Ричард Докинз - Рассказ предка

RENDEZVOUS 17 Although disputed by some palaeontologists , molecular and morphological data strongly support lissamphibian monophyly, and hint at order of branching shown here . Basal date from palaeontological evidence , others from maximum likelihood trees of mtDNA .

RENDEZVOUS 18 - 19 Phylogeny and dating from molecular and morphological/palaeontological studies.

RENDEZVOUS 20 Rendezvous date generally accepted . Ray-finned fish phylogeny is currently in a state of flux , although the traditional view followed here is broadly supported. Divergence dates based on fossil data . Some groups deliberately omitted for simplicity, as phylogeny not robust.

RENDEZVOUS 21 Phylogeny based on morphological data , Divergence dates based on fossil data .

RENDEZVOUS 22 Agnathan grouping based on genetic data which contradicts most fossil-based phylogenies (but these specialised groups show secondarily character lost, making morphological data difficult to use). Rendezvous date tightly constrained by fossil data . Lamprey-hagfish divergence time suggested by molecular maximum likelihood trees .

RENDEZVOUS 23 Molecular clock data places lancelet split close to basal deuterostome divergences here, estimated at 570 Mya according to medium-fuse dating of Cambrian Explosion (see the Velvet Worm's Tale).

RENDEZVOUS 24 Rendezvous date constrained by surrounding nodes. Possibly closer to ambulacrarians than to lancelets .

RENDEZVOUS 25 Ambulacrarian grouping and basal divergences from recent genetic data , assuming medium fuse Cambrian explosion. Genetic studies also give deep-branching Xenoturbellida , although exact placement not robust. Echinoderm phylogeny and dating from genetic, morphological, and fossil data .

RENDEZVOUS 26 Rendezvous date (about 590 Mya) from recent molecular clock studies , and broadly consistent with fossil data . Protostome phylogeny recently revised : here a single broad scheme has been followed , based on genetics and morphology. Three branches consist of several phyla grouped together. These are: Cephalorhyncha , Gnathifera (including Acanthocephala and Myzostomida), and Erachiozoa (phoronids and brachiopods). Edysozoan phylogeny relatively robust : main uncertainties are the onychophore/arthropod grouping and basal inclusion of chaetognaths, here placed according to morphological/genetic data , Many ecdysozoan dates constrained by 'small-shelly' onychophore fossils (see the Velvet Worm's Tale). Lophotrochozoa branching order much more uncertain: annelid/mollusc/sipunculid group robust , nemerteans probably sister to this , branching order of others unsure.

RENDEZVOUS 27 Phylogeny based on molecular data . These often weakly support a paraphyletic Acoela, but morphological data strongly supports acoelomorph monophyly: divergence date thus arbitrary. Rendezvous date based on genetic distance estimates . assuming protostome/deuterostome split of 590 Mya and bilaterian/cnidarian split of 700 Mya.

RENDEZVOUS 28 - 29 Order of branching of cnidarians and ctenophores is still uncertain . Certain molecular data weakly support the order used here . Within cnidarian phylogeny now conventional, dates from genetic studies calibrated to timescale used here.

RENDEZVOUS 30 Trichoplax placement unsure , but possibly near the base of the Metazoa .

RENDEZVOUS 31 Sponges generally interpreted as basal meta-zoans, although occasionally molecular data hint that they might be paraphyletic . Rendezvous date of 800 Mya based on molecular clock data , recalibrated using protostome-deuterostome divergence of 590 Mya; this conflicts with absence of fossilised sponge spicules before the latest Precambrian, although these may represent a derived character.

RENDEZVOUS 32 & 33 Rendezvous dates roughly estimated from molecular trees , assuming Rendezvous 31 at 800 and 34 at 1100 Mya. Position of Mesomycetozoea (Ichthyosporea) based on mtDNA sequences , rather than (less extensive) rRNA .

RENDEZVOUS 34 Rendezvous date of roughly 1100 Mya commonly argued (but may not be particularly robust). Revised molecular studies now place Microsporidia in Fungi , possibly at the base . Morphology and genetics place Ascomycota and Basidiomycota as closest relatives. rDNA additionally identifies Glomeromycota as sister to both , with previous 'zygomycetes' two (as shown here), or more paraphyletic branches. Divergence dates from molecular clock reseated to fit rendezvous date used here.

RENDEZVOUS 35 Grouping of most amoebas and slime moulds as sister group to Metazoa+Fungi has substantial molecular support , although unconventional rooting of the eukaryotic free may collapse Rendezvous 34, 35, 36, and 37 into one . Divergence date arbitrarily placed halfway between two surrounding nodes.

RENDEZVOUS 36 Ribosomal RNA data grouping plants with animals and fungi now recognised as erroneous . As explained in the text of Rendezvous 37, the position of the plants in the eukaryotic phylogeny is uncertain, and the scheme adopted here is somewhat arbitrary. Rendezvous date constrained by 1200 Mya fossils ; 1300 Mya broadly consistent with molecular clock studies (e.g. ). Within plants, phylogeny and relative dates from molecular data . although inclusion of red algae sometimes disputed .

RENDEZVOUS 37 Branching order and divergence dates of major eukaryote groups uncertain (hence polytomy shown). Ribosomal RNA studies erroneously place different groups as early branching lineages due to long branch attraction; amended frees only able to place eukaryotic branches far from the Archaea , implying much later divergence than Rendezvous 38: dates of Rendezvous 37-39 estimated to nearest 500 My.

RENDEZVOUS 38 Rendezvous date uncertain; molecular clock data suggests roughly 2 billion years ago . Divergence dates and (conventional) phylogeny estimated from rRNA studies .

RENDEZVOUS 39 Tree inherently difficult to root because there is no outgroup, and changes in mutation rate along different lineages obscure the 'centre' of the tree, It is often rooted between Archaea and Eubacteria (cross A), but other possibilities exist (cross B), , and so is presented unrooted. Changes in rooting will affect overall branch lengths, so these cannot truly represent time and are thus somewhat arbitrary. Eubacterial phylogeny based on robust biochemical characteristics (e.g. cell wall glycoproteins) and rare genomic events (e.g. indels) ; rRNA trees can have long branch attraction problems, but indicate that the divergences within the bacteria are deep . Bacterial DNA exchange problematic for building a single tree, unless a core of unswapped genes exists .

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