Bio 201 F11 Lect 20 (True)r

Bio 201 F11 Lect 20 (True)r - Biology in the News [see...

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Unformatted text preview: Biology in the News [see folder on BB] A recent review paper, which can be found here h<p:// 331/6020/1032.short discusses how cases of homoplasy can be important tools for understanding the geneFcs and development underlying independent evoluFon of similar traits in unrelated lineages parFcularly important examples include •  evoluFon of petals in plants (evolved at least 6 Fmes independently) •  evoluFon of eye structures (many Fmes from a simple photoreceptor organ) •  increased body length in amphibians (evolved several Fmes by increasing length of vertebrate; most other vertebrates evolved greater length by increasing the number of vertebrae) as we have studied in Bio 201, having the correct tree is key to idenFfying homoplasies; but also knowing how traits develop is key to idenFfying whether certain traits in quesFon (e.g. neural crest cells in urochordates versus vertebrates) are homologous or homoplaseous •  h<p:// cntn_id=118776&WT.mc_id=USNSF_51&WT.mc_ev=click h<p:// nd mid term exam 2 •  •  •  •  •  •  •  •  Wed. October 26th in class covers material from Mon. 26‐Sept. through Fri. 21‐Oct. (10 lectures) pracFce quesFons will be posted; review sessions – next slide Be on Fme –  >10 min late will not be allowed into room Bring only your ID and pencils –  All other materials have to be lea on periphery of the room 35 mulFple choice quesFons + 3 bonus bio news quesFons lowest of the three mid terms is dropped, avg. of other 2 = 60% of your grade Only documented medical/family/accident excuses accepted •  we need to be NOTIFIED before end of the day on the day of the exam review sessions for 2nd mid term exam •  •  •  •  •  •  •  Alvin ‐ Monday ‐ 10:00 ‐ 11:00 Safa ‐ Monday 2:00 ‐ 3:00 Harrison ‐ Monday ‐ 4:00 ‐ 5:00 Redwan ‐ Tuesday ‐ 9:00 ‐ 10:00 Dana ‐ Tuesday ‐ 2:30 ‐ 3:30 Dana ‐ Wednesday ‐ 10:00 ‐ 11:00 all are in Life Sciences 026 – Bring Your QuesFons! Diversifica=on of jawed vertebrates (Gnathostomes) lampreys Sharks and rays (Chondrichthyes) Bony fishes (Osteichthyes) Tetrapods Bony fishes include: Ray‐finned fishes Coelacanths Lungfishes Sharks, rays, raEishes, chimaeras (=Chondrichthyes) •  ~850 extant species •  CarFlaginous skeletons –  Derived condiFon (ancestor had bony skeleton) •  But have bony, mineralized teeth and some parts of skeleton have mineralized granules Sharks and rays (also raEishes and chimaeras) (Chondrichthyes) •  Large liver, containing oil –  Helps buoyancy (bony fish use a different structure) –  BUT animal will sink if it stops moving –  Unclear how or whether sharks actually sleep –  Some sharks gulp air from surface into stomach; use as air bladder •  Sharks also need to keep moving to keep water flowing into mouth and over gills –  Rays use special muscles to do this Fish adaptaFon (all fish, not just sharks) •  Lateral line system –  All groups of fish have this –  Tiny organs down the length of the body surface for sensing changes in water pressure –  Used to detect sound waves and water movements Bony fish diversifica=on (Chondrichthyes) sharks & rays Ray finned fishes (AcFnopterygii) Sarcopterygii Lobe finned fishes (AcFnisFa) Lungfishes (Dipnoi) Tetrapods Bony fish diversifica=on •  ~20‐25,000 species, vast majority are ray‐finned species (~1/2 of all vertebrate species) •  EvoluFonary success story: huge diversity –  Found in almost all types of aquaFc habitats –  Great size diversity (~1 cm to 6m) Dorsal fin (rays) Lateral line Pectoral fins Pelvic fins taxonomic overview of the class AcFnopterygii •  •  contains two “subclasses”: Chondrostei and Neopterygii Chondrostei (52 species) consists of : sturgeons, paddlefishes, reedfishes, and bichirs •  Neopterygii consists of two “infraclasses” Holostei and Teleostei –  Holostei consists of bowfin (1 species) and gars (7 species) •  infraclass Teleostei contains all other bony fish (~20,000 species) – “teleosts” Huge morphological and physiological diversity, h<p:// fish/erpetoichthys‐calabaricus.html, h<p://, h<p:// media/inline/ 00045784‐1C74‐123B‐9C7483414B7F0000 _1.gif Bony fish adapta=ons •  •  •  Swim bladder for buoyancy –  Air sac, adjustable by exchanging gas with blood –  Fish can stop moving and not sink (saves energy) Bony fish probably evolved in fresh water –  Swim bladder may have been a primiFve lung for use in shallow water habitats Fins of ray‐finned fishes –  Long flexible rays of bone ‐ good for maneuvering •  Most species have flat, thin, lightweight scales –  For protecFon and ease of movement through water Reproduction Most dioecious (separate sexes) Some species are Hermaphrodites -Some simultaneous hermaphrodites-have gonads of both sexes -Others serial hermaphrodites– change sex during life time External fertilization Eggs not buoyant - need shallow water Most reproduce in coastal, estuary areas-rich in food Some species show parental care Why would be advantageous to change sex during lifeFme? •  If female fecundity increased with body size –  When small, be a male –  When large be a female h<p:// Why would be advantageous to change sex during lifeFme? Female Male Male Female •  If males fight for access to females –  Larger males get more maFngs –  When small, be a female –  When large, be a male Lobe‐finned fishes (Subclass Ac=nis=a) •  Different from ray‐fins •  Fins are fully muscular extensions of the skeleton –  jointed •  Very successful, many genera 400‐150 mya –  Extensive fossil record •  Only one extant genus (La#meria) –  Coelacanth –  Skeleton mostly carFlage but this is a derived condiFon Coelacanth Thought extinct 65 mya Discovered 1938 off Africa 2 known species Deep sea (500- 2500ʼ) -cold, well oxygenated water Large (5-6 ft) Bear live young Two living species of La#meria L. chalumnae L. menadoensis •  Original discovery from Comoro Islands was named La#meria chalumnae –  Steel blue in color •  Recent discovery in 1999 from Sulawesi has been named La#meria menadoensis –  Brown in color Bony fish diversifica=on (Chondrichthyes) sharks & rays Ray finned fishes (AcFnopterygii) Lobe finned fishes (AcFnisFa) Lungfishes (Dipnoi) Amniotes Lungfishes (subclass Dipnoi) •  Extant 6 species found in South America –  Many lineages were present 350‐400 mya •  Inhabit ponds and swamps (fresh water) •  Lobed fins •  Have gills but also gulp air into lung organs, connected to pharynx •  Ancestor of amphibians and all tetrapods was a lungfish Origin of tetrapods ~400‐300 mya An early tetrapod (‘tetrapod fish’) Acanthostega, a Devonian tetrapod (408 to 360 mya) fish Early amphibians were very similar Campbell Fig. 34.16 Tetrapods – Movement onto Land Pectoral and pelvic skeletal modifications adaptations for walking may have evolved while these animals still lived in water Recent fossil find in Canada from ~375 mya Benefits – “empty niche” Australian lungfish Neoceratodus forsteri h<p://‐us/news/2007/october/news_12547.html Challenges – Reduce water loss Eliminate wastes Large Temperature range air changes temp quickly low specific heat water has very high heat capacity much more stable environment Gravity animals neutrally buoyant in water on land – hard to support body, keep upright, move, etc. Vertebrate kidneys •  Fish ‐ ancestral kidney –  ExcreFon of nitrogenous waste •  Freshwater environment is hypotonic –  Salts less concentrated than in Fssues •  Freshwater fish, amphibians ‐ adapted to excrete excess water –  Frogs ‐ can reabsorb water from bladder while on land to preserve water lost through skin •  Terrestrial vertebrates ‐ primary goal is to preserve water –  RepFles and birds ‐ excrete nitrogen mostly in the form of uric acid ‐ requires li<le water –  Mammals ‐ excrete nitrogen mostly in form of urea, not as efficient at preserving water as uric acid –  yet sFll helps preserve water (Chondrichthyes) sharks & Ray finned fishes rays (AcFnopterygii) Lobe finned fishes Lungfishes (AcFnisFa) (Dipnoi) Amphibians Amniotes Invasion of land Amphibians – frogs, salamanders, caecilians (limbless burrowing amphibians) First Vertebrates on Land Need water / moisture many have aquatic larval stages adults – aquatic, terrestrial, both Respiration Lungs (not in all) Skin Oral Cavity Eggs - no shell dehydrate easily show different degrees of parental care incubate on adult mouth brood bubble nest (Chondrichthyes) sharks & Ray finned fishes rays (AcFnopterygii) Lobe finned fishes Lungfishes (AcFnisFa) (Dipnoi) Amphibians Amniotes AmnioFc egg The Amniote egg ‐ enabled fully terrestrial lifestyles Amniote egg •  Allantois ‐ waste disposal •  Shell and chorion ‐ permits gas exchange, relaFvely impermeable to water •  Amnion ‐ fluid filled ‐ prevents dehydraFon, also cushions embryo from shocks •  Yolk sac ‐ nutrients, transported to embryo by blood vessels •  Albumen ‐”egg white” also provides nutrients turtles REPTILES tuataras mammals amphibians ? Ancestral amniote lizards & snakes crocodilians birds Reptiles lizards, snakes, turtles crocodilians - closer to birds >17,200 species (more than half are birds) Keratin scales => skin is waterproof (and does not permit gas exchange Lungs - respiration Shelled eggs - amniotic Desiccation resistant shells Can complete life cycle on land Ectotherms (all reptiles) Internal body temperature determined by environment Control body temperature => behavior heating & cooling through exposure and protection from solar radiation anapsids diapsids EXTINCT ? Note: birds are nested within reptiles synapsids mammals turtles diapsids tuataras synapsids anapsids ? Ancestral amniote lizards & snakes crocodilians birds Lepidosaurs mammals turtles Squamates tuataras synapsids anapsids lizards & snakes diapsids ? Ancestral amniote Archosaurs crocodilians birds Posi=on of the birds within dinosaurs Plesiosaurs Ornithischians Ichthyosaurs Pterosaurs snakes lizards Lepidosaurs crocodilians Saurischians Dinosaurs Archosaurs Diapsids Birds Class Aves = Birds, evolved during Mesozoic (65-251 mya) Share with reptiles Amniotic eggs Scales on legs Lizard foot Chicken foot h<p:// 2073/2173306329_9f29ba6b35.jpg?v=0 h<p:// pix/anolfoot.jpg [China] [Europe] [China] Birds: ~9600 species 2g (hummingbird) 150 kg (ostrich) DisFnguishing features of birds Feathers Hollow long bones Fused lower leg bones Furcula Forelimb modified into a wing with three digits Four chambered heart (all archosaurs have this) with one aorFc arch •  Small lungs with 9 airsacs: unidirecFonal flow •  Endothermic (“warm‐blooded”) •  •  •  •  •  •  EvoluFon of fine scale feather structure •  Early on, simple structure likely aided thermoregulaFon •  Fine scale stucture enabled flight Bird bones Ulna (in forelimb) Bumps on ulna are sites of a<achment of secondary flight feathers h<p:// h<p:// Bird wings: digits 2,3,4 of the forelimb h<p:// ...
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This note was uploaded on 12/16/2011 for the course BIO 201 taught by Professor True during the Fall '08 term at SUNY Stony Brook.

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