Biodiversity and Evolution Chapter 4 Part 1 Introductions

Core Case Study: Why Should We Care about the American Alligator?

 Largest reptile in North America  Importance of gator holes and nesting mounds • Gator holes hold freshwater during dry spells and serve as habitats for many aquatic species

Core Case Study: Why Should We Care about the American Alligator?

 1930s: Hunters and poachers  1967: endangered species; protected from poaching  1977: comeback, threatened species

Types of Diversity

   Species diversity Genetic diversity Ecosystem diversity  Functional diversity – variety of processes such as matter cycling and energy flow

Natural Capital: Major Components of the Earth

’

s Biodiversity

What is classification?

  Classification • a systematic arrangement of organisms into groups or categories Taxonomy • science of classifying organisms

Why Classify?

   Set up an organized system so scientists can communicate Study similarities and propose relationships between organisms Show evolutionary linkages between organisms

Why Classify?

  Prevents misnomers such as starfish and jellyfish Prevents duplicated names • International Naming Congress

Common Names

 One species can have many different names • Example: Mountain lion, puma, cougar, or panther?

•Vary among languages and regions

Keys to Binomial Nomenclature

Felis domesticus



Must be in Latin



Must be in italics or underlined



Genus (1

st

word) must be capitalized



Species (2

nd

word) must be lowercase

Correct or Incorrect?



Triticum Aestivum - wheat



Felis domesticus - cat



canis lupus - wolf



Canis familiaris - dog



Populus deltoides - cottonwood

DICHOTOMOUS KEY

  Identification tool Uses paired statements to assist a person in learning the identity of an object.

• Characteristics such as structure and behavior  Think of a dichotomous key as a type of scavenger hunt!

DICHOTOMOUS KEY EXAMPLE

1. a. tail fins are horizontal—whale………………….go to 2 b. tail fins are vertical—fish……………………….go to 3 2. a. has teeth or tusk—toothed whale………………..go to 4 b. has no teeth………………………...

BALEEN WHALE 3. a. has gill slits behind mouth—shark…….………...go to 4 b. has no gill slits……………………..

NONSHARK FISH 4. a. black with white underside………….

KILLER WHALE b. tusk, gray with dark spots………………....

NARWHAL 5. a. head is hammershaped……..

HAMMERHEAD SHARK b. tail is half the body length……….

THRESHER SHARK

Hierarchy of Classification

        Domain Kingdom Phylum Class Order Family Genus Species         Dear King Philip Came Over For Good Soup

Inclusive: broad or general in scope Inclusive: broad or general in scope Exclusive: limited and restricted; specific

Your Turn!

 Leaf and Seed Identification Kits

Biodiversity and Evolution Chapter 4 Part 2: Natural Selection

Six Major Kingdoms of Species as a Result of Natural Selection

Evolution by Natural Selection

 The Struggle for Existence • Darwin realized that high birth rates and a shortage of life's basic needs would force organisms to compete for resources.

Evolution by Natural Selection



Fitness

• Ability of an individual to survive and reproduce in its specific environment • Result of adaptations.

Individuals in Populations with Beneficial Genetic Traits Can Leave More Offspring

 Natural selection: acts on individuals 

Differential reproduction

– individuals with a certain desirable trait leave more offspring than other members

The Genetic Makeup of a Population Can Change

 Populations (not individuals) evolve by becoming genetically different  Genetic variations • First step in biological evolution • Occurs through mutations in reproductive cells

Individuals in Populations with Beneficial Genetic Traits Can Leave More Offspring

 When environmental conditions change, populations • Adapt • Migrate • Become extinct 

Genetic resistance

– ability of one or more organisms in a population to tolerate a chemical designed to kill it • Malaria

A group of bacteria, including genetically resistant ones, are exposed to an antibiotic Most of the normal bacteria die The genetically resistant bacteria start multiplying Eventually the resistant strain replaces the strain affected by the antibiotic Normal bacterium Resistant bacterium

What do you think…

 Will human adaptations allow our skin to become more resistant to the harmful effects of UV radiation, our lungs to cope with air pollutants, and our livers to better detoxify pollutants?

Adaptation through Natural Selection Has Limits

 Genetic change must precede change in the environmental conditions • If the genes aren’t there, the change won’t take place!

 Reproductive capacity – species that reproduce in greater numbers at a higher frequency adapt more quickly

Things to remember:

 “ Survival of the fittest ” strongest ” is not “ survival of the  Organisms do not develop traits out of need or want

Classification Systems

 Taxonomy – science of classifying organisms • Assigns each organism a universally accepted name that has biological significance

Classification Systems

 Taxonomic classification may change with expanding knowledge about new and known organisms

How do scientists classify new organisms?

 They study their characteristics.

 They try to see if they are similar to other already known organisms.

 They group a new organism with others that have similar characteristics.

The Fossil Record Tells Much of the Story of Evolution



Fossils

• Physical evidence of ancient organisms • Reveal what their internal structures looked like • Represents only 1% of all species that have ever lived  Fossil record is incomplete: why?

Fossilized Skeleton of an Herbivore that Lived during the Cenozoic Era

Scientists need to study organisms COMPLETELY

Whale’s closest relative?

Whale’s closest living relative!

What characteristics are important?

 Similarities in DNA and RNA • Genes show similarities at the molecular level • More similar the DNA, the more recently they shared a common ancestor • Myosin: Humans and Yeast?

Your Turn!

 Lords of the Wild • Panda Bears • 29:30 – 33:00   Computer Lab Phylogenetic Analysis Using Molecular Data Sets •

PART A ONLY

Biodiversity and Evolution Chapter 4 Part 3: Species Richness vs. Evenness

Species Diversity: Variety, Abundance of Species in a Particular Place



Species diversity

•

Species richness

– number of different species in a community •

Species evenness

– abundance of organisms within each type of species

Species Diversity: Variety, Abundance of Species in a Particular Place

 Most species-rich communities • Tropical rain forests • • Coral reefs Ocean bottom zone • Large tropical lakes

Species Diversity: Variety, Abundance of Species in a Particular Place

 1,700 different species of beetles in a SINGLE tree • Tropical Rainforest – Panama •

Species Richness?

•

Species Evenness?

Worldwide Richness?

 Diversity varies with geographical location • Richness is highest at tropics • Lowest at the poles

Science Focus: Species Richness on Islands (Ease of Study)



Species equilibrium model, theory of island biogeography

• Rate of new species immigrating should balance with the rate of species extinction  Island size and distance from the mainland need to be considered

Species-Rich Ecosystems Tend to Be Productive and Sustainable

 Species richness seems to increase productivity and stability  Organisms more resilient; greater genetic diversity

Species-Rich Ecosystems Tend to Be Productive and Sustainable

 Research suggests annual net primary productivity reaches its peak with 10-40 primary producer species

Your Turn!

 Species Diversity Index

Biodiversity and Evolution Chapter 4 Part 4: Speciation

Geologic Processes Affect Natural Selection

 Tectonic plates affect evolution and the location of life on earth • Location of continents and oceans • Species physically move, or adapt, or form new species through natural selection  Earthquakes  Volcanic eruptions

225 million years ago 65 million years ago 135 million years ago Present

Changes in Ice Coverage in the Northern Hemisphere During the last 18,000 Years

Speciation



Speciation

is the formation of new species.

• Group of organisms that breed with one another and produce fertile offspring.

What factors are involved in the formation of new species?

 The gene pools of two populations must become

separated

for them to become

new

species.

 As new species evolve, populations become

reproductively isolated

from each other.

Geographic Isolation



Geographic isolation

occurs when two populations are separated by geographic

barriers

such as rivers, mountains, bodies of water.

Geographic Isolation

 Does not guarantee the formation of new species • May separate certain types of organisms

(small rodents)

but not others

(birds).

Genetic Drift

 Individuals may carry alleles in different relative frequencies than did the which they came.

larger

population from

The Founder Effect

 Situation in which allele frequencies change as a result of the migration of a small subgroup

Reproductive Isolation

 When the members of two populations cannot interbreed and produce fertile offspring,

reproductive isolation

has occurred.

Reproductive Isolation



Each population will respond to natural selection as

separate

units

Geographic Isolation Can Lead to Reproductive Isolation

Extinction is Forever



Extinction



Endemic species

• Species found only in one area • Particularly vulnerable • Golden Toad (Costa Rica) died out when habitat dried up

Extinction Can Affect One Species or Many Species at a Time



Background extinction

– throughout most of history species have disappeared at a low rate •

Average annual extinction = 1 to 5 species for every million on earth



Mass extinction

• Significant rise in extinction rates • Scientists estimate between 3 and 5 mass extinctions during the history of the Earth

Video Clip

 Endangered Animals • Echo 25:44 – 31:30

Science Focus: We Have Two Ways to Change the Genetic Traits of Populations



Artificial selection



Genetic engineering, gene splicing

 Consider • Ethics • Morals • Privacy issues • Harmful effects

Natural Selection on Polygenic Traits

 How does natural selection affect polygenic traits?

1.

2.

3.

Directional Selection Stabilizing Selection Disruptive Selection

Directional Selection

 When individuals at one end of the curve have higher

fitness

than others  Range of phenotypes shifts as some individuals survive and reproduce while others

fail

Stabilizing Selection

 When individuals near the

center

of the curve have higher fitness than at either end • Keeps the center of the curve at its current position •

Narrows

the overall graph

Stabilizing Selection



Example

• Human babies born at an average mass are more likely to survive than babies born either much smaller or much larger than average

Disruptive Selection

 When individuals at the

upper

and

lower

ends of the curve have higher fitness than individuals near the middle  If the pressure of natural selection is strong enough and long enough, the curve will split, creating two distinct

phenotypes

Disruptive Selection



Example

• If average-sized seeds become scarce, a bird population will split into two groups: • One that eats

small

seeds and one that eats

large

seeds

Your Turn…Seed Lab!

 Step 1 – Sort your pile of sunflower seeds according to number of stripes • Only count ONE side  Step 2 – Place your seeds in appropriate tubes  Step 3 – Create a paragraph describing a situation which lead to EACH of the following types of selection • Directional • • Stabilizing Disruptive

Biodiversity and Evolution Chapter 4 Part 5: Ecological Roles

Each Species Plays a Unique Role in Its Ecosystem



Ecological niche

• Role a species plays in an ecosystem • Pattern of living (reproduction, amount of sunlight, space, temperature, etc.) 

Habitat

• Location organism lives

Keystone, Foundation Species Determine Structure, Function of Their Ecosystems



Keystone species

– have a large effect on the types and abundances of other species in an ecosystem • Pollinators • Top predator

Keystone, Foundation Species Determine Structure, Function of Their Ecosystems



Foundation species

• Create or enhance their habitats, which benefit others • Elephants • Beavers

Case Study: Why Should We Protect Sharks?

 Keystone species • Eat dead and dying fish in the ocean • Strong immune systems • Wounds do not get infected • Almost never get cancer • Could help humans if we understood their immune system

Each Species Plays a Unique Role in Its Ecosystem



Generalist species

• Broad niche • Live in different places, eat different food, high range of tolerance •

Examples?



Specialist species

• Narrow niche • More prone to extinction •

Examples?

Specialist Species and Generalist Species Niches

Niches Can Be Occupied by Native and Nonnative Species



Native species

– organisms that normally live and thrive in a particular ecosystem 

Nonnative species

invasive, alien, or exotic species • May spread rapidly • Not all are villains

Indicator Species Serve as Biological Smoke Alarms



Indicator species

– species that provide early warnings of damage to a community or ecosystem • Can monitor environmental quality • Trout • • Birds Butterflies • Frogs

Coal Canaries: 1800s – 1900s

 Coal miners took caged canaries into mines to act as early warning sentinels  If birds stopped singing and appeared to be distressed miners knew there were poisons being released

Case Study: Why Are Amphibians Vanishing?

   Sensitive biological indicators of environmental changes Adult amphibians • Eat more mosquitoes than birds Genetic storehouse of pharmaceutical products

Case Study: Why Are Amphibians Vanishing?

 Habitat loss and fragmentation  Prolonged drought  Pollution  Increase in UV radiation (no protection for eggs)  Parasites, viral and fungal diseases  Climate change  Nonnative predators and competitors

Strange Days on Planet Earth Video Clip

 Troubled Waters: Frogs and Atrazine