Temporal Sequences Maggie Koopman and Erik Hoffmann 0 0 Now First hard parts 1 0 Time is on my side First multicellular 2 0 First eukaryotes 1 5 billion years 3 0 First life 4 0 The beginning The Outcrop Sometimes you have a lot to work with The Outcrop and sometimes you don t The Outcrop No crystalline rocks No absolute dating Imprecise age calibration 2 meters 10 yrs or 10 million Dooley et al 2004 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 The Outcrop Cover Prevents examination vegetation loose sediment soil snow ice permafrost Dooley et al 2004 The so so Outcrop Constant Motion 2 5 Ma 100 km Modified from Tibert et al 2003 No 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 1982 Dooley et al 2004 Gingerich 1983 Limitations 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 population Geary et al 2002 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 Biases Lineage size hard parts frequency Location range availability Temporal resolution sub stage level Character sets Usefulness Interest Does 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 time M J Benton M A Wills and R Hitchin 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 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 Depend on branching RCI relative completeness index point estimates and GER gap ratio index calc Of ghost ranges SCI stratigraphic consistency index 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 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 RCI Fig 1 a b Benton et al 1999 SCI 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 Molecular Clock Divergence Estimates and the Fossil Record of Cetartiodactyla Jessica M Theodor J Paleontology 78 1 2004 p 39 44 Why this paper Ties molecular clocks to the fossil record Introduces cetaceans and hippopotamids 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 Boisserie et al 2005 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 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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