Ap Bio Chapter 22, 23, & 24

Front 1

What is speciation?

Back 1

Speciation is the process where one species splits into 2 or more species. It creates diversity and explains why many species share features.

Speciation is the bridge between microevolution and macroevolution.

Front 2

What is microevolution?

Back 2

(changes in allele frequency in a population)

Front 3

What is macroevolution?

Back 3

(evolution at the species level)

Front 4

What is the biological species concept?

Back 4

The biological species concept states a species is a group of populations whose members have the ability to interbreed in nature and produce viable, fertile offspring (but don’t produce viable, fertile offspring with members of other groups).

Front 5

reproductive isolation

Back 5

Reproductive isolation consists of biological barriers that prevent two species from interbreeding and producing viable, fertile offspring.

Front 6

Barriers blocking gene flow

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Barriers block gene flow between and reduce the formation of hybrids (offspring that results from the mating of two different species). Sometimes it takes more than one barrier to isolate a species’ gene pool.

Front 7

2 Types of Barriers

Back 7

-Prezygotic and Postzygotic

There are two separate types of barriers based on isolation before or after fertilization. Prezygotic (before the zygote) barriers block fertilization and postzygotic (after zygote) barriers contribute to reproductive isolation after the hybrid is formed.

Front 8

Prezygotic barriers:

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-Habitat isolation- Two species occupy different different habitats in the same area but rarely encounter one another (water fowl and birds on land).

-Temporal isolation- The species breed at different times of the day, seasons, or years preventing reproduction (Eastern spotted skunk breeds in late winter and western spotted skunk breeds in late summer).

-Behavioral isolation- Courtship rituals that attract mates of the same species (male blue-footed boobie high stepping to show his blue feet to a potential mate).

-Mechanical isolation- mating is attempted but difference prevent successful completion (the shells of two species of snails spiral in different directions preventing their genitals from aligning properly).

Front 9

What are some other definitions of species?

Back 9

The morphological species concept characterizes a species by their body shape/structure. The issue with using this distinction is trying to agree on which structures distinguish a species.

The ecological species concept looks at a species based on its ecological niche (how the members of the species interact with the living and nonliving parts of their environment).

The phylogenic species concept defines a species as the smallest group of individuals that share a common ancestor, forming one branch on the tree of life.

Front 10

Discuss speciation with or without geographic separation.
W/ Allopatric (other country) and Sympatric (same country)

Back 10

Allopatric (other country) speciation occurs when gene flow is interrupted when a population is split into geographically isolated sub populations (river changes course and divers two populations or the water levels in a lake decreases creating two smaller lakes with separate populations).

The separation can cause gene pools to diverge. Different mutations, natural selection, and genetic drift can change the allele frequency in the two populations. Reproductive isolation can then arise from the genetic divergence Ex. Mosquito fish p. 423

Sympatric (same country) speciation occurs in populations that live in the same geographic area (it isn’t as common as allopatric speciation).

Sympatric speciation can occur if gene flow is reduced by polyploidy, habitat differentiation, and sexual selection.

Front 11

Habitate differentiation
when does it occur?

Back 11

-Habitate differentiation occurs when genetic factors let a subpopulation exploit a habitat or resource not used by the parent population. The North aAmerican Apple maggot fly is an example. The fly’s original habitat was the Hawthron tree, but 200 years ago some populations colonized apple tree planted by European settlers. Apples mature faster then hawthorn fruit, and though natural selecetion the apple feeding flies develop faster. The apple feeding flies now have temporal istolation (breeding times) from the hawthrown feeding flies.

Front 12

Sexual selection
when does it occur?

Back 12

-Sexual selection typically occurs when females select mates based on appearance and is thought to be a possible answer to the number of cichlids species produced in East Africa’s Lake Victoria (up to 600 species from a few colonizing species). See figure 22.2

Front 13

What is Polyploidy and when does it occur?

Back 13

Polyploidy occurs when an accident happens during cell division giving one cell too many chromosomes. It is not common in animals (the grey tree frog is thought to originate this way) but happens more frequently in plants.

Front 14

Two types of polyploidy

Back 14

autopolyploidy and allopolyploidy

Front 15

Autopolyploidy

Back 15

An autoplolyploidy is an individual that has two chromosome sets dervived from a single species.

An example would be a plant cell that has double the number of chromosomes because cell division didn’t occur (cell no longer diploid [2n] but tetraploid[4n]). A tetraploid can produce fertile tetraploid offspring through self pollination or mating with other tetraploid plants but are now reproductively isolated from diploid plants.

Front 16

Allopolyploidy

Back 16

An allopolyploidy is a fertile polyploidy hybrid that can only mate with others like itself but not with either parent species that created it. (Remember, hybrids are created when two different species mate, but most are sterile. Some infertile hybrid plants can propagate asexually and after many generations change from a sterile hybrid into a fertile polyploidy).

Allopolyploidy is very rare but has created at least 5 plant species in the last 150+ years.

-Habitate differentiation occurs when genetic factors let a subpopulation exploit a habitat or resource not used by the parent population. The North aAmerican Apple maggot fly is an example. The fly’s original habitat was the Hawthron tree, but 200 years ago some populations colonized apple tree planted by European settlers. Apples mature faster then hawthorn fruit, and though natural selecetion the apple feeding flies develop faster. The apple feeding flies now have temporal istolation (breeding times) from the hawthrown feeding flies.

-Sexual selection typically occurs when females select mates based on appearance and is thought to be a possible answer to the number of cichlids species produced in East Africa’s Lake Victoria (up to 600 species from a few colonizing species). See figure 22.2

Front 17

What are hybrid zones?

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Hybrid zones are regions where members of different species meet and mate, producing some offspring of mixed ancestry. They occur where the habitats of the interbreeding species meet. This is seen when the habitats of the yellow-bellied toads (livein higher altitudes) and red bellied toads (live in lower altitudes) meet. The toads do meet and reproduce in a hybrid zone, but the offspring have poor survival and reproductive survival rates dues to embryonic and morphological anomalies (abnormal tadpole mouthparts and ribs fused to the spine).

Front 18

Overtime there are three outcomes for hybrid zones:

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-Rienforcement of barriers- Less fit hybrids and natural selection strengthens Prezyotic barriers and reduce the formation of unfit hybrids.

-Fusion of species- Two hybrid species fuse into a single species (reverse speciation).

-Stability- Hybrid zones become stable, continuing to produce hybrid organisms.

Front 19

What is punctuated equilibrium?

Back 19

Punctuated equilibrium involves periods time in the fossil records where no new species appear punctuated by times when many new species appear, then become extinct.

Some species don’t show punctuated, but gradual changes over time.

Front 20

Where are the richest sources of fossils found?

Back 20

The sedimentary rock layers (strata) have the greatest number of fossils.

The fossils give us a detailed account of biological changes that have occurred over time, but it is still an incomplete record (fossils destroyed by geological changes, organisms that existed but didn’t form fossils, or fossils that still remain undiscovered).

Fossils and rocks can be dated using radiometric dating (the decay of radioactive isotopes). The rate of decay of the isotopes is based on the time it takes for ½ of the parent isotope to decay, the half-life. This time to decay is stable and unaffected by temperature or pressure. Carbon-14 decays quickly with a half-life of 5730 years, whereas uranium 238 decays slowly with a half-life of 4.5 billion years.

Front 21

How was the geologic record created?

Back 21

The study of fossils lead to the creation of the geologic record. The geologic record divides the Earth’s history into four eons (Hadean, Archaean, Proterosoic, and Phanerozic), and eons are subdivided into eras.

The Phanerozic eon is divided into the Paleozoic, Mesozoic, and Cenozoic eras (each ear is then divided into periods). See p.439

Front 22

Discuss plate tectonics.

Back 22

The theory of plate tectonics explains the movement of continents over time (Pangaea).

The continents are part of plates of the Earth’s crust and float on the hot, underlying portions of the mantle. Convection causes the plates to move in a process known as continental drift. The plates move a few centimeters each year.

The continents drift affects life on Earth by altering habitats over long periods of time, affecting climate over long periods of time, and creating large scale allopatric speciation.

Front 23

Discuss mass extinction.

Back 23

Mass extinction occurs when large numbers of species become extinct. The fossil record shows that most of the species that have ever lived have become extinct.

Five mass extinctions have occurred during the last 500 million years. The Permian and Cretaceous extinctions are the most well known of the five.

Front 24

The Permian extinction

Back 24

The Permian extinction marks the boundary between the Paleozoic and Mesozoic eras (251 million years ago) and claimed roughly 96% of marine animals. Major volcanic eruption occurred during this time creating layers of lava hundreds to thousands of feet thick. High amounts of carbon dioxide raised the Earth’s temperatures, lower oxygen levels in the oceans, and affected the ozone layer.

Front 25

The Cretaceous extinction

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The Cretaceous extinction occurred 65.5 million years ago and marks the boundary between Mesozoic and Cenozoic eras. This is when the dinosaurs become extinct, possibly by an asteroid.

Front 26

The consequences of mass extinctions are as follows:

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-Loss of an evolutionary lineage (once an organism becomes extinct, evolution is changed forever)
-Altering ecological communities by changing the types of organisms

Front 27

Discuss adaptive radiation.

Back 27

Adaptive radiation constitutes periods of evolutionary change where groups of organisms form new species whose adaptations left them fill different riches in their community.


After each of the 5 mass extinctions surviving organisms became adapted to new riches ushering in large scale adaptive radiation.

After the extinction of the dinosaurs, mammals changed due to adaptive radiation.

Regional adaptive radiation is also seen in areas like the Hawaiian archipelago. The islands were formed from volcantic eruption and were there “nacked”. Organisms slowly inhabited the islands (traveling by way of wind and weather), with each islands displaying its own diversity.

Front 28

Discuss heterochrony.

Back 28

Heterochrony are evolutionary changes in the rate of timing of developmental events.

An organism’s shape is affected by the growth rates of different body parts during its development. If you change the rates of development, you alter the adult organisms form.

Heterochrony can also affect the timing of reproductive development. If sexual organs develop at a faster rate than normal, the organisms may retain juvenile structures even though they have become sexually mature (salamander that still retains gills and larval structures but are sexually mature). This is known as paedomorphosis (retention in an adult organism of juvenile features found in its evolutionary ancestors).

Front 29

Discuss evolutionary changes based on spatial patterns.

Back 29

Evolutionary changes can result form alterations in genes that affect the placement (special organization) of body parts. Where an organism’s limbs or wings, or where a plant’s flowers are placed is affected by regulatory genes (know as homeotic genes). One of these genes, the Hox gene, affect where many different embryonic organisms’ appendages are located.

Front 30

Discuss prokaryotes.

Back 30

Prokaryotic organisms (bacteria and archaea) were the first forms of life on Earth, and are cells lacking a nucleus or membrane bound organelles.

The oldest known prokaryotic organisms are approximately 3.5 billion years old cells:

-The abiotic synthesis of small organic molecules like amino acids and nitrogenous bases.

-These small molecules form protocells (droplets with a membrane and internal chemistry).

Front 31

What was Earth’s early atmosphere like?

Back 31

Earth’s early atmosphere was made up of little oxygen, lots of water vapor, nitrogen, carbon dioxide, methane, ammonia, and hydrogen.

It was hypothesized (by Oparin and Haldane) that in Earth’s early atmosphere organic molecules were formed using the energy from lightening strikes and intense UV radiation to combine simple molecules.

The first genetic material on Earth was most likely RNA (not DNA). Short pieces of RNA could be created by ribozymes (RNA catalyst) and nucleotide building blocks.

The oldest known fossils from early Earth (3.5 million years ago) are stromatolites (layered rocks that form from certain prokaryotic activity).

IN 3.4 million year old stromatolites found in South Africa, scientists discovered Cyanobacteria (photosynthetic bacteria). These bacteria began producing oxygen (and still do today).

Front 32

Discuss the structures of prokaryotic organisms.

Back 32

Most prokaryotes are unicellular, and much smaller than eukaryotic cells.

They all have a cell wall, which helps maintain shape, prevent bursting in hypotonic environments, and provide protection.

If prokaryotic cells are places in hypertonic environments, they shrink and move away from the cell wall (plasmolysis). This inhabits reproduction (and why salt is used to preserve foods and prevent spoilage).

The cell walls of prokaryotic organisms is made up of peptidogylcan (eukaryotic cell walls are made up of chitin or cellulose). Peptidoglycan covers the entire bacterium and anchors others molecule from the cell surface.

Front 33

Bacteria are classified by...

Back 33

Bacteria are classified by the composition of their cell walls, and the differences can be seen using Gram staining (discovered by Hans Christian Gram). Gram positive bacteria lower amounts of peptidoglycan, and simple walls. Gram negative bacteria have lower amounts of peptidoglycan, but more complex walls vontaining lipopolysaccharides.

Front 34

Gram positive bacteria stain darker (purple) because....

Back 34

Gram positive bacteria stain darker (purple) because of the large amounts of peptidoglycan. Gram negative bacteria help protect them from our body’s defenses and the lipids in the peptidoglycan are toxic (causing fever and/or shock). The cell walls also makes gram negative bacteria more resistant than Gram positive bacteria to many antibiotics.

Front 35

The cell wall of many prokaryotes are surrounded by...

Back 35

The cell wall of many prokaryotes are surrounded by a sticky protein or polysaccharide layer known as a capsule. Some capsules protect against attacks form a host cell’s immune system or protect form dehydration in dry conditions.

Front 36

Some bacteria form _____ when needed nutrients for survival aren't available...

Back 36

Some bacteria form endospores when needed nutrients for survival aren’t available, allowing the bacteria to become dormant until favorable conditions arise. Some endospores are so durable they can even survive boiling (temperatures of 121*C or 250*F are needed to destroy them [boiling is 212*F]). Theses bacteria can survive for centuries because of their endospore formation. –can live for centuries/100s of years

Front 37

Some prokaryotes have the ability to stick to one another or other objects by...

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Some prokaryotes have the ability to stick to one another or other objects by hairlike appendages known as fimbriae (gonorrhea use it to stick to a host’s mucus membrane).

Pili are short hair like structures on bacteria that allow two cells to pull together and transfer DNA (sometimes called sex pili).

Front 38

Discuss motility in prokaryotes

Back 38

Taxis is the directed movement toward or away from a stimulus, and about half prokaryotes are capable of it. Chemotaxis is an example (moving toward or away from chemicals).

Flagella are the most common form of motility in prokaryotes. Bacteria flagella consist of a motor, hook, and filament.

Front 39

Discuss the internal structure and DNA of prokaryotic organisms.

Back 39

Prokaryotic cells lack membrane bound organelles, but some prokaryotes do have specialized membranes (in foldings of the plasma membrane) that perform metabolic functions. Other prokaryotes can store metabolic by-products in simple compartments made of protein.

Prokaryotes have less DNA than eukaryotes. Prokaryotes have circular chromosomes, where eukaryotes have linear chromosomes.

Prokaryotes don’t have a nucleus, their DNA is found in the nucleoid (area of cytoplasm). They also have smaller rings of DNA (only containing a few genes) known as plasmids.

Ribosomes are smaller in prokaryotes than eurkaryotes. This difference allows particular antibiotics to affect bacteria (blocking protein synthesis) but not eukaryotic cells.

Front 40

Discuss nutritional and metabolic adaptations in prokaryotes.

Back 40

Prokaryotes can be classified by how they obtain energy. Prokaryotes can be autotrophs (photoautotrophs- light as energy source or chemoautotrophs- inorganic chemicals as energy source) or heterotrophs (photoheterotrophs light as energy source or chemoheterotrophs- organic compounds as energy source).

Oxygen also plays a role in metabolism. Obligate aerobes need oxygen for cellular respiration, obligate anaerobes are poisoned by oxygen. Some obligate anaerobes exist using fermentation and others use anaerobic respiration (substances other than oxygen are used as electron acceptors in the electron transport chain [nitrate or sulfate ions]).

Prokaryotic organisms can metabolize nitrogen (eukaryotic organisms must obtain nitrogen from nitrogen containing compounds). Some prokaryotes can turn atmospheric nitrogen into amino acids or other organic molecules, this is known as nitrogen fixation. Nitrogen fixation is essential for plants (bacteria in the roots fix atmospheric nitrogen into amino acids or other organic molecules, this is known as nitrogen fixation. Nitrogen fixation is essential for plants (bacteria in the roots fix atmospheric nitrogen into a form they can use).

Front 41

Discuss metabolic cooperation in prokaryotes.

Back 41

Coorperation between prokaryotic organisms allows them to use environmental resources they couldn’t utilize individual. Metabolic cooperation between different prokaryotic species often occurs in colonies called biofilms. Bacteria cells in a biofilm secrete signaling molecules that attract other cells, increasing the size of the colony. The cells produce polysaccharides and proteins that allow the cells to stick to one another and to other objects. Biofilms are common in nature (containing industrial products, medical equipment, and causing tooth decay).

Single bacterial cells can’t perform photosynthesis and nitrogen fixation at the same time (oxygen inactivates the enzymes needed for nitrogen fixation). Heterocystes helps bacterial cells to do both. The hetrocysts are surrounded by thick walls to prevent oxygen from entering, allowing them to perform nitrogen fixation. Heterocysts helps bacterial cells do both. The heterocysts are surrounded by thick walls to prevent oxygen from entering, allowing them to perform nitrogen fixation.

Front 42

Discuss reproduction in prokaryotes.

Back 42

Prokaryotes rapidly reproduce by binary fission (some can double every 20 minutes). Bacteria don’t overtake the Earth because they exhaust their food supplies, face competition from other microorganisms, are consumed by other organisms, and poison themselves with waste.

Genetic mutations during bacterial reproduction are rare but do provide diversity in prokaryotic organisms. Diversity in bacteria also comes about from genetic recombination (combining the DNA from two sources- like meiosis and fertilization in humans).

Front 43

Bacteria have genetic recombination through the following mechanisms:

Back 43

Transformation
Transduction
Conjugation

Front 44

Transformation

Back 44

-Transformation- involves the untake of DNA from an organism’s surroundings or other bacteria (harmless S. pneumoniae transformed into pneumonia if exposed to a pathogenic strain).

Front 45

Transduction

Back 45

-Transduction- Phages (viruses that infect bacteria) carry prokaryotic genes from one host cell to another, the DNA is incorporated into the recipient’s chromosome, and a recombinant cell is formed. (Figure 24.15)

Front 46

Conjugation

Back 46

Conjugation- DNA is transferred between two prokaryotic cells (usually the same species) while there are temporarily joined. The pilus of the donor cell attaches to the recipient cell, and retracts pulling the two cell together. A “mating bridge” forms and DNA is transferred to the donor cell.

Front 47

If a bacterial cell has a piece of DNA or a plasmid known as the F factor (fertility) or F plasmid, it will form____and___ during conjugation.
These cells are said to be___.

Cells that don’t have a F factor or F plasmid are___, and are ____ during conjugation.

Back 47

If a bacterial cell has a piece of DNA or a plasmid known as the F factor (fertility) or F plasmid, it will form pili and donate DNA during conjugation. These cells are said to be F+.

Cells that don’t have a F factor or F plasmid are F-, and are recipients during conjugation.

*** If a copy of the F factor is transferred during conjugation, a F- cell will become F+. ****

Front 48

How is antibacterial resistance transferred?

Back 48

A genetic mutation confers antibiotic resistance to a bacterium, and the gene mutation is often found in the plasmid (R plasmid). This is then passed on during conjugation.

Front 49

Discuss the differences between bacteria and archaea.

Back 49

Most prokaryotic organisms are bacteria with which we are familiar, from pathogenic species to beneficial species.

Archaea are prokaryotes that share similarities with bacteria and eukaryotic organisms.

Many live in extreme environments where other organisms would perish. These archaea are known as extremophiles. Extreme halophiles live in highly salty environments (Great Slat Lakes or Dead Sea). Extreme thermophiles live in very hot temperatures (volcanic springs). Methanogens are archaea that live in areas with oxygen and produce methane when producing energy.

Front 50

List the major groups of bacteria.

Back 50

Proteobacteria are a large group of gram negative bacteria that include autotrophs, heterotrophs, and chemoautotrophs. This group has fix subgroups:
-Alpha proteobacteria
-Beta proteobacteria
-Delta proteobacteria
-Epsilon proteobacteria

-Chlamydias
-Spirichetes
-Cyanobacteria
-Gram positive bacteria

Front 51

Alpha proteobacteria

Back 51

This group includes many nitrogen fixing bacteria

Front 52

Beta proteobacteria

Back 52

Soil bacteria that recycle nitrogen

Front 53

Gamma proteobacteria

Back 53

- includes pathogens like Legionella (Legionnaire’s disease), Salmonella, Vibro cholerae (chlorella), and E coli.

Front 54

Delta proteobacteria

Back 54

Myxobacteria that form myxospores where conditions aren’t favorable.

Front 55

Epsilon proteobacteria

Back 55

Campylobacter (blood poisoning) Helicobacter pylori (stomach ulcers).

Front 56

Chlamydias

Back 56

Can only live in animals, are gram negative, and cause Chlamydia.

Front 57

Spirichetes

Back 57

Are Gram negative, helical bacteria (syphilis and Lymes dsease).

Front 58

Cyanobacteria

Back 58

Are Gram negative photoautotrophs

Front 59

Gram positive bacteria

Back 59

Characteristics :
Decomposers, Streptococcus, Staphylococcus, Clostridium botulinum, Bacillus anthracis (anthrax), and Mycoplasmas (only bacteria with no cell walls).

Front 60

Discus prokaryotic chemical recyclers.

Back 60

Some prokaryotes function as decomposers, breaking down dead organisms and waste (turingin it into carbon, nitrogen, or other elements).

Some prokaryotes break down molecules into forms that can be used by other proganisms (Cyanobacteria convert carbon dioxide into oxygen, nitrogen fixation).

Front 61

Ecological interactions (other word for it) and the 3 types

Back 61

Symbiosis is an ecological relationship where two species life in close contact with one another. The following are types of symbiosis:
-Mutualism- Symbiotic relationship where both species benefit.
-Commensalism- Symbiotic relationship where both species benefits and the other isn’t helped or harmed.
-Parasitism- Symbiotic relationship where one species benefits (parasites and the other is harmed (host). Parasite that cause disease are pathogens.

Some prokaryotes enter into a Symbiotic relationship with a much larger host, the small prokaryote is then known as a symbiont.

Front 62

Discuss how prokaryotes affect us as humans.

Back 62

Many bacteria are mutualistic, like E. coli that lives in our intestines (they out number the cells in our bodies 10:1. Our intestines give them a place to live and food to eat, and they help break down waste.

Pathogenic bacteria cause disease, and are the most well known. They usually cause illness by producing exotoxins (poisons produced by the bacteria) or endotoxins (poisons produced and released only when bacteria die).

*Cholera produce exotoxins, and Salmonella, E. coli 157 both produce endotoxins.
*Bacteria are used to make cheese, sauerkraut, and soy sauce.
*Some bacteria can be used to make plastics.
*Bioremediation is the use of bacteria to remove pollutants from the air, soil, or water.