Evolution Flashcards
Evolution
A process of inheritable change within a species or population, over long periods of time
what does evolution lead to?
the formation of new species from those that already exist
what may bring on evolution?
by natural selection in response to a change in the environment
Darwin’s theory
theory of natural selection
first person to put forward the fact that evolution occurs
Darwin
How did Darwin come up with his theory
he said that species have not remained unchanged, but have evolved from pre-existing species by process of gradual change
why did Darwin say we should study this?
he said that if species have arisen by gradual change, then it should be possible to learn something about their ancestry from the structural similarities and differences between them from their embryology and fossil records
during Darwin’s voyage, what did he conclude
plant and animal species have arisen from one another by a process of slow and gradual change over many years, brought about by natural selection
DARWIN AND WALLACE’S THEORY OF EVOLUTION
reproduction
species have a fast reproductive rate, producing large numbers of offspring
DARWIN AND WALLACE’S THEORY OF EVOLUTION
population
however the numbers in a population remain more or less constant over long periods of time
DARWIN AND WALLACE’S THEORY OF EVOLUTION
competition
competition for limited resources between members of a population
low number of offspring survive
DARWIN AND WALLACE’S THEORY OF EVOLUTION
variations
variations are found among the members of a population
many are inheritable
DARWIN AND WALLACE’S THEORY OF EVOLUTION
suitability
the offspring with variations that make them more suited to the environment have a better chance of surviving
they reproduce and pass on the favourable variations
DARWIN AND WALLACE’S THEORY OF EVOLUTION
less suited
the offspring that are less well suited to their environment die before reproducing
DARWIN AND WALLACE’S THEORY OF EVOLUTION
repeated
repeated generation after generation
favourable adaptions are selected to survive and reproduce
species
group of similar organisms that are capable of interbreeding and producing fertile offspring
all the genes of a population make up the
genepool
2 factors that bring about evolution
variation
natural selection
what does genetic variation give rise to?
differences in the genotype and phenotype
3 causes of genetic mutation
meiosis
sexual reproduction
mutation
meiosis as a cause of genetic mutation
gives different gene combinations in gametes
sexual reproduction as a cause of genetic mutation
gives rise to new combinations of parental genes in the zygote
mutation as a cause of genetic mutation
gives rise to allelic genes or changes in structure or number of chromosomes
natural selection leads to constancy as long as
as long as the environment doesn’t change and the species adapted to it
if the environment changes
natural selection promotes the emergence of new forms
3 examples of natural selection
peppered moth of manchester
bacterial strains resistant to Penicillin
flies resistant to DDT
2 sources of evidence for evolution
comparative anatomy *
comparative embryology
comparative anatomy
the study of evolution based on structural similarities and differences between different organisms
1 example of comparative anatomy in animals
the pentadactyl limb
the pentadactyl limb of a human
hand for grasping
the pentadactyl limb of a bat
wing for flying
the pentadactyl limb of a whale
fin for swimming
structures with a common basic plan
homologous structures
example of adapted radiation
homologous structures that are adapted to different environments and ways of life
comparative embryology
even though animals as adults have very different features, they may have many similarities in the early embryos
write a note on genetic variation (L.C)
differences between individuals of the same species
arising from change in genes
caused by e.g meiosis
if passed on to next generation, may be the basis of evolution
write a note on natural selection (L.C)
mechanism of evolution
best adapted individuals survive
produces more offspring
survival is related to the environment
Describe how studies of comparative anatomy provide evidence for the occurrence of evolution (L.C)
organisms have structures with basic common plan
adapted for different functions
e.g pentadactyl limb
similarities indicate a common ancestor
