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A2 Essay question help on speciation!

Give an account of how evolutionary change may take place in populations and how this could lead to speciation.

I've literally no idea whats going on here. Like no idea what to include. It's a 13 mark one too! Help!
Original post by Lafox
Give an account of how evolutionary change may take place in populations and how this could lead to speciation.

I've literally no idea whats going on here. Like no idea what to include. It's a 13 mark one too! Help!


It's been a few months since I did this, but if I remember you have to really talk about 'Isolating Mechanisms'.

There are two main Isolating Mechanisms I can remember. Allopatric and Sympatric Speciation, so talk about those! (That's probably 2 marks in the bag mentioning the fancy terms)

Describe what these fancy terms mean. So, 'Allopatric' Is the physical/ geographical separation of a single species (boom, another mark) If a species is divided, say by a river or mountain (This is in Biological terms the 'Geographical Barrier'), each group will adapt and change to survive in their particular environment, say if one side of the river was ice cold, the species on that side will adapt to cold weather eg. thick fur. And vice-versa for the group on the let's say, bloody freezing side of the river. (Another mark (or two, or three?!?) there!)

Go onto describe 'Sympatric Speciation' If you don't know what that means, don't loose sleep over it. I'll let you know now. This is where the barrier between the species is behavioural rather than geographical, (Bingo! Tick!) so now the entire species occupies one single geographical area. (Ding ding ding! Another tick) Let's say the species to start with, during a mating season will have the mating call of a simple hum or whistle, the species male's and females will recognise this call, and go on to mate and expand the species. But if a small group of the species suddenly find another call attractive, they won't respond to the simple hum. We'll go overboard and say the new attractive call, for this small group is Carly Rae Jepsens 'Call me Maybe'. (I reckon that's another mark) We now have one group that answers to the simple hum and another that answer's to the Top 40 chart, this these two groups will no longer find each other attractive, and will more than likely mate independently, thus causing speciation as the gene pools of the two groups no longer mix, and separate.

This separation, in both cases will cause changes that will gradually become so extreme that the groups will form 'sub groups' in the species. The change will continue until the two sub groups are no longer able to interbreed, thus two new species have been formed (yeah why not, tick)

The information I gave you will have to be tailored to more Biological terms (So replace 'Call me Maybe' with another call/ sound) You can go into other details, such as coat or appearance or even mating dances, like some species of bird will carry out (think about what type of Speciation this is!)

Sympatric remember, means that the speciation takes place in one location, and is caused by behavioural change, or even change in the anatomy (say the males and females are non compatible).

Allopatric means the speciation occurs due to Geographical separation, and the resulting adaptation to the individual environments on either side of the 'Physical Barrier'.

Sorry that it's so rough by the way, I haven't done Biology in some time, and I'm using this kind of thing as a pre-uni refresh!

Hope it helps!
(edited 10 years ago)

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