BIOL 103 Lecture Notes - Lecture 11: Sympatric Speciation, Lake Malawi, Sky Island
21 Oct 2017
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Biological species concept: can interbreed with each other: cannot test with asexual species, cannot test with fossils, hybrid may live but may be sterile/ partially sterile, similar species but do not interbreed. Mallard and black duck: anas platyrynchus vs. anas rubripes co-occur in north america but do not interbreed; hybrids are viable fertile separated by breeding habits etc. grey areas in speciation definition. Sex chromosomes and fertility: haldane" rule and the mule. Mule = offspring of horse vs. donkey one of the sexes is infertile: xy sex is the infertile offspring haldane made a rule about this, heterogametic sex is the one that is infertile. Mule = donkey jack vs. horse mare. Mule = donkey jack (male) x horse mare (female); more common. Hinny = horse stallion (male) x donkey jennet (female) incompatibility of the xy chromosomes etc. really hard to get stallions to mate with jennets more unusual.
