lecture 23- plant speciation pt 2

allopatric speciation

peripatric speciation

parapatric speciation

sympatric speciation

allopolyploidy

polyploid speciation accounts for ___% of documented speciation events in angiosperms

15

introgression

permenant incorporation of genes (or whole organelles) of one species into another

what leads to introgressed alleles

extensive hybridization and backcrossing

hybridization

hybridization rates in plants

occurs in about 25% of all plant species, at least 70k naturally occuring hybrids reported

premating barriers that help maintain species boundaries

ecogeographic, temporal (seasonal and diurnal), floral (behavioral and structural), reproductive mode (self-fertilization and agamospermy)

postmating prezygotic barriers that help maintain species boundaries

incompatability (pollen-style)

postmating postzygotic barriers that help maintain species boundaries

incompatability (seed), hybrid inviability, hybrid floral isolation, hybrid sterility, hybrid breakdown

hybrid inviability

hybrids between ecogeographically separated species

hybrid floral isolation

hybrids may lack a pollinator

hybrid sterility

viable hybrids may be unable to reproduce

hybrid breakdown

F1 hybrids may be viable & fertile, but not later generation hybrids

origin of reproductive barrier in phlox

species are infertile, offspring are sterile, phlox drumm produces pink and red flowers but in allpoatry with phlox cusp its pink flowers. color shift prevents hybridization