Brainscape's Knowledge GenomeTM


Top Flashcards (Certified)
All Flashcards

Biology > EVOLUTION > Flashcards

EVOLUTION Flashcards

1
Q

Theory

A
  • Every day language = educated guess
  • Sciences = explanatory model that accounts for a very large body of evidence
  • Scientific theories provide basis for explaining observations of the natural world and for making testable predictions
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Evolutionary Theory (general)

A
  • All life forms are fundamentally similar at cellular and molecular level
  • Evolution explains the history of life on earth
  • Evolution is the process by which organisms change over time
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Evolution of Evolutionary Theory
(important people)

A

Aristotle (384 - 322 BCE)
Georges-Louis Leclerc de Buffon (1707-1788)
Carl Linnaeus (1707-1778)
Erasmus Darwin (1731-1802)
Chevalier Lammark (1744-1829)
Charles Darwin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Early Theories: Aristotle

A
  • Most Europeans accepted the idea that all living things had been created in their present forms and were immutable
  • They could not change and had not changed
  • All natural phenomena developed through strongly held religious beliefs
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Early Theories: Buffon

A
  • Applied scientific methods to the detailed study of anatomy
  • Studied animal structures
  • Considered their functions
  • Puzzled by some features that seemed to have no purpose
  • E.g. he studied pig toes, they have toes that don’t reach the ground
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Evolutionary Theory: Linnaeus and Erasmus Darwin

A
  • Proposed life changed over time
  • Erasmus (Charles Darwin’s grandfather) suggested life might have evolved from a single original source
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

How old was the world originally thought to be, and what contradicted this belief?

A
  • Scientists thought would was 1,000 years old
  • Scientists began to find fossils, which contradicted this belief
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Fossils

A

Any ancient remains, impressions, or traces of an organism or traces of its activity that have been preserved in the Earth’s crust
* Fossils dated back to minimum age of 1,000 years

Preserved materialized remains of organisms
* The closer to the surface, the more recent the ancestor
* Organisms die and become trapped in sediments
* Fossilization is a comparatively rare event
* Fossil record is incomplete

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Palentology

A

Study of fossil organisms to learn about prehistoric life
* Cuvier (1769-1832) was a paleontologist

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Geology

A

Study of the Earth’s physical structure
* Lyell (1797-1875) was a geologist

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Cuvier

A

Through study of paleontology, noted the following:
* Fossils of very simple organisms are found in all depths of fossil deposits
* Fossils of more complex organisms are found only at shallow depths in younger rock
* Fossils in shallower depths are more likely to resemble living species
* Rock layers contain fossils of many species that do not occur in layers above or below them

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Catastrophism

A
  • Fossil observation offered strong support that life evolved from simple to complex
  • Cuvier believed that species themselves didn’t change

**Catastrophism **= global catastrophes, such as fossils, caused the widespread extinction of species
* Cuvier believed these speicies were then replaced w another newly created set of species

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Uniformitarianism

A
  • Charles Lyell (father or modern geology)
  • 1830 - put forth his theory/principles of uniformitarianism

**Uniformitarianism = **
* Earth has been changed by same processes in the past that are occurring in the present
* Geological change is slow and gradual, rather than fast and catastrophic
* Natural laws that influence these changes are constant and eternal, they operated in the past w the same intensity they do today
* Lyell’s theories directly challenged belief in a young Earth (1,000 years old or less)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Evolutionary Theory: Lamarck

A
  • Student of Buffon
  • First scientist to offer a mechanism for the evolution of a species
  • Evolutionary change resulted from two distinct principles:
  • Use and disuse
  • Inheritance of acquired characteristics
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Lamarck’s First Principle: Use and Disuse

A

Structures an individual uses become larger and stronger while structures not used become smaller and weaker
* E.g. athlete’s muscles increase in size (structures in use), astronauts returning home have reduced muscles from lack of use (structures not in use)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Lamarck’s Second Principle: Inheritance of Acquired Characteristics

A

Individuals pass down characteristics acquired during lives
* E.g. if adult giraffe stretched its neck during its lifetime, then its offspring would be born w slightly larger neck

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Lamarck’s Findings

A

Though Lamark’s theory was flawed, he made significant contributions to our understanding of evolution
* All species evolve over time
* A species evolves in response to its environment and becomes better adapted to that environment
* E.g. bunnies fur turns white in winter, helps blend in w snow and hide from predators
* Changes are passed from generation to generation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Charles Darwin

A
  • By the 19th Century, there was growing evidence that Earth was old
  • Ideas of the history of the Earth and its life-forms were being challenged
  • Charles Darwin linked ideas from paleontology, Geology, geography biology, and his own observations to come up w a mechanism of evolution: Natural Selection
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Who was Charles Darwin

A
  • Born in 1809 in Shropshire, England
  • Son of a local doctor and wedgusod heiress
  • Parents wanted him to study medicine
  • Found more interest in natural word
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

Voyage of the HMS Beagle

A

In 1831 at 22, Darwin set sail on HMS Beagle for a 5 year trip to record and collect specimens for the British Navy
* They had hoped that Darwin would find evidence of biblical creation

On his voyage, Darwin:
* Collected thousands of specimens
* Collected fossils that resembled existing animals
* Volcanic Galapagos Islands had species similar to South American natives
* Made most discoveries in galapagos
* Species differed from island to island

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

Patterns in Diversity

A
  • Species vary globally: species varied depending on where they lived on Earth
  • Species vary locally: species had different features depending on local habitat
  • Species vary over time: species evolve from one common ancestor
  • Become different creatures over time
  • Geological change
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

Darwin’s Finches

A
  • Collected on galapagos
  • Beaks modified to suit food source
  • Descended from common mainland ancestor
  • Different species formed on separate islands
  • New species branch out from old ones
23
Q

Evolution/Descent with Modification

A
  • Darwin proposed descendants of the earliest organisms spread into various habitats over millions of years
  • Species changed over time based on adaptations to their environment
  • E.g. brown hare (woodland area) → white coat of fur in snowy climate
  • White rabbit fatter to keep warm in winter
24
Q

Survival of the Fittest

A
  • Fitness of an individual is ability of an individual to survive and reproduce in its environment
  • Individual w adaptations survive and reproduce
  • Survival of the fittest
  • Natural selection
25
Pathway to a Theory (Darwin)
* 1837 returns to England * “Transmutation” of species **Artificial selection** * Bred pigeons * Experiments in gardens and greenhouses * Environments have similar selective effect **Struggle for survival** * More offspring produced than can survive to reproduce, favoured variations reproduce * 1858 receives paper from wallace * 1859 published “on the origin of species”
26
Evidence for Darwin's theories
Homologous vs analogous structures Embryonic homologies Vestigial structures
27
Homologous Structures
Share a common evolutionary origin, not function * E.g. human, cat, whale, and bat all contain similar bone structures, but different function Share a more recent common ancestor * E.g. forelimbs of terrestrial vertebrates. Whale flippers are human forelimbs
28
Analogous Structures
Share similar function, but not origin or structure * E.g. bird and bee wing
29
Vestigial Structures
Rudimentary or non-functioning structures that are present in reduced form → humans have 17 * These structures had importance in past → no longer have active functions * Changing environmental conditions no longer favour the selection * E.g. whale pelvis, appendix in humans
30
Artificial Selection
* Darwin searched for examples of selection pressures among domestic animals * Breed pigeons for certain traits → similar to how we manipulate dogs * Selected traits may be bred in relatively few generations * Environment provides selection pressures in the wild
31
Struggle for Survival
* Thomas Malthus Essay on principle of population * Organisms produce more offspring than are able to survive * Favourable variations would tend to be preserved; unfavourable variations die out
32
Natural Selection
* Published: On the Origin of the Species in 1859 Individuals vary in population * Favourable variations result in traits being passed on * Survival is not random * Sheer weight of Darwin’s research and observations make theory hard to refute
33
Artificial Selection (Bacteria)
Artificial selection = selective breeding of domesticated plants and animals to produce offspring w genetic traits that humans value * Has occurred for many years * Darwin observed that artificial selection could produce great deal of change in species over a short period of time * Cous Odder = equivalent to a human women’s breast tissue
34
Issues with Artificial Selection
* Traits for desire, rather than purpose (medical issues): German sheperd hips, Pug noses, Pug heads * Playing “God” w unknown ripple effect consequences * Decrease genetic diversity * Create monocultures that can be wiped out by one disease
35
Antibiotic Resistance in Bacteria
TB, Tuberculosis * Caused by rod-shaped bacterium, Mycobacterium tuberculosis Streptomycin * Developed in 1940s to treat TB * By 1970s it was almost completely eradicated In 2006, outbreak of extensively drug-resistant tuberculosis strain in KwaZulu-Natal in South Africa * By 2008, it had spread to over 49 countries * Over ⅓ of world’s population was affected How does antibiotic resistance occur? * Natural selection * Antibiotic discovered between 1940 and 1950 by Alexander Flemming
36
Natural Selection in TB
* Patients prescribed antibiotics for 6-9 months to cure * Some patients do not complete treatment * Bacteria still hanging around end up surviving, duplicating, and passing on their now new resistance to this treatment * These bacteria have survived through natural selection
37
Modern Synthesis
* Darwin had no concept of the actual mechanism of inheritance * Genetics now, is heavily integrated into evolutionary theory * Organisms vary by number of genes * Large genomes present more opportunities for mutation = More chance for error * Sexual reproduction increases variation compared to asexual reproduction/mitosis
38
Genes vs Alleles
* Genes = unit of inheritance that governs the character of a particular trait * Segment of DNA coding for single polypeptide * Alleles = alternate forms of the same gene * E.g. there is one gene that orders for eye colour and different alleles on that gene will determine the colour of the eye
39
Homozygous vs Heterozygous
Individuals of a given trait can either be: Homozygous dominant = 2 copies of dominant allele * Individual shows that trait → e.g. BB = brown eyes Homozygous recessive = 2 copies of recessive allele * Individual shows recessive trait → e.g. bb = blue eyes Heterozygous = 1 copy of the dominant allele, 1 copy of recessive allele * Individuals show dominant allele → e.g. Bb = brown eyes
40
Gene Pools and Variation
* Gene pool = consists of all the alleles in all the individuals that make up a popu;ation * Phenotype = an organism's expressed trait → i.e. one that you can see * Genotype = traits that an individual has that have been acquired from parents
41
Hardy-Weinberg Equilibrium
Population not undergoing change do not evolve * HWE quantifies genes by measuring allele frequency * HWE requires constant conditions HWE occurs only if all the five conditions are met: * Population very large * Random mating * No mutations occur * No migration occurs (gene flow) * No natural selection occurs **p^2 + 2pq + q^2 = 1 and p + q = 1** p^2 = frequency of AA genotype 2pq = frequency of Aa genotype q^2 = frequency of aa genotype
42
Why Study HWE
* HWE is not realistic and does not occur in real life * In nature, HWE doesn’t occur for long periods of time * Concept is useful as it provides a “no change” baseline * Makes it possible to recognize when gene pool is changing * If 5 above conditions are not met, then genetic equilibrium is distributed and gene pool frequencies may change * When gene pool frequencies of alleles change within a population * Called microevolution = evolution on a small scale
43
Types of Microevolution without Natural Selection (list)
1. Genetic Drift 2. Gene Flow 3. Mutations 4. Selection
44
Genetic Drift
* Changes to allele frequency by chance in small populations **Bottleneck effect = **dramatically reduces population, and thus the gene pool due to natural disaster * By chance, only certain allele are represented * This decreases genetic variation in a population * Reduces population ability to adapt to environmental change **Founder effect =** individuals leaving a population to establish a new one (a few individuals leave one area and they colonize a new area) * The smaller the colony, the smaller the genetic gene population * The change in allele frequencies of this new population relates to the genetic makeup of the founders of the colony
45
Gene Flow
Genetic flow is a random process * Involving exchange of genes with another population, when retile individuals migrate between populations * Movement of genes in or out of population disrupts genetic equilibrium * Also reduces genetic differences between populations
46
Mutations
* Source of new alleles * May be neutral, harmful or beneficial * Affects the fitness of individual * Harmful mutations usually result in death of gamete
47
Selection
* Natural + artificial; source of variation * Mutation provide variation in traits that are selected by outside influences * Natural selection acts on individual phenotypes which are passed on to subsequent generations * Variation environments favour multiple phenotypes
48
Types of Microevolution with Natural Selection (list)
1. Stabilizing Selection 2. Disruptive Selection 3. Directional Selection 4. Sexual Selection
49
Stabilizing Selection
* Where the average phenotype is favoured * Selection against individuals exhibiting variation in a trait that deviates from the current average * Most common form of selection * Phenotypic extremes are selected against → e.g. human birth weights * Stabilizing selection = culls extreme variations from the population * E.g. eliminating individuals that are unusually light or dark * Trend towards phenotypic variation and maintenance of the status quo
50
Directional Selection
* Directional selection = selection that favours an increase or decrease in a phenotypic trait * Common in artificial selection where we select favourable traits * Can follow dramatic follow dramatic change in environment → e.g. migration, flood * Individuals at one extreme are more successful in future generations → e.g. peppered moth, hummingbird bill length * Directional selection shifts the overall makeup of the population by favouring variants of one extreme → e.g. trend towards darker colour, perhaps bc landscape blackened by lava
51
Disruptive Selection
* Selection favours 2 or more variations that differ from the population average * Usually at two extremes of the trait * Environmental change produces two distinct food sources * e.g. hummingbird bill length, tall and short flowers are a good source for short billed and long billed hummingbirds, but not medium billed hummingbirds * Birds on the extreme ends of this trait will be more successful and contribute more offspring to later generations * Diversifying selection favours variants of opposite extremes over intermediate individuals * E.g. relative frequencies of very light and very dark snails have increased. Perhaps snails have colonized a patchy habitat where a background of white snd is studded w lava rocks
52
Sexual Selection
* Favours selection of any trait that a partner deems valuable * Continued selection has resulted in sexual dimorphism or physical differences in the sexes Female mate choice * Bright colours, behaviour, physical traits Male competition * Evolved physical traits to aid in sexual competition e.g. antlers * Fight to gain control over territory that is home to females they can mate with → e.g. peacock tails, fiddler crab claws
53
Cumulative Selection
* Evolution of complex features * Mutations are a result of chance, natural selection is not * Accumulation of favourable mutations results in complex structures such as the eye
54
Altruism
* One organisms benefits from another’s behaviour * Believed that well-being of others is greater than the survival of oneself * E.g. insect colonies (workers vs queen) birds (care and feeding of young), monkeys and humans * Kin selection and care increases chance of genes being passed on

Biology (7 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions