Temporal SequencesTime is on my sideThe OutcropSlide 4Slide 5Slide 6Slide 7PowerPoint PresentationSlide 9No Outcrop!Slide 11Slide 12Slide 13LimitationsLimitations cont.Slide 16Slide 17Slide 18Does the fossil record need to be complete?Quality of the fossil record through time M. J. Benton, M. A. Wills and R. HitchinWhat does this paper do?The Congruence MetricsStratigraphic consistency index (Huelsenbeck 1994)Slide 24Slide 25What causes poor matching of age and clade data? Bias in the metricMolecular Clock Divergence Estimates and the Fossil Record of CetartiodactylaWhy this paper?Molecular Clocks vs. the Fossil RecordSlide 30Slide 31Take home messagesReferencesTemporal SequencesMaggie Koopman and Erik HoffmannTime is on my sideNow!First hard partsFirst multicellularFirst eukaryotesFirst life!The beginning!1.5 billion years1.02.03.04.00.0The OutcropSometimes you have a lot to work with...The Outcrop...and sometimes you don’t!The OutcropDooley et al., 2004No crystalline rocks• No absolute dating • Imprecise age calibration2 meters = 10 yrs or 10 million?The OutcropDooley et al., 2004Unconformities• Stratigraphic gaps caused by non-deposition or erosion• The bigger the time window, the bigger and more frequent the gaps will beThe OutcropDooley et al., 2004Cover• Prevents examination• vegetation• loose sediment/soil• snow/ice/permafrostThe (so-so) OutcropModified from Tibert et al., 2003.100 km2.5 MaConstant MotionNo Outcrop!•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, 1982Dooley et al., 2004Gingerich, 1983Limitations• Preservable hard parts only!• Morphological change only!Limitations cont. • Can’t detect fine changes.•Small directional changes followed by reversals show up as variability within the populationGeary et al., 2002•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 backPunctuated Equilibrium•Lineage (size, hard parts, frequency)•Location (range, availability)•Temporal resolution ((sub)stage level)•Character sets•Usefulness/InterestBiasesDoes the fossil record need to be complete?Can we work around the gaps?Can we derive viable sequences from a spotty record?Quality of the fossil record through timeM. J. Benton, M. A. Wills and R. Hitchin•Offers evidence that the fossil record provides uniformly good documentation of past life.What does this paper do?• Assesses the congruence between stratigraphy and phylogeny.•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)The Congruence MetricsDepend on branching point estimates and calc. Of ghost rangesStratigraphic 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.Figure 2•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)Fig 1 a/b Benton et al 1999RCI SCIWhat 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 densityMolecular Clock Divergence Estimates and the Fossil Record of CetartiodactylaJessica M. TheodorJ. Paleontology 78 (1), 2004, p 39-44Why this paper?•Ties molecular clocks to the fossil record•Introduces cetaceans and hippopotamidsMolecular 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 sequenceBoisserie et al., 2005Take 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 sequencesReferencesBenton, M.J., M.A. Wills, and R. Hitchin 2000, Nature. 403, 534-537Benton, M.J. 2001, Proceedings of the Royal Society of London B. 268, 2123-2130Boisserie, J.-R., F. Lihoreau, and M. Brunet 2005, Proceedings of the National Academy of Science 102 (5), 1537-1541Dooley Jr., A.C., N.C. Fraser, and Z.-X. Luo 2004, Journal of Vertebrate Paleontology. 24 (2), 453-463Geary, D.H., A.W. Staley, P. Muller, and I. Magyar 2002, Paleobiology. 28 (2), 208-221Gingerich, P.D. 1983, Science. 222, 159-161Gingerich, P.D. 1984, Science. 226, 995-996Gingerich, P.D. 2002, Cetacean EvolutionGould, S.J. 1984, Science. 226, 994-995Huelsenbeck, J.P. 1994, Paleobiology. 20 (4), 470-483Koch, C.F. 1978, Paleobiology. 4 (3), 367-372Levinton, J., L. Dubb, and G.A. Wray 2004, Journal of Paleontology. 78 (1), 31-38Lihoreau, F., and J.-R. Boisserie 2004, Journal of Vertebrate Paleontology 24 (Supp. 3), 83ARose, K. 2001, Science. 293, 2216-2217Schindel, D. 1982, Paleobiology. 8 (4), 340-353Schopf, T.J.M. 1982, Evolution. 36 (6), 1144-1157Theodor, J.M. 2004, Journal of Paleontology. 78 (1), 39-44Tibert, 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, 263-299Wills, M.A. 1999, Systematic Biology. 48 (3),
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