PowerPoint PresentationSlide 2Slide 3Slide 4Slide 5Slide 6Slide 7Slide 8Slide 9Slide 10Slide 11Slide 12Slide 13Slide 14Slide 15Slide 16Slide 17Slide 18Slide 19Slide 20Slide 21Slide 22Slide 23Slide 24Slide 25Slide 26Slide 27Slide 28What is an Animal?What is an Animal?3. Nervous tissue & muscle tissue1. Multicellular, heterotrophic eukaryotes that ingest food: (Metazoa).(Metazoa).4. Life history (mostly):diploid dominates, sexual w/ small flagellated sperm & large immobile egg cleavage, blastulation, gastrulation … Fig 32.12. Cells a) lack cell wallsb) supported by collagen (ch 7 & Fig 40.2)c) unique intercellular junctions: tight junctionsFig 7.30 desmosomes (except Porifera) gap junctions+. Glycogen: (Fig 5.6) carbohydrate store.http://ntri.tamuk.edu/cell/ribosomes.htmls = Svedberg units: the rate of sedimentation in a centrifuge, related to molecular weight and 3-D shape … varies across phyla. Fig 5.25Small SubUnit (SSU) & Large SubUnit (LSU) RNA(or DNA that codes it)are important character statesin molecular phylogenetics.the ‘outgroup’Evaluating hypotheses of basal animal phylogeny using complete sequences of large {LSU} and small {SSU} subunit rRNA.Medina et al. 2001. Proc. National Academy Of Sciences USA 98:9707-9712.Fig. 1. Comparison of ML SSU and LSU trees (A and B, respectively). ML bootstrap (100 replicates) values are shown at the nodes. < indicates bootstrap less than 50%. (Bar = 0.1 substitutions per site.) molluskechinodermurochordatechordateplatyhelminththe ‘outgroup’Similarbut notidenticalFig. 2. …strict consensus of two MP trees {Maximum Parsimony = most simple} based on combined SSU and LSU data. molluskechinodermurochordatechordateplatyhelminthThe text’ traditional’ phylogeny (Fig. 32.4), & SSU phylogeny (Fig. 32.8) closely correspond to the best consensus of ribosomal SSU & LSU data(note: Medina et al. 2001 didn’t look at all the phyla in Fig. 32.4) Fig. 32.8no - differentiated tissues - yes 1radial vs bilateral symmetry w/ cephalizationEchinoderms secondarily radial2‘Body Plans’Fig 32.8: the newmolecular phylogeny3blastopore mouth first anus first4exoskeletonLophophore on larvaeThe trigger of the Cambrian explosion(s) is still uncertain …Whether the burst was the result of an increase in oxygen, an ecological arms race or something else, the elaboration of Hox complexes {homeobox genes} may have been necessary … http://www.amsci.org/amsci/articles/97articles/Erwin-7.html the radiation {of animals} … through the Cambrian explosionCambrian explosion … a mere 40 million years. … the most extraordinary pace … in the fossil record, 3 explosions?Fig 32.14If compare Fig 32.1 (Ontogeny) to Fig 32.3 (Phylogeny - hypothetical), Ontogeny and Phylogeny is divided into two sections. The first is the history of the idea of recapitulation … In the second part Gould presents his own ideas on heterochrony …acceleration or retardation of different developmental processes (growth, sexual maturation, morphological changes, etc.), …Haeckel proposed this as a literal law, which it is not.But ‘scratch a myth and find a truth:’ The evolution of morphology involves the modification of basic developmental processes involving ancient HoxHox genes genes (Fig 21.15) and there are similarities in ontogeny across species. looks like ‘Ontogeny Recapitulates Phylogeny’‘Ontogeny Recapitulates Phylogeny’?… the common ancestor to fruit flies and mice had one gene …In Drosophila this gene has become three separate genes (gray, green, orange).These genes underwent further expansion, duplication and sequence modifications …in the mouse there are a greater number of related genes to control and direct the formation of an abdominal region ... Similar expansions and modifications can be seen in other Hox genes as one goes from more primitive to more advanced animals and body plans. … In the developing embryo, an animal's body plan emerges under the guidance of developmental control genes, including a cluster called the the HoxHox genes genes. Modifications in body plans arise from modifications - duplications and subsequent sequence changes- of developmental genes, such as those found in Hox clusters. ©American Scientist http://www.amsci.org/amsci/captions/captions97-03/Erwin-cap9.html?138,96 Fig 21.15http://129.137.140.39/freshman/bio103/diverse/camb/choanoflagellate.htmChoanoflagellates … The structure of the single cell resembles the feeding cells (choanocytes) of living sponges, often thought to be the most ancient living animals. C&R Fig 28.26Monophyletic origins of the metazoa: an evolutionary link with fungi.Wainright et al. Science 1993 Apr 16;260(5106):340-2http://megasun.bch.umontreal.ca/protists/salp/summary.html… comparisons of small subunit ribosomal RNA sequences describes the evolutionary origin and early branching patterns of the kingdom Animalia. From these data, it was inferred that animals and fungi share a unique evolutionary history animals and fungi share a unique evolutionary history and that their last common ancestor and that their last common ancestor was a flagellated protist similar to extant choanoflagellates.was a flagellated protist similar to extant choanoflagellates.Hsp70 sequences indicate that choanoflagellates are closely related to animals.Snell et al. 2001. Current Biology 11 (12): 967-970 JUN 26 2001 {Hsp = Heat shock proteins}Review: How was metazoan threshold crossed? The hypothetical Urmetazoa.Muller WEG. 2001. Comp Biochem & Physiology A -Molecular & Integrative Physiology 129:433-460.Abstract:… During the last few years, cDNAs/genes coding for informative proteins have been isolated and characterized from sponges, …The analyses of their deduced amino acid sequences allowed a molecular biological resolution of the monophyly of Metazoa. … classify the Porifera as true Metazoaclassify the Porifera as true Metazoa. …1http://www.amsci.org/amsci/articles/97articles/Erwin-3.htmlMorphological and molecular evidence agree that the most primitive of living animal phylathe most primitive of living animal phyla are the sponges (Phylum Porifera).are the sponges (Phylum Porifera). Sponges have only a few cell types differentiated to perform specialized functions, and they lack the sort of cell-to-cell junctions that form sheets of tissues in higher forms.