D4.1 Natural Selection Flashcards
Where can evidence for evolution be found
fossils
base sequences in DNA and RNA
amino acid sequences in proteins
homologous structures
selected breeding
natural selection
organisms better adapted to their environment survive and produce more offspring
evolution occurs through this
theory of evolution developed by
charles darwin
what other idea did charles darwin develop - more detailed
idea of organic evolution by natural selection
paradigm shift
significant and fundamental change in how the world is viewed
when can natural selection occur
if there is variation
what does variation result in - 1
sexual reproduction during meiosis in gamete formation and fertilisation
how does variation occur in meiosis
- random assortment of chromosomes
- crossing over
- random fusion of gametes during fertilisation
results of meiosis
new combinations of existing characteristics that may affect survival and opportunities to reproduce
variations arise as product of what
as the product of mutation, giving entirely new alleles
germ line mutations
mutations in ovaries or testes
may be passed to offspring
overproduction of offspring in the wild leads to
naturally to their competition for resources
a breeding pair births what
a breeding pair of offspring
what is everything except a breeding pair of offspring
casualties of the struggle
what limits population size
environmental factors
space
light
food
what to limiting factors do
limit carrying capacity of a species population
factors that promote natural selection
over production of offspring and competition for resources
what do density independent factors do
affect survival of individuals in a population, causing numbers to fluctuate
how are favourable characteristics expressed
in phenotypes of some of the offspring
what do offspring with favourable characteristics gain
may be able to survive better and reproduce
others will be less be able to compete successfully to survive and reproduce
basis for natural selection
differences between individuals in adaptation, survival and reproduction
fitness
an organisms ability to pass its genetic material to its offspring
its reproductive success
selective advantage in alleles
those with the alleles that confer a selective advantage are more likely to breed and pass on these alleles to future generations
natural selection is a result of
intraspecific competition since they compete for the same resources
what does a mutation for selective advantage do
improves their change of surviving intraspecific competition
how is a change in environment a disadvantage
likely to operate on individuals and cause change to gene pools
aquired characteristics
arent heritable
the peppered moth in terms of evolutionary change
due to industrial revolution pollution the tree barks etc became black causing dark moth species to increase
what is the dark moth species increasing known as
industrial melanism
advantage of peppered moths and result
sooty moths could camouflage the best and became the dominant species
sexual dimorphism
differences in appearance between males and females of the same species such as in colour, shape, size and structure
sexual selection
selection arising through preference by one sex for certain characteristics in individuals of the other sex
birds of paradise living feature
rainforests of papua new guinea in south east asia
birds of paradise visual feature
male bird is brightly coloured and female is plane
what did difference in physical appearance lead to in birds of paradise
evolution
male got brighter colours and feathers to attract females
what would happen if there was a change in appearance or behaviour in birds of paradise
males and females may no longer being attracted and so no breeding
what birds of paradise feature is likely to attract a mate
males with most impressive plumpage and courtship
what can sexual selection affect
success and evolution
peacocks visual features
male species of peafowl
have bright, iridescent tail feathers with eye spot patterning presented during courtship
sexual selection in peacocks
tail becoming increasingly long and pattern more elaborate
what does peacocks visual feature do
makes it prone to predation and reduces the likelihood of survival
what does natural selection do
well adapt individuals to their environment
what does sexual selection do
enhances changes of breeding success
can be seen as a stronger evolutionary force because variation in mating success can amplify selection and maintain new genetic variation
guppies living feature
native to the mountain forest streams of north-east venezuela, margarita, trinidad and tobago
guppies visual feature
complex variation in colouring and patterning
most camouflage from spots to resemble gravel
hypothesis for male colouration 1
presence of predators, substrate type of stream affects survival, leading to spot brightness changing
hypothesis for male colouration 2
spot brightness increases when there is low predation
hypothesis for male colouration 3
high sports brightness attracts predators
endler did an experiment on guppies
what was it
3 levels of predation
weak, no and dangerous predator
used to reflect the density of predators in the wild
what happened to the guppies with dangerous predators
mean number of spots decreased
what happened to the guppies with no or weak predators
spots kept increasing
males had more colourful patterning
types of spots
line gravel favoured large spots and coarse gravel favoured small spots
natural selection in guppies
finding food
predators can see brighter fish
sexual selection in guppies
brighter males are more likely to mate and pass on alleles
