330-Notes - Summary Vertebrate Biology (Concordia University) PDF

lOMoARcPSD|11130845 330-Notes - Summary Vertebrate Biology Vertebrate Biology (Concordia University) Scan to open on Studocu Studocu is not sponsored or endorsed by any college or university Downloaded by Wenj...

lOMoARcPSD|11130845 330-Notes - Summary Vertebrate Biology Vertebrate Biology (Concordia University) Scan to open on Studocu Studocu is not sponsored or endorsed by any college or university Downloaded by Wenjay Delavin ([email protected])  lOMoARcPSD|11130845 Lecture 1: Diversity, Classi昀椀ca琀椀on, and Evolu琀椀on of Vertebrates ◦ Climate Change and Invasive Species ◦ There are over 70,000 extant species of vertebrates. ◦ Vertebrates inhabit a wide range of habitats and display an incredible size range from 0.1g to 100,000kg. ◦ They exhibit a variety of feeding, social, and reproduc琀椀ve behaviors, as well as parental and non- parental care. ◦ The rich diversity within some species is a product of 500 million years of evolu琀椀on. ◦ Species diversity peaked in the mid-Miocene (between 14 and 12 million years ago) and has been declining since. Major Groups: Non-amniotes ◦ Non-amniotes lack the amnio琀椀c egg and have embryos enclosed by maternally produced membranes. ◦ This group includes jawed 昀椀shes, jawless 昀椀shes, and amphibians. Major Groups: Amniotes ◦ Amniotes contain an amnio琀椀c egg and embryos with three membranes that come from the embryos themselves. ◦ This group includes sauropsids (turtles, lizards, snakes, alligators, crocodiles, birds) and synapsids (mammals with placentas). Vertebrate Life Begins ◦ Vertebrate life is contextualized within geologic 琀椀me, shaped by con琀椀nental movements over geological 琀椀me scales. ◦ Con琀椀nental shi昀琀s resulted in global climate changes that in昀氀uenced the evolu琀椀on of vertebrate species adapted to speci昀椀c environmental condi琀椀ons. ◦ During the Paleozoic, terrestrial vertebrates evolved and spread in tropical regions, as much of Pangaea was located on the equator. ◦ By the middle of the Cenozoic, most of the terrestrial climates in the higher la琀椀tudes of the Northern and Southern hemisphere were temperate rather than tropical, leading to di昀昀erent trajectories in vertebrate evolu琀椀on. Learning Objec琀椀ves ◦ Appreciate the diversity of vertebrates and its rela琀椀onship to Earth history. ◦ Understand the history and u琀椀lity of binomial nomenclature. ◦ Understand terms used to describe the organiza琀椀on of phylogene琀椀c trees and construct a simple, phylogene琀椀c tree. Binomial Nomenclature ◦ Scien琀椀昀椀c naming of species became standardized with the publica琀椀on of Carolus Linnaeus's monumental work, "Systema Naturae", in 1758. Downloaded by Wenjay Delavin ([email protected])  lOMoARcPSD|11130845 ◦ Species are given two names, a genus name and a species name, based mainly on anatomical features. ◦ The goals of scien琀椀昀椀c naming of species include uniqueness, universality, and stability. ◦ Species names are changed regularly for reasons such as taxonomic revisions and the principle of priority. Vertebrate Classi昀椀ca琀椀on ◦ Phylogene琀椀c systema琀椀cs is a method of classifying organisms based on shared ancestry, using morphological, molecular, and behavioral data. ◦ Cladis琀椀cs is a speci昀椀c method within phylogene琀椀c systema琀椀cs that emphasizes monophyly and parsimony. ◦ Phylogene琀椀c systema琀椀cs assumes that all living organisms share a common ancestor and represents the history of life as a branching tree. Phylogene琀椀c Trees and Cladis琀椀cs ◦ A phylogene琀椀c tree or cladogram represents the evolu琀椀onary rela琀椀onships among taxa. ◦ Clades are groups of organisms that have a single evolu琀椀onary origin and include all descendants and its common ancestor. ◦ Homoplasy, convergent evolu琀椀on, and parallel evolu琀椀on present challenges to determining phylogene琀椀c rela琀椀onships. Principle of Parsimony ◦ The principle of parsimony states that the most plausible phylogeny is the one requiring the fewest number of changes in structure. ◦ Ancestral and derived traits are used to determine shared derived characters and the most parsimonious evolu琀椀onary rela琀椀onships. Taxonomic Rela琀椀onships and Phylogenies ◦ Phylogenies are hypotheses that can be falsi昀椀ed as new data comes in. ◦ Vertebrate phylogeny reconstruc琀椀on is a con琀椀nual process that allows for the formula琀椀on of hypotheses about the sequence of evolu琀椀on of vertebrates. ◦ Fossils and evolu琀椀onary hypotheses are used to understand the evolu琀椀on of vertebrates and their traits. Lecture 2: Shared Traits and Subphyla of Chordates Metazoa and Phylum Chordata ◦ Metazoa is the animal kingdom containing more than 30 phyla, including chordata ◦ Chordates are established in rela琀椀on to other phyla by anatomical, physiological, biochemical, and developmental characters ◦ Sponges are the most basal metazoan Synapomorphies and Other Shared Features ◦ Synapomorphies of Phylum Chordata include notochord, dorsal hollow neural tube, segmented postanal tail, and endostyle ◦ Other shared features include pharynx, bilateral symmetry, and le昀琀-to-right symmetry Downloaded by Wenjay Delavin ([email protected])  lOMoARcPSD|11130845 Three Subphyla of Chordata ◦ Vertebrates, Urochordates (tunicates), and Cephalochordates (lancelets) are the three subphyla of chordates ◦ Urochordates are 昀椀lter-feeding, free-swimming larvae with sedentary adults ◦ Cephalochordates exhibit 昀椀sh-like locomo琀椀on, respira琀椀on through the skin, and shared features with vertebrates Dis琀椀nguishing Features of Vertebrates De昀椀ni琀椀on and Other Features ◦ Vertebrates are animals with vertebrae forming a spinal column ◦ Other dis琀椀nguishing features include cranium, prominent head with complex sense organs, neural crest, large brains, complex endocrine organs, muscularized gut tube, mul琀椀chambered heart, mineralized 琀椀ssues, and gills derived from endoderm Jawless Fishes and Other Dis琀椀nguishing Features ◦ Jawless 昀椀shes lack true vertebrae, and some jawed 昀椀shes retain the notochord as adults ◦ Other dis琀椀nguishing features include the absence of true vertebrae in jawless 昀椀shes and the reten琀椀on of notochord in some jawed 昀椀shes Embryonic Development and Vertebrate Body Embryonic Germ Layers ◦ Vertebrate bodies form from ectoderm, endoderm, and mesoderm ◦ Ectoderm forms skin, nervous system; endoderm forms diges琀椀ve tract lining, glands; mesoderm forms muscles, skeleton, circulatory and urogenital systems Subdivisions of the Coelom ◦ The coelom becomes subdivided in vertebrates and di昀昀ers across them ◦ Subdivisions include rela琀椀vely simple in sharks, area around the lungs in salamanders, and paired pleural recesses in cats Development of Mesoderm and Pharyngeal Region ◦ Mesoderm is divided into somi琀椀c, intermediate, and lateral plate mesoderm ◦ Pharyngula includes internal skeletal components, associated muscles, nerves, and blood vessels Development of the Brain ◦ The brain receives input from various senses and coordinates motor ac琀椀vi琀椀es ◦ It is associated with the olfactory system and becomes an integra琀椀ve and associa琀椀ve area- Forebrain ◦ Input from balance, hearing, taste and touch. Coordinates outgoing voluntary and involuntary motor ac琀椀vi琀椀es- Hindbrain ◦ Info from the eyes are projected-Midbrain Adult Tissue Types and Organ Systems Tissue Types Downloaded by Wenjay Delavin ([email protected])  lOMoARcPSD|11130845 ◦ Vertebrate adult 琀椀ssue types include epithelial, muscular, neural, and connec琀椀ve 琀椀ssue ◦ Mineralized connec琀椀ve 琀椀ssue is composed of cells that secrete a proteinaceous 琀椀ssue matrix made up of collagen and calcium hydroxyapa琀椀te crystals Organ Systems and Cranial Skeleton ◦ Vertebrate organ systems include the cardiovascular system, excretory system, and reproduc琀椀ve system ◦ The cranial skeleton protects the brain, anchors teeth, and provides a琀琀achment sites for muscles Cardiovascular System and Excretory/Reproduc琀椀ve Systems ◦ The cardiovascular system moves oxygen and nutrients through closed circulatory system ◦ The excretory system disposes waste products and regulates body's minerals and water, while the reproduc琀椀ve system involves gametes and specialized Lecture 3: Early Vertebrates Conspicuous Features of Early Vertebrates ◦ Dis琀椀nct head end with tripar琀椀te brain, cranium, and complex sense organs ◦ Pharyngeal muscles used in respira琀椀on rather than 昀椀lter feeding ◦ External armor (mineralized 琀椀ssues) for ac琀椀ve preda琀椀on Evidence of Early Vertebrates ◦ Earliest vertebrate fossils found during the Cambrian, approximately 525 million years ago ◦ Examples include Haikouichthys (Myllokunmingia) and torpedo-shaped arandaspids from the Late Ordovivian ◦ Conodont elements, thought to be early vertebrates, with doubts remaining Mineralized Tissues in Early Vertebrates ◦ Some early vertebrates had mineralized 琀椀ssues, while others like Cambrian vertebrates and extant cyclostomes did not ◦ Mineralized 琀椀ssues composed of hydroxyapa琀椀te represented a major evolu琀椀onary advance ◦ Possible original selec琀椀ve advantages of mineralized 琀椀ssues include protec琀椀on from predators and storage/regula琀椀on of phosphorus and calcium Marine Origin of Vertebrates ◦ Paleontological evidence indicates earliest vertebrate fossils are from marine sediments ◦ Compara琀椀ve physiological evidence suggests marine origin based on body 昀氀uid osmolal concentra琀椀on ◦ Hag昀椀shes, as early vertebrates, have concentrated body 昀氀uids like surrounding seawater Extant Jawless Fishes: Hag昀椀shes and Lampreys ◦ Hag昀椀shes lack jaws, paired 昀椀ns, specialized reproduc琀椀ve ducts, and mineralized 琀椀ssues Downloaded by Wenjay Delavin ([email protected])  lOMoARcPSD|11130845 ◦ Lampreys have car琀椀laginous vertebral structures, large complex eyes, and two semi-circular canals ◦ Key features of cyclostoma include a single median nostril, unar琀椀culated gill arch skeleton, and a tongue with kera琀椀nous teeth Hag昀椀shes ◦ Primi琀椀ve Features of Hag昀椀shes ◦ Lack of vertebrae, image-forming eyes, lateral line system, and electrorecep琀椀on ◦ Body 昀氀uids have the same concentra琀椀on as seawater ◦ Possess slime glands for predator deterrent and unique reproduc琀椀ve characteris琀椀cs Hag昀椀sh Behavior and Characteris琀椀cs ◦ Elongated, scaleless, deep-sea inhabitants with unique foraging and ven琀椀la琀椀on methods ◦ Secrete large quan琀椀琀椀es of mucus and proteinaceous threads as a predator deterrent ◦ Approximately 75 species, all marine with nearly worldwide distribu琀椀on Lampreys Di昀昀erences from Hag昀椀shes ◦ Possession of car琀椀laginous vertebral structures, large complex eyes, and two semi-circular canals ◦ Adult parasi琀椀c lampreys use 琀椀dal ven琀椀la琀椀on for respira琀椀on ◦ Life cycle involves parasi琀椀c and nonfeeding adult forms Lamprey Biology and Behavior ◦ Larvae are sedentary 昀椀lter feeders, while adults parasi琀椀ze other 昀椀shes for nutri琀椀on ◦ Adults of di昀昀erent species range in size from 10 cm to 1 m and occur in temperate la琀椀tudes ◦ Some species have become invasive, impac琀椀ng na琀椀ve species and requiring control measures. Jawed Vertebrates Evolu琀椀on of Jawed Vertebrates ◦ Jaws permi琀琀ed new behaviors such as grasping, cu琀 ng prey, and courtship rituals ◦ Paired 昀椀ns improved locomo琀椀on, provided an琀椀-predator defenses, and served as visual signals ◦ Evolu琀椀on of toothed jaws, jointed branchial arches, and other increased complexi琀椀es Basic Body Plan of Jawed Vertebrates ◦ Evolu琀椀on of toothed jaws, jointed branchial arches, and hypobranchial musculature ◦ Presence of olfactory tracts, gill slits, and other anatomical features ◦ Development of Hox genes and their role in gene琀椀c control of development Evolu琀椀on of Gnathostomes ◦ Diversi昀椀ca琀椀on of jawed vertebrates into Osteichthyes, Chondrichthyes, Acanthodians, and Placoderms ◦ Presence of more re昀椀ned gene琀椀c control allowed for the evolu琀椀on of new anatomical possibili琀椀es ◦ Gnathostomes have more complex body structures compared to jawless vertebrates Downloaded by Wenjay Delavin ([email protected])  lOMoARcPSD|11130845 ◦ Hox genes: Group of related genes that specify the regional iden琀椀ty of cells along the anterior- posterior axis of the developing embryo ◦ All extant vertebrates have two clusters of Hox genes, resul琀椀ng from the duplica琀椀on of the single Hox gene complex present in non- vertebrate chordates. ◦ Duplica琀椀on of the Hox gene complex allowed for the evolu琀椀on of phylogene琀椀c and anatomical diversity in gnathostomes by allowing more re昀椀ned gene琀椀c control of development that resulted in new anatomical possibili琀椀es. ◦ Living in Water: Physiological Adjustments ◦ Adapta琀椀ons to Aqua琀椀c Environment ◦ Paired 昀椀ns improved locomo琀椀on and provided an琀椀-predator defenses ◦ Evolu琀椀on of toothed jaws allowed for grasping and cu琀 ng prey, as well as courtship rituals ◦ Development of Hox genes in vertebrates allowed for gene琀椀c control of anatomical diversity Lecture 4: Properties of Water and Aquatic Habitats Characteris琀椀cs of Water ◦ Water covers 73% of Earth's surface, with a variety of habitats, but most water is held in ocean basins. ◦ Freshwater cons琀椀tutes only 0.01% of water on Earth, but it supports 40% of ray-昀椀nned 昀椀sh species. ◦ Water is over 800 琀椀mes denser than air, leading to minimal e昀昀ect of gravity on aqua琀椀c vertebrates' size. ◦ Higher viscosity of water makes movement more di昀케cult, resul琀椀ng in streamlined aqua琀椀c vertebrates and one-way 昀氀ow of water through gills. Physiological Di昀昀erences Between Water and Air ◦ Oxygen content in water is 1/20 to 1/4 that of air, making 琀椀dal ven琀椀la琀椀on more di昀케cult and less u琀椀lized. ◦ Electricity can be used by aqua琀椀c vertebrates to detect/stun prey and evade predators due to higher electrical conduc琀椀vity of water. ◦ Water's heat capacity is 3,500 琀椀mes greater than air, leading to li琀琀le temperature change over the day in aqua琀椀c habitats. ◦ Aqua琀椀c vertebrates face challenges in avoiding extremely warm temperatures and have adapted to maintain buoyancy. Respira琀椀on and Buoyancy in Aqua琀椀c Vertebrates Obtaining Oxygen ◦ Aqua琀椀c vertebrates obtain oxygen through gills employing a unidirec琀椀onal 昀氀ow of water and countercurrent exchange to assure e昀케cient oxygen di昀昀usion into the blood. ◦ Fish living in low oxygen environments use lungs or accessory respiratory structures to supplement oxygen needs. Downloaded by Wenjay Delavin ([email protected])  lOMoARcPSD|11130845 Buoyancy Adjustment ◦ Many 昀椀shes maintain neutral buoyancy with swim bladders, adjus琀椀ng the bladder size to go deeper or shallower. ◦ There are two types of swim bladders: physostomes and physoclists, each with dis琀椀nct mechanisms for gas exchange. ◦ Some primi琀椀ve bony 昀椀shes use lungs as swim bladders, while car琀椀laginous 昀椀shes use the liver to create neutral buoyancy. Sensory Adapta琀椀ons in Aqua琀椀c Environments Vision and Chemorecep琀椀on ◦ Vision in water is limited to viewing distances of only hundreds of meters, leading aqua琀椀c vertebrates to supplement vision with taste, smell, and other senses. ◦ Chemical receptors are well developed in aqua琀椀c vertebrates, allowing them to detect odors at very low concentra琀椀ons and 昀椀nd their natal stream using chemical signatures imprinted as juveniles. Lateral Line System and Electrorecep琀椀on ◦ The lateral line system, a sensory system on the body surface, detects changes in speed and direc琀椀on of mo琀椀on via water displacement. ◦ Electrorecep琀椀on, the ability to detect external electric 昀椀elds, is u琀椀lized by aqua琀椀c vertebrates for various func琀椀ons such as prey detec琀椀on and territorial defense. Osmoregula琀椀on and Thermal Regula琀椀on Osmoregula琀椀on ◦ Osmoregula琀椀on is the process of maintaining water and salt balance to prevent 昀氀uids from becoming too concentrated or too dilute. ◦ Di昀昀erent aqua琀椀c vertebrates face dis琀椀nct challenges in maintaining water and salt balance based on their environment. Thermal Regula琀椀on ◦ Most 昀椀sh and amphibians are ectotherms, relying on external sources of heat to raise body temperatures, while marine mammals u琀椀lize insula琀椀on and countercurrent exchange systems to retain metabolic heat. Body Size and Adapta琀椀ons in Aqua琀椀c Vertebrates Surface Area-to-Volume Ra琀椀o ◦ As objects get larger, surface area-to-volume ra琀椀os decrease, making temperature regula琀椀on in water easier for larger vertebrates. ◦ Larger body size confers a degree of stability in the internal environment of aqua琀椀c animals. Summary of Aqua琀椀c Adapta琀椀ons ◦ Morphological and physiological adapta琀椀ons in aqua琀椀c vertebrates re昀氀ect the challenges faced in water, including streamlining, countercurrent exchange of blood and water 昀氀ow, maintaining buoyancy, and heterothermy. Downloaded by Wenjay Delavin ([email protected])  lOMoARcPSD|11130845 ◦ Aqua琀椀c vertebrates supplement vision with other senses, par琀椀cularly chemorecep琀椀on, the lateral line sensory system, and electrorecep琀椀on. ◦ Freshwater and marine vertebrates deal with di昀昀erent water and ion exchange challenges. Lecture 5: Chondrichthyes Biology Evolu琀椀on of Jaws and Paired Appendages ◦ Sharks are known for their predatory traits ◦ Evolu琀椀on of jaws and paired appendages led to various func琀椀ons: - Grasping and cu琀 ng prey; herbivory - Grasping of mates during courtship - Grasping of juveniles during parental care - Refuge and nest building - Steering Car琀椀laginous Fishes and Bony Vertebrates ◦ Gnathostomata contains two groups: ◦ Car琀椀laginous 昀椀shes (Chondrichthyes) ◦ Bony vertebrates (Osteichthyes) Chondrichthyes - The Car琀椀laginous Fishes ◦ Endoskeleton is car琀椀laginous ◦ Descendants of a radia琀椀on of ancient 昀椀shes (>400 mybp) ◦ Four main groups within Chondrichthyes: - Galeomorpha (shallow, warm waters) - Squalomorpha (deep waters) - Batoidea (ray/skate spp.) - Chimaeriformes (deepwater spp.) Evolu琀椀onary Specializa琀椀ons of Chondrichthyes ◦ Mosaic of derived and ancestral characteris琀椀cs ◦ Ancestral characteris琀椀cs include simple gill openings, den琀椀琀椀on, and 昀椀n structure ◦ Derived characteris琀椀cs include loss of bone, car琀椀laginous vertebral centra, rostrum over ventrally-placed mouth, lipid-昀椀lled liver, and high blood urea ◦ Unique tooth replacement system where teeth are rapidly displaced every 8-10 days ◦ Many sharks and some rays have a heterocercal tail which produces forward and upward thrust ◦ Presence of placoid scales with diverse func琀椀ons Re昀椀ned Sensory Systems ◦ Electrorecep琀椀on (Ampullae of Lorenzini) ◦ Excellent chemorecep琀椀on with the ability to detect odors at ‹ Ippb ◦ Well-developed vision for low light intensi琀椀es and sensi琀椀vity due to a tapetum lucidum ◦ Mechanorecep琀椀on through the lateral line for sensing vibra琀椀ons Downloaded by Wenjay Delavin ([email protected])  lOMoARcPSD|11130845 Shark Anatomy and Feeding Specializa琀椀ons ◦ Extant sharks and rays have a derived type of hyostylic jaw suspension allowing the upper jaw to be projected and retracted during feeding ◦ Sharks exhibit various feeding specializa琀椀ons such as pelagic 昀椀lter feeding, ambush preda琀椀on, mammal preda琀椀on, inshore preda琀椀on, and benthic scavenging/preda琀椀on ◦ Sharks use mul琀椀ple senses when hun琀椀ng, including sound to catch their a琀琀en琀椀on ◦ Bioluminescence and bio昀氀uorescence are u琀椀lized for camou昀氀age, intraspeci昀椀c recogni琀椀on, and communica琀椀on Shark Diversity and Reproduc琀椀on ◦ Whale sharks are the world's largest 昀椀sh, while the dwarf lanternshark is the smallest ◦ Sharks display universal internal fer琀椀liza琀椀on and exhibit both oviparity and viviparity ◦ Shark reproduc琀椀on involves various feeding strategies and the possibility of killing a shark before it reproduces, making them vulnerable to over昀椀shing ◦ Not all sharks are solitary, with some forming social networks and exhibi琀椀ng 昀椀ssion-fusion behavior. Skates, Rays, and Ra琀昀ishes ◦ Skates and rays are mainly bo琀琀om-dwelling, benthic feeders with some being pelagic 昀椀lter feeders ◦ Rays may contain poisonous spines in their tails ◦ Ra琀昀ishes are deepwater species with unique physical characteris琀椀cs and feeding habits. Lecture 6: Osteichthyes (Bony Fishes) ◦ Diversity and Evolu琀椀on ◦ Osteichthyes is the most diverse group of vertebrates, with over 34,000 species. ◦ All extant tetrapods are derived from ancestral bony 昀椀shes. ◦ The main radia琀椀ons of bony 昀椀shes occurred around 360-410 million years ago, leading to specializa琀椀on of feeding mechanisms and locomo琀椀on. Dis琀椀nct Characters ◦ Ancestral characters include dermal bone (reduced) and gas bladder. ◦ Shared derived characters consist of opercular and pectoral girdle bone elements, 昀椀n webs supported by bony dermal rays, endochondral bone, and autostylic jaws (unique to bony 昀椀shes). Sister Groups of Osteichthyes ◦ Ac琀椀nopterygii (ray-昀椀nned 昀椀shes) have rays spread out like a fan of bones at the base of the 昀椀ns. ◦ Sarcopterygii (昀氀eshy(lobe)-昀椀nned 昀椀shes) have rays of paired 昀椀ns that extend from a central sha昀琀 of bones in a leaf-like manner to support 昀椀n web. ◦ Dipnoi (lung昀椀shes), Coelacanths, and Tetrapods are also sister groups of Osteichthyes. Downloaded by Wenjay Delavin ([email protected])  lOMoARcPSD|11130845 Sarcopterygii (Fleshy-Finned Fishes) ◦ Abundant 360-410 mybp ◦ Represented today by four non-tetrapod genera, including 3 'Dipnoans' (lung昀椀shes) and 1 coelacanth. ◦ Extant freshwater 'Dionoans' have one con琀椀nuous 昀椀n for dorsal, caudal, and anal 昀椀ns. ◦ Australian lung昀椀sh mainly use gills and use lungs only when stressed, while South American/African lung昀椀shes depend on breathing air with lungs. Es琀椀va琀椀on in African Lung昀椀shes ◦ African lung昀椀shes undergo prolonged torpor or dormancy during hot or dry periods, induced by heat or drying of habitat. ◦ During dry seasons, they burrow in bo琀琀om mud, folding into a U-shape, and form an outer protec琀椀ve envelope with mucus, es琀椀va琀椀ng for less than 6 months to over 4 years. Coelacanths ◦ Dis琀椀nct features of coelacanths include 昀椀n webs origina琀椀ng from elongate muscular bones, a unique symmetrical three-lobed tail, and a rostral organ used in electrorecep琀椀on. ◦ They are bo琀琀om-dwelling, viviparous, and were 'discovered' in 1938 and 1998 in East Africa and Indonesia, respec琀椀vely. Ac琀椀nopterygii (Ray-Finned Fishes) ◦ Largest Radia琀椀on of Vertebrates ◦ Early forms had symmetrical caudal 昀椀ns, fewer bony rays in 昀椀n membranes, and less dermal armour, leading to greater 昀氀exibility in 昀椀ns and mobility. ◦ They also developed jaws with short maxilla, allowing increased suc琀椀on and volume. Extant, Primi琀椀ve Ac琀椀nopterygii ◦ Gars, bow昀椀n, bichirs, and paddle昀椀shes are examples of primi琀椀ve Ac琀椀nopterygii with unique characteris琀椀cs and adapta琀椀ons for their respec琀椀ve environments. Teleost Specializa琀椀ons Protrusible Oral Jaws ◦ Teleosts have further specialized jaw apparatus for a variety of feeding modes, with independent evolu琀椀on occurring 3-4 琀椀mes. Pharyngeal Teeth ◦ Teleosts have powerful movements for holding/manipula琀椀ng prey, with upper and lower pharyngeal teeth capable of independent movement. Fins and Dermal Armour ◦ Teleosts have symmetric (homocercal) caudal 昀椀ns and use the swim bladder for buoyancy regula琀椀on, allowing for specialized use of paired 昀椀ns for various ac琀椀vi琀椀es. ◦ As locomo琀椀on improved, dermal armour reduced, resul琀椀ng in increased body 昀氀exibility. Downloaded by Wenjay Delavin ([email protected])  lOMoARcPSD|11130845 Major Clades of Teleosts ◦ Teleosts are divided into four major clades: Osteoglossomorpha, Elopomorpha, Clupeomorpha, and Euteleostei, each with their own unique characteris琀椀cs and species. Reproduc琀椀on and Adapta琀椀ons Reproduc琀椀on in Freshwater and Marine Environments ◦ Most bony 昀椀shes are oviparous, with freshwater and some marine 昀椀shes laying adhesive, demersal eggs and providing some degree of parental care. ◦ Marine species produce large numbers of small, buoyant, transparent eggs, specialized for feeding on marine plankton. Deep-Sea and Coral Reef Adapta琀椀ons ◦ Deep-sea 昀椀shes have adapta琀椀ons for reduced ac琀椀vity, increased light sensi琀椀vity, and specialized feeding mechanisms, while coral reef 昀椀shes have protrusible jaws and bright colora琀椀on for preda琀椀on avoidance and visual signaling. Summary of Bony Fishes ◦ Bony 昀椀shes are divided into two main lineages: Sarcopterygii and Ac琀椀nopterygii, with the la琀琀er being the most species-rich and numerous vertebrates. ◦ Evolu琀椀on of protrusible jaws, pharyngeal teeth, and locomotory structures has been crucial in their diversification, especially in later evolved teleosts. Lecture 7: Evolu琀椀on of Tetrapods Basal Tetrapodomorphs ◦ Tiktaalik, also known as the '昀椀shapod', exhibited both 昀椀sh and tetrapod features ◦ Fish features included 昀椀n rays, 昀椀ns, well-developed gills, and poorly ossi昀椀ed vertebrae ◦ Tetrapod features included the loss of bony operculum, par琀椀al support of body out of water with limb-like 昀椀ns, and a long snout for feeding outside water Advantages of Terrestrial Ac琀椀vity ◦ Avoidance of seasonal droughts, juvenile preda琀椀on, searching for food, juvenile dispersal, laying eggs in moist environments, and basking in the sun to elevate body temperature are poten琀椀al advantages of terrestrial ac琀椀vity ◦ Lobed 昀椀ns were useful for stalking prey in shallow, plant-昀椀lled lagoons Tetrapod Origins ◦ Earliest known tetrapods date back to 360 million years ago ◦ Related to lobe-昀椀nned 昀椀shes, some lineages became secondarily aqua琀椀c, while others became fully terrestrial ◦ Amniotes have radiated into most terrestrial life zones with developed feeding and locomotor specializa琀椀ons Downloaded by Wenjay Delavin ([email protected])  lOMoARcPSD|11130845 Major Groups: Non-Amniotes ◦ Lack the amnio琀椀c egg and have embryos enclosed by maternally-produced membranes ◦ Include jawed 昀椀shes, jawless 昀椀shes, and amphibians Major Groups: Amniotes ◦ Contain an amnio琀椀c egg with embryos having three membranes that come from the embryos themselves ◦ Include sauropsids (turtles, lizards, snakes, alligators, crocodiles, birds) and synapsids (mammals with placentas) Living on Land Extant Tetrapods ◦ Amniotes comprise most tetrapods living today, while non-amniotes include amphibians ◦ The presence of an amnio琀椀c egg may provide advantages for reproducing on land Support on Land ◦ Skeletal bones must be rigid to resist the force of gravity and forces exerted during movement ◦ Bone remodeling is important for tetrapods as their skeletons experience greater stress than those of aqua琀椀c animals ◦ The vertebrate skeleton has major subdivisions: axial and appendicular skeleton Locomo琀椀on on Land ◦ Fric琀椀on is needed between the feet and ground for propulsion, making locomo琀椀on energe琀椀cally more expensive than in water ◦ Limbs derived from 昀椀ns, with dis琀椀nct hinge joints in ankles, support hind-limbs and fore-limbs Ea琀椀ng on Land ◦ Terrestrial vertebrates use jaws and teeth to seize prey, manipulate items in the mouth with tongues/cheeks, and have lengthened skulls ◦ Specializa琀椀ons include tongue projec琀椀ons, salivary glands, and venomous salivary secre琀椀ons in some taxa Respira琀椀on ◦ Tidal ven琀椀la琀椀on with lungs is facilitated by the high oxygen content of air ◦ Non-amniotes use posi琀椀ve pressure buccal bumping to in昀氀ate lungs, while amniotes use hypaxial-mediated expansion of the rib cage to create nega琀椀ve pressure for air intake. Physiological Adapta琀椀ons Thermoregula琀椀on on Land ◦ Regula琀椀ng body temperature is cri琀椀cal for most tetrapods, usually at higher temperatures than the surrounding environment ◦ Ectothermy and endothermy are two thermoregula琀椀on strategies with their respec琀椀ve advantages Downloaded by Wenjay Delavin ([email protected])  lOMoARcPSD|11130845 Conserving Water on Land ◦ Tetrapods have a well-developed urinary bladder for water recovery and waste storage ◦ Water is evaporated from the body surface, and tetrapods have adapta琀椀ons to conserve water Sensory Systems in Air ◦ Vision is transferred with less disturbance, allowing longer viewing distances ◦ Taste and smell are facilitated by olfactory receptors in nasal passages, with extremely sensi琀椀ve detec琀椀on capabili琀椀es Blood and Gravity ◦ Terrestrial tetrapods have double circula琀椀on to overcome the challenges of gravity and blood 昀氀ow ◦ Vertebrates that live in water have single circula琀椀on, which di昀昀ers from the double circula琀椀on in terrestrial tetrapods Thermoregula琀椀on on Land ◦ Ectothermy and endothermy are two thermoregula琀椀on strategies with their respec琀椀ve advantages. Comparison of Air and Water Proper琀椀es of Air vs. Water ◦ The physical proper琀椀es of air and water have disadvantages and advantages for terrestrial vertebrates ◦ Air has lower density and viscosity, higher oxygen content, and di昀昀erent heat capacity and conduc琀椀vity compared to water Sensory Systems in Air vs. Water ◦ Vision, taste, and smell are in昀氀uenced by the transi琀椀on from water to air, with novel features and adapta琀椀ons in terrestrial tetrapods Support on Land vs. Water ◦ Skeletal bones must be rigid to resist the force of gravity and forces exerted during movement on land, leading to di昀昀erent skeletal structures and adapta琀椀ons compared to aqua琀椀c animals Respira琀椀on in Air vs. Water ◦ Tidal ven琀椀la琀椀on with lungs is facilitated by the high oxygen content of air, contras琀椀ng with the respiratory adapta琀椀ons of aqua琀椀c vertebrates Blood and Gravity in Air vs. Water ◦ Terrestrial tetrapods have double circula琀椀on to overcome the challenges of gravity and blood 昀氀ow, which di昀昀ers from the circula琀椀on in aqua琀椀c vertebrates. Downloaded by Wenjay Delavin ([email protected])  lOMoARcPSD|11130845 Lecture 8: Amphibian Biology and Conserva琀椀on Extant Tetrapods ◦ Amniotes: most tetrapods living today ◦ Non-amniotes: amphibians Amphibian Characteris琀椀cs ◦ Moist, scaleless, permeable skin ◦ Most have four, well-developed limbs (loss of limbs is a derived character in some) ◦ Three lineages: salamanders, frogs and toads, caecilians Shared Derived Characters ◦ Cutaneous gas exchange Poison (granular) glands in the skin ◦ Sensory areas in the inner ear ◦ Levator bulbi muscle for bulging eyes ◦ All adults are carnivorous ◦ Rela琀椀vely li琀琀le morphological specializa琀椀on associated with di昀昀erent dietary habits Salamanders ◦ Generalized amphibian body form with elongate shape and four func琀椀onal limbs ◦ Paedomorphosis - reten琀椀on of larval characteris琀椀cs in the adult form ◦ Diversity in aqua琀椀c and terrestrial species ◦ Specializa琀椀ons in cave and plethodon琀椀dae salamanders ◦ Variety of aqua琀椀c species with di昀昀erent adapta琀椀ons Frogs and Toads (Anurans) ◦ Specializa琀椀on of body for jumping ◦ Geographically widespread ◦ Diversity in burrowers, semi-aqua琀椀c jumpers-swimmers, specialized aqua琀椀c, arboreal, and terrestrial walkers and hoppers Caecilians ◦ Specializa琀椀on of body for burrowing or aqua琀椀c lifestyle ◦ Greatly reduced eyes ◦ Geographically widespread in tropics ◦ Pair of protrusible tentacles for sensing chemical substances Amphibian Life Histories ◦ Diverse reproduc琀椀ve modes and parental care ◦ Courtship displays and internal fer琀椀liza琀椀on in salamanders ◦ Kleptogeneis in salamanders ◦ Variety in anuran vocaliza琀椀ons and reproduc琀椀on Downloaded by Wenjay Delavin ([email protected])  lOMoARcPSD|11130845 ◦ Reproduc琀椀ve modes and parental care strategies to reduce egg/tadpole preda琀椀on ◦ Internal fer琀椀liza琀椀on and viviparity in caecilians Tadpole Ecology and Metamorphosis ◦ Morphological specializa琀椀ons and advantages ◦ Stages of tadpole metamorphosis s琀椀mulated by thyroxine ◦ Water and gas exchange in larvae and adults ◦ Behavioural control of water loss ◦ Defense mechanisms of amphibian skin Amphibian Conserva琀椀on ◦ Factors involved in amphibian declines: habitat destruc琀椀on, overexploita琀椀on, climate change, UV-B radia琀椀on, chemical contaminants, diseases ◦ Introduc琀椀on of amphibians as pests ◦ Ac琀椀ons for conserva琀椀on and reasons behind them. Lecture 9: Vertebrate Life on Land Amnio琀椀c Advantage for Life on Land ◦ The amnio琀椀c egg serves as a life support system providing energy for development, gas exchange, waste and water storage, and embryo protec琀椀on. ◦ Laying eggs on land bypasses the aqua琀椀c larval stage and allows for larger eggs and o昀昀spring. Amniote Characters ◦ Skin impermeability limits water loss and may include scales, hair, nails, and feathers. ◦ Complex jaw musculature and teeth, such as temporal fenestra琀椀on, aid in breathing with ribs. Evolu琀椀on of Vertebrates ◦ Synapsids have a single opening between each eye, while sauropsids have either none or two temporaltenestrae. ◦ Synapsids played a dominant role during the Permian Period. ◦ Terrestrial VertebratesAmphibians, jawless and jawed 昀椀shes, and car琀椀laginous/bony 昀椀shes are non-amniotes, while mammals, rep琀椀les, and birds are amniotes. ◦ Sauropsids include terrestrial, aqua琀椀c, and amphibious species, while synapsids are mostly terrestrial. Evolu琀椀onary Split of Amniotes ◦ Before the split, amniotes had few derived characters associated with terrestrial living. ◦ Sauropsids and synapsids independently evolved parallel strategies and adapta琀椀ons for terrestrial life. Downloaded by Wenjay Delavin ([email protected])  lOMoARcPSD|11130845 Respira琀椀on and Locomo琀椀on Challenges Challenges in Early Tetrapods and Extant Lizards and Salamanders ◦ The issue of locomo琀椀on and respira琀椀on working together arises due to the inability to run and ven琀椀late lungs simultaneously. ◦ As the lizard moves, air interference occurs, and limbs and feet are used in alternate pairs. Overcoming Challenges in Sauropsids and Synapsids ◦ Sauropsids reoriented limbs underneath the trunk for upright posture and lost ventral ribs, while synapsids retained bipedality and evolved a diaphragm for respira琀椀on. ◦ Both lineages evolved di昀昀erent respiratory adapta琀椀ons, such as gular pumping, immobile lungs, and posteriorly extended sternum. Advantages of Evolved Strategies ◦ The evolved strategies allowed for easier limb movement, less interference with air昀氀ow, and more e昀케cient means of gas exchange between the respiratory system and bloodstream. ◦ Bipedality in birds and increased trunk 昀氀exibility in lizards and other respiratory adapta琀椀ons were advantageous for long-distance traveling and short bursts of ac琀椀vity. Gas Exchange and Oxygen Transporta琀椀on ◦ Atmospheric Pressure and Oxygen Concentra琀椀on at High Eleva琀椀ons ◦ At high eleva琀椀ons, the air is thinner and contains signi昀椀cantly lower concentra琀椀ons of oxygen than at sea level, leading to reduced oxygen di昀昀usion from air in lungs to blood in pulmonary capillaries. Respira琀椀on in Birds at High Al琀椀tudes ◦ Birds increase oxygen par琀椀al pressure in their lungs to di昀昀use oxygen to muscles by passing inhaled air through posterior air sacs and parabronchial lungs, maintaining higher oxygen par琀椀al pressure in lungs than in blood. Oxygen Transporta琀椀on to Muscles ◦ The contents of all blood capillaries mix to determine the oxygen par琀椀al pressure in arterial blood, resul琀椀ng in enhanced oxygen carrying capacity of the blood. Conserving Water and Waste Elimina琀椀on Kidneys and Waste Elimina琀椀on ◦ Kidneys selec琀椀vely remove water-soluble toxins and convert ammonia to urea or uric acid for excre琀椀on, conserving water. Bladder and Waste Elimina琀椀on ◦ Bladders in sauropsids and synapsids serve as storage areas for concentrated urine, used for territoriality and ma琀椀ng, while birds lack a bladder and process urine in the cloaca. Downloaded by Wenjay Delavin ([email protected])  lOMoARcPSD|11130845 Summary and Feedback Lecture Summary ◦ Terrestrial vertebrates comprise synapsids and sauropsids, which evolved parallel, complementary, and dissimilar strategies for terrestrial living. ◦ Species in each lineage evolved abili琀椀es to run long distances, maintain endurance, and evolved di昀昀erent respiratory and waste elimina琀椀on adapta琀椀ons. ◦ Pedagogical Training Feedback ◦ The lecture covered the challenges faced by terrestrial vertebrates, the strategies they evolved, and the adapta琀椀ons for high-al琀椀tude 昀氀ying birds. ◦ The feedback form was provided for the audience to submit their comments. Downloaded by Wenjay Delavin ([email protected])