Descent with Modification

Question 1

How can evolution be defined

Answer 1

Darwin’s phrase, descent of modification (or evolution) explains life’s unity and diversity
Natural selection is a cause of adaptive evolution

Question 2

Adaptation

Answer 2

A heritable trait that increases biological fitness of an individual in a particular environment compared to individuals without that trait

Question 3

3 categories of adaptations and examples

Answer 3

Structural - physical features (penguins have blubber to protect from freezing temps, giraffes have long necks allows them to browse leaves off trees and avoid food competition, chameleons use camouflage, carnivores have sharp canines to kill)
Behavioral - learned or inherited actions/activities (bears hibernate to escape the cold, fish swim in schools for protection, geese fly south in fall to stay warm and find food, porcupines curl up in a ball)
Physiological - internal and cellular processes (snakes produce poisonous venom, pesticide and antibiotic resistance)

Question 4

1 inferences based on Darwin’s 3 observations

Answer 4

Observation #1 - for any species, population sizes would increase exponentially
Observation #2 - nonetheless population tend to be stable in size (except for seasonal fluctuations)
Observation #3 - resources are limited
INFERENCE #1 Production of more individuals than the environment can support leads to a struggle for existence among individuals of a population, with only a fraction of their offspring

Question 5

2 inferences based on Darwin’s 2 observations

Answer 5

Observation #4 - members of a population vary extensively in their characteristics
Observation #5 - much of this variation is heritable (transmissible from parent to offspring)
INFERENCE #2 Survival depends in part on inherited traits, individuals whose inherited traits give them a high probability of surviving and reproducing are likely to leave more offspring than others
INFERENCE #3 This unequal ability of individuals to survive and reproduce will lead to a gradual change in population, with favorable characteristics accumulating over successive generations

Question 6

Biological Fitness

Answer 6

Ability of an individual to survive to reproductive age, find a mate, and produce live fertile offspring relative to that ability in other individuals in the population

Question 7

How does Natural Selection Occur

Answer 7

Occurs when heritable phenotypic variation in a population leads to differential reproductive success (unequal ability of individuals to survive and reproduce)

Question 8

Phenotype

Answer 8

Organism’s observable characteristics or traits, including its 1. physical form and structure 2. development properties 3. biochemical and physiological properties 4. behavior

Question 9

Why might certain traits lack heritable phenotypic variation

Answer 9

A heritable trait has a genetic basis, no phenotypic variation may be shown for that specific trait since individuals carry the same genes
High phenotypic variation may result from environment effects but are not heritable (hair length)

Question 10

Natural Selection

Answer 10

Increases adaptation of organisms in their environment over time

Question 11

Do individuals evolve? Does natural selection create new traits?

Answer 11

Individuals do not evolve, populations evolve over time
Natural selection edits or selects for traits already present in population

Question 12

2 common misconceptions of evolution why are they misconceptions?

Answer 12

1. Natural selection is same as evolution - not true since natural selection is mechanism, or cause, of evolution
2. Natural selection is the only mechanism that can lead to evolution - not true since other mechanisms like gene flow, genetic drift, and mutations can also lead to evolution

Question 13

3 common misconceptions of evolution why are they misconceptions?

Answer 13

1. Evolutionary change occurs in individuals - evolution occurs in populations, natural selection just sorts existing variants among individuals ex. giraffe neck length
2. Evolution is goal directed - adaptations do not occur because organisms want them to, mutations occur by chance ex. roses can’t grow thorns on purpose
3. Evolution perfects organisms - not all traits are adaptive, some are limited by genetic, historical, or environmental constraints ex. humas can grow wings and fly

Question 14

Artificial Selection
examples?

Answer 14

Modifying species by selecting and breeding individuals with desired traits
ex. cattle, sheep, dogs, flowers, vegetables (cauliflower, broccoli, kale, cabbage -> wild mustard)

Question 15

How is Artificial Selection done?

Answer 15

Offspring of each generation vary, those that are like what the breeder wants are selected for further breeding, the rest aren’t allowed, this is repeated and eventually the small differences add up to large

Question 16

Examples of evidence for natural selection

Answer 16

ex. artificial selection, transitional fossil record, anatomical record(homologous structures, analogous structures, vestigial structures and comparative embryology), molecular biology record, biogeography, and direct observations of evolution (peppered moths and antibiotic/pesticide/herbicide resistance)

Question 17

6 most cited types of fossils
definition?
identify an image

Answer 17

Molds - formed when organism decays completely, leaves behind hollow physical impression
Cast - forms when minerals and sediment deposit into a mold and hardens over time, physical replica of the hard structures of the organism
Permineralized fossils - form as organisms decompose slowly, allows minerals to infiltrate interior of cells and harden into stone
Carbon film (compression) fossils - carbon residue of soft-bodied organism (black, dark/light brown in color)
Trace fossils - indirect evidence of life (footprints, tooth marks), evidence of organism activity
True-form(intact) fossils - preserve entire natural form of organism, soft tissues remains intact

Question 18

limitations/biases associated with fossil record
explain?

Answer 18

Habitat Bias - organisms that live where sediment is actively being deposited (beaches, swamps) are more likely to fossilize (burrowing organisms more likely to fossilize)
Taxonomic and tissue bias - organisms (with bones or shells) and more likely to decay slowly and leave fossil evidence, tissues with a tough outer coat that resists decay (pollen) fossilize more readily
Temporal bias - more recent fossils are more common than ancient fossils (older fossils in sedimentary rock layers, pushed further into earth
Abundance bias - organisms that are abundant, and present for a long time leave evidence more often than species that are rare, local, or last for a short time

Question 19

Homologous structures (homology)
examples?

Answer 19

Body parts that share a common ancestor, but not the same function
ex. forelimb bones in human arm, horse leg, bat/bird wing, seal flipper

Question 20

Analogous structures (homoplasy)
examples?

Answer 20

Body parts that perform the same function but have different evolutionary history, no common ancestor
ex. walking limbs of insects and vertebrates, wings of birds and bats, eye of octopus and human, cranium of vertebrates and exoskeleton head of insects

Question 21

What is the difference between homology and homoplasy

Answer 21

Homology - common ancestor, different function, divergent evolution
Homoplasy - different ancestor, common function, convergent evolution

Question 22

Differentiate between convergent and divergent evolution

Answer 22

Convergent - process in which species that are not closely related to each other independently evolve similar traits (common function different ancestor)
Divergent - process in which a trait held by a common ancestor evolves into different variations over time (common ancestor, different function)

Question 23

Vestigial structure
examples?

Answer 23

Reduced or incompletely developed structure that serves no (or little) functions
Remnants of structures that were functional in ancestral species
ex. appendix, little toe, wisdom teeth, pelvic bones in whales and sharks, goose bumps are vestigial traits

Question 24

Why are traces of our evolutionary past also evident at molecular level

Answer 24

All living organisms share the same genetic material, similar genetic codes, same basic process of gene expression, same molecular building blocks (amino acids, nucleotides)

Question 25

Homologous (orthologous) genes

Answer 25

Sequences of related genes found in different species used to determine how species are evolutionarily related to one another

Question 26

What do more DNA differences in homologous genes(or amino acid differences in proteins) between 2 species mean?

Answer 26

The more distantly the species are related

Question 27

What do few differences in homologous genes(or amino acid difference in the proteins they encode) between 2 species mean?

Answer 27

The more closely they are related

Question 28

Biogeography
examples?

Answer 28

Describes the distribution of life forms over geographical areas past and present
ex. when a landmass breaks off or a few individuals are blown off and diverge as they adapt in isolation to island environment
ex. marsupials in South America and Australia are related

Question 29

How are the peppered moths during the Industrial Revolution evidence of natural selection

Answer 29

Changed in color, originally they had light coloration and camouflaged against light trees
Pollution during the revolution blackened the trees by soot causing light-colored moths to die
Dark-colored moths flourished because they were able to camouflage

Question 30

How did DDT resistance arose in mosquitos and how it this evidence of natural selection

Answer 30

Mosquitos that carried the DDT resistant alleles survived and reproduced over several generations then mosquitos were entirely resistant to DDT
Resistance occurs with over exposure to toxic compounds
Result of built-in genetic and molecular biological defense mechanisms

Question 31

Explain 2 ways that bacteria became resistant to antibiotics and how antibiotic resistance is evidence of natural selection

Answer 31

By genetic mutation
By acquiring resistance from another bacterium (a simple mating process called “conjugation” by which bacteria can transfer genetic material
Resistance occurs when antibiotic loses its ability to control or kill bacteria