Evolution Flashcards
1
Q
Adaption def
A
a structure, behaviour, or physiological process that helps an organism survive and reproduce in a particular environment
2
Q
Mutations def
A
Changes in the genetic material of an organism (can occur spontaneously in DNA replication during the S phase of interphase before the cell divides)
3
Q
Mutations and evolution link?
A
- Necessary for evolution; creates more genetic variation in population
- Must occur in sex cells to have potential to be inherited
- Results in changes that are structural, functional, or physiological
4
Q
Mutations types
A
- Neutral; non-coding protein, no immediate effect
- Harmful; however may become favourable in a changing environment
- Beneficial; increases reproductive success of organism and accumulates in population over time
5
Q
Selective Advantage def
A
a genetic advantage that improves an organism’s chance of survival, usually in a changing environment
6
Q
Genetic Variation cause
A
- Results from large # of possible combos of genes that offspring can inherit
- Sexual reproduction, crossing over, mutations
7
Q
Genetic Variation and evolution link?
A
- The greater the # of genes, the more targets for mutations to occur
- Certain inherited traits that prove advantageous will survive changing environmental conditions so that they can be passed on
- Or else, all traits would be favoured or all traits would be not favoured
8
Q
Natural Selection def
A
Process by which nature favours the reproductive success of some individuals in a population over others; traits which may change characteristics in a population over time
9
Q
Selective Pressure def
A
any environmental condition that selects for certain characteristics of an individual and selects against other characteristics
10
Q
Does natural selection have an end goal?
A
- has no will, purpose, direction
- can’t anticipate changes in environment
- selects organisms most fit right now
- results simply from the ability of certain individuals in any population to survive environmental conditions and reproduce
11
Q
Fitness def
A
The relative contribution an individual makes to the gene pool of the next generation by producing offspring that survive long enough to reproduce
12
Q
Evolution def + can individuals evolve?
A
Process by which the genetic material (DNA) of a species changes over time
Individuals do not evolve because their DNA does not change. However, groups of peoples’ genetic makeup may change due to certain individuals being able to survive
13
Q
Archbishop James Usher
A
- God makes perfect creations
- Earth is recent, created on Sun October 23, 4004 BC
- Earth and its lifeforms are unchangeable based on the unchanging characteristics of their natural surroundings
14
Q
Baron Georges Curvier
A
- Studied fossils and found that;
- Each stratum (layer of rock) of sedimentary rock contained distinctive fossilized species
- The deeper the stratum, the more dissimilar the species are from modern life
- Catastrophism: local catastrophes could cause widespread extinctions which would then be replaced by newly created ones that migrated
15
Q
James Hutton (1795)
A
Actualism: geological formations are the result of slow processes that occurred in the past and is ongoing today
16
Q
Charles Lyell
A
Uniformitarianism:
- Same processes that change Earth occurred in the past
- These processes are constant and eternal
- Geological change is slow, gradual
17
Q
Lyell’s and Hutton’s work suggested;
A
- An old Earth
- Dramatic changes could result through small changes over long periods of time
- If Earth is slowly changing, could slow subtle changes occur in populations?
18
Q
Georges Buffon + Erasmus Darwin + Charles Linnaeus
A
*Common ancestor that create a new species*
- Buffon: species change over time, giving rise to new species
- Darwin: all life forms came from single source
- Linnaeus: some species give rise to other new ones through hybridization and interbreeding
19
Q
Jean-Baptiste Lamarck (1744)
A
- Spontaneous generation: new simple species were made from nonliving matter, that grew more complex over time
- Inheritance of Acquired Traits: Traits an organism gets during its lifetime (phenotypic change) gets passed on to future generation
eg. Elephants needed to stretch trunks to reach water, and over time, elephants will pass this trait to their offspring, resulting in long trunks. - For species to survive for long periods of time, they must adapt to changing environment
- Adaptations to environment result in traits that can be inherited by offspring
20
Q
Charles Darwin
A
- Formulated theory of evolution by natural selection
- Naturalist on a voyage on HMS Beagle to Galapagos Islands
21
Q
Charles Darwin observations
A
1. Fossils of extinct animals looked very similar to living animals
- Why would living and extinct organisms that looked similar be found in the same region?
2. Animals that were near each other looked more similar
- Why not just randomly distributed?
3. Galapagos species look similar but varied slightly between islands
- Why such a diversity of species in a small area?
- Perhaps these species were modified from a common ancestor?
4. Artificial selection
- Traits can be passed on from parent to offspring; Humans CHOOSE which are allowed to reproduce
- Overtime, a population begins to look a specific way - Can this happen in nature?
5. The finches on the Galapagos Islands closely resembled those on the adjacent coastline.
22
Q
Alfred Russel Wallace (1823) w/ Charles Darwin
A
- All life came from unknown organism (common ancestor)
- As organisms spread out over different environments, they adapted to help them survive by natural selection
23
Q
Relative Age of fossil
A
- Assumption of the chronology for rock strata and corresponding sequence for location of fossils found in layers
- Deeper the deposits = older
- Not accurate as tectonic plates means layers move
24
Q
Absolute Age of fossil
A
- Amount of radioisotopes found in fossil
- Radioisotopes: atoms w/ unstable nuclear arrangement that undergoes radioactive decay
- Radioactive decay: subatomic particles are released from nucleus which results in change due to loss of protons
- Half-life: time required for half a radioactive material to undergo decay
- During each half-life, 50% of parent isotope decays into daughter isotope
25
Evidence of evolution points?
- Artificial selection
- Biogeography
- Fossil record
- Comparative anatomy
- Divergent/convergent/coevolution
- Biochemistry (protein/dna)
26
Artificial Selection def
Humans can affect proportion of alleles among individuals of species that get passed on; choose who gets to reproduce
27
Artificial Selection connection?
If people can alter traits, then the environment can have a selective effect and cause small changes in a species (which over time, may give rise to different species)
- *NATURAL SELECTION, CHANGE IS SLOW, INHERITABLE TRAITS*
28
Biogeography def
the study of geographical distribution of species, past and present; Darwin hypothesized that species evolve in one location then spread out to other regions.
29
Biogeography points
**1. Species on islands are unique (endemic) and show similarities to each other**
- Not found on places with similar environments
- Suggests that groups of endemic species formed after their ancestors reached the islands; related to each other
**2. Species show strong similarities to the nearest mainland**
- Suggests island species evolved from mainland species as adapted to conditions on island due to different environmental conditions
**3. Organisms that live close to each other are more likely to be related than those that are far away but in similar environments**
**4. Fossils of same species can be found on coastline of neighbouring continents**
- Due to separation of Pangea into modern day land
- Suggests that given enough time, things can change
30
Biogeography connection?
- Similar structures in an area could be related
- Single ancestral species could give rise to similar but distinct new species, especially when isolated on separate islands
- *COMMON ANCESTOR, ADAPT TO ENVIRONMENT, CHANGE IS SLOW*
31
Fossil Record def
occurs when organism is buried and compressed under many layers of sediment which force the deposits to harden
32
Fossil Record connection?
- Older Earth (radioisotopes dating)
- When arranged by age, show progressive evolutionary change to greater complexity
- Deeper layers showed simpler structures different from modern day
- Vertebrates appear later so organisms were not put on Earth at the same time (Common ancestor)
- Transitional forms that link older fossils to modern day species
- *CHANGE IS SLOW, ORGANISMS ARE MADE PERFECT*
33
Comparative Anatomy def
comparison of body structures between species
34
Comparative Anatomy points
1. **Homologous Structures**: similar in structure but different in origin
- Anatomical similarities between species result because of common ancestor which then adapted to environment
- eg. Bones fusing together
2. **Comparative Embryology**: comparison of early stages of animal development
- Closely related organisms go through similar stages in embryonic development (eg. gill pouches and tail) which diverge as genes got turned on/off
3. **Analogous Structures**: similar in function but different in origin
- Similar selective pressures so came upon same strategy to survive
- Do not share common ancestor
4. **Vestigial Features**: structures that serve no useful function in organism
- Ancestor needed the structure but got reduced over time as it is no longer advantageous and it uses resources
35
Comparative Anatomy connection?
- Species evolved from ancestor that had a use for structure
- Organisms are not created perfect
- Similar structures (past and present) could be related to each other
- Common ancestor = divergent evolution (analogous structures show convergent evolution)
- *COMMON ANCESTOR, ADAPT TO ENVIRONMENT, OFFSPRING IS MODIFIED, GOD DOESN'T MAKE PERFECT CREATURES*
36
Divergent Evolution def
2 species evolve increasingly different traits resulting from different selective pressures (homologous features)
37
Convergent Evolution def
2 species become similar in phenotype in response to similar selective pressures (analogous/homoplasies features)
38
Adaptive Radiation def
- divergent evolution + allopatric speciation simultaneously among a number of groups to produce 3+ species - common ancestor into lots of diff species - 1 common ancestor -\> different selective pressures (food) -\> species evolve -\> specialized, can’t interbreed - eg. Ground finches first arriving at Galapagos Islands and then specializing
39
Coevolution def
process in which species evolves in response to the evolution of another species
40
Divergent/convergent/coevolution connection?
- Demonstrates how species could evolve from ancestral species
- Species that are unrelated are able to develop similar traits due to similar selective pressures
- Differing selective pressures can lead to divergence of traits
* - COMMON ANCESTOR, ADAPT TO ENVIRONMENT, GOD DOESN'T MAKE PERFECT CREATURES*
41
Protein points
- Different species have common proteins
- # of differing amino acids show evolutionary relationships
42
Protein connection?
Share common ancestor = similar amino acid sequences because less time to mutate + diverge
## Footnote
*- COMMON ANCESTOR, CHANGE IS SLOW*
43
DNA connection?
- Common genetic code shows that all life on Earth are related
- Closely related species show similar DNA patterns while those not closely related have more differences in sequence
* - COMMON ANCESTOR*
44
Hardy Weinberg
- Mathematical relationship that shows that allele frequencies won’t change from generation to generation as long as;
**1. Population is large**
**2. Mating opportunities are equal**
**3. No mutations occur**
**4. No migration occurs**
**5. No natural selection occurs; everyone will survive and reproduce**
- This is impossible as these conditions cannot be maintained
45
5 Factors Causing Evolution points
1. Genetic drift
2. Genetic flow (migration)
3. Sexual selection
4. Mutations
5. Natural selection
46
1. Genetic Drift def
random change in genetic variation from generation to generation due to chance; more significant in small populations as individuals represent a greater proportion of a particular allele
47
1. Genetic Drift types
1. **Bottleneck Effect**: changes in gene distribution that result from rapid decrease in population size
- Survivors are not representative of original gene pool
2. **Founder Effect:** change in a gene pool that occurs when a few individuals start a new isolated population
- Founders will not carry all of the alleles from original gene pool - Diversity in new gene pool will be limited
- New population will be different from the old population
48
1. Genetic Drift effect
Changes frequencies of alleles
49
2. Gene Flow (Migration) def
- net movement of alleles from one population to another through the movement of gametes - Increases genetic variation: adding alleles to gene pool that may be new to population - Decreases genetic differences: combining gene pools of populations
50
2. Gene Flow (Migration) effect
Movement of genes will change allele frequencies in either or both populations
51
3. Sexual Selection def
favours selection of any trait that influences the mating success of individual
52
Sexual Dimorphism def
- Striking differences in physical appearance of males and females
- Adaptions have evolved to increase reproductive success
53
Nonrandom mating def
- Mating for a particular phenotype/inbreeding
- Increases proportion of homozygous individuals in a population
- Random mating is very uncommon as not all individuals have equal reproductive success
54
4. Mutations points
- Only source of new genetic material
- Caused by unrepaired changes in DNA (chromosome breakage during meiosis)
- Must occur in gametes to be passed on
55
4. Mutations effect
If beneficial, will accumulate over time as will help individual survive + reproduce (changes allele frequencies)
56
Polyploidy def
- mutation that results in 3+ sets of chromosomes - Doubling of genetic material - Good if tolerated; may provide an advantageous trait, and if not have other chromosome to fall back on
57
5. Natural Selection as driving force behind evolution?
- Ultimate fate of all genetic combos rests in ability to produce individuals best adapted to survive and reproduce
- The environment selects the best adapted phenotype and favours a set of alleles
- Beneficial mutations are selected for and will accumulate
58
5. Natural Selection effect
Over many generations, frequencies of alleles of many different traits may change resulting in significant changes in traits of the population
59
Types of Natural Selection
- Stabilizing Selection: intermediate are most favoured by environment
- Directional Selection: favours one of the extremes; occurs during environmental change or when members of population migrate to new habitat
- Disruptive Selection: favours both extremes; leads to divergent evolution
60
Microevolution def
changes in allele frequencies and phenotypic traits within populations and species
61
Natural Selection theory points!!
**1. Individuals in a population have different traits which may be inherited**
- Some traits are more advantageous than others which increases their chance of survival
**2. These individuals produce far more offspring than the environment can support**
- Leads to competition for survival
**3. The individuals best suited for the environment will leave more offspring, resulting in a change in the genetic makeup of the population (EVOLUTION)**
- Their favourable variations will become more common
62
Is natural selection random?
- Genetic variations are inherited randomly (mutations, sexual reproduction)
- However, natural selection is not random
- Environment dictates which variations are favourable
- Over time, common ancestor will give rise to many other species
63
Macroevolution def
large-scale evolutionary changes occur which are significant enough to warrant classification of groups into distrinct genera (eg. adaptive radiation of mammals after dinosaurs)
64
Speciation def
formation of new species from existing species
65
Species def
populations that interbreed or have the ability to interbreed with each other and make viable offspring under natural conditions; members of different species are reproductively isolated from one another
66
How to differentiate between species?
- morphology
- behavior or biological means (reproductive isolating mechanisms for sexually reproducing organisms).
67
Prezygotic Mechanisms
_a) Prevent Mating_
**1. Ecological Isolation**
- Species that occupy seperate habitats that do not encounter each other for reproduction
**2. Temporal Isolation**
- Species that live in the same habitat but are separated in time when their reproductive cycles occur at different times
**3. Behavioral Isolation**
- Species that can be separated when a distinct mating ritual is required for recognizing or selecting a mate
_b) Restrict Fertilization_
**1. Mechanical Isolation**
- Structural differences in reproductive organs which prevent copulation
**2. Gametic Isolation**
- Prevent fertilization at molecular level
- Gametes recognize each other using molecular markers
68
Postzygotic Mechanisms
_Prevent hybrid zygotes from reproducing;_
**1. Zygotic Mortality**
- No fertilized zygotes/embyros develop into maturity because of chromosomal incompatability
**2. Hybrid Inviability**
- Hybrid offspring are unlikely to live long
**3. Hybrid Infertility**
- Offspring is strong/healthy but sterile - Not classified as a species because it’s a dead end
69
Formation of Species process
1. **Reproductive isolation** of original population
2. **Genetic isolation** (no combining of gene pools)
3. **Mutations** **and selective pressure** processes are not shared
4. **Time to develop reproductive isolating mechanisms** which prevent mating/fertilization, or successfuly development of zygotes
5. Significant evolutionary changes that occur in either population will result in **differences between 2 gene pools**, creating a separate species
70
Sympatric Speciation def
- Speciation in which populations within the same geographical areas diverge and become reproductively isolated
- Relies on other reproductive isolating mechanisms forming within original population
- Genetic change that results in reproductive barrier between the offspring and parent population would cause a new species in a single generation
71
Allopatric Speciation
- Speciation in which a population is split into 2+ isolated groups by a geographic barrier
- Eventually, gene pool of split population becomes so distinct that 2 groups are unable to interbreed (natural selection, mutation, genetic drift, gene flow)
72
Why are smaller populations more likely to become new species?
Smaller gene pool means that new mutations may become fixed in population simply by chance
73
Gradualism def
- model of evolutation that views evolutionary change as slow and steady before + after divergence
- big changes occur by the accumulation of many small changes
74
Puncuated Equilibrium def
model of evolution that views evolutionary history as long periods of equilibrium that are interrupted by periods of divergence
75
REVIEW: EVOLUTION POINTS and WHO
1. Competition due to limited resources *(Malthus)*
2. Organisms must adapt or die *(Curvier, Lamarck)*
3. Common ancestor *(Darwin Sr, Buffon, Linnaeus)*
4. Change is slow + gradual *(Hutton + Lyell)*
5. Those better suited leave more offspring *(Darwin)*
6. Traits can be inherited by offspring but they are modified *(Lamarck)*
7. Individuals of a population vary
76
Types of adaptions?
- structural: special body parts
- physiological: systems to allow body to perform certain biochemical reactions
- behavioural: special ways an organism behaves to survive
77
How do adaptations develop?
Adaptations are the result of gradual, accumulative changes in a species that help an organism survive and reproduce
78
Variations def
differences between individuals, which may be structural, functional, or physiological; environmental conditions determine whether a variation is positive or negative or neutral
79
Genetic variation in a population results from what?
The variety of genetic information in all individuals of the population
80
Can mutations mean the survival of the whole population?
Yes, as a **new allele** that results from **random mutation** may provide a selective advantage. Those with the advantage may survive long enough to reproduce.
81
Con of artificial selection?
Reduced genetic diversity
82
Example of how new species can form?
1. Individuals from species on new environment, some survived due to mutations and have advantageous traits
2. Their ability to survive allowed them to reproduce
3. Offspring passed on traits that helped them to survive
4. Natural selection = species began to change into new one
5. Individuals moved to different islands = adaptive radiation
