evolution 🔬 Flashcards
what is the Cambrian explosion?
it is a massive burst of evolution over a very short period of time and hundreds of species went up to millions
why did the Cambrian explosion happen?
it was because of a sudden increase in oxygen levels which made predation feasible- prey also had to respond to the changes
OR
Calcium concentrations increased
OR
it was just an artefact of good preservation of folssil in rocks
what are the key features of the origin and history of life?
- changes
- progression
- complexity increases over time
- diversity increases over time
- life strategies are reflected in kingdoms
- DNA in genomes is a common feature and correlates apparent relatedness
what is the process which explains the diversity of life?
evolution
organisms become more diverse, from bacteria to animals via single celled/ very simple eukaryotes, fungi, plants ect
what explains the relatedness of life?
DNA sequence evidence confirms the relatedness as a result of evolution
what explains the complexity of organisms?
evolution
- we share the world with simple viruses and similar biological principles operate across the spectrum of complexity
what is radiosynthetic fungi?
it is a type of fungal pigment melanin which can absorb gamma rays and convert it to energy
what does it mean by ‘the diversity and durability of life’?
it means that species have evolved to fill every ecological niche
what explains how life can change over time?
evolution
- it explains how species change over time and adapt to altered enviroment, how new species emerge and how some species cant adapt to changes in their surroundings (which leads to extinction)
what is the theory of evolution?
its about genetic diversity, selection pressures and survival of the fittest
give examples of selection pressures?
- competition of resources
- predation
- disease
- adverse environmental change such as temperature, oxygen levels ect
- competition for a mate
why did survival of the fittest develop?
its the genetic differences between individuals ensure some are between able to cope with a selection pressure in the environment
they survive/ thrive better to produce more offspring
50% of those offspring will carry an advantageous mutation, this becomes more frequent in the population over generations
what is evolutionary mechanism based on?
its based on molecular mechanism
random genotype mutation causes increased production of offspring who also inherit the genotype
why is MRSA so dangerous?
as patients with it have recently failing to respond to antibiotics ‘antibiotic resistance’
what are fossil records?
theyre the remains of organisms preserved in rocks, peat or ice
its made of hard tissue such as bones and shells
you can carbon date fossils to find out the age of them
the older the fosssil, the deeper in the rock it is
what does ‘nature is a tinkerer, not an inventor?
it means that new proteins are evolved but the shuffling of old ones like making different lego models from the same pieces
what is the definition of a species?
its a group of organisms with similar features which can interbreed to produce fertile offspring and which are reproductively isolated from other species
what are the isolating mechanisms involved in speciation?
geographical isolation - allopatric, thought to be the most important isolating mechanism
elecolgical isolation - live in the same place but in different habitats
ecological isolation-
what are the isolating mechanisms involved in speciation?
geographical isolation - allopatric, thought to be the most important isolating mechanism
ecological isolation - live in the same place but in different habitats
temporal isolation- breeding at different times
Behavioural isolation- e.g., courtship rituals are different
Mechanical isolation- anatomical differences prevent mating
Gametic isolation- gametes can’t unite
Hybrid isolation- offspring produced are infertile – sympatric
what is microevolution?
this is about stabilising advantageous mutations in the population and about changes in allele frequency in response to environmental pressure
what is artificial selection?
this is when humans act as the selection pressure
we controlled the evolution of crop plants, food, animals and dogs
how are are genes selfish?
they are only trying to become more prevalent/ successful
they do this by modifying your cells and ultimately your body so you pass these modifications on
an example of this is cancer which is very short-sighted, uncontrolled cell division so its not a long-term solution for survival
what is sexual selection?
it is when individuals are selected for sexual reproduction
the result is not about death but the unsuccessful competitor but few or no offspring
it can either involve female choice (intersexual) or male-male competition (intrasexual)
this helps to explain sexual dimorphism and indicates ‘good’ genes present
the ‘prize’ in this case is successful mating and the transition of genes from one generation to the next
what is the downside to sexual selection?
it might end up with reduced survival fitness in the case of intersexual selection e.g. tall feathers don’t make flying efficient but they do make the males more attractive to the females
this might also help to answer some difficult questions in evolution by explaining some strange characteristics as ‘fashion’ first before functionality
are there any downsides to evolution?
evolution is blind to the future as over specialisations and dead ends are possible
evolution has to make use of pre-existing structures
how is extinction normal?
maybe some animals deserve to go extinct and whatever happens in the world, there will be other animals to fill those niches and evolve to fill the gaps
what is the order among primates?
Hominidae
hominini
- homo
- chimpanzee
what is parentology?
its the scientific study of life which existed prior to, and sometimes including, the start of the holocene epoch (about 11.7 thousand years ago)
what is geochronology?
its the science determining the age of rocks, fossils and sediments using signatures inherited in the rocks themselves using radiometric dating
what is our closest relative and how long ago ago did we differentiate from them?
chimpanzees
lolecular data suggests we were the same about 5-8 million years ago based on immunological distance and molecular clock
what are the 2 differences between humans and chimpanzees (in terms of DNA)?
nucleotide substitutions
- ~35 million nucleotide substitutions
- only about 1% of the whole genome is different
insertion and deletion of DNA
- ~5 million insertions and deletions
- 100 million base pairs
- over 1000 large regions of >2000 base pairs which in total make up to 10 mullion base pairs difference between chimps and humans
what is paleogenetics?
it is the study of early humans and other ancient populations
it uses methods of genetics to study such as extracting DNA from bones and sequencing their genomes,
what is the human evolution timeline according to primate groups?
Homininae
- Sahelanthropus
-Ardipithecus
- Australopithecus
Homo
- Homo habilis
- Homo erectus
- Neanderthal
- Denisovan
- Homo sapienswhat is the tradtional view to explain where europeans came from?
- they were hunter gatherers - 45,000 years ago
- the farming migration from the middle east -9000 years ago
this meant that farming is seen as a ‘cultural revolution’
what is the new view to explain where europeans came from?
- the asian namad ‘ghost lineage’ about 4-5000 years ago
- first came from siberia (24,000 years ago) to Scandinavia (8000 years ago) and the new world (14000 years ago)
- then from Scandinavia to central and western Europe (4000 years ago)
- this accounts for 20% of the genome of europeans
- people from southern Europe have very little of this genome
where do british people come from?
- from a mixture of scandinavian countries, France, Germany and other western European countries
- this makes sense historically but it depends where in the UK you look
