Vertebrate Phylogeny BIOL 252 AUGUST 23, 2018 DR. STACY FARINA Irisarri et al., Nat Ecol Evol. 2017 Sep; 1(9): 1370–1378. Cladogram (or Phylogeny) A B C D E F A hypothesis of evolutionary relationships represented as a tree Cladogram (or Phylogeny) tips nodes branches “Nodes” represent hypothetical common ancestors Cladogram (or Phylogeny) A B C D E F “Tips” can be individuals, species, or large groups of organisms Cladogram (or Phylogeny) Individual B Individual A Individual C Individual D Individual EIndividual F “Tips” can be individuals, species, or large groups of organisms Cladogram (or Phylogeny) Grey seal Harbor seal Weddell seal California sea lionSteller seaWalrus lion “Tips” can be individuals, species, or large groups of organisms Cladogram “Tips” can be individuals, (or species, or large groups Pinnipedia of organisms (seals & sea lions) Phylogeny) Musteloidea (weasels & otters) Ursidae (bears) Canis familiaris (domestic dog) Canis lupus (gray wolf) Vulpes vulpes (red fox) Cladogram “Tips” can be individuals, (or species, or large groups Pinnipedia of organisms (seals & sea lions) Phylogeny) Musteloidea (weasels & otters) Ursidae (bears) Canis familiaris (domestic dog) Canis lupus (gray wolf) NOTE: Vulpes vulpes using “Linnaean ranks” in this class. (red fox) We will not be A clade is a group of organisms that includes an ancestor and all descendants of that ancestor. A B C D E F A clade is a group of organisms that includes an ancestor and all descendants of that ancestor. A B C D E F How many clades are represented on this phylogeny? A clade is a group of organisms that includes an ancestor and all descendants of that ancestor. How many clades are represented on this phylogeny? Clades are monophyletic groups by definition. A monophyletic group includes an ancestor and all descendants of that ancestor. A B C D E F Paraphyletic ancestor and only some descendants. groups Seal are not clades. They include an Sea lion Dog Dolphin Whale Hippo Polyphyletic descendants but not all of their ancestors. groups Seal are not clades. They include some Sea lion Dog Dolphin Whale Hippo Nodes can be “rotated” or flipped and still show the same relationships. Seal Sea lion Dog Dolphin Whale Hippo Nodes can be “rotated” or flipped and still show the same relationships. Dog Seal Sea lion Dolphin Whale Hippo Nodes can be “rotated” or flipped and still show the same relationships. Seal Sea lion Dog Dolphin Whale Hippo Nodes can be “rotated” or flipped and still show the same relationships. Whale Dolphin Hippo Sea lion Seal Dog How are trees used to study anatomy? Convergent evolution evolution of wings Convergent evolution Convergent evolution Homoplasy: noun referring to an instance of convergent evolution Convergent evolution A trait is considered a homoplasy if the common ancestor did not have the trait. Homology Homology: noun referring to an instance of shared ancestry of a trait Homology A trait is considered homologous if it is present in the common ancestor. Homologous as… Convergent as… Homologous as… Convergent as… Homologous to… (same origin) Vestigial Structures A vestigial structure is “invisible” to natural selection (only impacted by drift or mutation) until it affects survival and reproduction. Loss of structures Ear flaps Seal Sea lionDog Dolphin Whale Hippo Stream-lined Stream-lined body shape body shape Seal Aquatic (good swimmers) Sea lion Dog Aquatic (good swimmers) Dolphin Whale Hippo About Linnaean ranks… Class: Aves Class: Reptilia Phylogenies are Hypotheses Synapomorphies • Synapomorphy: Shared, derived trait Where do we fit on the animal tree? DEUTEROSTOMES Vertebrates Tu n i c a t e s Lancelets Echinoderms + Acorn Worms DEUTEROSTOMES Echinoderms + Acorn Worms DEUTEROSTOMES Echinoderms + Acorn Worms DEUTEROSTOMES Chordata Vertebrates Tu n i c a t e s Lancelets DEUTEROSTOMES Chordata Lancelets DEUTEROSTOMES Chordata Tu n i c a t e s Chordata Vertebrates What makes a Tu n i c a t e s chordate? Lancelets Chordate Synapomorphies • Notochord Chordate Synapomorphies • Notochord • Dorsal hollow nerve cord Chordate Synapomorphies • Notochord • Dorsal hollow nerve cord • Pharyngeal gill slits Chordate Synapomorphies • Notochord • Dorsal hollow nerve cord • Pharyngeal gill slits • Subpharyngeal gland Chordate Synapomorphies • Notochord • Dorsal hollow nerve cord • Pharyngeal gill slits • Subpharyngeal gland • Post-anal tail • Notochord • Dorsal hollow nerve cord Vertebrates • Pharyngeal gill slits • Subpharyngeal gland • Post-anal tail What makes a Tu n i c a t e s chordate? Lancelets Larval tunicate: • Notochord • Dorsal hollow nerve cord Vertebrates • Pharyngeal gill slits • Subpharyngeal gland • Post-anal tail Tu n i c a t e s Lancelets *Synapomorphies can be present at any point in development PHYLOGENIES ARE HYPOTHESES Based on anatomical traits Based on DNA similarities (morphological data) (molecular data) Biologists believe that tunicates share a more recent common ancestor with vertebrates, based on molecular data. VERTEBRATES VERTEBRATES Vertebrates What makes a vertebrate? Archosauria Testudines Lepidosauria Mammalia Amphibia What makes a Dipnoi vertebrate? Coelacanthiformes Actinopterygii Chondrichthyes Petromyzontiformes Myxiniformes Urochordata Vertebrate Synapomorphies • Vertebral column Vertebrate Synapomorphies • Vertebral column • Skull - cartilage and/or bone Vertebrate Synapomorphies • Vertebral column • Skull - cartilage and/or bone • Enlarged brain (3-5 divisions) Vertebrate Synapomorphies • Vertebral column • Skull - cartilage and/or bone • Enlarged brain (3-5 divisions) • Neurogenic placodes Vertebrate Synapomorphies • Vertebral column • Skull - cartilage and/or bone • Enlarged brain (3-5 divisions) • Neurogenic placodes • Muscular, chambered heart Vertebrate Synapomorphies • Vertebral column • Skull - cartilage and/or bone • Enlarged brain (3-5 divisions) • Neurogenic placodes • Muscular, chambered heart • Semicircular canals (inner ear) Vertebrate Synapomorphies • Vertebral column • Skull - cartilage and/or bone • Enlarged brain (3-5 divisions) • Neurogenic placodes • Muscular, chambered heart • Semicircular canals (inner ear) • Complex sensory structures –Ears, paired eyes, nose • Specialized digestive organs –Stomach, intestine, liver, and pancreas, Archosauria Testudines Lepidosauria Mammalia Amphibia Dipnoi Coelacanthiformes Actinopterygii Chondrichthyes Petromyzontiformes Cyclostomata Myxiniformes Urochordata Cyclostomata: Living Jawless Fishes Hagfishes (Myxiniformes) Lamprey (Petromyzontiformes) Previous Hypothesis (No longer accepted) Hagfishes (Myxiniformes) Lamprey (Petromyzontiformes) Are hagfish vertebrates? When molecules guide morphological study… Ota et al., 2013. Identification of vertebra-like elements and their possible differentiation from sclerotomes in the hagfish. Nature Communications 2:373. When molecules guide morphological study… All species of hagfishes have mesenchymal precursors to cartilaginous vertebrae, even though most species don’t develop them Ota et al., 2013. Identification of vertebra-like elements and their possible differentiation from sclerotomes in the hagfish. Nature Communications 2:373. Hagfish and lamprey likely have lost vertebral elements Ota et al., 2013. Identification of vertebra- like elements and their possible differentiation from sclerotomes in the hagfish. Nature Communications 2:373. Myxiniformes – Hagfishes slime glands eye (reduced gill slits or missing) Hagfish tooth plates (Keratin) keratin tooth plates Hagfish at a whale fall Knotting Petromyzontiformes - Lamprey Lamprey oral disc with keratin teeth Keratin teeth; only in marine species Archosauria Testudines Lepidosauria Mammalia Amphibia Gnathostomes Dipnoi Jaws Coelacanthiformes Actinopterygii Chondrichthyes Petromyzontiformes Myxiniformes Urochordata JAWS GNATHOSTOMATA Gnatho = Jaws Stoma = Mouth Jaws Gnathostomes Placoderms† Ostracoderms† Myxiniformes Petromyzontiformes Evolution of Jaws Jaws allowed Archosauria vertebrates to Testudines capture large and diverse prey, Lepidosauria causing them to Mammalia grow large and diversify in diet. Amphibia Gnathostomes Dipnoi Jawed Vertebrates Jaws Coelacanthiformes (65,000+ species) Actinopterygii Chondrichthyes Petromyzontiformes Lamprey (42 species) Myxiniformes Hagfishes (81 species) Urochordata Gnathostome Synapomorphies • Jaws • Paired nasal openings Gnathostome Synapomorphies • Jaws • Paired nasal openings • Forelimbs and hindlimbs Gnathostome Synapomorphies • Jaws • Paired nasal openings • Forelimbs and hindlimbs • Teeth Archosauria Testudines Lepidosauria Mammalia Amphibia Chondrichthyes Dipnoi Chimeras, sharks, Coelacanthiformes skates, and rays Actinopterygii Chondrichthyes Petromyzontiformes Myxiniformes Urochordata Chondrichthyes Chimeras, sharks, skates, and rays Chondrichthyan synapomorphies • Cartilagenous skeleton Chondrichthyan synapomorphies • Cartilagenous skeleton • Tesselated cartilage Chondrichthyan synapomorphies • Cartilagenous skeleton • Tesselated cartilage Chondrichthyan synapomorphies • Cartilagenous skeleton • Tesselated cartilage • Placoid scales Chondrichthyan synapomorphies • Cartilagenous skeleton • Tesselated cartilage • Placoid scales • Pelvic claspers Holocephala (chimera) characteristics: Head clasper Single gill opening Elasmobranchii Synapomorphy: 5 gill openings.