Natural Selection Flashcards
(30 cards)
What is natural selection?
The process by which the organisms that are best adapted in a particular environment are most likely to survive and reproduce, passing on advantageous alleles to their offspring
What does anatomical adaptation mean?
An adaptation involving the form and structure of an organism
What does physiological adaptation mean?
An adaptation involving the way the body of the organism works
What does behavioural adaptation?
An adaptation involving programmed or instinctive behaviour making organisms better adapted for survival
What is Darwin’s theory of evolution?
-All organisms show variation due to mutations
-If the conditions change some organisms will be better suited to the new environment than others
-There will be competition, those better adapted will survive (survival of the fittest)
-Those which survive will reproduce and pass on the allele to the next generation
-The new offspring will have the allele for the beneficial characteristic creating an increase in allele frequency
-This repeats over time and a species may evolve into a new species which is different to the original species
What types of bacteria are there?
-Bacteriostatic = to stop e.g stopping the bacterias protein production
-Bacteriocidal = to kill e.g preventing bacteria making cell walls
What is horizontal gene transfer?
Happens between different species of bacteria
What is transformation?
When there is no direct contact, the DNA is released by one and absorbed by another
What is conjugation?
The direct transfer of genetic material between two bacteria
What is the process of speciatation?
-A population becomes separated into two groups that are reproductively isolated, so there is no gene flow between groups
-The two groups environments are different so each has favourable characteristics
-This means the allele frequencies within the groups will change in different ways
-This will mean that eventually the two populations will be unable to interbreed, resulting in different species
What are the different types of isolation?
-Geographical isolation = a physical barrier separating two populations e.g a river or mountain range
-Ecological isolation = when two populations live in the same region but develop preferences for different parts of the habitat
-Seasonal isolation = when the timing of flowering or reproduction drifts away from the norm of the group
-Behavioural isolation = when courtship or the mating pattern change so animals do not recognise each other
-Mechanical isolation = a mutation changing the genitalia of animals making it physically impossible to breed
What is allopatric speciation?
Happens when populations are physically or geographically separated in some ways
What is sympatric speciatation?
When populations of a species are living in the same place and become reproductively isolated by mechanical, behavioural or seasonal changes
What is the definition for speciation?
The formation of new species
What does endemic mean?
A species which evolves in geographical isolation and is only found in one place
What does selection pressure mean?
The pressure exerted by a changed environment or niche on individuals in a population which causes changes in the population as a result of natural selection
What is industrial melanism?
The evolution of dark coloured individuals in a habitat that has been made darker by industrial pollution
What does post-zygotic mean?
Isolation which happens after fertilisation
What does pre-zygotic mean?
Isolation which happens before the gametes fertilise to create a zygote
What does directional pressure mean?
It is shown when there is a change from one dominant phenotype to another
-this is due to a change in environment where one phenotype is selected over others
-this can lead to speciation
Difference between evolution and natural selection?
Natural selection is the process by which evolution occurs but natural selection doesn’t necessarily lead to the evolution of a new species
What is beating bacteria step 1?
-Penicillin was discovered which only effects gram positive bacteria
-A range of bacteria were then discovered which affected a range of bacteria
-Antibiotics were described freely
-Antibiotics can add 20 years to peoples lives in the UK and USA
What is bacteria fight back?
-By the 1960s many bacteria became resistant to penicillin
-The bacteria now had an advantage and due to natural selection the mutation became more prevalent
-Infections were on the rise again
What is beating bacteria step 2?
-The antibiotic methicillian was produced but bacteria then became resistant
-There are many multi-resistant strains of bacteria now
