Ecological speciation

• Caused by divergent selection, evological factors
• Often through Pleiotropy?

Speciation by Genetic Conflict

• Selfish mutations have been found that transmit more copies to the next generation

Speciation by Sexual Selection

• Rapidly speciating animals will sometimes differ more in their secondary sexual traits (male coloration, vocalization)
• Pulse rate in crickets
• Why is it usually easier to discern plant families by their flowers? SHouldnt these change faster?

Reinforcement of Reproductive Isolation

• Once two populations have already developed some isolation, hybrids will have lower survival or Fertility rate
• Selection against low-fitness hybrids is called reinforcement.

Speciation by polyploidy

• When a diploid species geonome is doubled, a tetraploid is the result, with 4 copies of every chromosone
• Example: hybridization among goatsbeard species generated new allopolyploid species within the last several centuries.