Download Speciation 2 and more Lecture notes Biology in PDF only on Docsity!
Speciation 2
• Reproductive Isolation
• Sympatric speciation
• Tempo of evolution
• Hybrid zones
Jan 28, 2013
Reproductive Isolating Mechanisms
Prezygotic barriers Isolation^ Habitat^ Temporal Isolation^ Behavioral Isolation^ Mechanical Isolation Isolation^ Gametic Individuals different of species ATTEMPT^ MATING FERTILIZATION (a) (c) (e) (f) (b) (g) (d) Reduced Hybrid Viability^ Reduced Hybrid Fertility Breakdown^ Hybrid FERTILIZATION OFFSPRING^ VIABLE,^ FERTILE Postzygotic barriers (k) (h) (i) (j) (l)
Temporal Isolation: timing of reproduction differs
Behavioral Isolation: courtship behavior in Birds of Paradise
Figure 24.
Normal light
Monochromatic
orange light
P. pundamilia
P. nyererei
EXPERIMENT
Mechanical isolation
http://homepages.indiana.edu/web/page/normal/20691.html pygidium paramere Dr. Armin Moczek
Damselfly genitalia
Sympatric Speciation
Hybrid polyploid speciation
2N=12 2N=
4N=
Tragopogon miscellus
Figure 24.11- Species A 2 n = 6 Species B 2 n = 4 Normal gamete n = 3 Meiotic error; chromosome number not reduced from 2 n to n Unreduced gamete with 4 chromosomes Hybrid with 7 chromosomes Unreduced gamete with 7 chromosomes Normal gamete n = 3 New species: viable fertile hybrid (allopolyploid) 2 n = 10 Figure 24.10 (^) EXPERIMENT RESULTS Initial population of fruit flies pseudoobscura^ ( Drosophila ) Some flies raised on starch medium Mating experiments after 40 generations Some flies raised on maltose medium Female Starch Maltose Male Maltose Starch in experimental group^ Number of matings 22 9 8 20 Starch^ Female population 1 Male Starch population 2 Number of matings in control group 18 15 (^12 ) population 2^ Starch Starch population 1
