Interactions Among Organisms: Predation, Parasitism, Commensalism, and Mutualism

1. The student is expected to:12A interpret relationships,including predation, parasitism,commensalism, mutualism, andcompetition among organisms

2. KEY CONCEPT Organisms interact as individuals and as populations.

3. Competition and predation are two important ways inwhich organisms interact. • Competition occurs when two organisms fight for thesame limited resource. • Intraspecificcompetition • Interspecificcompetition

4. Predation occurs when one organism captures and eats another.

5. Mutualism: both organisms benefit • There are three major types of symbiotic relationships.

6. Commensalism Human Our eyelashes are home to tiny mites that feast on oil secretions and dead skin. Without harming us, up to 20 mites may be living in one eyelash follicle. Ø Demodicids Eyelash mites find all they need to survive in the tiny follicles of eyelashes. Magnified here 225 times, these creatures measure 0.4 mm in length and can be seen only with a microscope. + Ø + Organism is not affected Organism benefits • There are three major types of symbiotic relationships. • Commensalism: one organism benefits, the other is unharmed

7. Braconid wasp Braconid larvae feed on their host and release themselves shortly before reaching the pupae stage of development. 0 Parasitism + _ Hornworm caterpillar The host hornworm will eventually die as its organs are consumed by wasp larvae. _ Organism benefits Organism is not affected 0 • There are three major types of symbiotic relationships. • Parasitism: one organism benefits, the other is harmed

8. There are three major types of symbiotic relationships. • Parasitism meet their needs as ectoparasites (such as leeches) and endopaasites (such as hookworms)

9. The student is expected to:7D analyze and evaluate how the elements of natural selection, including inherited variation,the potential of a population to produce more offspring than can survive, and a finite supply ofenvironmental resources, result in differential reproductive success;12A interpret relationships, including predation, parasitism, commensalism, mutualism, andcompetition among organisms

10. KEY CONCEPT Each population has a density, a dispersion, and a reproductive strategy.

11. Population density is the number of individuals that live in a defined area. • Population density is a measurement of the number of individuals living in a defined space. • Scientists can calculate population density.

12. Clumped dispersion Uniform dispersion Random dispersion Geographic dispersion of a population shows how individuals in a population are spaced. • Population dispersion refers to how a population is spread in an area.

13. clumped • There are three types of dispersion.

14. uniform • There are three types of dispersion.

15. random • There are three types of dispersion.

16. Survivorship curves help to describe the reproductive strategy of a species. • A survivorship curve is a diagram showing the number of surviving members over time from a measured set of births.

17. Type I—low level of infant mortality and an older population • common to large mammals and humans • Type II—survivorship rate is equal at all stages of life • common to birdsand reptiles • Survivorship curves can be type I, II or III. • Type III—very high birth rate, very high infant mortality • common to invertebrates and plants

18. The student is expected to:11B investigate and analyze how organisms, populations, and communities respond to external factors; 12A interpret relationships, including predation, parasitism, commensalism, mutualism, and competition among organisms;12D recognize that long-term survival of species is dependent on changing resource bases that are limited

19. KEY CONCEPT Populations grow in predictable patterns.

20. Changes in a population’s size are determined by immigration, births, emigration, and deaths. • The size of a population is always changing. • Four factors affect the size of a population. • immigration • births • emigration • deaths

21. Population growth is based on available resources. • Exponential growth is a rapid population increase due to an abundance of resources.

22. Logistic growth is due to a population facing limited resources.

23. A population crash is a dramatic decline in the size of a population over a short period of time. • Carrying capacity is the maximum number of individuals in a population that the environment can support.

24. Ecological factors limit population growth. • A limiting factor is something that keeps the size of a population down. • Density-dependent limiting factors are affected by the number of individuals in a given area.

25. predation • competition • Density-dependent limiting factors are affected by the number of individuals in a given area. • parasitism and disease

26. unusual weather • natural disasters • human activities • Density-independent limiting factors limit a population’s growth regardless of the density.

27. The student is expected to:11B investigate and analyze how organisms, populations, and communities respond to external factors; 11D describe how events and processes that occur during ecological succession can change populations and species diversity;12F describe how environmental change can impact ecosystem stability

28. KEY CONCEPT Ecological succession is a process of change in the species that make up a community.

29. Succession occurs following a disturbance in an ecosystem. • Succession regenerates or creates a community after a disturbance. • a sequence of biotic changes • damaged communities are regenerated • new communities arise in previously uninhabited areas

30. primary succession — started by pioneer species • There are two types of succession.

31. secondary succession — started by remaining species • There are two types of succession.