Evolution: Evolution and Natural Selection Essay

Submitted By poohbear4
Words: 691
Pages: 3

Once you’ve got life – how it evolves

Modern systhesis – is called evolution. It means descent with modification.
Homologous character or gene – acquired thru shared ancestory.
Theory of natural selection – mechanismof adaptation and adaptive evlution.

Descendants of ancestral forms
Vertrebrates have common anscertor with something in the past
It requires
Variation in populations – can arise thru mutations in dna. Ie a point mutation – wher ea single base pair is changed which changes protein or a loss of large stretch of dna. An insertion or a deletion
It requires heritability – that genes are passed down. And that the genetic change codes for a phenotypic chagen that is inherited
Natural selection – ppl with beneficial mutations that allow individuals to survive and reproduce. Nt just survive but can outcomepete things. They reproduce more than othe. Its reproduction of the fittest. Whoever leaves the most offspring is the winner. They reproduce more effectively than others

Evidence for evolution
Its a theory – there is enough evidence that it should be a law
They look at fossil record – interpreting life forms they see – and then relate it to the diversity of life they see
They look at strata in fossil record and see how they change.
Comparative anatomy 0 and embryology
Look at homology of structures in both modern and offisilsed taxa. Take the embryo. Ie the human and a bird or fish, and they are so similar. Homology
U can see that in some point inthe past, we had a common ancestor that diverged into modern day.
Comparative biochemistry – similar molecular mechanisms
See squirt – doesn’t use heomoglobbin - uses single cell thing. Heomobloggin first appeared in something else.
Dna – sequence – sequence a bunch of genes related to each other in an organism and other organisms. Align them and see different sequences. And they r not that different from each other
We use rna to transcribe dna into msg and translate this into proten. This is complex. Unlikely to have evolved independently from each other as even bacteria thru to to vertebrates, use similar dna processes

What Darwin observed
Went out and looked at diversity in lots of diff places.
He especially looked at south ameria and galapogis islands.
Walking thru the andes, he noticed there were distinct sets of fossil in some areas and not others
Travelled up to equador . travelled there and say birds and animals. There was a turnover of birs as he went thru different regions
Next place – went to galapogis islands – noticed that there were lots of organisms closely related to species in south America. This gave him idea of descent with modification. Gradualism
Slow continuous actions – ie erosion and sedimentation
Uniformitariansim – mechanism of change are constants…