Questions and Answers
What is critical for most tetrapods to regulate?
body temperature
Which of the following are thermoregulation strategies?
Tetrapods do not have adaptations to conserve water.
False
Terrestrial tetrapods have ______ circulation to overcome blood flow challenges.
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What are the three lineages of amphibians?
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All amphibians have scales.
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Match the amphibian types with their characteristics:
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What is a characteristic shared by all adult amphibians?
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What is one major factor contributing to amphibian declines?
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Which of the following describes the amniotic egg's function?
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All vertebrates are amniotes.
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What is one adaptation of sauropsids for terrestrial life?
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Which group of vertebrates lacks the amniotic egg?
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Species diversity of vertebrates peaked during the mid-Miocene.
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What are the three germ layers from which vertebrate bodies form?
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The principle of ______ states that the most plausible phylogeny is the one requiring the fewest changes in structure.
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Match the following subphyla of Chordata with their characteristics:
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Which system is responsible for moving oxygen and nutrients in vertebrates?
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Jawless fishes possess true vertebrae.
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What is the function of the swim bladder in fish?
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The evolutionary origin of vertebrates is associated with ______ evidence.
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Which adaptation allows aquatic vertebrates to detect electric fields?
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All tetrapods have amniotic eggs.
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Name two major groups of jawed vertebrates.
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Study Notes
Vertebrate Biology
Diversity, Classification, and Evolution of Vertebrates
- There are over 70,000 extant species of vertebrates that inhabit a wide range of habitats and exhibit an incredible size range.
- Vertebrates display a variety of feeding, social, and reproductive behaviors, as well as parental and non-parental care.
- The rich diversity within some species is a product of 500 million years of evolution.
- Species diversity peaked in the mid-Miocene (between 14 and 12 million years ago) and has been declining since.
Major Groups: Non-amniotes and Amniotes
- Non-amniotes lack the amniotic egg and have embryos enclosed by maternally produced membranes.
- This group includes jawed fishes, jawless fishes, and amphibians.
- Amniotes contain an amniotic 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 geological time, shaped by continental movements over geological time scales.
- Continental shifts resulted in global climate changes that influenced the evolution of vertebrate species adapted to specific environmental conditions.
Binomial Nomenclature and Phylogenetic Trees
- Species are given two names, a genus name and a species name, based mainly on anatomical features.
- The goals of scientific 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 Classification
- Phylogenetic systematics is a method of classifying organisms based on shared ancestry, using morphological, molecular, and behavioral data.
- Cladistics is a specific method within phylogenetic systematics that emphasizes monophyly and parsimony.
- Phylogenetic trees or cladograms represent the evolutionary relationships among taxa.
Features of Vertebrates
- Vertebrates have vertebrae forming a spinal column.
- Other distinguishing features include a cranium, prominent head with complex sense organs, neural crest, large brains, complex endocrine organs, muscularized gut tube, multi-chambered heart, mineralized tissues, and gills derived from endoderm.
Early Vertebrates
- Earliest vertebrate fossils found during the Cambrian, approximately 525 million years ago.
- Some early vertebrates had mineralized tissues, while others like Cambrian vertebrates and extant cyclostomes did not.
- Possible original selective advantages of mineralized tissues include protection from predators and storage/regulation of phosphorus and calcium.
Marine Origin of Vertebrates
- Paleontological evidence indicates that the earliest vertebrate fossils are from marine sediments.
- Comparative physiological evidence suggests a marine origin based on body fluid osmolal concentration.
Extant Jawless Fishes: Hagfishes and Lampreys
- Hagfishes lack jaws, paired fins, specialized reproductive ducts, and mineralized tissues.
- Lampreys have cartilaginous vertebral structures, large complex eyes, and two semi-circular canals.
Jawed Vertebrates
- Jaws permitted new behaviors such as grasping, cutting prey, and courtship rituals.
- Paired fins improved locomotion and provided anti-predator defenses.
- Evolution of toothed jaws, jointed branchial arches, and other increased complexities.
Properties of Water and Aquatic Habitats
- Water covers 73% of Earth's surface, with a variety of habitats, but most water is held in ocean basins.
- Freshwater constitutes only 0.01% of water on Earth, but it supports 40% of ray-finned fish species.
- Water is over 800 times denser than air, leading to minimal effect of gravity on aquatic vertebrates' size.
Physiological Differences Between Water and Air
- Oxygen content in water is 1/20 to 1/4 that of air, making respiration more difficult and less utilized.
- Electricity can be used by aquatic vertebrates to detect/stun prey and evade predators due to higher electrical conductivity of water.
Respiration and Buoyancy in Aquatic Vertebrates
- Aquatic vertebrates obtain oxygen through gills employing a unidirectional flow of water and countercurrent exchange to assure efficient oxygen diffusion into the blood.
Sensory Adaptations in Aquatic Environments
- Vision in water is limited to viewing distances of only hundreds of meters, leading aquatic vertebrates to supplement vision with taste, smell, and other senses.
- Chemical receptors are well-developed in aquatic vertebrates, allowing them to detect odors at very low concentrations and find their natal stream using chemical signatures imprinted as juveniles.
Body Size and Adaptations in Aquatic Vertebrates
- As objects get larger, surface area-to-volume ratios decrease, making temperature regulation in water easier for larger vertebrates.
- Larger body size confers a degree of stability in the internal environment of aquatic animals.### Evolution of Jaws and Paired Appendages
• The evolution of jaws and paired appendages led to various functions, including: + Grasping and cutting prey + Grasping of mates during courtship + Grasping of juveniles during parental care + Refuge and nest building + Steering
Carthaginous Fishes and Bony Vertebrates
• Two groups of vertebrates: + Carthaginous fishes (Chondrichthyes) + Bony vertebrates (Osteichthyes)
Chondrichthyes - The Carthaginous Fishes
• Characteristics: + Endoskeleton made of cartilage + Descendants of a radiation of ancient fishes (>400 mybp) + Four main groups: - Galeomorpha (shallow, warm waters) - Squalomorpha (deep waters) - Batoidea (ray/skate spp.) - Chimaeriformes (deepwater spp.)
Evolutionary Specializations of Chondrichthyes
• Mosaic of derived and ancestral characteristics • Ancestral characteristics: + Simple gill openings + Dentition + Fin structure • Derived characteristics: + Loss of bone + Cartilaginous vertebral centra + Rostrum over ventrally-placed mouth + Lipid-filled liver + High blood urea • Unique tooth replacement system • Heterocercal tail for forward and upward thrust • Placoid scales with diverse functions
Refinded Sensory Systems
• Electroreception (Ampullae of Lorenzini) • Excellent chemoreception with ability to detect odors at <1 ppb • Well-developed vision for low light intensities and sensitivity due to tapetum lucidum • Mechanoreception through the lateral line for sensing vibrations
Shark Anatomy and Feeding Specializations
• Derived type of hyostylic jaw suspension • Various feeding specializations, including: + Pelagic filter feeding + Ambush predation + Mammal predation + Inshore predation + Benthic scavenging/predation • Use of multiple senses when hunting, including sound to catch attention
Shark Diversity and Reproduction
• Whale sharks are the largest fishes, while dwarf lanternsharks are the smallest • Sharks display universal internal fertilization and exhibit both oviparity and viviparity • Shark reproduction involves various feeding strategies and the possibility of killing a shark before it reproduces, making them vulnerable to overfishing • Not all sharks are solitary, with some forming social networks and exhibiting aggregation-fission behavior
Osteichthyes (Bony Fishes)
Diversity and Evolution
• Most diverse group of vertebrates, with over 34,000 species • All extant tetrapods are derived from ancestral bony fishes • Main radiations of bony fishes occurred around 360-410 million years ago, leading to specialization of feeding mechanisms and locomotion
Distinct Characters
• Ancestral characters: + Dermal bone (reduced) + Gas bladder • Shared derived characters: + Opercular and pectoral girdle bone elements + Bony dermal rays supporting fin webs + Endochondral bone + Autostylic jaws (unique to bony fishes)
Sister Groups of Osteichthyes
• Acnwpterygii (ray-finned fishes) have rays spread out like a fan of bones at the base of the fins • Sarcopterygii (fleshy-finned fishes) have rays of paired fins that extend from a central shaft of bones in a leaf-like manner to support fin webs • Dipnoi (lungfishes), Coelacanths, and Tetrapods are also sister groups of Osteichthyes
Teleost Specializations
Protrusible Oral Jaws
• Further specialized jaw apparatus for various feeding modes
Pharyngeal Teeth
• Powerful movements for holding/manipulating prey
Fins and Dermal Armour
• Symmetric (homocercal) caudal fins and use of swim bladder for buoyancy regulation • Reduced dermal armour, resulting in increased body flexibility
Tetrapod Origins
Basal Tetrapodomorphs
• Tiktaalik, a 'fishapod', exhibited both fish and tetrapod features • Fish features: + Fin rays + Gills + Poorly ossified vertebrae • Tetrapod features: + Loss of bony operculum + Partial support of body out of water with limb-like fins + Long snout for feeding outside water
Advantages of Terrestrial Activity
• Avoidance of seasonal droughts, juvenile predation, searching for food, juvenile dispersal, laying eggs in moist environments, and basking in the sun to elevate body temperature are potential advantages of terrestrial activity
Tetrapod Origins
• Earliest known tetrapods date back to 360 million years ago • Related to lobe-finned fishes, some lineages became secondarily aquatic, while others became fully terrestrial • Amniotes have radiated into most terrestrial life zones with developed feeding and locomotor specializations
Amniote Biology
Major Groups: Non-Amniotes
• Lack the amniotic egg and have embryos enclosed by maternally-produced membranes • Include jawed fishes, jawless fishes, and amphibians
Major Groups: Amniotes
• Contain an amniotic 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 • Non-amniotes include amphibians
Support on Land
Skeletal System
• Skeletal bones must be rigid to resist the force of gravity and forces exerted during movement
Locomotion on Land
Terrestrial Vertebrates
• Limbs derived from fins • Distinct hinge joints in ankles, supporting hind-limbs and fore-limbs
Eating on Land
Terrestrial Vertebrates
• Use jaws and teeth to seize prey • Manipulate items in the mouth with tongues/cheeks • Have lengthened skulls
Respiratory System
Terrestrial Vertebrates
• Tidal ventilation with lungs is facilitated by the high oxygen content of air • Non-amniotes use positive pressure buccal bumping to inflate lungs, while amniotes use hypaxial-mediated expansion of the rib cage to create negative pressure for air intake
Thermoregulation on Land
Ectothermy and Endothermy
• Regulating body temperature is critical for most tetrapods, usually at higher temperatures than the surrounding environment • Ectothermy and endothermy are two thermoregulation strategies with their respective advantages
Conserving Water on Land
Terrestrial Tetrapods
• Well-developed urinary bladder for water recovery and waste storage • Water is evaporated from the body surface, and tetrapods have adaptations to conserve water
Sensory Systems in Air
Terrestrial Tetrapods
• Vision is transferred with less disturbance, allowing longer viewing distances • Taste and smell are facilitated by olfactory receptors in nasal passages, with extremely sensitive detection capabilities
Blood and Gravity
Terrestrial Tetrapods
• Double circulation to overcome the challenges of gravity and blood flow • Tetrapods that live in### Terrestrial Vertebrates
- Terrestrial vertebrates consist of synapsids and sauropsids, which developed parallel, complementary, and dissimilar strategies for living on land.
- Both lineages evolved abilities to run long distances and maintain endurance.
- They also developed different respiratory and waste elimination adaptations.
Lecture Coverage and Feedback
- The lecture covered the challenges faced by terrestrial vertebrates and the strategies they evolved to overcome them.
- Part of the lecture focused on the adaptations of high-altitude flying birds.
- A feedback form was provided for the audience to submit their comments and feedback.
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Description
This quiz covers the diversity, classification, and evolution of vertebrates, including the impact of climate change and invasive species.
