1. Ch. 6: Evolutionary Processes/Outcomes

2. Plants and Environment 1) Liebig (1840) –Law of the Minimum: Growth/distribution depends on environmental factor most limiting A Festive MoB CuMnZn Clapping Nicely

3. Plants and Environment 2) Shelford (American: early 1900s) –Upper limits for factors –Proposed “Theory of Tolerance”

4. Plants and Environment Phenotype: appearance Genotype: genetic make-up Phenotype: determined by genotype & environment

5. Plants and the Environment Equation: V p = V g + V e V p = total phenotypic V g = variation due V e = variation due Focus V g

6. Plants and the Environment Adaptation: –1) Genetically –2) With How determine trait adaptation? Hard! Genetic importance

7. Plants and the Environment Genetic basis: Heritability (h 2 ): resemblance between relatives due h 2 = V g / V p –V g = variation due to –V p = total

8. Plants and the Environment 1 approach: slope regression line (r 2 ) y = mx + b; m is slope r 2 =0 r 2 =0.52 r 2 =1

9. Plants and the Environment Plant height ex. Fig. 6.3 (r 2 )=0.21 or 21% (h 2 )=0.21 or 21%

10. Genetic Variation More better (generally) Why? –1) Raw material evolution (change genetic makeup) –2) Dominant alleles mask “lethal recessives:” fatal if Finish this sentence: If you were haploid you’d be __________________

11. Genetic Variation Problem: genetic drift! Loss Small pop’ns Small population (9 inds.)Large population (50 inds.) Start: 50% mix 2 alleles

12. Genetic Variation Ex, Wollemi “pine” (Australia)

13. Loss of Genetic Variability Ex, Wollemi “Pine” (Australia) Extinct 2 mya, 2 groups found 1994. Discoverer David Noble Famous quote……

14. Loss of Genetic Variability Ex, Wollemi “Pine” (Australia) No measurable genetic diversity! Collecting seeds by helicopter

15. Genetic Variation Sources new genetic variation? –1) Mutation: Heritable. Rare: 10% of pop’n. each generation (new mutation) –2) Immigration.

16. Plants and the Environment Recall: Adaptation: –1) Genetically determined trait –2) With survival or reproductive benefit How show benefit? Hard! Ex

17. Adaptation Story Homoblasty = same twig/leaf forms

18. Adaptation Story Homoblasty = same Different twig/leaf forms (plant age) = heteroblasty –Also called “juvenile” Ex, many Junipers (Juniperus)

19. Adaptation Story Young plants (0-3 m tall) “divaricate” (wide-angled) Older (> 3 m): normal Pennantia corymbosa normaldivaricate

20. Adaptation Story –Adaptation climate? –Adaptation herbivores (moas)? Plagianthus regius normal divaricate Moas?

21. New Zealand’s Moas Ratites (Order) 11 species Giant moa leg bones Giant moa replica

22. New Zealand’s Moas Hunted extinct by Maori

23. Adaptation Story How study defense hypothesis? Other

24. Adaptation Story Divaricate: 30-70% less loss Branches resist Divaricate

25. Adaptation Story Non-native mammals not affected (shearing teeth) –Heteroblastic species declining

26. Plants and the Environment Recall: Adaptation: –1) Genetically determined trait –2) With survival or reproductive benefit How show benefit? Hard!

27. Variation due to Environment V p = V g + V e

28. Variation due to Environment Phenotypic plasticity: vary form/physiology

29. Variation due to Environment Ex, heterophylly: different –(“hetero”=other; “phyll”=leaf) Fig. 6.5 Emergent vs. Submerged leaves

30. Species as ecological tool Now: species as tool Issues: –Species indicators –Plants adapt at –Revegetation/reforestation: does where

31. Species Species def’n. –Species: Populations morphologically similar & –Biological species approach –Others: cladistics, etc.

32. Species Good indicators: Ex, Quercus laevis (turkey oak). Dry sandy soils (sandhills)

33. Species Bad indicators: widespread Differences genetic ( ?) or environmental ( ?) How evaluate? V p = V g + V e