1 / 24

Evolution and Life Histories II

Evolution and Life Histories II. LS: 4 days. LH example: Thrip egg mites. Life History Principles. Generally begin with birds Reproductive output is accessible. Reproductive output can be easily manipulated and adjusted. Individuals can be marked for identification.

wilma-farmer
Download Presentation

Evolution and Life Histories II

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Evolution and Life Histories II

  2. LS: 4 days • LH example: Thrip eggmites

  3. Life History Principles • Generally begin with birds • Reproductive output is accessible. • Reproductive output can be easily manipulated and adjusted. • Individuals can be marked for identification.

  4. The evolution of clutch size • Optimal clutch size • ? How much energy should an individual allocate to an episode of reproduction; e.g., how many eggs? • Trade-off: The more offspring produced, the fewer resources available for each individual. • Lack’s prediction: Selection should favor a clutch size that maximizes the number of surviving offspring. • Clutch size should be a reproductive strategy.

  5. Starting hypotheses Assumptions: 1. eggs are all the same size 2. current reproductive effort does not affect subsequent performance Tradeoff: Probability of individual survival < with > clutch size Prediction: Number of surviving offspring = clutch size x probability of individual survival Optimal clutch size = 5

  6. Number of Clutches N = 4489 A test of the prediction: 1960-1982 Number surviving as a function of clutch size Parental lifetime fitness can decrease from care necessitated by large broods.

  7. Future effects of clutch size on daughters’ performance Collared Flycatchers

  8. Effect of age at first reproduction on size of subsequent clutches • e.g. Collared Flycatchers Begin at different ages Begin with extra eggs

  9. How large should offspring be? • Trade-off between number and size of offspring. • Produce many small OR few large? • Can be dictated by environmental context; i.e., the reproductive strategy may include phenotypic plasticity • e.g. Stator limbatus (a seed beetle)

  10. Seed beetle: Stator limbatus Blue palo verde seed Poor host: < 1/2 larvae survive Cat-claw acacia seed Good host: most larvae survive

  11. Stator limbatus The model: Size decreases with an increased number of sibs Minimum size at which offspring survive is smaller on good host Offspring survival Optimal offspring size for parent is larger on poor host Parental fitness Prediction: larger eggs on poorer host

  12. Restricted to one host 1st egg on on host - then switched

  13. A phylogenetic constraint on clutch size. • A fitness enigma?

  14. A. neotesselata (17.0 mL) A. sexlineata (7.1 mL) A. tesselata (24.2 mL)

  15. Karyotype of Aspidoscelis neotesselata

  16. Intraspecific divergence in life histories in A. tesselata (a parthenogenetic species)

  17. Fort Sumner

  18. Aspidoscelis tesselata Pattern class E Pattern class C

  19. Assignment: Sunday March 21 • Watch “Life”: Cable TV, Discovery Channel • Making the series, 6 P.M. • Reptiles and Amphibians, 7 P.M.

More Related