Evolution Flashcards
What are the evidences of evolution?
Homologous structures
Analogous structures
Comparative embryology
Vestigial structures
Molecular biology
Homologous genes
Biogeography
Fossil records
Artificial selection
Direct observation
What are homologous structures?
homo = the same logous = having a correspondence / relation
shared physical structure, therefore common ancestor
same structure (bones in same relative position), different function / appearance = ADAPTIVE RADIATION
What are analogous structures?
ana = again, anew, TOWARDS logous = having a correspondence / relation
similar function, different structure, therefore convergent evolution
What is comparative embryology?
some homologous structures only seen in embryos
therefore, development programmes of vertebrates have small variation of common ancestor
What are vestigial structures?
homologous structures to other organisms, yet NO PURPOSE
therefore, reduce = evolutionary “leftovers” = vestigial structures
What is molecular biology?
principle of common descent
REINFORCED by modern biochemistry + molecular chemistry
code to translate nucleotide sequences into amino acid sequences
ESSENTIALLY SAME 4 FOR ALL ORGANISMS (A,C,G,T)
DNA similarity (diversification) = relatedness of organisms
What are homologous genes?
idea behind 2 species have ‘same gene’ bc of common ancestor
What is biogeography?
geological distribution of organisms follows pattern of distribution of evolution and tectonic plate movement
evidence: fossils
e. g.: marsupials common in Australia & placentals rare
What are fossil records?
preserved remains of previously living organisms
most organisms never fossilize
What does fossilisation occur?
soft body parts decay, hard parts (calcium carbonate) remain
absence of condition = formation of deposits
= fossils
+ preserved trails = covered by sediments (becomes sedimentary rock), forms in stratas
How are fossils dated?
radiometric dating = process that measures radioactive decay of certain elements
What is artificial selection?
intentional reproduction of individuals in a pop. with desirable traits
What is direct observation?
visible evidence of evolution
e.g. colour change, chemical resistance
What is speciation
pop. of a species gradually diverge into seperate species by evolution
What is Darwin’s theory?
natural selection:
mutations = variation
unfavourable mutations selected against
reproduction and mutation
favourable mutations increase survival
reproduce
MOST RESPONSIVE SURVIVES
What is Lamark’s theory?
species changed as a result of the habitual use/disuse of a feature
modifications passed in genes over time
What are the factors of the natural selection theory?
- traits are heritable
- overproduction of offspring - competition for resources
- struggle for survival - environmental pressures = diff. reproduction
- variation in pop.
- reproduce
- evolution
What is the mneumonic for the theory of evolution?
ICE AGE
Inherited variation
Competition
Environmental pressures
Adaptation
Genotype frequency
Evolution
What are the different types of evolution?
divergent
convergent
parallel
coevolution
punctuated equilibrium
gradualism
Can you explain divergent evolution for me?
2 species gradually become diff.
responsible for diversity of 1st cell
responsible for evolution
specification
homologous structures
e.g. Finches
Can you explain convergent evolution for me?
not closely related
independently evolve similar traits
result of environmental pressures
analogous structures
e.g. insects / bats / birds
MIMICRY - consequence of warning coloration
Can you explain coevolution to me?
equal to / more than 2 species evolve in tangent by exerting selection pressures on each other
usually close environmental interactions
e.g. parasite, prey & predator, competition, mutalism
Can you explain to me punctuated equilibrium?
evolutionary change in short periods of time (~ 500,000 years) and tied to speciation
contrasts Darwin’s theory, evolution only happens in rapid bursts
Can you explain to me gradualism?
gradual selection & variation
small variations eventually change population
What are the types of selection and draw their graphs?
directional
disruptive
stabilising
sexual selection
artificial selection
What does directional selection involve?
extreme phenotypes favoured, therefore shift to that phenotype
advantageous allele increases, consequence of diff. survival & reproduction compared to other phenotypes
What does disruptive selection involve?
extreme values favoured over intermediate ones
trait variance increases = division into 2 species
What does stabilising selection involve?
favours intermediate traits / variants
pop. mean stabilises on non-extreme trait
most common type of selection
What does sexual selection involve?
members of 1 biological sex choose mates of the opposite sex
compete wt members of same sex for access to opposite sex
What does artifical selection involve?
humans use plant / animal breeding to selectively develop particular phenotypic traits by selecting which would sexually reproduce
What are the mechanisms of evolution?
PRINCIPLE: evolution can only occur if there is change in gene frequency wtin a pop. over time
mutations
natural selection
gene flow
genetic drift
Can you explain what the mechanism of evolution known as mutations means?
random change in pop.’s gene pool
change in DNA of 1 / more chromosomes
mutations = new alleles = VARIATION
Can you explain what the mechanism of evolution known as natural selection means?
occurs when organisms subjected to environmental pressures
genes of less fit organisms eventually lost
MOST IMPORTANT MECHANISM
Can you explain what the mechanism of evolution known as gene flow means?
evolution during migration from 1 group to another
migrating individuals interbreed = VARIATION
therefore establishes gene flow
increases similarity btw remaining pop.s of the same species
Can you explain what the mechanism of evolution known as genetic drift means?
small group of individuals leave pop. & establish a new pop. in a geographically isolated region
fitness of species does not = genetic drift
DOES NOT OCCUR IN LARGE POP.
