens -790

- 5-8% - not named yet.

Vertebrates, excluding freshwater fishes -

1090 species.

179 species of mammals (15 species still

to be named in 1995). 110 speciesendemic or 61 %.

558 species of birds (171 endemic

252 species of reptiles (159 endemic):

Lizards 126 species, (75% endemic)

Snakes 112 species (54% endemic)

Crocodiles -2 species (50% endemic)

Invertebrates:

2782 species of mollusks

54 millipedes

44 centipedes

20,000 insect species

341 species of spiders

Philippine Biodiversity

GENETIC DIVERSITY

Genetic Information in all cells

Deoxyribonucleic Acid

DNA contains instructions for traitsGENES

Make the structures and complexchemicals necessary for life

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Genetic diversity


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Biodiversity (2)

Ecosystem diversity

Biomes Distinct climate

Certain species, especially vegetation

Functional diversity

Fig. 4-2, p. 61

Functional DiversityThe biological and chemical processes such as energyflow and matter recycling needed for the survival of species,communities, and ecosystems.

Genetic DiversityThe variety of genetic materialwithin a species or a population.

Species DiversityThe number and abundance of speciespresent in different communities

Ecological DiversityThe variety of terrestrial andaquatic ecosystems found inan area or on the earth.

Fig. 4-2, p. 61

Coastalmountainranges

Deciduousforest

Prairiegrassland

Coniferousforest

DesertConiferousforest

Coastal chaparraland scrub

AppalachianMountains

MississippiRiver Valley

GreatPlains

RockyMountains

GreatAmerican

Desert

SierraNevada

Fig. 4-4, p. 63

San Francisco

Las Vegas

Denver

St. Louis

Baltimore

Average annual precipitation

100-125 cm (40-50 in.)75-100 cm (30-40 in.)50-75 cm (20-30 in.)25-50 cm (10-20 in.)below-25 cm (0-10 in.)

Science Focus: Insects

Around for ~400 million years Bad reputation

Useful to humans and ecosystems

Vital roles in sustaining life

Pollinators

Natural pest control

Renewing soils

Fig. 4-A, p. 62


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Fig. 4-A, p. 62

4-2 How Does the Earths LifeChange over Time?

Concept 4-2A The scientific theory ofevolution explains how life on earth

changes over time through changes in thegenes of populations.

Concept 4-2B Populations evolve whengenes mutate and give some individuals

genetic traits that enhance their abilities tosurvive and to produce offspring withthese traits (natural selection).

Evolution

Populations of organisms

change (evolve) overgenerations (time)

Explains how many differentkinds of organisms cameinto existence SPECIES

Explains how modernorganisms are related topast organisms

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Explains whyorganisms look andbehave the way they

do

Provides a basis forexploring therelationships among

different groups oforganisms

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Evolve

Ability to adapt to their environment through theprocess of evolution

Favorable characteristics are selected for andpassed on to offspring

Called adaptations

Driven bynatural selectionor survival of thefittest

Natural Selection

Natural selection is the drivingforce in evolution

Organisms that have certain

favorable traits are better ableto successfully reproduce thanorganisms that lack these traits


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Natural Selection

Survival of organisms withfavorable traits cause a gradual

change in populations overmany generations

Also Called Survival of theFittest

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Theory of Evolution

Fossils

Mineralized and petrified remains

Skeletons, bones, and shells

Leaves and seeds

Impressions in rocks

Fossil record incomplete: ~1% of allspecies

Charles Darwin, On the Origin ofSpecies, 1859

Population Changes over Time

Populations evolve by becominggenetically different over time

Genetic variability mutations

Random changes in DNA molecules ingenes

Can occur spontaneously

External agents: radiation Can create a heritable trait

Natural Selection

Adaptive traits - genetically favorabletraits that increase the probability to

survive and reproduce

Trait heritable and lead to differentialreproduction

Faced with environmental change

Adapt through evolution

Migrate

Become extinct

Three Myths about Evolutionthrough Natural Selection Refuted

1. Survival of the fittest does not meansurvival of the strongest

2. Organisms dont develop traits just

because they would be useful: giraffes

and long necks

3. There is no grand plan of nature tocreate more perfectly adapted species

no trend toward genetic perfection

4-3 How Do Geological Processes andClimate Changes Affect Evolution?

Concept 4-3Tectonic platemovements, volcanic eruptions,earthquakes, and climate changehave shifted wildlife habitats, wipedout large numbers of species, and

created opportunities for the evolutionof new species.


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Plate Tectonics

Effects on evolution

Locations of continents and oceansdetermine earths climate

Movement of continents allow species tomove and adapt

Earthquakes and volcanoes affect biological

evolution by separating populations of aspecies and allowing new species to develop

Present65 million years ago

135 million years ago225 million years ago

Fig. 4-6, p. 66

Earths Long-Term ClimateChanges

Cooling and warming periods affectevolution and extinction of species

Change ocean levels and area

Glaciers expanding and contracting

Climate changes

Opportunities for the evolution of new

species

Many species go extinct

18,000

years beforepresent

Modern day

(August)

Northern Hemisphere

Ice coverage

Fig. 4-7, p. 67

LegendContinental ice

Sea ice

Land above sea level

4-4 How Do Speciation, Extinction, andHuman Activities Affect Biodiversity?

Concept 4-4 Human activitiesdecrease the earths biodiversity bycausing the premature extinction ofspecies and by destroying ordegrading habitats needed for the

development of new species.

Speciation

Speciation One species splits into two or more

species that can no longer breed andproduce fertile offspring

Geographic isolation

Reproductive isolation


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Science Focus: ChangingGenetic Traits

Artificial selection

Selective breeding: crossbreeding varieties

within same species to enhance desired traits

Grains, fruits, vegetables, dogs, other animals

Genetic engineering

Add, delete, or alter DNA segments

Add desirable genes from other species

New drugs, pest-resistant plants

Controversial

Extinction (1)

Biological extinction Entire species gone

Local extinction All members of a species in a specific area

gone

Endemic species vulnerable to extinction

Background extinction

Speciation generally more rapid thanextinction

4-5 What Is Species Diversityand Why Is It Important?

Concept 4-5 Species diversity is amajor component of biodiversity andtends to increase the sustainability of

some ecosystems.

Species Diversity

Species richness

Species evenness

Varies with geographic location

Richness and Sustainability

Hypothesis Does a community with high species

richness have greater sustainability andproductivity?

Research suggests yes

4-6 What Roles Do SpeciesPlay in an Ecosystem?

Concept 4-6 Each species plays aspecific ecological role called itsniche.


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Ecological Niche (1)

Species occupy unique niches and playspecific roles in an ecosystem

Includes everything required for survivaland reproduction

Water

Sunlight

Space

Temperatures

Food requirements

Ecological Niche (2)

Generalist species

Specialist species Native species

Nonnative species

Spread in new, suitable niches

envi sci lecture 4

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