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Download Evolution and Ecology
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Questions from week one? • Lecture one: see white perch gonads • Lecture two: White perch - opportunistic feeders • Lecture one: Lateral line Red vs white muscle • Red (aerobic) – High capillary density – Appears red due to O2 binding pigments myoglobin and hemoglobin – Allows adequate oxygenation on muscle – Metabolizes lipids in mitochondria • White (anaerobic) – Converts glycogen to lactate – Increases pH Evolution and Ecology Fishes of Wisconsin Goal: an overview of phylogeny and functional morphology in the context of ecology – When traits evolved • The characteristics of main groups – Functional morphology • Background to understand how traits affect ecology Evolution basics and terminology • Natural Selection • Ecological niche – Position in an ecosystem; how an organism makes a “living” • Adaptive Radiation – Divergent evolution to fill ecological niches driven by natural selection (cichlids) • Functional Morphology – Relationship between form and function Taxonomic Nomenclature • • • • • • • Kingdom – Animalia Phylum – Craniata Class – several Order – in fishes, always ends with -iformes Family – in fishes, always ends with -idae Genus – complex nomenclatural conventions Species – complex nomenclatural conventions Cladograms Agnatha Chondrichthyes Sarcopterygii Actinopterygii Osteichthyes Bony fish Gnathostomata Jaws Jawless Fishes Superclass: Agnatha Agnatha Chondrichthyes Sarcopterygii Actinopterygii Osteichthyes Bony fish Gnathostomata Jaws Jawless Fishes Superclass: Agnatha • Absence of jaw (agnathous) • Absence of paired fins • Presence of notochord Jawless Fishes Hagfishes (Order: Myxiniformes) • • • • Notochord (no vertebrae) Exclusively marine 30-35 species Harvested commercially – “eel-skin” leather • Knots Jawless Fishes Lampreys (Order: Petromyzontiformes) • • • • • • Vertebrae Oral disk - grasp prey and create hole Dorsal and caudal fins Lateral line system Well-developed eyes ~ 40 species Jawed Fishes Superclass: Gnathostomata Agnatha Chondrichthyes Sarcopterygii Actinopterygii Osteichthyes Bony fish Gnathostomata Jaws Jawed Fishes Superclass: Gnathostomata Composed of: – Cartilaginous fishes (Class: Chondricthyes) – Lobe-finned fishes (Class: Sarcopterygii) – Ray-finned fishes (Class: Actinopterygii) longnose gar (Lepisosteus osseus) Jawed Fishes Class: Chondrichthyes Agnatha Chondrichthyes Sarcopterygii Actinopterygii Osteichthyes Bony fish Gnathostomata Jaws Class: Chondrichthyes Cartilaginous fishes • Sharks, rays, skates and chimaeras • 850 extant species • Cartilaginous skeleton • Jaw teeth in rows • Placoid scales (most) Jawed Fishes Class: Osteichthyes Agnatha Chondrichthyes Sarcopterygii Actinopterygii Osteichthyes Bony fish Gnathostomata Jaws Class: Osteichthyes • Diverse class The bony fishes – Subclass Sarcopterygii – Subclass Actinopterygii • Lungs or swimbladder • Bony skeleton – Some ossification Sublass: Sarcopterygii Lobed-finned fishes • Characterized by fleshy fins with bony, leg-like supports Lemur – Coelacanths (Infraclass: Actinistia) – Lungfishes (Infraclass: Dipnoi) – Tetrapods Latimeria Neoceratodus Sublass: Actinopterygii Ray-finned fishes • Dominant fishes on the planet – Approx. 24,000 species • Possess fin rays Sarcopterygii vs Actinopterygii Pectoral fin Coelocanth Teleost Relict Actinopterygians • Infraclass Chondrostei – mostly cartilaginous with some bone – Sturgeons, paddlefish, bichirs and reed fish • Infraclass Neopterygii (“new wing”) – Gars and bowfin bowfin (Amia calva) lake sturgeon (Acipenser fulvescens) bichir (Polyterus spp.) Actinopterygians continued: Teleostei - the main line of fish evolution • Compose ~95% of all extant species (~23,680) • Characterized by – cycloid or ctenoid scales – increased cranial complexity – swim bladders (usually) Major Trends in Fish Evolution • Changes in cranium and jaw structure – Branchiostegal rays – Pre-maxilla separation • Changes in movement – Loss of external armor – Fins – Air bladders Branchiostegal Rays • Maintains a flexible seal between operculum and body as oral cavity expands – Allows for active pumping of water across gills – Allows for feeding methods based on suction Jaw Structure “Primitive” PM MX MX PM “Derived” Jaw Structure cont… Brook trout – primitive, maxilla included in gape Largemouth bass – derived, maxilla excluded from gape • Scales Loss of external armor – Reduction in heaviness, increase in flexibility – Note: • surviving Chonrosteians have no scales over most of their bodies • many teleost have eliminated scales Spines • Spine development followed loss of external armor – Anti-predator device Movement of Pelvic Fins From Abdominal to Thoracic Position “Primitive” “Derived” Abdominal Position • Anterior shift associated with increased maneuverability Thoracic Position – Pelvic fins help control movement rather than just stabilize Caudal Fin Evolution • Heterocercal – Provide lift • Homocercal – Improved thrust – Closely related to development of neutral buoyancy Swimbladder • Lungs evolved before swim bladders • Swimbladder – Trend of importance • in respiration • in buoyancy Basic Body Types • Fusiform • Laterally compressed (Deep-Bodied) • Dorso-ventrally compressed (Flat-fish) • Cylindrical/Attenuated Fusiform Body Type “classic” fish shape Brown Trout Largemouth Bass Pike Fathead Minnow Laterally Compressed/Deep Bodied Body Type (Acrobatics and Maneuvering) Bluegill Sunfish Butterfly Fish Dorso-ventrally Compressed Body Type (Bottom Dwellers) California Halibut Flathead Catfish Mottled Sculpin Lake Sturgeon Cylindrical/Attenuated Body type (Hiders/Burrowers) American Eel Hagfish Basic Mouth Types Superior Terminal Sub-Terminal Inferior Mouth Shapes • O - shaped (maximum area to perimeter) – Creates a vacuum in the water – expanding pre-maxila outward – Found commonly in Planktivores • V-Shape or Duck Bill Shape – Vacuum less directed and less powerful – Allows for prey capture from the side – Found commonly in large Piscivores Largemouth Bass Jaw Protrusion Decreases distance between predator and prey Increases the amount of suction force generated PM PM MX MX Extreme Jaw Protrusion! Mouth Size • Mouth Size matches prey size. Putting it together with Fin Placement Rover-Predators Fusiform, Streamlined body Forked Tail, Narrow or Average Peduncle Terminal mouth -Fins more or less evenly distributed for stability and manuverability -Constantly moving and searching for prey Lie and Wait predators Acceleration Specialists Flexible, Torpedo-Like Body Thick Caudal Peduncle Large Gape Ventrally-placed Pectoral Fin Small Pectoral and Pelvic fins relative to body size Posterior-placed Median Fins (Dorsal and Anal) Maneuvering Specialists – Adaptations for Suction Feeding Spines for Defense Laterally Compressed Body Large Fins Relative To Body Size Small protrusible mouth Fins Evenly Distributed Spines for Defense Laterally Positioned Pectoral Fins Bottom Rovers Humped Back Enlarged Pectoral Fins Subterminal or Inferior Mouth Flattened Head Barbels Bottom Clingers Flattened Head and Body Modified, Closely Spaced Pelvic Fins Enlarged Pectoral Fin
