3.2 - Natural Selection Flashcards
What is natural selection?
the process which leads to evolution by which organisms with favourable adaptations have a selective advantage and survive to pass on their genes
What is evolution?
a gradual change in allele frequency over time due to natural selection
how does evolution occur via natural selection?
G - genetic variation
E - environmental change (selection pressure)
N - natural selection
I - inheritance (bacteria: binary fission) (increase allele frequency)
E - evolution
what is a niche?
the position occupied by an organism in its ecosystem where is has the best chance of survival
what are the three ways that organisms are adapted to their environment
- anatomical adaptation
- behavioural adaptations
- physiological adaptations
what are anatomical adaptations and give an example
a favourable change in the structure of an organism which makes it better suited to its environment.
example: blubber in whales
what are behavioural adaptations and give an example?
a favourable change in the actions of an organism which increases its chance of survival.
example: hibernation in bears
what are physiological adaptations and give an example?
a favourable change in bodily/metabolic functions of an organism which make it better suited to its environment
example: venom in snakes
What is speciation?
The formation of a new species from an existing species which happens as a result of the isolation of parts of a population.
what is reproductive isolation?
Isolated populations experience
different conditions. The allele frequencies change, therefore the genotypes and phenotypes of the isolated groups change. Eventually, the two members of the
split populations can no longer
breed.
What are the two types of speciation?
- allopatric speciation
- sympatric speciation
what is allopatric speciation
Takes place when populations are physically or geographically
separated in some way. Known as geographical isolation
what is adaptive radiation?
takes place when one species
evolves rapidly to form a
number of different species,
each filling a particular
ecological niche.
what is an endemic species?
If a species has evolved in
geographical isolation and is
only found in one place
what is sympatric speciation?
takes place between populations of a species living in the same place that become reproductively
isolated by mechanical, behavioural or seasonal changes.
what is ecological isolation?
Two populations inhabit the same region but develop preferences for different parts of the habitat
what is seasonal/temporal isolation?
two populations have different seasonal patterns
what is behavioural isolation?
when there are changes in courtship rituals or mating patterns which means animals do not recognise others as potential mates
what is mechanical isolation?
A mutation changes the genitalia of animals, making it difficult to mate
successfully with members of the population. they are not physically compatible
why is there an evolutionary race between antibiotics and bacteria?
- bacteria have evolved to adapt rapidly to become antibiotic-resistant due to mutations. Meaning they are not killed but survive and reproduce passing on the resistance to their offspring. Soon whole population will be resistant
CAUSES:
- Too widely prescribed and used
- Wide-spectrum antibiotics used first before testing
- Not completing the course of antibiotics
- Lack of basic hygiene in hospitals and care homes
- No big financial incentives for Big
Pharma to develop new antibiotics
how can we overcome these causes?
- restrict over-prescribing antibiotics and only prescribe if needed
- take tests to give antibiotics for the pathogens present or if they are present
- ensure patients take the full course of antibiotics
- educate people about the proper hygiene within hospitals and care homes
- put more investments into developing new antibiotics
