What is Evolution?
Evolution is the theory that all living and non-living things gradually change and diversify over time and there's quite a few ways for that to occur. Although evolution is just a theory, there is an abundance of evidence that has been scientifically tested over many years. Some of the approaches to studying evolution are fossils, comparative anatomy and embryology and molecular evidence. Evolution is broken up into 2 main categories; macro-evolution and micro-evolution.
Macro-Evolution is the change from one species to another and is broken up into another 2 categories; divergent evolution and convergent evolution. Divergent evolution is when small parts of a population are isolated from the rest and inhabit new areas. They adapt to their new, harsher habitat, then might find a way back to their old one and usually end up outcompeting their original ancestor. Convergent Evolution is when 2 different species live in the same environment and evolve to having similar characteristics, even though they have no common ancestor. For example, a dolphin, shark and penguin are all torpedo shaped to help them be faster and more agile swimmers.
Micro Evolution is the change within 1 species and is broken up into 5 categories; genetic drift, gene flow, mutations, natural selection and non-random mating. These mechanisms are further explained under "Changing Gene Pool". The fittest in a population is the one who contributes the best genes to the gene pool, and it gets passed down to future generations. If no evolution is occurring, then the frequency of change is the same, but if there's a change in frequency then the population is evolving.
Overall the evolution theory is the change of an organism that gradually occurs over time.
Macro-Evolution is the change from one species to another and is broken up into another 2 categories; divergent evolution and convergent evolution. Divergent evolution is when small parts of a population are isolated from the rest and inhabit new areas. They adapt to their new, harsher habitat, then might find a way back to their old one and usually end up outcompeting their original ancestor. Convergent Evolution is when 2 different species live in the same environment and evolve to having similar characteristics, even though they have no common ancestor. For example, a dolphin, shark and penguin are all torpedo shaped to help them be faster and more agile swimmers.
Micro Evolution is the change within 1 species and is broken up into 5 categories; genetic drift, gene flow, mutations, natural selection and non-random mating. These mechanisms are further explained under "Changing Gene Pool". The fittest in a population is the one who contributes the best genes to the gene pool, and it gets passed down to future generations. If no evolution is occurring, then the frequency of change is the same, but if there's a change in frequency then the population is evolving.
Overall the evolution theory is the change of an organism that gradually occurs over time.
Is Evolution True?
In my opinion, I believe that some aspects of evolution are true, but not others. For me, something such as natural selection makes sense, and is realistic. A mutation, or in other words a miscopy of DNA changes black fur colour to white, with white now the more favourable colour, the organism then passes the white hair gene down to future generations, is something I believe is true. I however, don't believe that every organism on Earth has evolved from a single celled organism. There is nowhere near enough evidence to prove this to a valid theory or persuade me to believe it, after all, there's a reason why it's still just a theory. That idea has always seemed a little far fetched to me and quite frankly goes against most religions which have a lot more history behind them than a scientific theory does.
Punctuated Equilibrium vs. Gradualism
Gradualism is the theory that evolution occurs slowly,
continuously over a long period of time.
Punctuated Equilibrium is the idea that short, quick
changes occur, and there are long periods
of time between change. This explains the lack of
"in-between" stages of species in fossils.
Changing Gene Pool
Genetic Drift: A random change or event that occurred, which can take an organism such as bacteria, or a trait out of a gene pool.
Gene Flow: Transferring genes from one population to another which can either introduce new variations of species or if the gene flow stops, populations that were once joined will change independently.
Mutations: A mutation is the change or miscopy in the DNA sequence in a cell, and when that DNA is copied the mutation will pass on. Can be positive, negative or neutral. An organism with a mutation can be passed on to future generations, therefor changing the gene pool.
Natural Selection: Organisms that are best suited, or fit to their environment survive, and pass their genetics on to the next generation. Offspring will likely also acquire the desirable traits that allowed for their parents survival.
Non-Random Mating: It's not very often that organisms mate randomly, instead they might choose others like you, or base it on criteria such as colour, size, song or territory. There is another way which is where one male has many females, called Harem.
Gene Flow: Transferring genes from one population to another which can either introduce new variations of species or if the gene flow stops, populations that were once joined will change independently.
Mutations: A mutation is the change or miscopy in the DNA sequence in a cell, and when that DNA is copied the mutation will pass on. Can be positive, negative or neutral. An organism with a mutation can be passed on to future generations, therefor changing the gene pool.
Natural Selection: Organisms that are best suited, or fit to their environment survive, and pass their genetics on to the next generation. Offspring will likely also acquire the desirable traits that allowed for their parents survival.
Non-Random Mating: It's not very often that organisms mate randomly, instead they might choose others like you, or base it on criteria such as colour, size, song or territory. There is another way which is where one male has many females, called Harem.
Dichotomous Key Example
1. a) has wings... go to 4
b) doesn't have wings... go to 2
2. a) has legs... go to 9
b) doesn't have legs... go to 3
3. a) has eyes... go to 8
b) doesn't have eyes... worm
4. a) has antenna... go to 5
b) doesn't have antenna... bat
5. a) has designs on wings... butterfly
b) doesn't have designs... go to 6
6. a) has 2 wings... go to 7
b) has more than 2 wings... dragonfly
7. a) has long antenna... cockroach
b) has short antenna... fly
8. a) has shell... snail
b) doesn't have a shell... snake
9. a) has 8 legs... go to 10
b) has more or less than 8 legs... go to 11
10. a) is fuzzy or has hair... tarantula
b) has no hair and is smooth... black widow
11. a) has 6 legs... ant
b) has more than 6 legs... centipede
b) doesn't have wings... go to 2
2. a) has legs... go to 9
b) doesn't have legs... go to 3
3. a) has eyes... go to 8
b) doesn't have eyes... worm
4. a) has antenna... go to 5
b) doesn't have antenna... bat
5. a) has designs on wings... butterfly
b) doesn't have designs... go to 6
6. a) has 2 wings... go to 7
b) has more than 2 wings... dragonfly
7. a) has long antenna... cockroach
b) has short antenna... fly
8. a) has shell... snail
b) doesn't have a shell... snake
9. a) has 8 legs... go to 10
b) has more or less than 8 legs... go to 11
10. a) is fuzzy or has hair... tarantula
b) has no hair and is smooth... black widow
11. a) has 6 legs... ant
b) has more than 6 legs... centipede