Concepts 4.1-4.3 (Evolution) Flashcards
What is speciation?
The evolutionary process by which new species arise through reproduction isolation
What does speciation cause?
Cause one evolutionary lineage to split into two or more lineages
What is allopatric speciation?
The ancestral population is divided by a physical barrier
What is sympatric speciation?
The ancestral population is divided without geographic barriers
What are prezygotic isolation barriers?
Geographic isolation, mechanical, behavioural isolation, mating time differences, ecological differences
What are postzygotic isolation barriers?
Fertilized egg/offspring inviable
What is the “Biological Species Concept”?
Defines species as groups of actually or potentially interbreeding natural populations that produce fertile offspring
What is adaptive introgression?
Inheritance of beneficial variation from related species (hybridisation) that accelerate adaptation to and survival in new environment
How does -ve frequency dependence occur?
(balancing selection)
Fitness of alleles higher when that allele is rare than when it is common
How does heterozygote advantage occur?
(Balancing sleection)
The heterozygotes for the alleles in question have higher fitness than either of the homozygotes
How does balancing selection maintain genetic diversity in a population?
By keeping alleles at frequencies higher than expected by chance
What is meant by ‘fitness’?
Success of an organism at surviving and reproducing
What is meant by ‘relative fitness’?
The success of a genotype
