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Tutorial topic #1

Tutorial topic #1. 1 page (300 word limit!) essay due Sept 26 th Deliver to hand-in box outside Biology Office 2521 Check website for details: Your tutorial section number Your TA name, location, office hours Where your tutorial meets during week of Sept 29 – Oct 3.

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Tutorial topic #1

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  1. Tutorial topic #1 • 1 page (300 word limit!) essay due Sept 26th • Deliver to hand-in box outside Biology Office 2521 • Check website for details: • Your tutorial section number • Your TA name, location, office hours • Where your tutorial meets during week of Sept 29 – Oct 3

  2. Heterogeneous distribution of organisms Interactions among organisms Contingency Environmental heterogeneity Finite and heterogeneous resources Mortality of organisms Evolutionary cause of ecological properties Ecological adaptations Life history Population dynamics Competition Predation The seven fundamental principles of ecology(Scheiner & Willig 2008. Theoretical Ecology) Biol 303 topics: Biol 302 topics: • Community structure & diversity • Succession • Productivity • Nutrient cycling • Global change

  3. Woodward Library reserve Life History lecture outline: • Definitions & context • Examples • Models • Research applications • Readings: • Krebs 5th ed. Chap. 10 (all) Chap. 12 (199-201) • Begon & Mortimer 1986. Chap. 6 • Barbour et al. 1999. Chap. 5

  4. Agriculture Scientific curiosity Why study? Theory Conservation

  5. Grey whale Polar bear Kangaroo Mountain pine beetle Species appear to “fit” their environments. Their evolved morphologies, behaviours and life styles seem to optimize their reproductive success. Animal examples:

  6. Venus flytrap Cattail Plant examples: Pitcher’s thistle (endangered species) Bristlecone pine

  7. Plant dispersal examples:

  8. Life history:“the pattern of energy allocation an organism makes to growth, survival, and reproduction throughout its lifespan” Definitions: Life history strategy (Stearns 1980): “a set of coadapted traits designed by natural selection to solve particular ecological problems” Focus on pattern Focus on process

  9. Life history traits: whole body size? 1. How large to grow? 2. How long to live? 3. When to reproduce? 4. How many offspring? 5. Disperse or stay put? module size? minutes? >1000 years? early in life? late in life? sexual? only once? asexual? many times? few large? many small? how far to travel ? how long to hibernate ?

  10. How many offspring? Offspring size? Number of reproductive episodes? How large to grow? How long to live? When to reproduce? Chemical defense? How fast to develop? Sporophyte vs gametophyte dominance? (plants) Dispersal? Relation of Life history to Life cycle: Example: coniferous tree Sexual vs asexual reproduction?

  11. F F F F F F F F F F F F F F F F F F F F Example: Asexual reproduction Generation F 1 2 3 • rapid population increase if environment stays favourable

  12. x F F F F F F Sexual reproduction Generation F 1 2 3 • slower increase than asexual but advantage when environment varies

  13. 1/3 4/8 16/24 . . . 1.0 1 2 3 . . . 8 Assume start a population with N = 3 comprising one asexual female, one sexual female and one male: Population composition (fraction asexual) Generation Asexual type dominates population in <10 generations

  14. Trade-offs – the time and energy devoted to one structure or function are not available for another Energy Maintenance Growth Reproduction • Body size • # modules (leaves, stems, roots) • Courtship behaviour, litter size • Flower size, # seeds • # reproductive episodes • Metabolism • Physiological tolerance • Disease/predator defense Fitness

  15. R G Young trees M

  16. G R Annual & perennial herbs M

  17. G R M Understory ferns

  18. Longest lived had shortest span of high egg production in early life Krebs Fig. 10.13 Survivorship of female fruit flies differing in egg production

  19. “Masting”

  20. Life History Models - Attempts to categorize and explain life history strategies • Habitat template model • Southwood (1977) • r – K model • McArthur & Wilson (1967) • C-S-R model • Grime (1977)

  21. Southwood’s habitat template model: • “species-eye” view of habitat variation • habitat favourability varies in space and time • different species “see” common patterns of variation: Time – constant, seasonal, unpredictable, ephemeral Space – continuous, patchy, isolated • 12 space x time combinations (= habitat templates)

  22. Southwood’s “Habitat templates” T = generation time H = habitat duration time L = length of unfavourable period R = range (migratory & trivial) U = unfavourable patch size

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