Expansion and Decline of Southern California Populations of Yucca Brevifolia (Agavaceae)<br />Jeffrey Collins and Chris Sm...
Global climate change<br />From Climate Change Art<br />
Global climate change<br />Organisms that can neither migrate nor adapt will go extinct.<br />
Mojave community<br />
Mojave community<br />
Mojave community<br />
Mojave community<br />
Mojave community<br />
Mojave community<br />
Mojave community<br />
Ecological niche modeling<br />After Dole et al., 2003<br />
Research questions <br />Do some Joshua tree populations show signs of population decline?<br />Does population decline co...
Demographic structure<br />
Survey methods<br />9 study sites<br />Elevation<br />Predicted fate<br />Previous observations<br />
Survey methods<br />9 study sites<br />Demographic survey<br />2-3 transects per site<br />50 m wide<br />50 trees<br />
Survey methods<br />9 study sites<br />Demographic survey<br />2-3 transects per site<br />Surveyed each tree<br />Number ...
Survey methods<br />9 study sites<br />Demographic survey<br />2-3 transects per site<br />Surveyed each tree<br />Tissue ...
Survey methods<br />9 study sites<br />Demographic survey<br />Genotyping<br />13 polymorphic microsatellite loci<br />Gen...
Demography<br />Size classes<br />Height<br />Number of branches<br />
Demography<br />Size classes<br />Stepwise Linear regression<br />DV: Median size class<br />IVs: Environmental normals<br...
February precipitation vs. size class<br />
Population genetics<br />7 polymorphic microsatellite loci<br />Wilcoxan sign rank test<br />Null hypothesis: no genetic b...
Population genetics<br />p2 + 2pq + q2 = 1<br />
Population genetics<br />7 polymorphic microsatellite loci<br />Wilcoxan sign rank test<br />Null hypothesis: no genetic b...
Population genetics<br />
Conclusions<br />Evidence for current population decline<br />Correlates with precipitation<br />
Conclusions<br />Evidence for current population decline<br /> No evidence of genetic bottlenecks<br />Possible explanatio...
Conclusions<br />Evidence for current population decline<br /> No evidence of population bottlenecks<br />Further work<br ...
Acknowledgements<br />Tyler Starr<br /><ul><li>Ramona Flatz
Jeremy Yoder</li></li></ul><li>Work cited and photo credits<br />Work cited<br />Dole KP, Loik ME, Sloan LC (2003) The rel...
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Expansion and decline of Southern California populations of Yucca brevifolia (Agavaceae)

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Presentation given in April 2010 at Willamette University.

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Expansion and decline of Southern California populations of Yucca brevifolia (Agavaceae)

  1. 1. Expansion and Decline of Southern California Populations of Yucca Brevifolia (Agavaceae)<br />Jeffrey Collins and Chris Smith<br />
  2. 2. Global climate change<br />From Climate Change Art<br />
  3. 3. Global climate change<br />Organisms that can neither migrate nor adapt will go extinct.<br />
  4. 4. Mojave community<br />
  5. 5. Mojave community<br />
  6. 6. Mojave community<br />
  7. 7. Mojave community<br />
  8. 8. Mojave community<br />
  9. 9. Mojave community<br />
  10. 10. Mojave community<br />
  11. 11. Ecological niche modeling<br />After Dole et al., 2003<br />
  12. 12. Research questions <br />Do some Joshua tree populations show signs of population decline?<br />Does population decline correlate with any environmental variables?<br />
  13. 13. Demographic structure<br />
  14. 14. Survey methods<br />9 study sites<br />Elevation<br />Predicted fate<br />Previous observations<br />
  15. 15. Survey methods<br />9 study sites<br />Demographic survey<br />2-3 transects per site<br />50 m wide<br />50 trees<br />
  16. 16. Survey methods<br />9 study sites<br />Demographic survey<br />2-3 transects per site<br />Surveyed each tree<br />Number of branches<br />Number of inflorescences<br />Location (via GPS)<br />Height<br />
  17. 17. Survey methods<br />9 study sites<br />Demographic survey<br />2-3 transects per site<br />Surveyed each tree<br />Tissue samples<br />≥10 trees per site<br />Labeled<br />Frozen<br />
  18. 18. Survey methods<br />9 study sites<br />Demographic survey<br />Genotyping<br />13 polymorphic microsatellite loci<br />Genotyped using PCR multiplexes<br />
  19. 19. Demography<br />Size classes<br />Height<br />Number of branches<br />
  20. 20. Demography<br />Size classes<br />Stepwise Linear regression<br />DV: Median size class<br />IVs: Environmental normals<br />February Precipitation<br />Annual Precipitation<br />July max temperature<br />Elevation<br />
  21. 21. February precipitation vs. size class<br />
  22. 22. Population genetics<br />7 polymorphic microsatellite loci<br />Wilcoxan sign rank test<br />Null hypothesis: no genetic bottleneck has occurred<br />Calculates distribution of Hexp based on n and k<br />
  23. 23. Population genetics<br />p2 + 2pq + q2 = 1<br />
  24. 24. Population genetics<br />7 polymorphic microsatellite loci<br />Wilcoxan sign rank test<br />Null hypothesis: no genetic bottleneck has occurred<br />Calculates distribution of Hexp based on n and k<br />Compares He to the distribution of Hexp<br />If He < Hexp, reject the null hypothesis<br />
  25. 25. Population genetics<br />
  26. 26. Conclusions<br />Evidence for current population decline<br />Correlates with precipitation<br />
  27. 27. Conclusions<br />Evidence for current population decline<br /> No evidence of genetic bottlenecks<br />Possible explanations:<br />No bottlenecks<br />Low sample size<br />Low power of Wilcoxan sign rank test<br />
  28. 28. Conclusions<br />Evidence for current population decline<br /> No evidence of population bottlenecks<br />Further work<br />Further genetic analysis<br />Analysis of population structure<br />MSVAR<br />Other methods of classifying age distributions<br />Leslie matrices<br />
  29. 29. Acknowledgements<br />Tyler Starr<br /><ul><li>Ramona Flatz
  30. 30. Jeremy Yoder</li></li></ul><li>Work cited and photo credits<br />Work cited<br />Dole KP, Loik ME, Sloan LC (2003) The relative importance of climate change and the physiological effects of CO2 on freezing tolerance for the future distribution of Yucca brevifolia. Global and Planetary Change 36, 137-146.<br />Godsoe W, Strand E, Smith CI, et al. (2009) Divergence in an obligate mutualism is not explained by divergent climatic factors. New Phytologist183, 589-599.<br />Cornuet JM, Luikart G (1996) Description and Power Analysis of Two Tests for Detecting Recent Population Bottlenecks From Allele Frequency Data. Genetics 144, 2001-2014.<br />

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