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Temporal Sequences

Temporal Sequences. Maggie Koopman and Erik Hoffmann. 1.5 billion years. 0.0. Now!. Time is on my side. First hard parts. 1.0. First multicellular. 2.0. First eukaryotes. 3.0. First life!. 4.0. The beginning!. The Outcrop. Sometimes you have a lot to work with. The Outcrop.

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Temporal Sequences

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  1. Temporal Sequences Maggie Koopman and Erik Hoffmann

  2. 1.5 billion years 0.0 Now! Time is on my side First hard parts 1.0 First multicellular 2.0 First eukaryotes 3.0 First life! 4.0 The beginning!

  3. The Outcrop Sometimes you have a lot to work with...

  4. The Outcrop ...and sometimes you don’t!

  5. No crystalline rocks 2 meters = 10 yrs or 10 million? The Outcrop • No absolute dating • Imprecise age calibration Dooley et al., 2004

  6. The Outcrop Unconformities • Stratigraphic gaps caused by non-deposition or erosion • The bigger the time window, the bigger and more frequent the gaps will be Dooley et al., 2004

  7. The Outcrop Cover • Prevents examination • vegetation • loose sediment/soil • snow/ice/permafrost Dooley et al., 2004

  8. The (so-so) Outcrop

  9. 2.5 Ma 100 km Constant Motion Modified from Tibert et al., 2003.

  10. No Outcrop!

  11. Resolution depends on depositional rates • High rates allow high resolution • Low rates allow low resolution • Negative rates erase the record • Not all environments are created equal! Schindel, 1982

  12. Dooley et al., 2004

  13. Gingerich, 1983

  14. Limitations • Preservable hard parts only! • Morphological change only!

  15. Limitations cont. • Can’t detect fine changes. • Small directional changes followed by reversals show up as variability within the population Geary et al., 2002

  16. Punctuated Equilibrium • Long periods (relative to species durations) of morphological stasis coupled with brief periods of very rapid morphological change • Stasis does NOT mean nothing is happening • Changes in soft parts • Changes in tolerances/behaviors • Small directional morphological change followed by doubling back

  17. Biases • Lineage (size, hard parts, frequency) • Location (range, availability) • Temporal resolution ((sub)stage level) • Character sets • Usefulness/Interest

  18. Does the fossil record need to be complete? Can we work around the gaps? Can we derive viable sequences from a spotty record?

  19. Quality of the fossil record through timeM. J. Benton, M. A. Wills and R. Hitchin

  20. What does this paper do? • Offers evidence that the fossil record provides uniformly good documentation of past life. • Assesses the congruence between stratigraphy and phylogeny.

  21. The Congruence Metrics • Valid techniques for comparing large samples of cladograms to try to estimate variations in congruence between the fossil record for different groups of organisms and for different habitats • RCI (relative completeness index) • GER (gap ratio index) • SCI (stratigraphic consistency index) Depend on branching point estimates and calc. Of ghost ranges

  22. Stratigraphic consistency index(Huelsenbeck 1994) • Fit of the record to the tree= proportion of the nodes that are stratigraphically consistent. • Significance of the fit= generate a null distribution for SCI under the hyp. That the statigraphic fit is not better than expected at random.

  23. Figure 2

  24. Hypothesis 1: congruence is better than random (bars to the left) • Alternative hypothesis: congruence is worse than expected from a random model: direct conflict between data (bars to the right) RCI SCI Fig 1 a/b Benton et al 1999

  25. What causes poor matching of age and clade data? Bias in the metric • Difference in quality of trees • Difference in quality of fossil record • Stratigraphic problems • Taxonomy • Sampling density

  26. Molecular Clock Divergence Estimates and the Fossil Record of Cetartiodactyla Jessica M. Theodor J. Paleontology 78 (1), 2004, p 39-44

  27. Why this paper? • Ties molecular clocks to the fossil record • Introduces cetaceans and hippopotamids

  28. Molecular Clocks vs. the Fossil Record • Artiodactyla/Cetacea split – 60 Ma • Earliest fossil whales 53.5 Ma • Earliest fossil artiodactyls 55 Ma • Odontocete/Mysticete split – 34-35 Ma • Rare at 34 Ma, good record ~30 Ma • Hippopotamid/Cetacean split • Earliest fossil whales 53.5 Ma • Earliest fossil hippos 15.6-15.8 Ma • Anthracotheres - ~43 Ma • New study using one mitochondrial and one nuclear gene sequence

  29. Boisserie et al., 2005

  30. Take home messages • The fossil record is necessary to calibrate molecular clocks (and refute the bad ones) • The fossil record fills gaps in phylogenetic trees, allowing us to confirm evolutionary sequences

  31. References Benton, M.J., M.A. Wills, and R. Hitchin 2000, Nature. 403, 534-537 Benton, M.J. 2001, Proceedings of the Royal Society of London B. 268, 2123-2130 Boisserie, J.-R., F. Lihoreau, and M. Brunet 2005, Proceedings of the National Academy of Science 102 (5), 1537-1541 Dooley Jr., A.C., N.C. Fraser, and Z.-X. Luo 2004, Journal of Vertebrate Paleontology. 24 (2), 453-463 Geary, D.H., A.W. Staley, P. Muller, and I. Magyar 2002, Paleobiology. 28 (2), 208-221 Gingerich, P.D. 1983, Science. 222, 159-161 Gingerich, P.D. 1984, Science. 226, 995-996 Gingerich, P.D. 2002, Cetacean Evolution Gould, S.J. 1984, Science. 226, 994-995 Huelsenbeck, J.P. 1994, Paleobiology. 20 (4), 470-483 Koch, C.F. 1978, Paleobiology. 4 (3), 367-372 Levinton, J., L. Dubb, and G.A. Wray 2004, Journal of Paleontology. 78 (1), 31-38 Lihoreau, F., and J.-R. Boisserie 2004, Journal of Vertebrate Paleontology 24 (Supp. 3), 83A Rose, K. 2001, Science. 293, 2216-2217 Schindel, D. 1982, Paleobiology. 8 (4), 340-353 Schopf, T.J.M. 1982, Evolution. 36 (6), 1144-1157 Theodor, J.M. 2004, Journal of Paleontology. 78 (1), 39-44 Tibert, N.E., R.M. Leckie, J.G. Eaton, J.I. Kirkland, J.-P Colin, E.L. Leithold, and M.E. McCormick 2003, in Olson, H.C. and R.M. Leckie, eds., Micropaleontologic Proxies for Sea-Level Change and Stratigraphic Discontinuities: SEPM Special Publication No. 75, 263-299 Wills, M.A. 1999, Systematic Biology. 48 (3), 559-58

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