Topic 13 - The Evolution of Animals II PDF

Topic 13 The evolution of animals II Learning Outcomes Define key characteristics of invertebrates Classify invertebrate organisms into clades based on embryological or anatomical characteristics Place the evolution of body symmetry and the embryological formation of the mouth on a phy...

Topic 13 The evolution of animals II Learning Outcomes Define key characteristics of invertebrates Classify invertebrate organisms into clades based on embryological or anatomical characteristics Place the evolution of body symmetry and the embryological formation of the mouth on a phylogeny Justify the importance of the notochord in the evolution of vertebrates Organize the key innovations of vertebrates on a phylogeny Associate key innovations of vertebrates with the names of the clades they define Describe how gill arches and rods have evolved in vertebrates Explain how specific structures found in the early tetrapods allowed vertebrates to colonize land Organize the key innovations of tetrapods on a phylogeny Associate key innovations of tetrapods with the names of the clades they define Classify adaptations based on the physical or chemical challenges faced by tetrapods on land Define and identify exaptations 2 https://www.wooclap.com/BIO1130 3  Topic 13 The evolution of animals II 13.1 – Invertebrates Animal phylogeny Protostomia 5 Invertebrates s f orm a r at e Inverteb tic group! le paraphy Invertebrates = absence of backbone (spine) 95% of all known animal species (1M insect species)! Many ancestral traits were lost Chordates (and vertebrates) evolved from deuterostome invertebrates Protostomia Porifera (sponges) Diploblastic Radial symmetry Sessile No true tissues Protostomia Ctenophora Diploblastic Radial symmetry Multiple layers of cells (tissues): a sensory epidermis networked nervous system. Protostomia Ctenophora Ctenophora Diploblastic Radial symmetry Multiple layers of cells (tissues): a sensory epidermis networked nervous system. Protostomia Cnidaria Diploblastic Radial symmetry Sessile polyp and swimming medusa Hydrostatic skeleton (gastrovascular cavity contraction). Protostomia Bilateria Bilateral symmetry evolved at the same time as triploblasty (mesoderm): 670Mya Acoela and platyhelminthes: Lost their body cavity (coelome) Protostomia Do not have a digestive tract Ecdysozoa Protostome animals that produce an exoskeleton (cuticle) periodically molted (ecdysis) à Compensating the increase of body size Arthropods show a very rigid exoskeleton made of protein and chitin and that is segmented into functional units Presence of ganglions (clustered of nerve cell bodies) Protostomia Caenorhabditis elegans Lamprima aurata Latrodectus hesperus Lophotrochozoa Helix pomatia Lumbricus terrestris Dugesia subtentaculata Protostome animals possess either: Lophophore: crown of ciliated tentacles around the mouth (feeding) Trochophore: specific larval stage Protostomia Echinodermata Bilateral symmetry Deuterostome (evidence from larval embryological data) Water circulatory system (ambulatory system) à nutrition, respiration, locomotion and excretion Protostomia  Topic 13 The evolution of animals II 13.2 – The notochord Chordata (530Mya) Chordates possess: A notochord: longitudinal flexible rod (mesoderm, anterior-posterior axis) Muscles attach to the notochord (locomotion) Dorsal nerve chord (ectoderm) Pharyngeal slits behind the mouth (filtration during feeding, gas exchange and bones of the skull) A post-anal tail with a skeleton and muscles Protostomia  Cyclostomes Chordata Cephalochordates Feeding through filtration in the pharynx. Lateral movement for locomotion Cyclostomes Lancelet Cephalochordates Feeding through filtration in the pharynx. Lateral movement for locomotion Cyclostomes Lancelet Urochordates Vertebrates may have evolved through paedomorphosis: à retention in an adult of juvenile features of its ancestors à larvae evolved the ability to reproduce before metamorphosis Cyclostomes à loss of 4 hox genes Vertebrates Skeletal system formed by a vertebral column (spinal cord = backbone) à Muscle attachment, protection of dorsal nerve tube à Solidification (cartilage or bone) of vertebrae à Duplication of hox genes Cyclostomes 21 Cyclostomes (vertebrates without jaws) No jaws à circular mouth Lampreys can be parasites of fishes. Cartilaginous skeleton without collagen Cyclostomes Gnathostomes (vertebrates with jaws) Modification of 2 skeletal rods (gill arches) Mandibular arch à jaws Hyoid arch à support structures Cyclostomes Anterior gill slits (suspension feeding à gas exchange) Mineralization of the skeleton Duplication of Hox genes à more complex body plans Chondrichthyes (cartilaginous fish) Skeleton made of cartilage: flexible and elastic connective tissue made of collagenous fibers Cartilaginous fish have placoid scales. Cyclostomes à homologous to vertebrate teeth (dentine + enamel) Homology = similarity due to shared ancestry Chondrichthyes (cartilaginous fish) Internal fertilization with 3 modes or reproduction: Oviparous: egg laying and external hatching Ovoviviparous: embryo feeds from the egg’s yolk, then hatches in the uterus Cyclostomes Viviparous: embryo feeds from the mother through the placenta and until birth Claspers for sperm transfer Osteichthyes (bony fish) Bones made of calcium phosphate Dorsal swim bladder filled with gas (flotation) Early osteichthyes had lungs Cyclostomes Most bony fish are oviparous Osteichthyes Ray-finned bony fish (Actinopterygii): à fins do not have an internal skeleton à rays project from basal bones Cyclostomes Osteichthyes Lobed-finned bony fish (Sarcopterygii): à internal skeleton to which muscles attach à Early lobed-finned bony fish lived in coastal wetlands and may have been able to “walk” on the substrate. Cyclostomes Cubitus Radius Osteichthyes Lobed-finned bony fish (Sarcopterygii): à internal skeleton to which muscles attach à Early lobed-finned bony fish lived in coastal wetlands and may have been able to “walk” on the substrate. Cyclostomes Dipnoi (lungfish) Functional lungs homologous to tetrapod lungs Also possess gills Can crawl in the mud (long pectoral fins) Resistance to dryness (burrowing in mud – torpor) Cyclostomes Dipnoi (lungfish) Functional lungs homologous to tetrapod lungs Also possess gills Can crawl in the mud (long pectoral fins) Resistance to dryness (burrowing in mud – torpor) Cyclostomes  Topic 13 The evolution of animals II 13.3 – Colonization on land by vertebrates Tetrapods Acanthostega Tetrapods = “Four limbs” with digits New land niches (all of the biotic and abiotic resources used by a species): à plants, insects, new ranges in temperature, humidity, Cyclostomes protection against predators, less competition, etc. Adaptations leading to colonization of land: Support of the body against gravity Breathing in the air Hearing in the air Resistance against dry environments Vascular system with lungs and organs Tetrapods Tiktaalik (“Large freshwater fish” in Inuktitut): fossil of a lobe-finned fish with both fish and tetrapod traits. Tiktaalik roseae (375Mya) Amphibians Urodela Anura Apoda Amphibian (“double life”): 1. Aquatic larval stage (gills, lateral line) herbivorous Cyclostomes 2. Metamorphosis (loss of tail, formation of legs) 3. Terrestrial predator adult stage Amniotes Air insulation (during the embryo development) and ventilation (thoracic cage in adults) 4 embryonic membranes: Chorion: outer-membrane (gas- exchange) Amnion: surrounds the cavity (mechanic protection) Cyclostomes Allantois: surrounds the disposal sac (metabolic wastes) Yolk sac: stock of nutrients Reptiles Dry skin with scales containing keratin à protection from desiccation Ectothermic (except birds) à behavioral adaptations to control body temperature Improved locomotion capacity (walking, running, flying) Birds Paleontological, embryological and genetic data show that birds are reptiles and are also bipedal dinosaurs. Feathers were first used for temperature regulation, courtship, protection, camouflage... …but later became an exaptation (opportunistic adaptation used for a new function, not initially selected for). Adaptations to flight: no bladder os aurs a re Din extinct! only one ovary not small gonads high metabolic rate absence of teeth light skull and skeleton wings and feathers Archaeopteryx (animal the closest to birds) Mammals Moose Kangaroo rat Mammary glands and production of milk (source of proteins, carbohydrates, lipids, minerals, vitamins, etc.) Endothermy Larger forebrain with ability to learn Differentiated teeth with specific functions Cyclostomes Hair and fat layer under the skin (insulation) Kidneys (excretion of metabolic waste, water retention) Primates Opposable thumb (adaptation for grasping) Large brain and short jaw Parental care and social behaviors Tree-dwelling animals (hand-eye coordination) Overlapping visual fields (orbits located at the front of the skull) à binocular vision (depth perception) Hominids: Primates Chimp Gorilla Human Orangutan Opposable thumb (adaptation for grasping) Large brain and short jaw Parental care and social behaviors Tree-dwelling animals (hand-eye coordination) Overlapping visual fields (orbits located at the front of the skull) à binocular vision (depth perception) Hominids: Karyotype: human (2n = 46) and chimpanzee (2n = 48) à 2 ancestral chromosomes fused to form the chromosome 2 in human Humans First hominins (sub-family of hominidae): ~6.5Mya Bipedal (walk on two legs) Reduced jaw bones Short digestive tract Language, complex and symbolic thought, artistic expression, manufacture of complex tools 99% of the human genome is identical to the chimpanzee à differences in the expression of 19 regulatory genes with large effects First representant of the Homo genus: ~2.5Mya (Homo habilis) Stone age tools (-3.4Ma) Ardipithecus ramidus (4.4Mya) found in Ethiopia Humans First hominins (sub-family of hominidae): ~6.5Mya Bipedal (walk on two legs) Reduced jaw bones Short digestive tract Chauvet Cave (37,000ya) Language, complex and symbolic thought, artistic expression, manufacture of complex tools H. neanderthalensis and H. sapiens (Sawyer and Maley - 2005) 99% of the human genome is identical to the chimpanzee à differences in the expression of 19 regulatory genes with large effects First representant of the Homo genus: ~2.5Mya (Homo habilis) Homo neanderthalensis (350,000ya) the closest relative species to Homo sapiens (share a common ancestor). à Some limited gene flow occurred between them.