1. © 2006 W.W. Norton & Company, Inc. DISCOVER BIOLOGY 3/e1 Adaptation & Speciation Normally over 2 days, going to ≥ slide 18 on day one, but we do not have this luxury this term.

2. © 2006 W.W. Norton & Company, Inc. DISCOVER BIOLOGY 3/e2 Adaptation An improvement to an organism over time Changes a population to better fit its environment The result of natural selection acting on genetic variation Environments change and new genetic variation arises, so adaptation never reaches perfection

3. © 2006 W.W. Norton & Company, Inc. DISCOVER BIOLOGY 3/e3 Adaptation Matches organisms to their environment

4. © 2006 W.W. Norton & Company, Inc. DISCOVER BIOLOGY 3/e4 Adaptation: 1. Matches organisms to environment 2. Can be complex 3. Accomplishes specific functions

5. © 2006 W.W. Norton & Company, Inc. DISCOVER BIOLOGY 3/e5 Populations Can Adjust Sometimes adaptations can be rapid Soapberry bugs, Fl adapted to an introduced species by obtaining shorter beaks in 30-50 years.

6. © 2006 W.W. Norton & Company, Inc. DISCOVER BIOLOGY 3/e6 Adaptations Are Not Perfect Natural selection has limitations:  Genetic constraints No variation, no adapting  Multiple effects of genes in development  Ecological trade-offs What is good for one thing may hurt in another

7. What are Species? Members of a species generally look alike  Bald eagles in Alaska (top) & Colorado (bottom)  But not always Species –are reproductively isolated from other species Barriers to reproduction between species

8. © 2006 W.W. Norton & Company, Inc. DISCOVER BIOLOGY 3/e8 Barriers to reproduction Prevent a zygote from being formed  Ecological isolation –species physically separated  Behavioral isolation –mating calls, rituals  Mechanical isolation –physically unable to mate Chihuahua and wolf cannot mate  Gametic isolation –gametes do not fuse

9. © 2006 W.W. Norton & Company, Inc. DISCOVER BIOLOGY 3/e9 Barriers to reproduction Barriers after zygote has formed  Zygote dies –offspring is never born  Hybrid performance –not as fit as parents Mules cannot reproduce w/ each other or w/ donkey or horse

10. © 2006 W.W. Norton & Company, Inc. DISCOVER BIOLOGY 3/e10 Some Species Interbreed But the species stay distinct Live at different elevations:  Gray – lower  Gambel – higher  hybrids - intermediate

11. © 2006 W.W. Norton & Company, Inc. DISCOVER BIOLOGY 3/e11 Complications: Some Species Can Interbreed But the species stay distinct for complex reasons Chihuahua -> small dog -> collie -> shepherd -> wolf Cat and bobcat We will keep it simple & ignore these

12. © 2006 W.W. Norton & Company, Inc. DISCOVER BIOLOGY 3/e12 Walking Sticks Adapting to match their environment (two mating pairs) Striped form (L) is well-hidden among the needle- like leaves w/ stripes, solid form among solid leaves

13. © 2006 W.W. Norton & Company, Inc. DISCOVER BIOLOGY 3/e13 The striped form of the species prefers needle- like leaves of the chemise (sheh-mēz) bush. The solid-green form prefers the solid green leaves of the wild lilac. The two forms are more likely to survive on their preferred plant.  Predators (birds) more likely to catch them if they are not on their preferred plant. Walking Sticks

14. © 2006 W.W. Norton & Company, Inc. DISCOVER BIOLOGY 3/e14 Walking Sticks Is a complex adaptation, more than coloration. Lilac and chemise bush leaves have different pulp, fiber, chemical contents, and plant toxins. The solid-green walking sticks have enzymes to better digest the leaves of the wild lilac. The striped form has enzymes adapted to better digest the leaves of the leaves of the chemise bush.

15. © 2006 W.W. Norton & Company, Inc. DISCOVER BIOLOGY 3/e15 Walking Sticks “Hybrid offspring” of a cross between solid and striped parents are less fit than offspring of a single form mating.  Do not blend as well on either Lilac or chemise bush leaves.  Predators are more likely to eat them.  Do not digest either plant as well as single forms.

16. © 2006 W.W. Norton & Company, Inc. DISCOVER BIOLOGY 3/e16 Walking Sticks Because “Hybrid offspring” (a solid & striped cross) are less fit than “single form” offspring, the population is adapting in one other way:  Individuals prefer to mate with others of the same color pattern. In nature, the two forms do not see each other much (they stay on their preferred plants). Mating experiments done in the lab.

17. © 2006 W.W. Norton & Company, Inc. DISCOVER BIOLOGY 3/e17 Walking Sticks Population is diverging with respect to alleles for:  coloration,  digestion,  dealing with plant toxins,  mating behavior. Disruptive selection is better adapting each form to their preferred plant.

18. © 2006 W.W. Norton & Company, Inc. DISCOVER BIOLOGY 3/e18 W/ time, disruptive selection will further diverge the two forms & further decrease their interbreeding. When the two forms loose the ability to interbreed, they will become two different species. Lecture To Here!

19. © 2006 W.W. Norton & Company, Inc. DISCOVER BIOLOGY 3/e19 Speciation When one species splits to form two species Results from reproductive isolation Often, it is a secondary consequence of changing populations Occasionally, is a direct consequence of a diverging population  The hybrid is less fit, walking sticks

20. © 2006 W.W. Norton & Company, Inc. DISCOVER BIOLOGY 3/e20 Speciation Without geographic isolation is called:  Sympatric speciation Such as chromosomal changes Due to geographical isolation is called:  Allopatric speciation (N & S rim of Grand Canyon)

21. © 2006 W.W. Norton & Company, Inc. DISCOVER BIOLOGY 3/e21 Allopatric Speciation Geographical separation prevents species from mating When reintroduced, they no longer mate

22. © 2006 W.W. Norton & Company, Inc. DISCOVER BIOLOGY 3/e22 Sympatric Speciation: Lake Victoria Cichlids Species reproductively isolated from: Sexual selection & mating behaviors Species differ in their diets

23. © 2006 W.W. Norton & Company, Inc. DISCOVER BIOLOGY 3/e23 Rates of Speciation Rates differ in different organisms Can occur in thousands or millions of years  Walking sticks, have a reason to evolve reproductive isolation quickly, hybrids are less fit speciation may occur in a couple thousand years.  European and N. American sycamore trees do not have a reason to evolve reproductive isolation they were separated geographically 20 mya & do not normally interbreed speciation has not yet occurred

24. © 2006 W.W. Norton & Company, Inc. DISCOVER BIOLOGY 3/e24 Speciation The splitting of one species into two has never been seen in animals  check back in a couple thousand years Walking sticks Apple maggots (worms)

25. © 2006 W.W. Norton & Company, Inc. DISCOVER BIOLOGY 3/e25 Russian Mad Scientist  He wanted a plant where you could eat both the roots and the leaves (beets).  Promised the Soviet Union he could do it if given enough funding. Russian scientist who crossed radishes with cabbage.

26. © 2006 W.W. Norton & Company, Inc. DISCOVER BIOLOGY 3/e26 Russian Mad Scientist He crossed cabbage & radishes  The hybrid offspring were sterile  The chromosomes did not match in meiosis Not a problem  Plants can be grafted (clones)  He obtained many hybrid clones  He grew the grafts for years

27. © 2006 W.W. Norton & Company, Inc. DISCOVER BIOLOGY 3/e27 Russian Mad Scientist He was either very lucky or very insane In one plant, a freak chromosomal abnormality occurred  The chromosomes doubled and were able to match in meiosis  This rarely happens He then bred the one fertile hybrid and studied it (it could self-pollinate)

28. © 2006 W.W. Norton & Company, Inc. DISCOVER BIOLOGY 3/e28 Russian Mad Scientist His breeding was a failure Instead of the leaves of a cabbage and the roots of a radish, he got the leaves of a radish and the roots of a cabbage! Yet, his creation could not breed with either a cabbage or a radish, due to chromosomal incompatibilities

29. © 2006 W.W. Norton & Company, Inc. DISCOVER BIOLOGY 3/e29 Russian Mad Scientist Cabbage Radishes Look what his failure obtained: Cabbage Radishes Cab-Rad

30. © 2006 W.W. Norton & Company, Inc. DISCOVER BIOLOGY 3/e30 Russian Mad Scientist Cabbage Radishes He had witnessed the birth of a new species He obtained three species from two Cabbage Radishes Cab-Rad  Not sure if it kept him from being sent to Siberia

31. © 2006 W.W. Norton & Company, Inc. DISCOVER BIOLOGY 3/e31 Implications of Adaptation and Speciation Understanding used to combat diseases  HIV  Bacteria

32. © 2006 W.W. Norton & Company, Inc. DISCOVER BIOLOGY 3/e32 Concept Quiz Which of the following is not a true example of an adaptation? A. Bats wanting to fly and developing wings B. Spots on a leopard for camouflage C. Long tongues in frogs for catching flies

33. © 2006 W.W. Norton & Company, Inc. DISCOVER BIOLOGY 3/e33 Fruit flies were raised on two food sources Flies preferred to mate with others raised on same food source Selection Causing Reproductive Isolation

34. © 2006 W.W. Norton & Company, Inc. DISCOVER BIOLOGY 3/e34 Concept Quiz One species of frog in a pond splits into two species because males develop two different mating calls. This is an example of: A. Ecological isolation B. Polyploidy C. Behavioral isolation

35. © 2006 W.W. Norton & Company, Inc. DISCOVER BIOLOGY 3/e35 Concept Quiz Which of the following is not a reproductive isolation mechanism? A. Hybrid fertility B. Zygote death C. Gametic isolation