b5 - speciation/ classification Flashcards
species
a group of organisms which can interbreed to produce FERTILE offspring
a population can evolve into new species - this requires
ISOLATION
- geographical isolation
- reproductive isolation
how speciation occurs
- come from common ancestors
- a geographical barrier may form eg river
- species become geographically separate
- competition for resources drives adaptations
- the adaptions make organisms different so cant reproduce
- became so different females dont physically recognise males
- have been apart so long that mating rituals have changed
why is it important to have a clear definition of species
some species are dying out - we need to know what a species is to monitor individuals of a species + protect the species
peppered moth - evidence of evolution
- were more white moths due to camouflaged in sky
- was a mutant of black moths
- industrial revolution covered trees in soot
- more black moths as they were camouflaged
who came up with peppered moth theory + who proved it
James W Tutt
Bernard Kettlewell
what are fossils
fossils are remains of the existence of dead organisms
- sometimes traces of organisms are left (TRACE fossils)
- plants / insects sometimes trapped in amber
- trunks of trees found after being buried in mud containing volcanic ash
how are fossils formed
- organism dies in water
- covered in sediment
- soft parts decay
- pressure from above turns sediment to rock
- minerals replace body tissues to form rock - hard parts more likely to fossilise
why is oxygen not included in the fossilisation process
don’t want decomposers to cause decay
decomposers need O2 for respiration
fossils - evidence for evolution
- shows organisms that lived in the past differ from those today (have evolved)
why is the fossil record incomplete
- not all organisms fossilise
- are deep underground (uncovered by erosion or plate shift)
antibiotics
chemicals that kill bacteria
discovered 1928 - Alexander Flemming
antibiotic resistance
- there is variation
- mutation occurs
- few bacteria develops genes which make them resistant to antibiotics
- bacteria are exposed to antibiotic - most die
- more resources for resistant bacteria to multiply
- if the course of antibiotics completes all bacteria is killed
- if course incomplete the resistant bacteria thrive
- antibiotic is no longer effective
MRSA superbugs
a bacteria that is resistant to antibiotics
resistant rats
- there is variation
- a mutation causes resistance
- non resistant rats die and resistant survive/ reproduce
- pass on resistant gene
- over generations resistance gene increases
alfred russel wallace
independently developed the theory of natural selection
warning colouration and mimicry - evidence for natural selection
- random mutation of colouring
- those without colouring are eaten so die
- those with colouring survive and reproduce
- pass the colouring allele onto offspring
- over generations freq of colouring allele increases
artificial classification
observable characteristics to group organisms according to similarities and differences
natural classification
classify organisms according to their evolutionary history and true relationships
carl line as
devised natural classification
taxonomic system
hierarchy of levels - contains 5 kingdoms
5 kingdoms
animals
plants
fungi
protocitista
prokaryotes
kingdoms divided further into
kingdom
phylum
class
order
family
genus
species
binomial naming
Genus species
eg Homo sapiens
genus has capital - typed in italics - underline if handwritten
evolutionary trees
represent natural classification and evolution from a common ancestor
evidence for natural classification
DNA sequencing
protein analysis
new top level
domain - 3 domains
(due to advancement of molecular analysis)
convergent evolution
independent evolution of similar features in different species
