Evolution Flashcards
(26 cards)
1
Q
what is evolution?
A
- process of gradual change in a species or population
- number of species on earth is a result of equilibrium between extinction and speciation
- allows for adaption to environments
2
Q
Ideas on evolution
A
- Plato: species are static, contrasts with other Greeks
- Leclerc in the 18th century reintroduced evolution after observing species in various areas
- 18th cent Hutton proposed geologic change
- 1830s Darwin and Wallace travel, Darwin proposed natural selection
3
Q
Processes and Patterns of Natural Selection
A
- Divergent: two species evolved in different directions from a common point
- Convergent: similar phenotypes evolve in species distantly related (bats and insects both fly)
- individual species undergo natural selection
4
Q
Fossils as Evidence for evolution
A
- scientists determine age and categorize fossils in relation to other organisms
5
Q
Anatomy as Evidence for evolution
A
- presence of structures that share a similar form in separate species
- whales, birds and dogs have similar morphology in appendages
- these are called homologous parts, may be a result of convergent evolution though
- some structures do not have an apparent function, implies remnants of ancestors
6
Q
Biogeographical evidence of evolution
A
- geographic distribution follows patterns explained by movement of tectonic plates
- broad groups from Pangea are dispersed globally
- Australia has many species that resemble mainland species
7
Q
what is phylogeny
A
- the study of evolutionary history and relations of organisms
- based on ancestry not traits
8
Q
what is a phylogenetic tree
A
- diagram summarizing evolutions
- comprised of nodes and branches
- Woese’s depicts the 3 domains: Eukarya, Archaea and Bacteria
9
Q
2 types of phylogenetic trees
A
- Rooted: base with a singular lineage diverging into the three domains
- Unrooted: common ancestor not shown, but relationships between species are
10
Q
Characteristics of a phylogenetic tree
A
- branch point: single lineage evolves into a new distinct one
- Basal taxon: lineage evolved early from the root that remains unbranched
- Sister taxa: two lineages from the same branch
- Polytomy: more than two lineages from a single branch, may suggest a missing link
11
Q
how is a phylogenetic tree constructed
A
- after analogous and homologous traits, traits are sorted into clades (based on common ancestor)
- clades vary in size but must come from a single point
12
Q
what is a shared ancestral characteristic
A
- trait present in an ancestor that all members of a clade have ex. vertebrate
13
Q
what is a shared derived characteristic
A
- trait derived at some point but not present in all ancestors
14
Q
what is natural selection
A
- “survival of the fittest”
- discovered by Darwin, further reinforced with Mendel’s pea plants
15
Q
what is modern synthesis
A
- how evolution effects genetic makeup which in return effects evolution
- natural selection only occurs if genetic variation is there
16
Q
stabilizing selection
A
- a non-extreme trait is preferred
- ex. robins lay 4 eggs as less may lead to less viable offspring, more may lead to malnourishment
17
Q
sexual selection
A
- differences in males and females other than reproductive organs
- males are usually larger and more colourful than females - dimorphisms
- may vary, sometimes females are bigger
18
Q
Frequency-Dependent Selection
A
- favouring of either common (+) or rare (-) phenotypes
- ex. Lizards in the USA have different mating techniques
- orange: strong, fight other males
- blue: strong pairing bonds
- yellow: small, sneak past orange
- negative increases genetic variation, positive decreases it
19
Q
Adaption
A
- heritable trait that increases or maintains survival in the present environment
- subject to natural selection
20
Q
Genetic Drift
A
- effect of chance on genotype composition
- ex. some individuals will have more offspring than others
- natural occurrences can magnify drift (bottleneck effect)
21
Q
Genetic Flow
A
- alleles flowing in and out of a population via migration
22
Q
Mutation
A
- changes within DNA
- if harmful, it is eliminated quickly through natural selection
23
Q
Non-Random mating
A
- picking a mate based on a certain factor or characteristic may lead to a change in population
24
Q
Environmental Variance
A
- some species are greatly impacted by the environment
- turtles and reptiles have temperature dependent sex determination
25
Directional Selection
- selection of phenotypes at on extreme of the existing variations
- white moths in the industrial revolution were phased out as black phenotype chosen to blend in with soot covered trees
26
Diversifying selection
- two or more distinct phenotypes that are advantageous
