more evidence for evolution Flashcards
what is biogeography
the study of how things are distributed round the world
what can biogeography tell us (3)
the native species
the species similar to those on the nearest land mass
the absent species
explain the distribution of marsupials
in Jurassic times the continents were connected, and marsupials arose in America 80MYA and walked from the Americas across the antarctica to Australia
what is convergent evolution
when distantly related species show similar adaptation pressures due to similar selection pressures (the same adaptation in different parts of the world) eg cacti in north merica and cacti in Africa
with the peppered moth why do the black and white form differ
a single mutation in a single gene
in the industrial revolution which allele frequency increased nd why
the black allele they had camouflage from birds
what can molecular genetics provide evidence for
the existence of a common ancestor
the genetic code is universal, what does this mean
every organism contains the same cellular machinery for decoding and copying genetic information eg dna and rna use ribosomes to create proteins
do more closely related organisms contain more or less nucleotide differences
less
what do olfactory receptor genes do
code for proteins that detect smells. the recptors act like lock and key and activate the brain to smell a particular scent
why were a large proportion of olfactory receptor genes pseudogenes
whales only use their nose for seconds to breathe, they cant smell underwater so wed expect mutations to arrive to knockout receptors
what are pseudogenes
sequences of DNA that were once a gene and are now non functional
toothless mammals have a non functional gene/pseudogene for
enamelin
why were lactase persistence levels highest in europe
strong pastoralist traditions
why are lactase persistence genes partial evidence of natural selection
people who digest milk with lactase were at an advantage as they could get more protein and fat and reproduce
