Evolution

[Wally]

Hey all,

this may seem like a stupid question but can someone explain what the question "how does evolution work?" is actually asking.

also how is parallel evolution different to convergent evolution??

[iNerd]

Parallel evolution: When species evolve from a common ancestor and remain similar over a period of time. A good example of this situation is the marsupials of the Australian and South American continents. Originally they both came from a common ancestry on the super-continent "Pangea". After the continents started to separate, but the two groups of marsupials developed along similar lines.

Convergent evolution: When species evolve from a different ancestry, but over time develop a similar physical characteristic as an adaptation to their common environment. Perhaps the most interesting example of a convergent evolution is a comparison of penguins, whales and sharks. All three are from different backgrounds: penguins are birds, whales are mammals and sharks are fish. But all three have developed a similar shape and mechanisms of movement through the water.

[Wally]

awesome, thanks heaps :]

[iNerd]

awesome, thanks heaps :]

lol is this biology Unit 4 or something because this is what I'm doing in Year 10 Science at the moment and I'm finding it very very dry alongside lack of incentive to do well in it as Biology isn't part of my VCE

[Wally]

yup, it only makes up a pretty small part of it tho

[Russ]

lol is this biology Unit 4 or something because this is what I'm doing in Year 10 Science at the moment and I'm finding it very very dry alongside lack of incentive to do well in it as Biology isn't part of my VCE

Evolution ties with plants as the least interesting topic in biology!

[herzy]

can someone explain what the question "how does evolution work?" is actually asking.

Evolution is based on the idea of survival of the fittest. When (genetically-based) variation exists in a given population, certain individuals will be selected for/favoured. These individuals will hence more likely (even if only slightly) to reproduce, and produce more (viable) offspring. Hence over time, their genotypes (i.e. the genetic basis of the advantage) will increase in frequency, until all members of the population share the trait. Expanded over (a lot of!) time, and many different traits and selection pressures, this explains how speciation and the evolution or development of species occurs.

A simplistic example is rabbits in the alpine region of Australia with varied colour (ranging from white to black). In each generation, black rabbits are slightly more likely to be predated upon than white rabbits. Hence after 5 generations, given no other selection pressures, gene flow or genetic drift, more white rabbits will be reproducing, and the 'white' allele will increase in frequency. Eventually, all rabbits will be white. Coupled with other factors (e.g. thicker fur, splayed feet, hibernation, different mating patterns), and enough time, the snow sub-species may differentiate to such a degree that they can no longer interbreed with the originals.

[herzy]

Also I would advise the following examples:

Convergent evolution: dolphins and sharks - this exemplifies analogous structures (fins, body shape) due to similar selection pressures, which is typical of convergent evolution.

Parallel evolution: marsupial example is good (see above)

The key difference is ancestry: convergent they do not share a common ancestor, parallel they share a relatively recent common ancestor, speciated, then continued to evolve similarly.

[Wally]

oh thanks for answering that
it was really helpful with the examples, i'd give +1 karma if i could but i can't.. so yeah thanks again =)

[herzy]

haha no worries. just curious, why can't you?

[iNerd]

haha no worries. just curious, why can't you?

To give karma you require 50 posts.

[Wally]

haha yeah what iNerd said

[herzy]

taaa, wasn't aware