Evolution , Variation &adaptation Flashcards
Natural selection
The process by which organisms best suited to their environment survive and reproduce passing On their characteristics to their offspring through genes
Darwin
Born in 1809
Most people believed god created everything
Finches t
What observations and analysis did Darwin make
Offspring generally resemble their parents - characteristics passed onto their next generation
No 2 individuals are identical - there’s a variety of organisms= !many changes/mutations may give rise to a new species therefore individual characterises survive
Organisms have the ability to produce larger numbers of offspring yet populations remain a stable size - STruggle for existence
Darwauns finches
Different finches in different islands in the Galápagos Islands and different to mainland
Varied in beak type - specialised for environment they lived in
Natural selection
Interspecific variation
Variation between members of different species
Intra specific variation
Variation between organisms WITHIN a species
Causes of variation
Generic and evvironmental
Genetic causss of variation
Mutations - changes to the DNA sequence and therefore the genes that code for proteins , can be physical or metabolic - if a mutation occurs in gametes = offspring
Meiosis - gametes produced, independent assortment and crossing over
Sexual reproduction - genes from 2 parents
Chance - due to chance ( which 2 gametes join )
Alleles - genes have different alleles. with a gene for a particular characteristic , different alleles produce different effects. different VERSIONS of alleles
Environmental causes of variation
All organisms affected by the environment which they live in
Eg scars
Environmental and genetic variation - both
COMBINATION
Height for example - fall parents and diet
Skin colour - parents and sunlight
What is variation
Differences between organisms characteristics
Discontinuous variation
A characteristic that can only result in certain values No inbetween values Discrete categories without intermediates No environmental influences Effect of few genes QualiTive data Bad chart Eg animal sex - male or female
Continuous variation
No distinct groups
Many intermediate species
Btoh environment and usually many genes influence
Quantative
Height
Distribution curves
Characteristics of normal distribution =
- mean , mode and median the same
- the distribution has a characteristic ‘ bell shaped ‘ that symmetrical about the mean
- 50% of rates are less than mean and 50% greater
- most values lie close of the mean value - the number of individuals at extremes are low
Standard deviation
Measure of how spread out the data is
Greater standard deviation = larger spread = larger variation
Statistical tests w
!!!!!
What is adaptation
Characteristics that increase an organisms chance of survival and reproduction
Anatomical adaptation
Physical features ( internal and external )
Behavioural adaptation
They way an organism acts , can be inherited or learnt from parents
Physiological adapatation ? What
Processes that take place inside an organism
Anatomical adaptations - examples
Body covering - eg hair, scale to spines, These can help and organism to fly or stay warm= provide protection , prevent waterloss
Camoglagu
Teeth - shape& type related to diet
Mimicry - copying another animals appearance of sounds ( harmless organism can fool predators )think they’re dangerous
Behavioural adaptations examples
Survival - playing dead
Coorship_ bahaviourals to attract a mate eg dance
Seasonal behaviours- allow an organism to cope with changes to environment
Migration- animals move from one region to another and back when environmental conditions are more favourable
Hibernation - heart rate , breathing and body temp slow down = conserving energy reducing requirements for food
Types of behavioural adaptations
Innate ( instinctive ) = genes
Leaned behavioural - learnt from experience or ?? from toher animals
Many are combo of both
Physiological adapatations
Poison production
Antibiotic production
Water holding
Reflexes , blinking , temp regulation
How does anatomical adapatation provide evidence for convergent evolution
Unrelated species begin to share similar traits
These similarities evolve because the organisms adapt to similar environments or other selection or other selection pressures
What does analogous structure mean
Performing same role But different structures
Adapted to perform the same function but have different origin
Eg fin of whale and fishb perform SAME role - different structures
Placental mammals
Placenta connects the embryo to its mothers circulatory system in the uterus , this nourishes the embryo
Marsupial mammals
Start life in the uterus then leave and enter the marsupium ( pouch)while stil embryos, they complete development by suckling milk
Simularities of marsupial and placental moles
Short and powerful limbs, huge front claws, no edxternal ears, limited eyesight
Both have streamlined, velvet fur
Differences of marsupial and placental moles
M have a hood area on front of its head. Placental has a thin snout, marsupial has a fused neck vertabrae
M are white- orange , placental is grey
What are seletion pressures
Factors that affect an organisms chance of survival or reproductive success
ORganisms best adapted to their enviornemnt are more likely to survive and reproduce
Steps of evolving and natural selection
- Organisms within a species show variation, their characterstics that are caused by differences in their genes ( genetic variation)
- Organisms best adapted to a sleection pressure survive- survival of the fittest
- successful organisms pass the allele encoding the advantageoys characteristics nto thier offspring. Organisms wiht non adventogeous gene are less likely to pass it on
- repeated every generation, over time the advantageous adaptation proportion increases. Frequency ncreases in populations gene poo l
- OVer time =evolutin of new speceis
Antibiotic resistance
Bacteria, few resistant
Bathed in antibiotics
Weak die adnd resitant bacteria mutiply, eventually all resistant
e.g.mrsa - ressitant to methicillin
pepper moths
in the 19th centuary - industlisation meant that plants turned black adn darker, moths changed from white to balck
THose that were black died
Pesticide resistance
Same pricipal as antibitoic resistance -but for insects
e.g. in 1950s, australia, pesticide used to kill sheep blwofies, within 6 years they developed rsistance. Pre adaptation=pre esiting advantage
reducing chance of pesticide resistance
Mixing 2 together to etend time for ressitance to emerge
GM
Reduce use of presticides
Only use for breakout now invasion
bacteria evolution
One strand of Flavobacterium - opportunities arisen, live in waste wter from factories hat produce nylon 6
Strain can digest it = nutrients
