BIOL 1200 Exam 1

Disruptive (graph shape, what happens to average and genetic variation?)

2 humps on the extremes (homozygotes favored; favors extreme phenotypes at both ends of the range) Maintains overall genetic variation

What is a population?

A group of individuals from the same species living in the same area at the same time and can interbreed

What is an outgroup?

A taxon that diverged prior to the taxa that are the focus of the study; helps to root the tree

What is a theory (in terms of Science)?

A theory is a tested and confirmed explanation for observations or phenomena

Different animals that possess homologous structures probably _____.

A. Evolved from the same ancestor

1. Charles Darwin was the first person to propose a. That evolution occurs b. A mechanism for evolution that was supported by evidence c. A mechanism for how evolution occurs d. That Earth is older than a few thousand years

A. a mechanism for evolution that was supported by evidence

What is fitness?

Ability of an individual to produce viable offspring relative to others of the same species; is increased by adaptations

What are some misconceptions of natural selection? (4)

Acclimation is Not Adaptation Evolution is Not Goal-Directed (this is Lamarckian) Evolution is Not Progressive (population is just as likely to lose or gain a characteristic) "Higher" or "Lower" Organisms? -> there is no hierarchy

H-W - know the equation! What are the allele and genotypes frequencies as given by the H-W principle?

Allele frequencies: p + q = 1 ; Genotype frequencies: p^2 + 2pq + p^2 = 1

What happens to allele and genotype frequencies once a population is in H-W equilibrium?

Allele frequency will not change, but genotype frequencies will

What is the hardy-Weinberg equation?

An assessment of evolution at a particular loci

How do you differentiate homoplasy from homology on a phylogenetic tree?

Analogy (homoplasy) similarity due to convergent evolution (populations performing the same role in similar environments)

What is a derived character? (3)

In-group characteristic One that is modified form of ancestral trait found in descendant evolutionary novelty unique to particular clade

What is the unit of natural selection?

Individual

Define cladistics (2)

Inferring trees focuses on synapomorphies (shared derived characters of the species under study) classifies organisms by common descent

In science, not popular culture, the term theory, generally applies to an idea that

Is generally considered to be a very strongly supported statement about nature

What will happen to the size an shape of beaks in medium ground finches, in the future?

It depends on the environment

Which of the following is a requirement for a good scientific hypothesis?

It must lead to testable predictions

In what sense does the Hardy-Weinberg principle act as a null hypothesis?

It specifies what should be observed if no evolution is currently occurring at a particular gene

1. A potential source of confusion in constructing a phylogeny tree is similarity between organisms that is due to a. Homology b. Shared ancestry c. Convergent evolution d. Adaptation

C. convergent evolution

What can we learn from phylogenetic trees? What can we not learn(2)?

Can learn - shows pattern of descent Cannot learn - does not show phenotypic similarity; indicate when a species evolve/how much change occurred in a lineage

How many generations of random mating are required to reach H-W equilibrium?

Can only come in to H-W equilibrium if the 5 assumptions (Random mating, no natural selection, no genetic drift, no gene flow, no mutation) are met

How are phylogenetic trees constructed?

Cladistic analysis begins with a data matrix and builds tree stem based on the principle that closely related species are likely to share derived traits called synapomorphies (tree is selected that best fits)

Darwin and Wallace's theory of evolution by natural selection was revolutionary because it ___.

Dismissed the idea that species are constant and emphasized the importance of variation and change in populations

1. Examining the figure, which type of selection has two peaks of frequency of individuals? a. Disruptive selection b. Stabilizing selection c. Directional selection d. Natural selection

Disruptive selection

As physicians and patients, how does one prevent, or minimize, the evolution of resistant of resistant microbes?

Don't use antibacterial soaps, don't request antibiotics, complete full regimen, never prescribe unneeded antibiotics, narrowly target bacteria

Top (terminal node)

Endpoint of a branch (represents living or extinct group)

Which of the following ideas would you consider to be common to both Darwin's and Lamarck's ideas about evolution?

Evolutionary change results from interactions between organisms and their environment

What is a phylogeny?

Evolutionary history & pattern of descent of a group of organisms

Phylogeny

Evolutionary history of a group of organisms

What is a transitional form? Give some examples.

Extinct fossil species are succeeded in the same region by similar living species (law of succession) Example: fossil sloth to present day sloth

The widespread use of DDT in the mid-1900s put pressure on insect populations to evolve resistance to DDT. As a result, large populations of insects today are resistant to DDT.

False

Why does antibiotic resistance evolve so quickly?

Food producing animals, doctors overprescribing, patients not completing regime, 70% of microbes in hospitals

What is the inheritance of acquired characteristics? (Founder, explanation)

Lamark Physiological changes acquired during an individuals' lifetime (such as the enlargement of a muscle through repeated use) were passed-on to its offspring

What are fossils, how are they formed?

Fossils - remains/traces of organisms from the past appearing in layers or strata from sedimentary rock Decomposition?

What is a synapomorphy, why are they important? (2)

Found in two or more taxa that is present in their most recent common ancestor but is missing in more distant ancestor They allow biologists to recognize monophyletic groups (clades, lineages)

What is genetic variation? Why is it important in natural populations?

Genetic variation - number and relative frequency of alleles that are present in a particular population Importance/ If low, no alleles that have high fitness under new conditions are likely to be present, resulting in an average decline of the fitness of a population

What is the Hardy-Weinberg (H-W) principle? Why is it characterized as the null hypothesis of population genetics(2) ? What is a null hypothesis?

H-W principle - acts as a null hypothesis when researchers want to test whether evolution or nonrandom mating is occurring at a particular gene If it functions then nothing is changing (assuming that the four mechanisms are not working); it specifies what should be observed if no evolution is currently occurring at a particular gene A null hypothesis is the hypothesis that there is no significant difference between specified populations, any observed difference being due to sampling or experimental error

Homologous structures(2)

Homologous structures: anatomical resemblances representing variations on a structural theme present in a common ancestor Functions can vary but the underlying structures are similar/homologous between various species

Which of the following statements best distinguishes hypotheses from theories in science?

Hypotheses usually are relatively narrow in scope; theories have broad explanatory power

What is the difference between a hypothesis (define) and a theory?

Hypotheses: a tentative explanation that is testable and falsifiable (accepted or rejected) and can never be "proven correct" A hypothesis may be disproven and can be a verified theory; hypotheses usually are relatively narrow in scope whereas theories have broad explanatory power

What is the unit of evolution?

Population

What are vestigial traits (3)? Give some examples.

Reduced versions of traits in related species; remnants of features that served important function in the organism's ancestors; can indicate common ancestry Example: Human tailbone (capuchin monkey tail to human coccyx); goosebumps (erect hair on chimp to human hair)

1. The most important feature that permits a gene to act as a molecular clock is a. Having a reliable average rate of mutation b. Its being acted upon by natural selection c. Having a large number of base pairs d. Having a larger proportion of exonic DNA than of intronic DNA e. Its recent origin by a gene duplication event

a. Having a reliable average rate of mutation

Individuals do not ____. Populations do.

adapt

Individuals ___ ___ change when they are selected, they simply what?

do not change; they produce more surviving offspring than other individuals do

Natural selection can only ____ or ___ heritable traits that vary in a population .

increase; decrease

Natural selection promotes traits/behaviors increasing chances of ______ and ______ while eliminating those traits and behaviors that are ______ to an organism.

survival; reproduction; detrimental/harmful

Who is Charles Darwin (3 main concepts - main point, how he found it, what did it lead to)

"Descent with Modification" principle (provided an explanation to how evolution occurs) -Viewed as both a pattern (subtle changes) and process (how this occurs) "Darwin's Finches" - noticed they all performed different roles in ecosystem -Difference in shape and size of beak allowed them to specialize food intake -Evidence led to natural selection Natural selection - "survival of the fittest"

Charles Lyell

Longer aged Earth; noticed fossils in rocks Changes in Earth's surface are slow, gradual, uniformed, constant change (Uniformitarianism)

What are the costs associated with being resistant to antibiotics?

Loss of function, compensatory mutations, suspend treatment, expense of maintain new genes and producing proteins

Imagine a species of bird in which females prefer to mate with brightly colored males. However, males with bright backs are more often preyed upon by hawks. Assuming that a wide variety of genetic variation exists in the species, which do you think is most likely result of natural selection.

Males will be selected to have bright chests and dull backs.

Why would allele or genotype frequencies change in a population (four reasons - know them!)

Natural selection, genetic drift, gene flow, mutation

What is extinction?

No longer living

Directional selection (graph shape, what happens to average and genetic variation?)

One hump (shifts towards more favored extreme) Average phenotype changes in one direction Genetic variation decreases

Stabilizing selection (graph shape, what happens to average and genetic variation?)

One hump in the center (heterozygotes favored) No change in average value of trait Genetic variation decreases

Taxonomy

Ordered division and naming of organism (structure hieararchy)

What is an ancestral character? (2)

Out-group characteristic Characteristic that existed in an ancestor

Georges Cuvier (3)

Paleontology (study of fossils) 1st to say Earth has changed and was older than expected due to fossils and rocks Speculated each boundary between strata represents a catastrophe that destroyed many species (Catastrophism occurred to change earth)

What were the early Greek philosophies regarding living organisms (how organized, did evolution occur, etc.)? 3 (Plato(2), Aristotle, type of events)

Plato - Traditional views of a young Earth inhabited by unchanging species; divinely created Aristotle - species were organized into a sequence/hierarchy based on increased size and complexity (humans at the top) Consequence of catastrophic events

Thomas Malthus (3)

Population increases exponentially and resources increase linearly (when there is intersection, disaster will occur) Competition for resources in each generation (large population and limited resources) People would die of starvation, war, etc. when population exceeded food supply

How did Malthus' ideas influence Darwin? How does population growth differ from growth of food supplies? What is a geometric progression, what is an arithmetic progression?

Population numbers increase geometrically (by some constant factor), food supplies increase arithmetically (by some constant difference) Population exceeds food supply results in death Geometric progression - sequence of terms in which the ratio of each term to the preceding one is the same throughout the sequences Arithmetic progression - a sequence of numbers in which a constant figure common difference is added to each term to give the next

What evolves, individuals or populations?

Populations

What factors are necessary for natural selection to occur(4)? Selection operates on what? Allele frequency changes occur in what(2)?

Populations vary in traits; traits are genetically heritable; more offspring are produced than can survive; survival and reproduction are non-random Selection operates on individuals Allele frequency changes occur in natural selection, genetic drift, gene flow, mutation; differential success and expression of least favorable genes

How does maximum parsimony help you to select among possible trees? (3)

Possibilities narrowed through applying this principle when finding the best tree in a large data set incorporates as few changes in DNA morphology as possible assumes the tree requires the fewest evolutionary events

The Hardy-Weinberg Theorem states that ___ and ___ have no affect on allele or genotype frequencies in populations.

Random Fertilization, Meiosis

How do you evaluate whether or not a population is in H-W equilibrium? (5)

Random Mating: Complete random breeding No natural selection No genetic drift (all genotypes should be equally fertile) No gene flow (no immigration or emigration - no animals leave or arrive) No genetic mutation

What are the assumptions of H-W? (5 + explain if possible)

Random Mating: individuals don't choose mate No Natural Selection: all members of parental generation survived and contributed equal numbers of gametes to one pool No genetic drift: no random allele frequency changes (assuming population was infinitely large) No gene flow: none added by immigration or lost through emigration (alleles in the offspring population came from the original population's gene pool) No mutation: no new alleles introduced to gene pool

Jean Baptiste Lamarck (4 + example of hypothesis)

Recognizes a mechanism for evolutionary change Inheritance of acquired characteristics "I can change what I pass on" Hypothesis: species evolve through the use and disuse of body parts and the inheritance of acquired characteristics Giraffe neck example: Recognizes what it needs to do to be successful in an environment and can willfully change bodily characteristics to pass onto offspring

Imagine two species that are thought to have a recent common ancestor. If this idea is correct, these two species most likely have____.

Several homologous structures

Homology

Shared characteristics of species based on shared ancestry

Alfred Russell Wallace

Similar to Darwin about natural selection (but Darwin published first)

Developmental Homology

Similarity in embryonic traits

Which of the following statements reflect aspects of Charles Lyell's ideas of gradualism and uniformitarianism that were incorporated into Darwin's theory of evolution?

Small constant changes accumulated over vast spans of time can produce dramatic results

What is special creation(2) and natural theology?

Special Creation -origin and diversity of life resulted from acts of God whereby each species was created separately (Evolution is implicitly rejected) Natural theology - provides arguments for the existence of God based on reason and ordinary experience of nature

Carl Linnaeus (2)

Special creation (factor of creation) - all species weren't equally different Father of taxonomy and made binomial nomenclature system for species

Why is phylogenetic reconstruction a non‐trivial task (why is it difficult?)?

The DNA differences is vast

Which of the following is the best description of a control for an experiment?

The control group is matched with the experimental group except for the one experimental variable

Homologous traits are

Traits that are similar in form due to shared common ancestry (they are also traits that result from genetic similarities; however, they have different developmental functions)

What is a molecular clock, and how do they help understand phylogenies? (2)

Uses constant rates of evolution of some genes to estimate the absolute time of evolutionary change (has to be DNA that is completely nonfunctional) calibrated by plotting number of genetic changes against dats of known points from fossil record

If a population gradually includes more individuals with a trait that has been subject to natural selection what would we expect to happen to allelic frequencies that to govern this trait.

We would expect changes in allele frequencies

Is it incorrect to say that vertebrates evolved eyes in order to see?

Yes; evolution is not goal-oriented

Evolution

a change in the characteristic in a population (genetic frequencies can result in the formation of a new species)

1. Evolution a. Can happen whenever any of the conditions for Hardy-Weinberg equilibrium are not met b. Must happen, due to organisms' innate desire to survive c. Requires the operation of natural selection d. Must happen whenever a population is not well adapted to its environment

a. Can happen whenever any of the conditions for Hardy-weinberg equilibrium are not met

1. During a study session about evolution, one of your fellow students remarks, "The giraffe stretched its neck while reaching for higher leaves; its offspring inherited longer necks as a result." Which statement is most likely to be helpful in correcting this student's misconception? a. Characteristics acquired during an organism's life are generally not passed on through genes b. Spontaneous mutations can result in the appearance of new traits c. Disuse of an organ may lead to its eventual disappearance d. Only favorable adaptations have survival value

a. Characteristics acquired during an organism's life are generally not passed through genes

1. The common ancestors of birds and mammals were very early (stem) reptiles, which almost certainly possessed three-chambered hearts (two atria, one ventricle). Birds and mammals, however, are alive in having four-chambered hearts (two atria, two ventricles). The four-chambered hearts of birds and mammals are best described as a. Homoplasies b. Vestiges c. Structural homologies d. The result of shared ancestry

a. Homoplasies

1. A polytomy on a phylogenetic tree represents a. Insufficient data to determine lineage relationship b. Most recent common ancestor c. A lineage that diverges from all other lineages in its group d. Sister taxa

a. Insufficient data to determine lineage relationship

1. What evidence suggest that limbless bodies are the results of convergent evolution of snakes and lizards? a. Snakes and lizards with limbless bodies evolved from different ancestors of legged lizards b. Three traits are shared by all snakes c. Limbless bodies do not share a most recent common ancestor d. Species adapted to their environments

a. Snakes and lizards with limbless bodies evolved from different and ancestors of legged lizards

1. Currently, two extant elephant species (X and Y) are placed in the genus Laxodonte, and a third species (Z) is placed in the genus Elephas. Thus, which of the following statements is true? a. Species X and Y share a greater number of homologies with each other than either does with species Z b. Species X ad Y are the result of artificial selection from an ancestral species Z. c. Species X and Y are not related to species Z d. Species X and Y share a common ancestor that is still extant (in other words, not yet extinct)

a. Species X and Y share a greater number of homologies with each other than either does with species Z

1. In the formula for determining a population's genotype frequencies, the 2 in the term 2pq is necessary because a. Heterozygotes can come about in two ways b. Heterozygotes have 2 alleles c. The population is doubling in number d. The population is diploid

a. heterozygotes can come about in two ways

1. Both ancestral birds and ancestral mammals shared a common ancestor that was terrestrial. Today, penguins (which are birds) and seals (which are mammals) have forelimbs adapted for swimming. What term best describes the relationship of the bones in the forelimbs of penguins and seals, and what term best describes the flippers of penguins and seals? a. Homologous; analogous b. Analogous; homologous c. Analogous; analogous d. Homologous; homologous

a. homologous; analogous

1. Sister taxa a. Represent groups of organisms that share an immediate common ancestor b. Diverge from all other lineages early in the history of the group c. Represent a polytomy d. Represent the common ancestor of taxa

a. represent groups of organisms that share an immediate common ancestor

Monophyletic

ancestor and all of its descendants

1. If, on average, 46% of the loci in a species' gene pool are heterozygous, then the average homozygosity of the species should be a. 23% a. 54% a. 46% b. There is not enough information to say

b. 54%

1. What was the prevailing belief prior to the time of Lyell and Darwin? a. Earth is millions of years old, and populations rapidly change b. Earth is a few thousand years old, and populations are unchanging c. Earth is millions of years old, and populations are unchanging d. Earth is a few thousand years old, and populations gradually change

b. Earth is a few thousand years old, and populations are unchanging

1. Which of the following statements best summarizes evolution as it is viewed today? a. It is synonymous with the process of gene flow b. It is the differential survival and reproduction of the most-fit phenotypes c. It represents the result of selection for acquired characteristics d. It is the descent of humans from present-day great apes

b. It is the differential survival and reproduction of the most-fit phenotypes

1. The importance of computers and of computer software to modern cladistics is most closely linked to advances in a. Fossil discovery techniques a. Molecular genetics a. Linnaean classification b. Radiometric dating

b. Molecular genetics

1. Identify the statement that describes the imperfection of natural selection. a. Though we may not consider the fit between the current skeletal arrangements and their functions excellent, we should not doubt that natural selection ultimately produces the best design b. Natural selection is generally limited to modifying structures that were present in previous generations and in previous species c. In many cases, phenotype is not merely determined by genotype, but by the environment as well d. Natural selection has not had sufficient time to create the optimal design in each case, but will do so given enough time

b. Natural selection is generally limited to modifying structures that were present in previous generations and in previous species

1. Which of the following are problematic when the goal is to construct phylogenies that accurately reflect evolutionary history? a. Polyphyletic taxa b. Polyphyletic and paraphyletic taxa c. Monophyletic taxa d. Paraphyletic taxa

b. Polyphyletic and paraphyletic taxa

1. According to the principle of maximum parsimony, a. Phylogenies based in DNA require the most base changes b. The preferred tree is the one that minimizes the amount of evolutionary change c. A large number of trees should be examined d. In the case of trees based on morphology, a parsimonious tree requires the most changes

b. The preferred tree is the one that minimizes the amount of evolutionary change

1. Over evolutionary time, many cave-dwelling organisms have lost their eyes. Tapeworms have lost their digestive systems. Whales have lost their hind limbs. How can natural selection account for these losses? a. Natural selection cannot account for losses, only for innovations b. Under particular circumstances that persisted for long periods, each of these structures presented greater costs than benefits c. The ancestors of these organisms experienced harmful mutations that forced them to find new habitats that these species had not previously used d. Natural selection accounts for these losses by the principle of use and disuse

b. Under particular circumstances that persisted for long periods, each of these structures presented greater costs than benefits

1. A shared ancestral character is a. An evolutionary novelty unique to a clade b. A character that originated in an ancestor of the taxon c. An outgroup character d. Shared by all mammas but not found in their ancestors

b. a character that originated in an ancestor of the taxon

1. Of the following anatomical structures, which is homologous to the bones in the wing of a bird? a. Bones in the hind limb of a kangaroo b. Bones in the flipper of a whale c. Bony rays in the tail fin of a flying fish d. Chitinous struts in the wing of a butterfly

b. bones in the flipper of a whale

1. When using a cladistic approach to systematics, which of the following is considered most important for classification? a. Shared primitive characters b. Shared derived characters c. Analogous primitive characters d. The number of homoplasies

b. shared derived characters

1. In seedcracker finches from Cameroon, small- and large-billed birds specialize in cracking soft and hard seeds, respectively. If long-term climatic change resulted in all seeds becoming hard, what type of selection would then operate on the finch population? a. Disruptive selection b. Stabilizing selection c. Directional selection d. No selection would operate because the population is in hardy-Weinberg equilibrium

c. Directional selection

1. Natural selection is based on all of the following except a. Individuals who survive longer tend to leave more offspring than those who die young b. Genetic variation exists within populations c. Individuals adapt to their environments and thereby evolve d. The best-adapted individuals tend to leave the most offspring

c. Individuals adapt to their environments and thereby evolve

Catastrophism

catastrophic events caused major changes in Earth's crust rather than gradual processes of change

1. A biologist studied a population of squirrels for 15 years. During that time, the population was never fewer than 30 squirrels and never more than 45. Her data showed that over half of the squirrels born did not survive to reproduce, because of both competition for food and predation. In a single generation, 90% of the squirrels that were born lived to reproduce, and the population increased to 80. Which inference(s) about this population might be true? a. The amount of available food may have increased b. The parental generation of squirrels developed better eyesight due to improved diet/ the subsequent squirrel generation inherited better eyesight c. The number of predators that prey upon squirrels may have decreased d. Both A and C could be true

d. Both A and C could be true

1. It has been observed that organisms on islands are different from, but closely related to, similar forms found on the nearest continent. This is taken as evidence that a. Common environments are inhibited by the same organisms b. The islands were originally part of the continent c. The island forms and mainland forms are converging a. Island forms and mainland forms descended from common ancestors

d. Island forms and mainland forms descended from common ancestors

1. Most Swiss starlings produce four to five eggs in each clutch. Starlings producing fewer, or more, than this have reduced fitness. Which of the following terms best describes this situation? a. Directional selection b. Artificial selection c. Sexual selection d. Stabilizing selection e. Disruptive selection

d. Stabilizing selection

1. Why don't similar genotypes always produce the same phenotype? a. Phenotype is the product of many environmental influences b. Genetic variants of ADH enzyme produce the same phenotype c. Parents alter their phenotypes and pass on this phenotype to progeny d. Animals display different phenotypes dependent on diet, not genotype

d. animals display different phenotypes dependent on diet, not genotype

1. Members of two different species possess similar-looking structures that they use in a similar fashion to perform the same function. Which of the following statements describes these structures originating from convergent evolution? a. Both species have structures that are not adapted to their particular environments b. The two species live at great distance from each other and have structures for flying c. The functions of the structures in adult members of both species are not similar a. These structures share function but do not share a common ancestry

d. these structures share function but do not share a common ancestry

Of the following which was the prevailing idea regarding the origin of species prior to Darwin? a. All species created independently b. The earth is very young c. Species are incapable of change d. Species could be arranged on a scale or into a hierarchical set of categories e. All of the above

e. All of the above

1. Which of the of the following is a true statement concerning genetic variation? a. It tends to be reduced by the process involved when diploid organisms produce gametes b. A population that has a higher average heterozygosity has less genetic variation than one with a lower average heterozygosity c. It arises in response to changes in the environment d. It is created by the direct action of natural selection e. It must be present in a population before natural selection can act upon the population

e. It must be present in a population before natural selection can act upon the population

Natural selection doesn't create new traits, but ____ or ___ for traits already present in the population. The _____ ______ determines which traits will be selected for or selected against in any specific population.

edits; selects; local environment

Natural selection is driven by the ______. (can reverse the ____ of individuals)

environment; fitness

Uniformitarianism

geological processes are uniform and have operated from the origin of Earth to the present

Sister group

groups occupying adjacent branches on the tree

Root

most ancestral branch in the tree; bottom/basal most node

When all individuals have the most favorable trait, it is ______ favorable.

no longer

Polytomy (what does it look like (1)and what does it indicate (2))

node depicting an ancestral branch dividing into 3 or more descendant branches indicates insufficient data were available to resolve which taxa are more closely related (more than two descendants emerge from a node); unresolved pattern of divergence

Node

point within tree where a branch splits into two or more branches

Successful characteristics are dependent on _________ characteristics deriving from the genome. Population evolves because of the ______ change.

pre-existing; environmental

Branch

represents a population through time

Natural selection can only _____, not _____.

select; create

Convergent evolution

similar traits evolve independently in species that do not share a recent common ancestry

Genetic Homology

similarity in the DNA sequences of different species (genetic code)

Outgroup (2)

taxon that diverged prior to the taxa that are the focus of the study taxon known to be outside of the group of interest to establish ancestor vs. derive

Divergent evolution

when two species evolve in diverse directions from a common point