The Evolution of Life Histories

1. The Evolution of Life Histories 報告者：王韋政 林致綱

2. Introduction • Callosobruchus maculatus 四紋豆象 • Ficedula albicollis白領姬鶲

3. This chapter… • Concentrate on Life history theory. • Two approaches: phenotypic and genetic. • Which trade-off can be measure. • Evolution of clutch size, delayed maturity and semelparity. • Phenotypic plasticity of life history.

4. Approaches to life history evolution • Phenotypic approach =>about the adaptive value of trait. • Genetic approach =>consider about gene frequencies.

5. Optimality models of life histories • Decision variables(life history trait) => age-specific values of fecundity and mortality • Currency => RVx = Σ(ly/lx) ．my ．e -r(y-x+1) • Constraint => fitness curve => trade-off curve

6. Measuring constraints Fecundity

7. Why phenotypic correlations can’t be used to measure? • Lack of non-adaptive variation in allocation. • Adaptive variation in allocation. or

8. How can constraints to be measured? • Experimental manipulations -Direct manipulation: clutch or brood size -Indirect manipulation: supplementary feeding • Genetic correlations -Breeding experiment -Selection experiment

9. Longevity (days) Fecundity

11. The cost of reproduction • Current reproduction can be increase only at the expense of future survival or fecundity. • Physiological or ecological origin.

13. male female Gustafsson and Sutherland, 1988

14. Cost of reproduction • Increased broods size ->increased their provisioning rates. (Nur, 1984a; Reid, 1987; Pettifor 1989) Blue tits Glaucous-winged gull

15. Trade-off between the number and fitness of offspring

16. Optimal clutch size in insects and birds • Lack’s hypothesis: As clutch increased, each of nestlings would survive less well

17. Optimal clutch size is determined bytrade-off between the number and fitness of offspring (Lack’s solution) • But, measured clutch size＜predicted most productive brood size (mpbs) …why? →there are four kinds of expanation

18. (1)Measurement of offspring fitness is incomplete • Need to include different survival of offspring in the post-fledging period (Lack , 1954) • Inclusion of the effects of brood size on post-fledging survival in insects and birds • mpbs↓ in some species

19. mpbs mpbs (2)Maximizing fitness per clutches does not maxmize lifetime fitness

20. (3)Muptiple oviposition

21. http://www.bbc.co.uk/devon/content/image_galleries/wildlife_15_gallery.shtml?22http://www.bbc.co.uk/devon/content/image_galleries/wildlife_15_gallery.shtml?22 (4)Stochastic variation in clutch size or fitness • When female do not have perfect control over the family size → optimum clutch size ＜mpbs • Blue tit →fitness measurement (geometric mean better than arithmetic mean)

22. Extreme of reproductive effort：semelparity and deferred maturity • Cole’s paradox： when offsprings → semelparity +1= Iteroparity • Solution of paradox： Cole neglect mortality in his model

23. If... Produce 2P/Y extra young→ semelparity low P/Y → Iteroparity P=parental survival Y=juvenile survival to the next breeding season

24. Iteroparity Semelparity Deferred maturity

25. Age at maturity

26. Deferred maturity：result from RV at age of maturity being dependent on experience rather than size

27. Comparative studies of life history traits • Habitat classification “r selection” and “k selection” • Relationships between life history traits are more strongly related to each other than they are to the environment.

28. Phenotypic plasticity • Reaction norm (norm of reaction): the relationship between phenotype and the environment for each genotype. • phenotypic plasticity: growth rate, morphology, egg production.

29. couch’s spadefoot toad https://webspace.utexas.edu/s681/webpage/LLAnura.html larvae of fly Ephydra cinerea http://bugguide.net/node/view/37112/bgimage Adaptive phenotypic plasticity? pied flycatchers (handicapped juvenile and re-nest) http://www.djsphotography.co.uk/BritishBirds/Flycatcher.htm

31. Conditions favouring the evolution of phenotypic plasticity • The environment changes on small scale geographically, or short interval →flightless thrips • The existence of environmental cues →great tit and peak caterpillar abundance (hatch asynchronously)

32. Individual optimization, directional selection and heritability • Genetic variation in clutch size： ex: lesser snow geese →why is there no response to selection? • If the trait is heritable and environmental variable which independently affects fitness.

33. Genetic variation in reaction norm

34. THE END