BIOL 116 Lecture Notes - Lecture 24: Genetic Drift, Sympatric Speciation, Zygote
7 Dec 2016
School
Department
Course
Professor
Document Summary
Species - evolutionary independent population or group of populations - no gene flow between different species. Smallest monophyletic group on tree of life that share one or more synapomorphies. Postzygotic isolation - if interbreeding occurs, do not produce viable offspring. Releasing pollen at different times fo the year. Mating fails because egg and sperm are incompatible. Mechanical mating fails because male and female reproductive structures are incompatible. Flowers and if bees or humming birds can pollenate based on stem length. Offspri(cid:374)g do(cid:374)"t develop (cid:374)or(cid:373)ally a(cid:374)d die as embryos. Male horse and female do(cid:374)key (cid:373)ake a (cid:373)ule that"s sterile. Disadvantages - reproductive solation cant be evaluated in fossils or species that reproduce asexually or when closely related populations are geographically separated. Ide(cid:374)tified (cid:271)y disti(cid:374)guishi(cid:374)g (cid:373)orphologi(cid:272)al feature (cid:894)size, shape (cid:272)olor (cid:895) Disadvantages - judging morphological features can be subjective, and cannot identify cryptic species (species cant be distinguished by looking at them, but really different)
