Summer24
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I get allopatric speciation but dont quite understand sympatric speciation.

It talks about premating mechanism and the postmating mechanism, in my book but I dont seem to understand.

and also what does hybirdisation do to the offspring's chromosome, what is hybrid steritility or inviability!!!???:confused:


can anyone explain?

THANKS
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TrollHunterGeneral
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What board are you doing? I'm doing OCR A2 Bio, got my central concepts paper in 2 days . Well all we need to know about sympatric speciation is that it is speciation that occurs within a population without any geographical barrier, and its most likely cause is polyploidy.
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Summer24
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(Original post by TrollHunterGeneral)
What board are you doing? I'm doing OCR A2 Bio, got my central concepts paper in 2 days . Well all we need to know about sympatric speciation is that it is speciation that occurs within a population without any geographical barrier, and its most likely cause is polyploidy.
Yes same here, I am doing OCR too. I dont understand why sympatric speciation occurs, if they are not geographically isolate!
is it because some of them mate at diferent season and therefore are not sexually active all year round?

and what exactly is Polyploidy? :confused:
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~*~rAiNbOw~*~
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sympatric speciation can occur as a result of:
-difference in structures
-difference in behaviours
-polyploidy
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TrollHunterGeneral
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(Original post by Summer24)
Yes same here, I am doing OCR too. I dont understand why sympatric speciation occurs, if they are not geographically isolate!
is it because some of them mate at diferent season and therefore are not sexually active all year round?

and what exactly is Polyploidy? :confused:
Polyploidy=mutation in the organisms that causes it to have more than 2 sets of chromosomes. Therefore meiosis screws up so no feasible gamete is produced and the organism is sterile. This causes the organism to be a completely different species as it cannot reproduce with the "original" organism to produce viable offsprings.
Then you have some stuff about autopolypoids where all 4 sets of chrom. come from the same parent plant and allopolypoids where 2 sets from from one organism and another 2 from a different organism. Therefore allopolypoids have a higher chance of producing viable gametes therefore can reproduce, albeit not with the original parent plant but they are still seen as a new species.
Most examples of polypoids are plants as animals can't really produce asexually but plants can (since mitosis still occurs normally).
If you still don;t understand, just read the textbook (I assume you have the OCR Biology 2 textbook?)
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Summer24
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(Original post by TrollHunterGeneral)
Polyploidy=mutation in the organisms that causes it to have more than 2 sets of chromosomes. Therefore meiosis screws up so no feasible gamete is produced and the organism is sterile. This causes the organism to be a completely different species as it cannot reproduce with the "original" organism to produce viable offsprings.
Then you have some stuff about autopolypoids where all 4 sets of chrom. come from the same parent plant and allopolypoids where 2 sets from from one organism and another 2 from a different organism. Therefore allopolypoids have a higher chance of producing viable gametes therefore can reproduce, albeit not with the original parent plant but they are still seen as a new species.
Most examples of polypoids are plants as animals can't really produce asexually but plants can (since mitosis still occurs normally).
If you still don;t understand, just read the textbook (I assume you have the OCR Biology 2 textbook?)


LOL I have a text book but didnt understand it, thats why I came on here.

ok let me get this straight. Polyploidy is one of the reasons for sympatric speciation. And this is when organism has two sets of chromosomes, therefore isn’t able to produce fertile offspring.
So if they can’t produce offspring dont they just die out?
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Toiletpaper8
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I'd say that allopatric is merely a subgroup, arguably, of sympatric. When you're geographically isolated - you're reproductively isolated too, regardless of selection pressure.
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Summer24
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(Original post by Toiletpaper8)
I'd say that allopatric is merely a subgroup, arguably, of sympatric. When you're geographically isolated - you're reproductively isolated too, regardless of selection pressure.
that doesnt help! :eyeball:

lol but you're profile made me laugh lol I needed that I am soooooo depressed becus of this stupid sympatric nonsense! :mad:
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hahaha_dontknow
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(Original post by Summer24)
I get allopatric speciation but dont quite understand sympatric speciation.

It talks about premating mechanism and the postmating mechanism, in my book but I dont seem to understand.

and also what does hybirdisation do to the offspring's chromosome, what is hybrid steritility or inviability!!!???:confused:


can anyone explain?

THANKS
i HATE speciation!
I do aqa and this is what i've been taught (if i remember correctly):
sympatric speciation:
occurs in the same geographical area.. no geographical barrier.
reproductive isolation occurs because of :
1) behavioural isolation
2) they occupy different niches
3) seasonal isolation - sexually mature at diff. times of the year
4) mechanical isolation
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