MEEMF 2011 – ED4 No arquivo ed4.nex está o alinhamento dos
Transcrição
MEEMF 2011 – ED4 No arquivo ed4.nex está o alinhamento dos
MEEMF 2011 – ED4 No arquivo ed4.nex está o alinhamento dos genes codificadores de proteínas mitocondriais de alguns mamíferos. Considere os seguintes informações de calibração retirados de Benton e Donoghue, (2007, Mol. Biol. Evol.). Dating the Tree of Life 27 Table 1 Constraints on Calibration Dates for Branching Points in the Tree of Life Minimum Age Constraint Node Human–chimp Human–macaque Mouse–rat Rabbit–mouse Human–mouse Dog–cat Dog–horse Cow–sheep Cow–pig Cow–dog Human–cow Human–armadillo Tenrec–elephant Human–tenrec Opossum–kangaroo Human–opossum Human–platypus Chicken–zebrafinch Emu–chicken Bird–crocodile Crocodile–lizard Mammal–bird Human–toad Equivalent to Clade Age-Indicative Fossil Homini–Pan Hominoidea–Cercopithecoidea Mus lineage–Rattus lineage Glires Archonta–Glires (Euarchontoglires) Caniformia–Feliformia Carnivora–Perissodactyla Bovinae–Antilopinae Ruminantia/Tylopoda–Suiformes Ferungulata Euarchontoglires–Laurasiatheria Boreoeutheria–Xenarthra Afrosoricida/Tubulidentata–Paenungulata Boreoeutheria/Xenarthra–Afrotheria Ameridelphia–Australidelphia Eutheria–Metatheria Theriimorpha–Australosphenida Galloanserae–Neoaves (Neognathae) Palaeognathae–Neognathae (Neornithes) Avemetatarsalia/Ornithodira–Crurotarsi Archosauromorpha–Lepidosauromorpha Sauropsida–Synapsida (Amniota) Reptiliomorpha–Batrachomorpha Sahelanthropus Proconsul Progonomys Heomys Heomys Tapocyon Tetraclaenodon Eotragus Mixtotherium Zhelestidae Zhelestidae Zhelestidae Phosphatherium Zhelestidae Pucadelphys Eomaia Phascolotherium Vegavis Vegavis Vjushkovisaurus Protorosaurus Hylonomus Lethiscus Maximum Age Constraint Youngest Recommended Oldest Recommended Date (MYA) Date (MYA) date (MYA) Date (MYA) 6.5 23.5 6 0.5 11.0 61.7 6 0.2 61.7 6 0.2 43 6 0.2 62.5 6 0.2 18.3 48.5 6 0.2 96.2 6 0.9 96.2 6 0.9 96.2 6 0.9 48.6 6 0.2 96.2 6 0.9 61.7 6 0.2 124.6 6 0.01 166.5 6 4.0 66 66 237 6 2.0 260.4 6 0.7 313.4 6 1.1 332.4 6 2.0 6.5 23.0 11.0 61.5 61.5 42.8 62.3 18.3 48.3 95.3 95.3 95.3 48.4 95.3 61.5 124.6 162.5 66 66 235 259.7 312.3 330.4 10 33.8 6 0.1 12.3 99.6 6 0.9 99.6 6 0.9 63.6 6 0.2 70.6 6 0.6 28.4 6 0.1 53.5 112 6 1 112 6 1 112 6 1 112 6 1 112 6 1 70.6 6 0.6 136.4 6 2.0 189.6 6 1.5 85.8 6 0.7 85.8 6 0.7 249.7 6 0.7 299 6 0.8 328.8 6 1.6 348 6 2.1 10 33.9 12.3 100.5 100.5 63.8 71.2 28.5 53.5 113 113 113 113 113 71.2 138.4 191.1 86.5 86.5 250.4 299.8 330.4 350.1 Evidence Biostratigraphy Biostratigraphy Magnetostratigraphy Biostratigraphy Biostratigraphy Bio/Magnetostraigraphy Bio/Magnetostratigraphy Biostratigraphy Biostratigraphy Biostratigraphy Biostratigraphy Biostratigraphy Biostratigraphy Biostratigraphy Biostratigraphy Direct date Biostratigraphy Biostratigraphy Biostratigraphy Biostratigraphy Biostratigraphy Biostratigraphy Biostratigraphy NOTE.—Branching points are indicated for key species, and their larger clade equivalences. The oldest and youngest dates are given, based on the literature, and on the Cambridge 2004 timescale (Gradstein et al. 2004). The youngest date is given for the minimum age constraint, and the oldest for the maximum age constraint, based on the date of the geological formation containing the age indicative fossil. The recommended dates are the youngest possible (i.e., minimum) date for the minimum constraint, and the oldest possible (i.e., maximum) for the maximum constraint. are poorly calibrated. Furthermore, molecular clock analy- ical evidence of one or more apomorphies of the clade in Usando o BEAST, estime o tempo de divergência entre: ses are rarely, if ever, framed around the availability of question. In all cases, the date is sought for branching bereliable calibration dates. Rather, they are characterized tween 2 extant species, and so we pursued each of the 2 by a) scientifically interesting questions and the availability lineages back to the point at which they shared their last Monodon/Lagenorhynchus of appropriate sequence data (Hedges and Kumar 2004). common ancestor, based on current phylogenetic evidence. b) Pontoporia/(Monodon, Lagenorhynchus) Together, these facts require that well-researched cali- Having 2 lineages meant, we could select the older of the 2 bration are available(Pontoporia, for the majority of available oldest fossils (table 1). c) dates Platanista/ (Monodon, Lagenorhynchus)) sequence data and, to this end, we provide detailed assessThe second step is to date the geological formation in d) Megaptera/ (Platanista, (Pontoporia, (Monodon, Lagenorhynchus))) ments of the paleontological data constraining the timing of which the oldest fossil, or fossils, occurs, or occur. The lineage splits between the main genomic models. identity of that geological formation is clear in all cases—earliestseu members of theirmão Zebrafish (ostariophysean) and Use como calibração a separação Homothecom grupo Pufferfish (euteleost) lineages, for example, both date from Minimum Constraints on Divergence Dates e a idade (Euarchontoglires/Lausiatheria) da raiz (Eutheria/Metatheria). the lithographic limestones of the Obere Solnhofener The indicated range of minimum branching dates Schichten of southern Germany. A geological formation (table 1) reflects both uncertainty in the dates (stratigraphic is a well-constrained succession of rocks with a clearly error) as well as the inferred duration of the fossiliferous marked base and top. In most cases, there is an extensive unit. Such a small range of dates, less than 1% in many biostratigraphic literature devoted to establishing the relacases, may seem startlingly low, but current geological tive age of the unit in question. For the Solnhofen lithotimescales (Gradstein et al. 2004) offer that level of preci- graphic limestones, ammonites and other fossils place sion. The quoted age range does not incorporate an estimate the unit in the lower Tithonian stage (zeta 2a zone) of the of uncertainty about whether the oldest fossil really belongs Upper Jurassic. That is a relative age, refined to a zonal level to the clade or about whether the clade might have origi- that may be less than 1 Myr in duration. Absolute chrononated much earlier. The date arose from a 2-step process: stratigraphic ages are then assigned by reference to the inter1) Which is the oldest relevant fossil within the clade in national standard, with precise ages established by question? 2) What is the best current age estimate for radiometric methods. The zeta 2a zone is part of the Hybothe geological formation that includes that fossil? niticeras hybonotum ammonite zone, the base of which coThe first step relied on our reading of current paleon- incides with the base of the normal-polarity Chron M22An tological data, and wide consultation on each date with rel- magnetozone that is dated at 150.8 MYA 6 0.1 Myr (Ogg evant experts. We excluded all uncertain or scrappy fossils, 2005); a minimum constraint on its age can be derived from the and retained only those for which there is definitive anatom- base of the succeeding, Semiformiceras darwini ammonite