Bio Exam 3 Maddie

What are stromatolites and how do they form?

- layered sedimentary rock structures -Microfossils are found here

what is a homeotic mutation

- mutations that transform one body region into another -also called Hox genes

Divergent Evolution

-1 specie that speciates -Homologous structures can differ from each other due to this process -Used to have a function ; but not anymore - modifies homologous structures for different functions

Why is gene duplication an important mechanism in evolution?

-A single gene is accidently copied into a new location in the genome -Leading to two copies of the gene -Duplicated genes are said to be homologous, and are considered to be part of a "gene family" -The antifreeze gene of icefish was duplicated from an ancestral digestive enzyme, followed by divergence of its function from the ancestral gene

What is a transitional form?

-Almost everything that has ever lived is extinct -(= BIG GAPS b/t living organisms) No continuum of life Ex- evolution of feathers

Gene flow

-Another NON-ADAPTIVE mode of evolution -Gene frequencies in a population change due to immigration and emigration in other populations (behaviorally, flood, wind, etc) -Can bring in new alleles that are more adaptive than those currently present (beneficial) -High gene flow can continually inject a population with alleles that are less favorable in the local environment (detrimental)

Founder effect

-Another common mode of genetic drift -Isolation of a small subset of a population to a new geographic location (dispersal of population) -Allele frequency of the subgroup can be very different from the parent population

Cuvier

-Asian and african elephants are different species -Got fossils from other animals that resemble elephants but aren't either african or asian -Led to his idea of extinction -Opposed idea of evolution

Genetic Bottleneck

-Common form of genetic drift -When the genetic diversity of a population is dramatically reduced over a short period of time due to a decrease in population size -

Lamarck

-Did not believe in Cuvier's extinction theory -Believed in biological change overtime -Lamarckism

James Hutton

-Father of modern geology -Theory of Uniformitarianism

What is "fitness?"

-Fitness is a property of individuals, but only populations evolve, not individuals -Fitness is determined by the environment -Environment determines fitness

What are all the ways fossils can form?

-Freezing/Refrigeration -Drying/Desiccation -Asphalt -Amber -Carbonization -Permineralization (most common): Minerals fill cellular spaces and crystalize & shape of original organism is preserved as a rock, No DNA

Allopatric speciation

-Lake Victoria -more predominant -isolation is created by reductions in gene flow -divergence occurs when mutation, genetic drift, and selection act upon populations separately

Island biogeography

-McArthur and Wilson model -

What is horizontal gene transfer?

-Prokaryotes exchanging DNA , then they can incorporate that into their cell -Virus steals DNA and transfers it into another host

Stratigraphy

-Rock layers of different aged laid down over great period of time -

What is meant by the Age of Microfossils?

-The period of Earths history from 3.5 billion years ago to 0.6 billion years ago -During this period of nearly 3 billion years, microfossils and ONLY microfossils are found -So? This supports Darwin's prediction that life evolved from "a simple, ancestral type"

Lyell

-Wanted to find how old the earth is -First to believe that the earth was more than 300 million years old -Critic of Cuvier's views of catastrophism -Religious views conflicted with his views on evolution

Theory of Uniformitarianism

-explains features of earth's crust over geologic time -rand canyon did not just crack, river eroding rock

How does the environment determine fitness?

Amount of hair (cold or warm environment) -Depends upon the environment whether a trait is favored or not

What was Darwin's interest in joining the mission of the HMS Beagle

As a companion to the captain of the ship assisting in surverying the geology and biology of sites, primarily in SA.

Cuvier Extinction theory

Asked how could this happen? -----> Catastrophism

Pitx1 in sticklebacks

example of how regulatory evolution can lead to morphological novelty and adaptation

What causes balanced versus unbalanced species compositions on islands?

More species balance is due to connection to mainland

What was the problem that the fossil record in 1859 created for Darwin's theory?

-fossils weren't fully understood, not really observed - the oldest fossil Darwin had could not be the common ancestor for all species -The oldest known fossils in 1859 were simply too complex to represent Darwin's "simple, ancestral type", so Darwin hypothesized that earlier, simpler life forms were missing from the fossil record

relationship between gene flow and speciation

-interbreeding -2 species can not form/differentiate in presence of gene flow

Sympatric speciation

-live side by side -Apple Maggot Fly -Flies that emerge from a host generally return to that host species to lay eggs later

Why is the biota more balanced in Madagascar than Hawaii?

-non volcanic -closer/used to be connected to mainland -reptiles, mammals, etc

Hardy Weinberg Principle (basic idea/assumptions)

-observed vs expected big difference then the population is evolving -Equation that describes populations that are NOT evolving -allele frequencies remain unchanged over time -

Endemism

. is the ecological state of a species being unique to a defined geographic location, such as an island, nation, country or other defined zone, or habitat type; organisms that are indigenous to a place are not endemic to it if they are also found elsewhere...

How did Darwin define evolution?

1) That all life on earth descended from some simple. common ancestral life form : Descent with modification 2)That the mechanism of evolution is "Natural Selection" :Does not deal with how species form

What are three things that can happen to duplicated genes?

1. Original copy can continue to normal thing and duplicated does that too 2. One of the copies can acquire a mutation that gives it a new function 3. Mutation that disrupts the function and then have the loss of a gene

What facts and inferences led to Darwin's theory of evolution by natural selection?

1. populations have unlimited capacity for reproduction, but they remain a constant size 2. individuals within populations vary 3. variation can be inherited 4. variations within populations affect individuals ability to survive and reproduce

Fossilized bones are discovered. Carbon dating indicates that they contain 1/4 of the normal amount of carbon-14 found in the bones of a living specimen. The half-life of carbon-14 is 5,70 years. Approx. how old are the bones?

12,000 years

Alfred Wallace

1823-1913 : Modern theory of evolution by natural selection

Genetic drift can lead to populations with reduced genetic variation. What is one evolutionary consequence of reduced genetic variation?

A decrease in the potential for adaption to changing environments

Higher genetic variation can be advantageous in which of the following environments?

A changing environment because genetic variation allows for different phenotypes to have an advantage under new environmental conditions

Who independently formulated the hypothesis of natural selection before Darwin published his work?

Alfred Russel Wallace

An endangered falcon population has been closely monitored and cared for in a protected area. Which data would be most appropriate to collect in order to best determine its recovery?

Comparison b/t the protected population and healthy population of average heterozygosity in a non-coding gene sequence

sickle-cell anemia example

Consider how selective pressures change in malaria-affected areas versus unaffected areas

Isthmus of Panama

Example of how geology and historical biogeography are connected

Tiktaalik-what are the intermediate characteristics?

Flat head, eyes on top, specialized fins with limb bones, neck, and small ribs ...

A forest killed 75% of a shrub population and 100% of the tall tress in an old-growth forest. After some time, the shrubs are much taller than those of a nearby population that was not affected by the fire. What evolutionary mechanism could explain this difference?

Genetic drift or directional selection

Natural selection acts on which of the following?

Heritable traits anda phenotypes. Heritable traits are passed on to the next generation. Genotypes determine the specific phenotype that is expressed, but it is the phenotype that is the direct target of natural selection

What influenced Dawrin's ideas about the evolution of species during his journey on the surveying mission of the HMS beagle?

His experience following a major earthquake in Chile

Which of the following is the mechanism that drives natural selection?

Individuals with traits better suited to their environments are more likely to survive and reproduce; therefore, their offspring are more likely to inherit these adaptive traits

In his original work on natural selection, Darwin was unable to provide a mechanism to explain which of the following?

Inheritance of traits: although Darwin knew that many traits were heritable, he could not provide an explanation as to how such traits were passed onto offspring

Which of the following is a unique property of evolution by gene flow?

It can result in an increase in genetic variation

Both dragonflies and pigeons have wings. What insight can this fact give us about evolution?

It demonstrates that evolution can give rise to traits that perform similar functions multiple, independent times. *similar structures b/t distantly related species can evolve independently

Which characteristic makes it least likely that an organism will be preserved in a fossil?

It lived in a tropical rain forest

The fossil record provides direct evidence for evolutionary relationships among living organisms and the history of life. So why is it so controversial?

Large gaps in the record suggest there is not enough evidence to support descent with modification.

Imagine that you are hiking up a mtn and you notice that the trees are becoming larger as you walk. You hypothesize that large size is an adaption to colder habitats. Which of the following would NOT be informative in supporting or rejecting this hypothesis?

Meausring as many trees as possible along the mountain and plotting the graph of the relationship b/t temperature and tree size

Which of the following population sizes (N) of bison would be most affected by genetic drift?

N=10 (smaller the population, the bigger the impact)

How is globin in Antarctic icefish an example of a fossil gene?

No longer make hemglobin, gene that used to be functional now have mutations that does not work anymore

prezygotic versus postzygotic isolating mechanisms

Pre: has not fused with sperm Post: already fused with sperm

Atavisms

Reoccurrence of an ancestral structure -Dolphin hind limb -lost structures can RETURN

After the rise of the Isthmus of Panama, how were North American species affected compared to South American species? Why the difference?

SA had been an island and NA had been connected -CA acted as a path and some species made it across -Species in the north were better competitors than species in the south -Did much better in migrating to SA -More traveled from north to south

Vestigial structures

Structure due to an ancestor, lost the function -Form of divergent evolution

Convergent Evolution

Structure that is shared b/t unrelated species -Evolved independently -The process whereby organisms evolve similar traits as adaptations to similar environments or selective pressures -Some similarities are due to descent from a common ancestor -Some differences are due to modification from a common ancestor -Some similarities are superficial; they evolved independently through convergence

How does the Church of England's initial response to Darwin's ideas compare with their current position?

The church was hostile to Darwin's work for many years but now accepts a scientific explanation of evolution

A population of birds exhibits high diversity in alleys for feather color. Human settlers overhung the population, causing a bottleneck effect. What might you predict about the population of birds that will exist after the bottleneck event?

The population will have less diversity in feather color because the variety of alleles will be reduced

What happens to populations that undergo genetic bottleneck and founder effects?

They have low allelic variation and therefore are prone to extinction. Variation is what allows differential response to environmental challenges

When does a hypothesis become a theory?

When several lines of evidence and multiple observations arrive at the same conclusion

When calculating allele frequencies, what does the chi-square statistic tell us?

Whether the gene frequencies in a population differ from random expectations and change through time

Genetic Drift

allele frequency changes generation to generation by chance alone -Flipping a quarter -Chance events become more important when population sizes are small -Low frequency in a population (1% has allele X), allele X is more likely fail to reproduce allele in all populations

Vicariance

continuous population that gets separated -River separates a population -Leads to allopatric speciation

What is the role of mutation in evolution?

creates new genes and new phenotypes

Habitat isolation

different preferred habitat or mating location

Behavioral isolation

differentiating mating rituals

Pax6

egulates eye development in mice, cavefish, and fly -ectopic expression of Pax6 of different species in flies

Phenotype

expression of a genotype through physical characteristic

Dispersal

form new populations separated from each other

How does continental drift explain biogeographic distribution of fossils?

fossils of the same species are located extremely far apart today because of the breakup of pangea, but when they were alive they inhabited the same environments

Which aspects of evolution are random, which are non-random?

genetic mutations that cause new genes are random, but natural selecton/selective pressures are due to the environment

Homologies vs Analogies

homologous structures are similar due to common ancestry. analogous structures are similar due to convergent evolution

How does pesticide and/or antibiotic resistance evolve?

over time individuals that survive, lead to populations that are more resistant Antibiotic Resistance is accelerated because bacteria can pass resistance genes to other, unrelated bacteria

What is the argument for why feathers are ancient and were lost in alligator/crocs

presence of croc/alligator fossils with feathers, but no they don't have feathers

mechanical isolation

reproduction organisms don't fit with each other

Gametic isolation

sperm and egg are incompatible

Why are traits such as albinism rare in most populations, but common in cave populations?

there is strong selection against albinism in most environments, so the trait is not passed on. The trait does not affect survival in cave populations, so it is more likely to be passed on

Why do birds show the lowest level of endemism?

they can fly, higher dispersal

Lamarckism

use/disuse theory - inheritance of acquired characteristics

What do high levels of endemism tell us?

what's there, evolved there