Experimental studies of extinction dynamics

Science

Volumn 286, Issue 5442, 1999, Pages 1175-1177

  Belovsky, Gary E ^a   Mellison, Chad ^a   Larson, Chad ^a   Van Zandt, Peter A ^a,b  

^a UTAH STATE UNIVERSITY   (United States)

^b UNIVERSITY OF LOUISIANA AT LAFAYETTE   (United States)

Author keywords

[No Author keywords available]

Indexed keywords

ARTEMIA; ARTICLE; ENVIRONMENTAL FACTOR; EVOLUTION; NONLINEAR SYSTEM; POPULATION; PRIORITY JOURNAL;

ANOSTRACA; ARTEMIA; ARTEMIA FRANCISCANA; DECAPODA (CRUSTACEA); PONTOPORIA BLAINVILLEI;

EID: 0033527632     PISSN: 00368075     EISSN: None     Source Type: Journal    
DOI: 10.1126/science.286.5442.1175     Document Type: Article

References (34)

1. J. M. Diamond, in Extinctions, M. H. Nitecki, Ed. (Univ. of Chicago Press, Chicago, 1984), pp. 191-246; R. H. MacArthur and E. O. Wilson, The Theory of Island Biogeography (Princeton Univ. Press, Princeton, NJ, 1967); D. M. Raup, Extinction: Bad Genes or Bad Luck? (Norton, New York, 1991).
2. J. M. Diamond, in Extinctions, M. H. Nitecki, Ed. (Univ. of Chicago Press, Chicago, 1984), pp. 191-246; R. H. MacArthur and E. O. Wilson, The Theory of Island Biogeography (Princeton Univ. Press, Princeton, NJ, 1967); D. M. Raup, Extinction: Bad Genes or Bad Luck? (Norton, New York, 1991).
3. J. M. Diamond, in Extinctions, M. H. Nitecki, Ed. (Univ. of Chicago Press, Chicago, 1984), pp. 191-246; R. H. MacArthur and E. O. Wilson, The Theory of Island Biogeography (Princeton Univ. Press, Princeton, NJ, 1967); D. M. Raup, Extinction: Bad Genes or Bad Luck? (Norton, New York, 1991).
4. M. E. Soulé, in Viable Populations for Conservation, M. E. Soulé, Ed. (Cambridge Univ. Press, Cambridge, 1987), pp. 1-10; G. Caughley J. Anim. Ecol. 63, 215 (1994).
5. M. E. Soulé, in Viable Populations for Conservation, M. E. Soulé, Ed. (Cambridge Univ. Press, Cambridge, 1987), pp. 1-10; G. Caughley J. Anim. Ecol. 63, 215 (1994).
6. S. R. Beissinger and M. I. Westphal, J. Wildl. Manage. 62, 821 (1988).
7. N. Richter-Dyn and N. S. Goel, Theor. Popul. Biol. 3, 406 (1972).
8. D. Goodman, in Viable Populations for Conservation, M. E. Soulé, Ed. (Cambridge Univ. Press, Cambridge, 1987), pp. 11-34; E. G. Leigh Jr. J. Theor. Biol. 90, 213 (1981); P. B. Stacey and M. Taper, Ecol. Appl. 2, 18 (1992).
9. D. Goodman, in Viable Populations for Conservation, M. E. Soulé, Ed. (Cambridge Univ. Press, Cambridge, 1987), pp. 11-34; E. G. Leigh Jr. J. Theor. Biol. 90, 213 (1981); P. B. Stacey and M. Taper, Ecol. Appl. 2, 18 (1992).
10. D. Goodman, in Viable Populations for Conservation, M. E. Soulé, Ed. (Cambridge Univ. Press, Cambridge, 1987), pp. 11-34; E. G. Leigh Jr. J. Theor. Biol. 90, 213 (1981); P. B. Stacey and M. Taper, Ecol. Appl. 2, 18 (1992).
11. W. J. Ewens et al., in Viable Populations for Conservation, M. E. Soulé, Ed. (Cambridge Univ. Press, Cambridge, 1987), pp. 59-68.
12. J. M. Brown and A. Kodric-Brown, Ecology 58, 445 (1977); I. Hanski and M. E. Gilpin, Biol. J. Linn. Soc. 42, 3 (1991).
13. J. M. Brown and A. Kodric-Brown, Ecology 58, 445 (1977); I. Hanski and M. E. Gilpin, Biol. J. Linn. Soc. 42, 3 (1991).
14. M. Shaffer, in Viable Populations for Conservation, M. E. Soulé, Ed. (Cambridge Univ. Press, Cambridge 1987), pp. 69-86.
15. Brine shrimp were hatched from commercial cysts and reared to adults in 40-liter aquaria containing aerated hypersaline water (90 parts per thousand). Shrimp were fed an aqueous suspension of dry baker's yeast (100 mg per aquarium per day). Sexes were separated as individuals became adults to prevent reproduction. The shrimp only sexually reproduce. Experimental populations were kept in 500-ml Nalgene bottles containing 400 ml of aerated hypersaline water and were kept in environmental chambers (25° to 27°C, 12 hours light:12 hours dark). Half of a bottle's solution was replaced and sediments were removed twice a week, and bottle walls were wiped with a sponge once a week to limit algae and bacteria as additional food and to reduce variation in pH.
16. A random number generator (normal distribution) provided each population's daily food ration. If a daily ration was negative, no food was supplied; this produces a more log-normal distribution.
17. Every 3 days, individuals in a bottle were counted, identified as to developmental stage, and sexed if adult. Three developmental stages were used [H. Heath, J. Morphol. 38, 453 (1924)]: nauplii (≤5 mm), juveniles (>5 and ≤9 mm), and adults (>9 mm), and population size was expressed in adult equivalents based on body mass (nauplius = 0.13 adult; juvenile = 0.63 adult). Population dynamics were restricted to live births by removal of cysts, which ensured short generation time.
18. Population extinction occurred when (i) all individuals disappeared and (ii) all individuals were adults of a single sex. However, when adult females remained, observations continued until all females died in order to make sure that they were not gravid. If all individuals in a population were nauplii or juveniles, then observations continued until sexes could be assessed and condition (ii) was met.
19. 2 = 0.81, n = 40, P < 0.001).
20. Nauplii received the same food level as their maternal population (Table 1) except the two highest maternal levels, which were reduced to 1.88 and 2.5 mg/day, because unused food increased pH to a lethal level.
21. 2 = 0.82.
22. S. L Pimm and M. E. Gilpin, in Perspectives in Ecological Theory, J. Roughgarden et al., Eds. (Princeton Univ. Press, Princeton, NJ, 1989), pp. 287-305; S. L. Pimm, H. L Jones, J. M. Diamond, Am. Nat. 132, 757 (1988); C. R. Tracy and T. L. George, ibid. 139, 102 (1992).
23. S. L Pimm and M. E. Gilpin, in Perspectives in Ecological Theory, J. Roughgarden et al., Eds. (Princeton Univ. Press, Princeton, NJ, 1989), pp. 287-305; S. L. Pimm, H. L Jones, J. M. Diamond, Am. Nat. 132, 757 (1988); C. R. Tracy and T. L. George, ibid. 139, 102 (1992).
24. S. L Pimm and M. E. Gilpin, in Perspectives in Ecological Theory, J. Roughgarden et al., Eds. (Princeton Univ. Press, Princeton, NJ, 1989), pp. 287-305; S. L. Pimm, H. L Jones, J. M. Diamond, Am. Nat. 132, 757 (1988); C. R. Tracy and T. L. George, ibid. 139, 102 (1992).
25. 2 = 0.61.
26. P) over time for all replicate populations under the same conditions were averaged; this eliminates statistical biases for individual population values [P. A. Van Zandt, thesis, Utah State University, Logan, UT (1997)].
27. r = 0.08.
28. E. Renshaw, Modelling Biological Populations in Space and Time (Cambridge Univ. Press, Cambridge, 1993).
29. 2 = 0.52).
30. M. Mangel and C. Tier, Proc. Natl. Acad Sci. U.S.A. 90, 1083 (1993).
31. A. A. Berryman and J. A. Millstein, Trends Ecol, Evol. 4, 26 (1989).
32. C. Caughley and A. Gunn, Conservation Biology in Theory and Practice (Blackwell, Oxford, 1995).
33. T. E. Lovejoy et al., in Conservation Biology: The Science of Scarcity, M. E. Soulé, Ed. (Sinauer, Sunderland, MA, 1986), pp. 257-285.
34. Supported by NSF (DEB-9322576); the Office of V.P. for Research, Utah State University; and the Utah Division of Wildlife Resources. We thank S. Jackson, C. Olsen, P. Lee, and J. Jacobson for counting populations; T. Crowl for commenting on experimental design and statistics; and J. B. Slade for commenting on the manuscript.