topic 5 Flashcards
what is evolution
a change in allele frequency over generations
what is natural selection
when more advantageous alleles are more likely to passed onto offspring via reproduction leading to a gradual change in a species over time
evolution by gene mutation
- mutations introduce new alleles into a population.
- lead to advantageous traits
- these traits more likely to be passed on, leading to evolutionary change.
- increase genetic variation within a population.
evolution by natural selection
Variation + Selection Pressure → Advantageous Traits Survive → Traits Passed On → Population Adapts.
Evolution occurs when heritable traits change in frequency over generations due to these processes.
what is speciation
the development of a new species
what must happen in order for speciation to occur
there must be some sort of isolating mechanism that prevents successful interbreeding between populations of species
why is reproductive isolation important to speciation
when it happens there is no more exchange of genes.
it prevents gene floww
what are the two types of speciation
allopatric speciation
sympatric speciation
allopatric speciation
when populations are geographically isolated from one another
sympatric speciation
random mutations beween two populations cause them to become reproductively isolated in the same environment
with no geographical barrier
allopatric speciation
two species will be geographically isolated
will respond to different selection pressures
will become less like each other
random mutations will accumulate
allele frequencies will change
random changes in allele frequency will cause genetic drift if popoulation is small
once two populations meet and are unable to breed they will belong to two different species
sympatric speciation
two populations overlap with no geographical barrier, will not interbreed and produce fertile offspring, no gene flow there is reproductive isolation
how does reproductive isolation occur in sympatric speciation
when random changes in the alleles and therefore the phenotypes of some individuals in a population prevent them from successfully breeding with other individuals in the populationh
temporal isolation
species exist in same area but reproduce at different times
ecological isolation
species may occupy different parts of the habitat
behavioral isolation
do not respond to each others courting behaviour will not attract individuals of oppposite sex
physical incompatibility
physical barriers such as changes in genitalia with prevents successful mating
how will the changes lead to isolation
lack of gene flow between two populations means allele frequencies may change in diff ways
lead to changes in phenotypes of two populations
if enough allele frequency differences arise they will eventually no longer be able to breed with each other
how was evidence validated to support the theory of evolution
theory sent to a scientific journal and 2-3 scientists would peer review and examine critically to check if his work is valid (use proper controls, use statistics, justified conclusions) theory paper sent back to mendel for alterations or clarification
then published in journal
would be presented at a scientific conference
What is genomics?
The branch of science that determines the sequence of bases in DNA to study genes.
How does genomics provide evidence for evolution?
By comparing base sequences of equivalent genes across species, showing similarities that indicate common ancestry.
What does the level of similarity in base sequences indicate?
High similarity = Recent divergence from a common ancestor.
Low similarity = Divergence occurred a long time ago.
How can genomics help establish relationships between organisms?
By determining when species diverged, helping trace evolutionary relationships.
What is proteomics?
The study of proteins, specifically sequencing their amino acid order in the primary structure.
