1 / 25

Lecture 9

Lecture 9 BIOL 3500 Chapter 11: Intraspecific Population Regulation Learning Objectives Contrast: Density dependance vs. independence Scramble vs. contest competition Home range vs. territory Define: “Self thinning” Philopatry Discuss: Effects of crowding Density Dependence

emily
Télécharger la présentation

Lecture 9

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. Lecture 9 BIOL 3500 Chapter 11: Intraspecific Population Regulation

  2. Learning Objectives • Contrast: • Density dependance vs. independence • Scramble vs. contest competition • Home range vs. territory • Define: • “Self thinning” • Philopatry • Discuss: • Effects of crowding

  3. Density Dependence • Refers to factors regulating population, effect is proportional to pop size. • Number of indiv affected depends upon intensity. • Ex: food limitation, communicable disease

  4. Birthrate & Mortality Rate • Density dependent factors can affect either or both

  5. Density Independence • Refers to pop-infuencing factors not influenced by pop size. • Typically what we call “natural disasters” • Ex: hurricanes, fire

  6. Competition • Will occur any time there are more individuals than a resource can support • One resource will limit • If it becomes plentiful, another resource will become limiting

  7. Two Types of Competition • Intraspecific • Between individuals of the same species (Chapter 11) • Interspecific • Between individuals of different species (Chapter 14)

  8. Two More Types of Competition • Scramble competition • All individuals are depressed equally • Too many pine trees planted in a forest (all will be small) • Contest competition • Some individuals are better at getting limited resources • Baby birds in a nest (big one gets most of food)

  9. Crowding and Tadpoles • Tadpoles grown in higher density population have lower mean body mass • Slower to reach maturity • Presumably compete for food

  10. Crowding and Clover • White clovers grown at high density have decreased mean weight

  11. Bluegills and Crowding • When stocked at high density, only small fish result • May never reach breeding size • Careful monitoring of size, control of stocking rates important • MSU website • NC State website

  12. Question • We already knew that limited resources cause reduced growth • We saw that competition causes limitation in resources, and affects growth • Is the response of an organism in competition different in intensity than just resource limitation?

  13. Competition and Limitation Two types of pots: 1 plant vs. 16 plants Broadleaf Peppermint Note: water is per pot Limitation + competition interact! (shape of curves is different)

  14. 7th Inning Stretch

  15. Horseweed • Unlike pine trees, tadpoles, or bluegills, horseweed is “self thinning” • If too crowded, competition will kill some

  16. Reproduction & Interspecific Competition Fecundity of females can change under competition Most notable in large mammals Bison have sharp drop Grizzly bears affected linearly

  17. Harp Seals • Age of sexual maturity depends upon population density

  18. Fecundity and Plants Corn and salt marsh plants

  19. Quick Review: • List all the ways that intraspecific competition can regulate a population.

  20. Stress and Competition in Animals • Crowding may cause increased aggression • Stress causes hormone changes, resulting in: • Retarded growth rate • Delayed onset of reproducton • Reproductive failure (miscarriage, low birth weight) • Immune system compromise

  21. Social Dominance • Among wolves, usually only alpha male and alpha female mate • All others are prevented from doing so • When food becomes limiting, subordinates are chased out of the pack • Lone wolves have harder time hunting (mortality increases)

  22. Home Range • Home range = area used by one individual over a year • Size often depends upon food needs • Type of food • Amount (ie: body size of individual) • Sex matters too. Males’ ranges generally bigger. Why?

  23. Diet, Body Size, and Home Range

  24. Territoriality • Territory = part of the home range, actively defended • Birds might sing, display, fight for an area • Grasshopper sparrows return to same territory yearly (philopatry)

More Related