L6 Speciation Flashcards
Why is it not enough to describe speciation events as occurring in sympatry or allopatry?
System is much more dynamic, and environments are always fluctuating can’t really be categorised - populations are constantly redistributed.
What is speciation?
A multilevel process occurring through space and time which forms new and distinct species
What are the main contributors to speciation?
Chance
Ecology
Reinforcement
When has chance led to divergence?
Mutation, natural disaster, spontaneous polyploidy, long term drift, founder effect
What is mutation order speciation?
When two populations diverge into similar environments, under similar selection pressures, but respond to them differently - the order of which mutations arise will be different
What is ecological speciation?
genotypes are adapted to different environments selection acts to favour those that to favour alleles adapted for those environments
What is founder effect speciation?
Like peripatric speciation, a small, satellite population will diverge from a large ancestral population. Genome of the new population depends entirely on the allele present in the few founding individuals
What is an example of the founder effect?
Paradise kingfishers, in papua New Guinea, small islands have morphologically different species. Genomes on each island are entirely dependent on the individuals that made it there
What is polyploidy?
Saltational origin of a new species, when individual has >2n
What are the advantages of polyploidy?
can utilise heterozygote advantage, or avoid it if it had genetic load
can exhibit extreme phenotypic traits
duplication on a large scale
What are the disadvantages of polyploidy?
Homoploid hybrids have greater genetic variation
How do the Timers crustae show speciation via differences in environmental ecology?
Two different ectomorphs inhabiting two different planet species, show a level of reproductive isolation named on host-plant ecology. Are adapted to different environments and so have a higher level of divergence because of this.
What is seen in pea aphids if you with the plant type they are on?
Different morphs on different plants, switching makes fitness go down
How do Howpea palms show speciation?
Via environmental differences, Are on an island in the pacific, see differences in inflorescence between two species, only differ at 4 loci, but see little interbreeding. Are isolated by different habitats - soil type and by different flowering times. They have been separated in the same environment by prezygotic barriers, and can assume they have never been allopatric.
