Unit 3: Evolution Flashcards
Charles Darwin’s observations that finches of different species on the Galapagos Islands have many similar physical characteristics support the hypothesis that these finch species:
originated from a common ancestor
What is the term for an inherited characteristic that improves an organism’s ability to survive and reproduce in a particular environment?
an adaptation
Which pattern of diversity did Darwin recognize when visiting the Galapagos Islands?
species varied locally
In biology, fitness is the ability of the individual to
contribute to the gene pool of the next generation
macroevolution
-the extinction of species
-the evolution of major new features of living things, such as wings or flowers
-speciation
Speciation and extinction both are evolutionary forms?
True
Which of the following speciation types is less likely to include successful hybrids?
Sympatric
adaptive radiation
Evolution from a common ancestor that results in a diverse species adaptive to different environments (aka divergent evolution)
disruptive selection
individuals at the upper and lower ends of the range of phenotypes that have higher fitness than individuals near the middle
genetic drift
change in the gene pool of a population due to chance
gradualism
evolution of a species by gradual accumulation of small genetic changes over a long period of time
microevolution
generation-to-generation change in the frequencies of alleles within a population
reproductive isolation
inability of two organisms to reproduce due to a physical or behavioural barrier
Sexual selection
Sexual selection is a “special case” of natural selection in which individuals compete for mates in order to pass on their genes to future generations.
Ex. A peacock’s tail is used to attract females for mating, ensuring that a male passes his genes on to the next generation.
Directional selection
a mode of negative natural selection in which an extreme phenotype is favored over other phenotypes, causing the allele frequency to shift over time in the direction of that phenotype.
Stabilizing selection
Stabilizing selection is a form of natural selection wherein individuals with moderate or average phenotypes are more fit (more likely to survive and reproduce). This form of selection picks against phenotypic extremes (e.g. the largest and the smallest are less fit)
natural selection
Natural selection is the process through which populations of living organisms adapt and change. Individuals in a population are naturally variable, meaning that they are all different in some ways. This variation means that some individuals have traits better suited to the environment than others.
artificial selection
Artificial selection is the process by which humans choose individual organisms with certain phenotypic trait values for breeding. If there is additive genetic variance for the selected trait, it will respond to the selection, that is, the trait will evolve.
founder effect
The Afrikaner population has a higher incidence of Huntington’s disease than the Dutch population in Holland does.
gametic isolation
Ex. A purple sea urchin’s sperm cannot fuse with a red sea urchin’s egg
mechanical isolation
Ex. Two species of bush babies have differently shaped genitals.
mimicry
Ex. A non-poisonous hoverfly looks like a poisonous wasp.
punctuated equalibrium
The lack of transitional species can be explained by this process.
What are the divisions on the Geological time scale marked by?
distinct changes in the types of fossilized life
What is true about mass extinctions that occurred in the past?
they were followed by diversification of some of the survivors
Which of the following statements is true about organisms in the same clade?
they share a common ancestor that belongs to the same clade
Why are paleontologists interested in the species Ardipethicus ramidus?
it indicates that chimpanzees have evolved different features, such as knuckle walking after the human and ape lineages diverged
Which of the following most likely appeared first as humans diverged from other primates?
bipedalism
Why are Europeans less susceptible to HIV?
natural selection forces, through previous exposure to HIV, have left the European population more immune to HIV
Prokaryotes have a cell wall made out of peptidoglycan, and plants have a ac cell wall made out of cellulose. What does this indicate
the cell walls are analysis structures
The rise of living material from non-living material is the basis of which early theory?
primary abiogenesis theory
Why is the artificial selection of crops a concern?
it may decrease the genetic diversity of the crops
What are the 2 main points Darwin makes in his book?
-All species of organisms living on Earth today are descended from ancestral species.
-The mechanism that causes species to change over time is natural selection.
How did the exoskeleton contribute to the evolutionary success of trilobites?
evolved spiny exoskeletons for defence, Many trilobites also evolved modified exoskeletons that would let them roll up into an armoured ball, as pill bugs do today. These evolutionary clues suggest that the exoskeleton played an important role in the success and survival of trilobites.
How did jointed limbs contribute to the evolutionary success of crustaceans?
Over time, the basic limb layout of the ancestral arthropod evolved into specialized forms suited for different functions, allowing arthropods to invade new niches and habitats, also allowing for movement
Why couldn’t terrestrial arthropods evolve to be as large as elephants
Arthropods inherited both an exoskeleton and jointed legs. These traits have opened up many opportunities in arthropod evolution, but they have also blocked other possibilities.
- Molting: Molting is more hazardous for larger animals.
- Exoskeleton strength: The exoskeleton may not be strong enough to support larger animals.
- Respiration: Many arthropods can only get enough oxygen to support small bodies
Decent with Modification
Darwin proposed that descendants of early ‘creatures’ moved to different locations on Earth over millions of years
Those descendants needed to modify or adapt to the environments around them
Natural Selection
Is a process where:
Heritable traits allow an organism to survive
Organisms successfully reproduce
Traits become more common with the regular population
Natural selection requires
Reproduction
a new generation must form
struggle for existence
2. Heredity
offspring resembles its parents (passes from one generation to the next)
3. Variation in population
differences among members in the same species
4. Fitness differences associated with variation in population
survival of the fittest
can’t all be neutral changes
some must be advantageous
when all 4 criteria are met:
organisms with the traits which yield the highest fitness will produce more successful offspring
the frequency of these types will increase within the population as each generation passes
for example: antibiotic resistance in Bacteria
Fitness:
Fitness is the relative reproductive success as measured by selection in a particular environment .
Fitness, furthermore, is the ability of an organism to transmit its genes to the next reproductively fertile generation, relative to other such genotypes in the same environment.
What is “Fitness”?
fitness does NOT mean athletic fitness
it is the probability that they are able to survive and reproduce
it is the average # offspring produced by a single genotype relative to # offspring produced by another genotype
Macroevolution
Large amounts of change
Give rise to new species; derivation of NEW species from ancestral species
Difficult to design experiments to test for this
Time scale is one of the biggest problems
Microevolution
Changes in gene or allele frequencies (Mendelian Genetics)
Changes within a species, between populations
Fine details of change at the gene or allele level
Relatively easy to design experiments to test this
Through the macroevolution and microevolution processes we either arrive at:
Speciation
-The origin of new species
Extinction
-The disappearance of a species
Speciation: Types
Allopatric – different home; and with no gene flow between them
Parapatric – side-by-side homelands
Sympatric – same homelands
Allopatric Speciation:
probably the major type of speciation in vertebrates
speciation by geographic isolation
most evolutionary biologists agree with this because it is easy to observe (macroevolution) in lots of examples
the bigger the barrier the more extreme the segregation
Parapatric Speciation:
less easy to comprehend, difficult to find examples
speciation in adjacent populations, with a hybrid zone
if selection favors different alleles in two parapatric populations a ‘cline’ in allele frequency is established
with strong selection, populations can differentiate into two reproducible isolated groups
example: heavy metal tolerance in grasses
Sympatric Speciation:
speciation within a population of the same geographic area
may not be important in motile animals
clearly occurs in plants
Types of Evidence:
Geographic distribution (Pangaea?)
The fossil record
Comparative anatomy
Comparative development
Molecular biology
Artificial Selection
Antibiotic resistance in bacteria
Continental Drift:
Alfred Wagener (1880-1930)
He believed in a supercontinent called PANGAEA
He believed in Continental Drift
Some reasons he believed this were:
Fit of continents
Similar species on different continents
Unique fossils
Paleomagnetism
Ocean floor spreading
The Fossil Record:
- almost all fossils are in sedimentary rock
-transitional forms are rarely in the same location as ancestral forms
(fossil formation is a relatively rare event) - the advantage of the fossil record over present-day observations of evolution is that higher-order evolutionary changes may be tracked
-The disadvantage is its difficult to determine selective forces that may have contributed to these changes (buried, scavenged, etc.)
Evidence Examples in the Fossil Record:
the Archaeopteryx
true missing link between reptiles and birds
discovered in Germany in 1861
reptilian features: teeth, 21 vertebrates in the tail
avian features: wishbone. feathers
the Coelacanths
lobed-finned fish thought to have evolved into terrestrial vertebrates about 200 million years ago
formerly known only as fossils
1938 a fisherman caught one, near Madagascar
Comparative Development & Anatomy:
There are 2 main categories that show similarity in structure:
Homologous structures
Vestigial organs
Homologous Structures
Darwin evolutionary explanation for homologous structures:
“A structure is similar among related organisms because those organisms have all descended from a common ancestor that had an equivalent trait”
Vestigial Structures
structures that are functionless in a species but homologous to a functioning structure in another species
points to a theory of common descent
extremely illogical if each creature were independently created
makes sense if organisms inherit traits from their ancestors with a gradual modification over time
e.g. whale pelvic girdle
Artificial Selection
occurs when humans selectively breed organisms for their (humans) own benefit!
examples
horse breeder
cat breeder
dog breeder
Heritability:
is one of the most important qualitative genetic properties
predicts the response to selection and expresses the reliability of the phenotype in determining the breeding value
what else do we know from our genetics unit about heredity
Artificial Selection types
3 Types:
directional selection
stabilizing selection
disruptive
Evolution never..
Evolution never takes a break.
We can see this through several situations today (complex features, mimicry, symbiosis, adaptation).
Why can pesticides be a double-edged sword?
While they pose a risk to health and the environment, they also ensure that our food supply is not damaged or destroyed by pests, significantly reducing crop losses. Balancing these aspects is at the heart of this complex issue.
speciation
Speciation occurs when a group within a species separates from other members of its species and develops its own unique characteristics
reproductive isolation-
the inability of a species to breed successfully with related species due to geographical, behavioral, physiological, or genetic barriers or differences
convergent evolution
defined as the process whereby distantly related organisms independently evolve similar traits to adapt to similar necessities
hybrid
Hybrid speciation can be broadly defined as the hybridization between two or more distinct lineages that contributes to the origin of a new species.
heredity
Heredity refers to the genetic heritage passed down by our biological parents.
temporal isolation
Temporal isolation happens when two or more species reproduce at different times
behavioural isolation
when species are reproductively isolated from others due to differences in behavior. Behavioral isolation is a way in which nature prevents interbreeding of species through behavioral differences.
mechanical isolation
where no fertilization occurs and thus reproduction does not occur. Mechanical isolation includes any physical barrier that prevents mating.
gametic isolation
Gametic isolation is a type of prezygotic barrier. Gametic isolation happens when the egg and sperm are released but a zygote is not formed. A zygote is the cell produced when an egg and sperm unite. The term ‘gamete’ refers to the reproductive cells like eggs and sperm.
hybrid isolation-
Hybrids are reproductively isolated from parent species. Hybrids may sometimes be reproductively superior. to parent populations. If hybrid x hybrid matings confer Darwinian fitness, hybrid speciation can occur.
hybrid infertility
Hybrid sterility refers to the infertility of the offspring of a successful primary cross. Thus, the primary cross would be successful, but the secondary cross would fail. Dimorphic species have anatomically distinguishable male and female forms.
2 types of sexual selection
Intrasexual Selection- males compete
Intersexual Selection (Fischer Process)- when females chooses
What is Eugenics
A quest for perfection of a species
Who is Lucy? What is her scientific name?
Female human ancestors 3.2 million years ago, Ardipithecus ramidus
Why was she thought to be special?
Halfway between common ancestors and human Lucy skeletons as analyzed, Lucy was human from 3.2 million years ago. She stood on 2 legs, (bipedal)
What questions were scientists hoping to answer using Lucy? Why couldn’t they answer this question?
When and why is the bypealting evolved? (She was too far recent), (she was already bipedal for several generations
Clark’s new research team was formed in what year? In what country?
1981, in Ethiopia
What was Clark’s team looking for?
Old sediment lands, looking for ancestral pieces called hominid fossils
On December 17th in the third field season, what was the first piece of the hominid fossil found?
Molar tooth of a hominid
When the team returned to Aramis in 1994, what problems did they encounter?
Not easy to find fossils, scavengers who chewed most fallen pieces, usually ravenged by hyenas
What was the first major bone that was found?
tibia
How many bones had the team found by the end of the 1994 field season?
A partial skeleton - 90 bones
How long ago did the team believe Ardi was alive?
Millions of years ago before Lucy (she was 4.4 million years old)
How old did they find out Ardi actually was using geochronology?
She was 4.4 million years old, he brought samples, crushed it down and saw how much argon was within the gas to see how old she was.
Where was Ardi found?
awash river in aramis
What did the team want to see in Ardi?
They wanted to see its face
What did Clark’s team hope Ardi would tell us?
If they walked on 2 feet, how would we become human?
In 2003 the Ethiopian government allowed Ardi to travel where? Why?
To travel to Japan for a new phase of analysis (making replicates and slides of the bones)
What was Ardi’s environment like?
Savanna is safer at first, usually, but Ardis dense forests.
What did Ardi look like? How did she move?
She walked up on two legs (bipedal) (she has erupted molar teeth which indicated that she was a young adult) (intersexual selection, natural selection taking place)
Why bipedal?
Because of an indication on her pelvis that hominids had which shows that she didn’t walk on all fours but on two legs like us. Comparing Chamipze pelvis to Ardis and showed major differences. Very frontal skeleton small brain. Neither the chimp nor the human.
After watching this documentary, why is Ardi so special?
Showed fossil record and can conduct as much research about what the creature was still when it was alive. Sofer knots and rigged bones, not knuckle walker, different pelvis indicated that she is bipedal, gripper feet. She had a small brain,
Explain pesticide resistance?
We have simply caused pest populations to evolve, unintentionally applying artificial selection in the form of pesticides. Individuals with a higher tolerance for our poisons survive and breed, and soon resistant individuals outnumber the ones we can control
Explain anti biotic resistance in bacteria?
natural selection. Bacteria can become resistant to antibiotics through mutations that alter the cellular targets of antibiotics or by acquiring dedicated resistance genes from other bacteria
Charles Lyell
Very religious geologist
Assumed consistency of natural laws (except in the origin of species, too vague)
kind of causes which affected the earth in the past = those in operation today
Attempted to refute Lamar’s theories of progress and evolution by “mocking” him about the giraffe’s neck
Darwin cams to read Lamar’s work by reading Lyell’s
Jean-Baptiste Lamarck
firm believer in the fixity of species
network idea instead of a chain of linear style
questioned the fixity concept at age 50, abandoned the notion of fixity of species (1800)
his idea didn’t take off because everyone believed in a life scale
spontaneous generation experiment
simple forms of life made unorganized matter and subtle fluid (electricity and nervous fluid)
The active fluid acts upon gelatinous matter to carve out channels and form simple organisms, fluid then circulate to “vilify” the structure
Facts about Darwin
born in England
at age 16 went to Edinburgh to study medicine
at age 18 went to Cambridge to become a minister
Mediocre student
Was recommended to go on the Beagle as an unpaid naturalist in 1831
What 2 main points did Darwin make in his book?
- All species of organisms living on Earth today are descended from ancestral species.
- The mechanism that causes species to change over time is natural selection.
Darwin’s Voyage:
-around the world journey for almost 5 years
spent most of his time investigating the geology
-South America
-Galápagos Islands
-Pacific coral reefs
-brought back samples to study further
-began to see the struggle for subsistence among the Tierra del Fuego
-noted great diversity among species within the Galápagos Islands
Darwin’s Finches
on the mainland, there were insect-eating warblers and woodpeckers
Vs the Galapagos niche was filled by finches that were usually seed-eaters
Darwin’s Conclusions
a seed-eating finch arrived on the island and since there were no warblers or woodpeckers they could adapt to eat all sorts of food
Seeds
Worms
Fruit
Leaves
Thomas Malthus
in 1838 Darwin read Malthus’ essay on the principle of population (1798)
Malthus argued a law-like relationship between population growth and food production
Malthus was widely believed to have demonstrated that population growth would outstrip food production unless population growth was put in check.
Alfred Wallace (1823-1913):
the COMPETITOR!
around the same time as Darwin was putting out his theories on paper
Naturalists collecting birds, insects, and mammals in S.E. Asia
he actually wrote Darwin describing the “theory of natural selection”
Panic:
Darwin did not want to get the “shaft” so he had Lyell and Hooker arrange for both his and Wallace’s paper to be published in the Journal of the Linnaean Society (1858)
he and Wallace had come up with the exact same ideas at the same time
Darwin knew Wallace has more credibility than he did so he wanted his paper published alongside Wallace’s
Francesco Redi (1668)
Conducted an experiment using maggots and meat
sealed- no eggs, no maggots, no flies
Open- eggs, no maggots, flies
Mesh cover- no eggs, no maggots, no flies
Conclusion- All living matter is a product of lIving matter
Lazzaro Spallanzani (1729-1799)
wanted to disprove spontaneous generation
set up flask experiment
he put the broth into two flasks and sterilized them both by boiling the broth
Once the flask was left open to the air
The other flask was stalked to keep any organisms that could be in the air
Microorganisms develop only in uncovered flasks
Louis Pasteur (1822-1875)
Similar experiments to Spallanzani, except both flasks allowed air to flow in
1959
One flask had a straight neck (allows both air and microorganisms to travel in)
Other flasks had an “s” shaped neck (only allows air in and no microorganisms)
The flask with the straight neck became contaminated with microorganisms
The flask with the “s” neck did not
Conclusion- living things don’t come from non-living things
Carl Linnaeus (1707-1778)
founder of modern systematics and classification
an advocate of the “typical species concept”
Completed most of his work on plants
He believed that species should be classified based on their productive parts
Binomial nomenclature
Georges-Louis Leclerc Comte de Buffon (1707-1788)
Looked after the royal gardens in France
Formulated a species concept based on interbreeding
questioned the fixity of species
Tried and succeeded in changing plants
Argued for an ancient earth
Challenged world view
The rise of living material from non-living material is the basis of which early theory?
primary abiogenesis theory
