Allopatric & Sympatric Speciation | A-level Biology | OCR, AQA, Edexcel
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Allopatric & Sympatric Speciation in
Allopatric & Sympatric Speciation in a Snap! Unlock the full A-level Biology course at http://bit.ly/2HhRJEt created by Adam Tildesley, Biology expert at SnapRevise and graduate of Cambridge University.
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The key points covered of this video include:
1. Speciation
2. Allopatric Speciation
3. Sympatric Speciation
Speciation
When two populations become too genetically distinct they are said to have speciated. Speciation is the evolution of two different species from an existing one. Populations are said to be reproductively isolated if there is no mixing of genes between them. If two populations are reproductively isolated for several generations, then genetic differences between them begin to accumulate. Eventually the populations are genetically distinct enough to be unable to breed and produce fertile offspring.
Allopatric Speciation
Reproductive isolation of two populations is often caused by physical barriers - this form of isolation leads to allopatric speciation. Allopatric speciation is the formation of two species from an original one due to geographical isolation. Common barriers to gene flow in allopatric speciation include rivers, mountain ranges and deserts. Species that are less able to disperse effectively will be more likely to speciate allopatrically.
Sympatric Speciation
Speciation can still occur without a geographic barrier - this type of speciation is called sympatric speciation. Sympatric speciation is the formation of two species from one original species due to reproductive isolation whilst occupying the same geographical location. Reproductive isolation in sympatric speciation can be created in several ways including: Temporal variation, Behavioural variation, Gametic variation.
Summary
Speciation is the evolution is the evolution of two new species from an original species due to reproductive isolation between populations
Allopatric speciation occurs when a geographical barrier isolates two populations for a significant period of time
Sympatric speciation occurs when there is no geographical barrier between populations
Reproductive isolation can arise in several, non-geographic, ways:
a. Temporal isolation - two populations breed at different times
b. Behavioural isolation - two populations have different courtship displays
c. Gametic isolation - gametes from two populations are genetically incompatible or unrecognisable
SnapRevise is the UK’s leading A-level and GCSE revision & exam preparation resource offering comprehensive video courses created by A* Oxbridge tutors. Our courses are designed around the OCR, AQA, SNAB, Edexcel B, WJEC, CIE and IAL exam boards, concisely covering all the important concepts required by each specification. In addition to all the content videos, our courses include hundreds of exam question videos, where we show you how to tackle questions and walk you through step by step how to score full marks.
Sign up today and together, let’s make A-level Biology a walk in the park!
The key points covered of this video include:
1. Speciation
2. Allopatric Speciation
3. Sympatric Speciation
Speciation
When two populations become too genetically distinct they are said to have speciated. Speciation is the evolution of two different species from an existing one. Populations are said to be reproductively isolated if there is no mixing of genes between them. If two populations are reproductively isolated for several generations, then genetic differences between them begin to accumulate. Eventually the populations are genetically distinct enough to be unable to breed and produce fertile offspring.
Allopatric Speciation
Reproductive isolation of two populations is often caused by physical barriers - this form of isolation leads to allopatric speciation. Allopatric speciation is the formation of two species from an original one due to geographical isolation. Common barriers to gene flow in allopatric speciation include rivers, mountain ranges and deserts. Species that are less able to disperse effectively will be more likely to speciate allopatrically.
Sympatric Speciation
Speciation can still occur without a geographic barrier - this type of speciation is called sympatric speciation. Sympatric speciation is the formation of two species from one original species due to reproductive isolation whilst occupying the same geographical location. Reproductive isolation in sympatric speciation can be created in several ways including: Temporal variation, Behavioural variation, Gametic variation.
Summary
Speciation is the evolution is the evolution of two new species from an original species due to reproductive isolation between populations
Allopatric speciation occurs when a geographical barrier isolates two populations for a significant period of time
Sympatric speciation occurs when there is no geographical barrier between populations
Reproductive isolation can arise in several, non-geographic, ways:
a. Temporal isolation - two populations breed at different times
b. Behavioural isolation - two populations have different courtship displays
c. Gametic isolation - gametes from two populations are genetically incompatible or unrecognisable
5 سال پیش
در تاریخ 1398/02/27 منتشر شده
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