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Animal Diversity: Introduction to Invertebrates & Vertebrates
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Animal Diversity 32. An Introduction to Animal Diversity 33. The Invertebrates 34. The Vertebrates Syllabus Biology (Brooker/Widmaier/Graham /Stiling, 4th ed., McGRAW- HILL Education) Animal Diversity 32. An Introduction to Animal Diversity Google image I. Characteristics of Animals II. History of Animal Life III. Animal Classification IV. Molecular Views of Animal Diversity 6 Table 32.1 Copyright © 2017 McGraw-Hill Education. All rights reserved. No reproduction or distribution without the prior written consent of McGraw-Hill Education. 7 Multicellularity Heterotrophs No cell walls Nervous tissue Movement Sexual reproduction Extracellular matrix Cell junctions Hox genes Similar rRNA Copyright © 2017 McGraw-Hill Education. All rights reserved. No reproduction or distribution without the prior written consent of McGraw-Hill Education. 8 • All animals are multicellular • Unique cell structure – No cell walls – An extensive extracellular matrix provides structural support – Unique cell junctions hold cells in place and facilitate communication among them • Anchoring, tight, and gap junctions Copyright © 2017 McGraw-Hill Education. All rights reserved. No reproduction or distribution without the prior written consent of McGraw-Hill Education. 9 (cellulose) (peptidoglycan) Google images 10 Extracellular Matrix (ECM) Copyright © 2017 McGraw-Hill Education. All rights reserved. No reproduction or distribution without the prior written consent of McGraw-Hill Education. 11 Extracellular Matrix (ECM) • Major macromolecules are proteins and polysaccharides – Proteins form large fibers – Polysaccharides give a gel-like character • Important roles – Strength and structural support – Tissue organization – Cell signaling Copyright © 2017 McGraw-Hill Education. All rights reserved. No reproduction or distribution without the prior written consent of McGraw-Hill Education. 12 Copyright © 2017 McGraw-Hill Education. All rights reserved. No reproduction or distribution without the prior written consent of McGraw-Hill Education. 13 Multicellularity Heterotrophs No cell walls Nervous tissue Movement Sexual reproduction Extracellular matrix Cell junctions Hox genes Similar rRNA Copyright © 2017 McGraw-Hill Education. All rights reserved. No reproduction or distribution without the prior written consent of McGraw-Hill Education. 14 Movement • Most have muscle and nerve cells organized into tissues – Muscle tissue is unique to animals • Most animals are capable of some kind of locomotion – Food acquisition – Escape from predators • Specialized sensory structures and nervous system to coordinate movement • Sessile species such as barnacles have moving appendages or a swimming larval stage Copyright © 2017 McGraw-Hill Education. All rights reserved. No reproduction or distribution without the prior written consent of McGraw-Hill Education. 15 sarcomere Google image 16 Multicellularity Heterotrophs No cell walls Nervous tissue Movement Sexual reproduction Extracellular matrix Cell junctions Hox genes Similar rRNA Copyright © 2017 McGraw-Hill Education. All rights reserved. No reproduction or distribution without the prior written consent of McGraw-Hill Education. 17 Sexual Selection • Nearly all animals reproduce sexually • Form of natural selection • Directed at certain traits of sexually reproducing species that make it more likely for individuals to find or choose a mate and/or engage in successful mating • In many species, affects male characteristics more intensely than it does female Google image Copyright © 2017 McGraw-Hill Education. All rights reserved. No reproduction or distribution without the prior written consent of McGraw-Hill Education. 18 Intersexual selection Birds of Paradise (https://www.youtube.com/watch?v=rX40mBb8bkU) Multicellularity Heterotrophs No cell walls Nervous tissue Movement Sexual reproduction Extracellular matrix Cell junctions Hox genes Similar rRNA Copyright © 2017 McGraw-Hill Education. All rights reserved. No reproduction or distribution without the prior written consent of McGraw-Hill Education. 20 Hox genes • Homeobox (Hox) genes are a family of transcription factors that determine the identity and positional information of cells along the anterior-posterior axis of an organism • Hox proteins ensure that the correct structures form in the correct places of the body • Hox gene complexity has been instrumental in the evolution and speciation of animals with different body patterns Copyright © 2017 McGraw-Hill Education. All rights reserved. No reproduction or distribution without the prior written consent of McGraw-Hill Education. 21 Copyright © 2017 McGraw-Hill Education. All rights reserved. No reproduction or distribution without the prior written consent of McGraw-Hill Education. 22 Mutation in the Antp gene Copyright © 2017 McGraw-Hill Education. All rights reserved. No reproduction or distribution without the prior written consent of McGraw-Hill Education. 23 Hox genes—cont’d • Relatively simple changes in the expression patterns of these genes can account for the large variation in arthropod appendage types • In vertebrates, shifts in patterns of expression in the embryo along the anteroposterior axis govern transition from one type of vertebra to another and short or long necks - Examples: Mice, chicken, goose, and snake neck length • Increases in the number of Hox genes may have led to greater complexity in body structure Copyright © 2017 McGraw-Hill Education. All rights reserved. No reproduction or distribution without the prior written consent of McGraw-Hill Education. 24 Figure 32.10 HoxC-6 gene expression and neck length. The transition between neck and truck vertebrate is controlled by the position of the HoxC-6 gene. Copyright © 2017 McGraw-Hill Education. All rights reserved. No reproduction or distribution without the prior written consent of McGraw-Hill Education. 25 Figure 25.15 Copyright © 2017 McGraw-Hill Education. All rights reserved. No reproduction or distribution without the prior written consent of McGraw-Hill Education. 26 Characteristics of Animals • • • • • • • • • • Multicellularity Heterotrophs No cell walls Nervous tissue Movement Sexual reproduction Extracellular matrix Cell junctions Hox genes Similar rRNA Copyright © 2017 McGraw-Hill Education. All rights reserved. No reproduction or distribution without the prior written consent of McGraw-Hill Education. 27 I. Characteristics of Animals II. History of Animal Life III. Animal Classification IV. Molecular Views of Animal Diversity 28 • Multicellular animals emerged at the end of the Proterozoic eon (over 590 mya) • First animals were invertebrates • A sudden increase in animal diversity occurred during the Cambrian explosion (533-525 mya) Eons: Proterozoic: 원생대; Paleozoic: 고생대; Mesozoic: 중생대; Cenozoic: 신생대 Copyright © 2017 McGraw-Hill Education. All rights reserved. No reproduction or distribution without the prior written consent of McGraw-Hill Education. 29 Animals evolved from a choanoflagellate-like ancestor • Closest living relative of animals are choanoflagellates – Single-celled protists • Have a single flagellum surrounded by a collar of cytoplasmic tentacles – Some are colonial – Some cells may have taken on specialized functions • Choanoflagellates bear a striking similarity to sponge choanocytes Copyright © 2017 McGraw-Hill Education. All rights reserved. No reproduction or distribution without the prior written consent of McGraw-Hill Education. 30 Figure 32.4 Copyright © 2017 McGraw-Hill Education. All rights reserved. No reproduction or distribution without the prior written consent of McGraw-Hill Education. 31 Cambrian "explosion" • All the modern phyla (sponges, jellyfish and corals, flatworms, molluscs, annelid worms, insects, echinoderms and chordates) appear in the fossil record relatively quickly in the geological time scale (millions of years). Copyright © 2017 McGraw-Hill Education. All rights reserved. No reproduction or distribution without the prior written consent of McGraw-Hill Education. 32 Google image Copyright © 2017 McGraw-Hill Education. All rights reserved. No reproduction or distribution without the prior written consent of McGraw-Hill Education. 33 Cambrian explosion • Favorable environment - warm temperatures, increases in atmospheric and aquatic oxygen (support a higher metabolic rate), changes in ocean chemistry (e.g., development of hard body parts such as supporting skeletons based on calcium carbonate ), development of ozone layer, etc. • Evolution of the Hox gene complex • An evolutionary “arms race” *likely exaggerated due to the proliferation of hard-bodied animals that fossilized much more readily than their soft-bodied precursors Colonisation of the Land • Animals (arthropods) may have ventured onto land early in the Cambrian. They probably didn't live on land, instead coming ashore to mate or evade predators. At this time the only land plants appear to have resembled mosses . • In the Silurian period (440 - 410 mya) some groups of plants and animals (arthropods first) colonised the land for the first time, probably as the result of competition in the marine ecosystems, plus the opportunity to escape predators and the availability of new terrestrial niches. https://sci.waikato.ac.nz/evolution/AnimalEvolution.shtml Google image Problems encountered in the land • Early land animals, like plants, had to solve the following problems: water conservation, gas exchange, reproduction and dispersal, and the fact that water no longer buoyed them up against the pull of gravity. • Like plants, animals evolved waterproof external layers, internal gas exchange systems, ways of reproducing that did not involve water, and strong support systems (endoskeletons and exoskeletons) that allowed them to move about on land. https://sci.waikato.ac.nz/evolution/AnimalEvolution.shtml Early Reptiles and Amniotic Eggs • As one of the greatest evolutionary innovations, the amniotic egg (~320 mya) allowed early reptiles to reproduce on land by preventing the embryo inside from drying out, so eggs could be laid away from the water. 양막 양수 Google image https://sci.waikato.ac.nz/evolution/AnimalEvolution.shtml Appearance of Modern Mammals • The mass extinction at the end of the Cretaceous period, 65 million years ago, wiped out the dinosaurs along with every other land animal that weighed much more than 25 kg. This cleared the way for the expansion of the mammals on land. • This unique situation was the starting point for the great evolutionary diversification of the mammals, which up until then had been nocturnal animals with the size of small rodents. By the end of the Palaeocene epoch (65 - 55.5 mya), mammals occupied many of the vacant ecological niches. https://sci.waikato.ac.nz/evolution/AnimalEvolution.shtml Google image I. Characteristics of Animals II. History of Animal Life III. Animal Classification IV. Molecular Views of Animal Diversity 42 척삭동물 극피동물 절지동물 선형동물 환형동물 연체동물 완족동물 태형동물 윤형동물 편형동물 자포동물, 유즐동물 Phylum (n = ~35) 해면동물 Figure 32.3 탈피 Superphylum 선구(전구)발생 Infrakingdom/ Branch Subkingdom (Diploblastic) 방사대칭 측색동물 Eumetazoa (진정후생물) 좌우대칭 (triploblastic) 후구발생 Copyright © 2017 McGraw-Hill Education. All rights reserved. No reproduction or distribution without the prior written consent of McGraw-Hill Education. 43 Traditional classification based on body plans • Morphological and developmental features traditionally used to classify animals: 1. Presence or absence of different tissue types 2. Type of body symmetry 3. Specific features of embryonic development Copyright © 2017 McGraw-Hill Education. All rights reserved. No reproduction or distribution without the prior written consent of McGraw-Hill Education. 44 Tissues • Metazoa – all animals – Divided based on whether they have specialized tissues (groups of cells with a similar structure and the same origin that act together to perform a specific function) – Parazoa (without specialized tissues or organs) • • Porifera – sponges May have distinct cell types – Eumetazoa (more than one type of tissue and organs) • All other animals Copyright © 2017 McGraw-Hill Education. All rights reserved. No reproduction or distribution without the prior written consent of McGraw-Hill Education. 45 Symmetry • Eumetazoa divided by symmetry • Radiata (radially symmetric) – Can be divided equally by any longitudinal plane through the central axis – Often circular or tubular in shape, with a mouth at one end • Bilateria (bilaterally symmetric) – Can be divided along a vertical plane to produce two halves – Have cephalization and dorsal and ventral sides – Have anterior and posterior ends Copyright © 2017 McGraw-Hill Education. All rights reserved. No reproduction or distribution without the prior written consent of McGraw-Hill Education. 46 Figure 32.5 Copyright © 2017 McGraw-Hill Education. All rights reserved. No reproduction or distribution without the prior written consent of McGraw-Hill Education. 47 Germ layers • Radiata and Bilateria differ in number of embryonic cell layers (germ layers) – Radiata have 2 layers (diploblastic) – Bilateria have 3 layers (triploblastic) • Cell layers develop during gastrulation – Inner layer – endoderm – Outer layer – ectoderm – Mesoderm - 3rd layer in bilateral animals • Forms muscles and most other organs Copyright © 2017 McGraw-Hill Education. All rights reserved. No reproduction or distribution without the prior written consent of McGraw-Hill Education. 48 Figure 32.6 Copyright © 2017 McGraw-Hill Education. All rights reserved. No reproduction or distribution without the prior written consent of McGraw-Hill Education. 49 척삭동물 극피동물 절지동물 선형동물 환형동물 연체동물 완족동물 태형동물 윤형동물 편형동물 자포동물, 유즐동물 Phylum (n = ~35) 해면동물 Figure 32.3 탈피 Superphylum 선구(전구)발생 Infrakingdom/ Branch Subkingdom (Diploblastic) 방사대칭 측색동물 Eumetazoa (진정후생물) 좌우대칭 (triploblastic) 후구발생 Copyright © 2017 McGraw-Hill Education. All rights reserved. No reproduction or distribution without the prior written consent of McGraw-Hill Education. 50 Embryonic development • Protostome – Blastopore becomes mouth – Cleavage is determinate • Fate of embryonic cells is determined early – Often exhibit spiral cleavage • Deuterostome – Blastopore becomes anus – Cleavage is indeterminate • Each cell produced by early cleavage can develop into a complete embryo – Radial cleavage Copyright © 2017 McGraw-Hill Education. All rights reserved. No reproduction or distribution without the prior written consent of McGraw-Hill Education. 51 Figure 32.7 Copyright © 2017 McGraw-Hill Education. All rights reserved. No reproduction or distribution without the prior written consent of McGraw-Hill Education. Jump to long image description 52 Other morphological characteristics used in classification • In the past, presence or absence of a coelom or body segmentation was used in construction of phylogenies • Molecular data suggest these features are unreliable in terms of understanding evolutionary history, but continue to be useful in describing differences in animal structure Copyright © 2017 McGraw-Hill Education. All rights reserved. No reproduction or distribution without the prior written consent of McGraw-Hill Education. 53 I. Characteristics of Animals II. History of Animal Life III. Animal Classification IV. Molecular Views of Animal Diversity 54 • Scientists now use molecular techniques to classify animals – Compare similarities in DNA, RNA, and amino acid sequences – Closely related organisms have fewer differences than those more distantly related • Advantage over morphological data in that genetic sequences are easier to quantify and compare – Example: A,T,G, and C of DNA – Morphological data are more subjective Copyright © 2017 McGraw-Hill Education. All rights reserved. No reproduction or distribution without the prior written consent of McGraw-Hill Education. 55 Genes used in molecular systematics • Studies often focus on the gene for small subunit ribosomal RNA (SSU rRNA) – Universal in all organisms – Changes slowly over time • Hox genes also often studied – Found in all animals – Duplications in these genes may have led to evolution of complex body forms • Phylogenies constructed using SSU rRNA and Hox genes are similar and often agree with those based on morphology Copyright © 2017 McGraw-Hill Education. All rights reserved. No reproduction or distribution without the prior written consent of McGraw-Hill Education. 56 Figure 32.11 Comparison of small subunit rRNA gene sequences from three animals and a protist. Copyright © 2017 McGraw-Hill Education. All rights reserved. No reproduction or distribution without the prior written consent of McGraw-Hill Education. 57 Difference between molecular and traditional phylogenies • Two new invertebrate clades: – Ecdysozoa • • • Nematodes, Arthropods, and a few other minor phyla Named for ecdysis (molting) Members secrete an exoskeleton that must be shed and regrown as the animal increases in size – Lophotrochozoa • • • Mollusks, Annelids, and several other phyla Named for the lophophore (feeding tentacles) and trochophore larva Some members have neither of these features (e.g., platyhelminthes), so classified strictly based on molecular data Copyright © 2017 McGraw-Hill Education. All rights reserved. No reproduction or distribution without the prior written consent of McGraw-Hill Education. 58 Aguinaldo et al. 1997 Nature “Evidence for a clade of nematodes, arthropods and other moulting animals” Ecdysozoa Lophotrochozoa Copyright © 2017 McGraw-Hill Education. All rights reserved. No reproduction or distribution without the prior written consent of McGraw-Hill Education. 59 척삭동물 극피동물 절지동물 선형동물 환형동물 연체동물 완족동물 태형동물 윤형동물 편형동물 자포동물, 유즐동물 Phylum (n = ~35) 해면동물 Figure 32.3 탈피 Superphylum 선구(전구)발생 Infrakingdom/ Branch Subkingdom (Diploblastic) 방사대칭 측색동물 Eumetazoa (진정후생물) 좌우대칭 (triploblastic) 후구발생 Copyright © 2017 McGraw-Hill Education. All rights reserved. No reproduction or distribution without the prior written consent of McGraw-Hill Education. 60
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