Speciation p2 Flashcards
What does higher taxa refer to
Any groupings above the species level for example genus
What is reinforcement
Defined as the evolution of enhanced reproductive isolation between populations due to natural selection for greater isolation
What is the outcome if hybrids have the same fitness
Hybridisation between the two emerging populations to the extent that reproductive isolation erodes
Whats the outcome if hybrids have reduced fitness
Lower survival and lower fertilitly, natural selection favours the evolution of reinforcement of prezygotic isolation
What can not usually evolve via reinforcement
Post zygotic isolation
What is reproductive character displacement
Defined as the accentuation of differences between sympatric populations for two species as a result of reproductive interactions between them
Example of reproductive character displacement
Fidecula fly catchers: pied and collared
When does polyploidy occur
When chromosomes fail to segregate during meiosis
Whats allopolyploid
Duplication of chromosomes in hybrids between species
Whats autopolyploidy
Duplication of chromosomes of the same species
Consequences of having more chromosomes than normal
Increase in the number of gene copies, tend to be reproductively isolated from diploid ancestors
What % in plants is involved in ploidy
15% and 31% in fern
Example of tetraploids
Trapogan goatsbeards
How do we reduce triploid offspring
Self fertilisation, vegetative propagation, habitat segregation
How can we capatilise on advantages of polyploidy
Heterozygote advantage
Extreme phenotypic traits
Chance to access new fitness optima
Whats hybrid speciation
Occurs when two or more distinct lineages contribute to the orgins of new species
Whats homoploid hybrid specaition
Speciation via hybridisation without a change in chromosome number
Example of homoploid hybrid specaition
Helianthus sunflowers
Example of adaptive radiation
Cichlid fish
Whats random genetic drift
Random changes in the frequencies of two or more alleles or genotypes within a populaiton
What does long term geographic isolation and drift lead to
Dobzhansky Muller incompatibilites
