Module 6 : Speciation Flashcards
(7 cards)
What is reproductive isolation?
when populations can no longer interbreed to produce fertile offspring , results in genetic isolation
What is genetic isolation?
when there is a lack of gene flow between populations due to reproductive barriers , prevents exchange of genes between populations so facilitates speciation
Reproductive barriers can be …
prezygotic or postzygotic
Define what prezygotic and postzygotic barriers are
give examples for prezygotic and state the type of offspring produced by postzygotic barriers
prezygotic-barriers that prevent fertilisation and formation of a zygote
(habitat isolation , variations in mating rituals)
postzygotic-barriers that result from hybridisation between different species
-often produce non fertile or non viable offspring
Define what speciation means
What are the 2 types of speciation?
Which type is more common in animals and which is more common in plants than in animals ?
the evolution of a new species from an existing one
allopatric and sympatric
allopatric is more common , sympatric is more common in plants
Make 5 points describing how allopatric speciation occurs
-some members of a population become geographically isolated by a physical barrier
-this barrier exposes different members of the population to different selection pressures
-these prezygotic barriers lead to reproductive isolation
-reproductive isolation prevents gene flow which leads to genetic divergence
-this causes the populations to evolve separately and form separate species
Make 4 points describing how sympatric speciation occurs
-this occurs in the same geographical location
-ecological o behavioural mechanisms such as mate selection , or chromosomal changes lead to the populations becoming reproductively isolated
-reproductive isolation prevents gene flow and leads to genetic divergence
-this causes populations to evolve separately and form separate species
