Bio 201 F11 Lect 19 (True) v2nr

Bio 201 F11 Lect 19 (True) v2nr - Biology in the News [see...

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Unformatted text preview: Biology in the News [see folder on BB] •  •  •  •  •  •  •  Heliconius is a genus of tropical bu9erflies that is known for ea<ng passionflower (Passiflora) plants as larvae and can efficiently find their food sources and extend their reproduc<ve output up to 2000 eggs given the right food condi<ons They are also known for their diverse and rapidly evolving colora<on (a form of warning colora<on as passion flower vines contain toxins which the bu9erflies incorporate to be poisonous to predators) Prof. Larry Gilbert at U Texas Aus<n leads a group studying a popula<on of Heliconius melpomene that appears to be undergoing specia<on A mountain range appears to be par<ally separa<ng the two subpopula<ons and preven<ng them from interbreeding (i.e. this is a poten<al example of allopatric specia<on) color pa9erns are involved in species recogni<on and ma<ng preferences, as well as predator avoidance mate preferences for their own color pa9erns appear to be driving the ini<al steps of specia<on a hybrid zone is present, which allows some gene flow between the popula<ons, which are only clearly differen<ated gene<cally at genes involved h9p://<on/ in color pa9erning evolu<onac<on.jsp?WT.mc_id=USNSF_51 nd mid term exam 2 •  •  •  •  •  •  •  •  Wed. October 26th in class covers material from Mon. 26‐Sept. through Fri. 21‐Oct. (10 lectures) prac<ce ques<ons will be posted; review sessions – next slide Be on <me –  >10 min late will not be allowed into room Bring only your ID and pencils –  All other materials have to be lee on periphery of the room 35 mul<ple choice ques<ons + 3 bonus bio news ques<ons 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 Ques<ons! Classes of echinoderms only need to know common names indicated in red •  Asteroidea ‐ sea stars •  Ophiuroidea ‐ bri9le stars •  Echinoidea ‐ sea urchins, sand dollars •  Holothuroidea ‐ sea cucumbers •  Crinoidea ‐ sea lilies and feather stars •  Concentricycloidea ‐ sea daisies Special case of symmetry evolu@on: Sea cucumbers •  Adults elongated along oral aboral axis •  Lay on sea floor on their sides –  Independently evolved dorsal ventral asymmetry •  This is essen<ally a form of bilateral symmetry (secondary bilateral symmetry) Braised Sea Cucumber with Oyster Sauce Sea urchin sushi h9p:// ac<on=view&current=UniSeaUrchin.jpg Sea urchin roe market in Japan h9p:// 85284970.Svlf3tyV.IMG_6587.jpg Deuterostomes LIFE 9th ed. Fig. 33.1 Formally NOT chordates Hemichordates “acorn worms” Echinoderms Urochordates called “tunicates” or “sea Cephalochordates squirts” (“lancelets”) Vertebrates echinoderms hemichordates Hemichordates Acorn worms Marine, worm‐like deuterostomes •  a Phylum of Deuterostomes (only briefly men<oned in the textbook) •  Have some similari<es to both echinoderms and chordates –  Tornaria larvae very similar to sea star larvae –  Have gill slits and dorsal nerve cord similar to chordates •  Do not have a notochord chordates Phylum Hemichordata Acorn worms and Pterobranchs 3 Body regions – Each with Coelomic space Proboscis Collar Trunk Class Enteropneusta Enteropneusts = “Acorn Worms” free living Hemichordates ~75 known species Up to 2m in length Pharynx Gill Slits - may be homologous to chordate gill slits U-Shaped Collect Food - primary function Also function in respiration Similarity of hemichordate Tornaria larva to sea star Bipinnaria larva h9p:// h9p:// bio182/labreview/embryo/bipinn.jpg Pterobranchs – Sedentary tubedwellers -secrete rigid tubes -colonial -most species: no dorsal nerve cord and only one gill slit Class Pterobranchia ~20 known species All very small (<12mm) Some species are colonial Collar tentacles capture small prey and perform gas exchange Invertebrate chordates Hemichordates “acorn worms” Urochordates called “tunicates” or “sea Cephalochordates squirts” (“lancelets”) Vertebrates Echinoderms 1. Notochord 2. Dorsal, hollow nerve cord 3. Pharyngeal slits 4. Muscular, postanal tail (postanal = behind anus) Chordates •  Share four fundamental structural features Notochord •  Flexible rod extending down the length of the animal •  Posi<oned between the diges<ve tube and the nerve cord •  Made of large, fluid‐filled cells encased in s<ff, fibrous <ssue –  ‐provides skeletal support •  Present in adults of some invertebrate chordates and some primi<ve (basal) vertebrates •  Only remnants remain in most adult vertebrates –  Discs in the spinal column are remnants of notochord –  Vertebrae replace notochord during early development the notochord of a sea squirt larva h9p:// honors/ls_honors/ascidian_notochord.jpg Human spinal discs Dorsal, hollow nerve cord •  Develops from plate of ectoderm which invaginates •  Becomes the central nervous system and brain •  Different from other animal phyla, which have ventral, solid nerve cords note: neural crest generally thought of as a vertebrate innova<on, but recent research has found neural crest‐like cells in urochordates Pharyngeal slits •  Slits in pharynx, just posterior to the mouth •  Slits allow water passing through the mouth to exit the body without going through en<re diges<ve tract Pharyngeal gill slits of the lancelet Amphioxus h9p:// Pharyngeal slits •  Invertebrate chordates –  Used for suspension feeding Pharyingeal gill slits of a cephalochordate •  Aqua<c chordates (including the cephalochordate above) –  Used for gas exchange (gills) •  involved in: –  Jaw evolu<on –  Ear evolu<on Muscular, postanal tail •  Most other animals, gut extends en<re length of the body •  In chordates, tail extends the body beyond the end of the gut •  Many aqua<c species use this tail for propulsion h9p://<es/science/ biological_sciences/lab13/images/tuniclarv.jpeg Urochordates •  Also called Tunicates, or Sea Squirts –  Eject jet of water when disturbed •  1mm to 60 cm long; some colonial •  Mobile larvae –  Many species show all 4 chordate hallmarks in larvae •  Sessile (non‐moving) adults –  Adhere to rocks or other hard surfaces –  Feed on par<cles and small organisms suspended in the water Colony of the blue bell tunicate, Clavelina puertosecensis Pharyngeal basket Ciona intes*nalis: a molecular gene@c model urochordate (tunicate) •  small genome compared to humans: ~16,000 genes •  has 80% of the genes that humans have –  many differences in # of members of gene families •  fairly easily cultured in the lab and can be gene<cally engineered •  crucial in studying the developmental evolu<on of the notochord and many other chordate traits http:// www.geochembio.c om/IMG/cionaintestinalis-adultlarva.jpg Cephalochordates Also called lancelets (shaped like a blade) Adults small, few cm or less, ~30 species known Adults have all the chordate hallmarks Live in sand at bo9om –  Feed on par<cles suspended in the water •  Most famous cephalochordate: Amphioxus •  •  •  •  –  Genome recently sequenced ~21,900 genes Muscle segments develop from blocks of mesoderm called Somites Hemichordates “acorn worms” Echinoderms Urochordates called “tunicates” or “sea Cephalochordates squirts” (“lancelets”) Vertebrates 1. Cranium (skull) 2. Brain elabora<on 3. Paired sense organs on head 4. Neural crest cells Features shared by all vertebrates (basal chordate groups do not have these) Cranium (skull) Brain elabora<on Paired sense organs on head Neural crest cells (but see previous slide on possible neural crest in urochordates) Neural crest cells ‐ ectodermal cells ‐can move to many places in developing body ‐differen<ate into: ‐spinal cord ‐peripheral nervous system ‐pigment cells (melanocytes) ‐car<lage ‐blood cells ‐skull and facial bones Evolu@on of basal vertebrates Cephalo‐ chordates Agnathans (Jawless fishes) Hagfishes Lampreys Gnathostomes (Jawed vertebrates)  Jaws  2 sets of paired appendanges  Ossifica<on Vertebral column 4 key vertebrate features (see previous slide) Vertebrate Evolution -vertebrates are thought to have evolved in estuaries (interface of salt and fresh water) Hagfishes (class Myxini) •  ~ 58 species, all marine •  Skeleton en<rely car<lage •  Don’t have vertebrae –  Single car<lage rod (=notochord) •  Scavenge on bo9om •  Mouth has tongue‐like structure with rasps (like teeth) for ripping dead material or live prey (usually polychaetes) •  Have slime as defense against predators Lampreys (class Cephalaspidomorphi) ~35 species Some freshwater, others marine External parasites of fish Feed using disc‐shaped mouth and rasp‐like tongue to penetrate fish skin and suck blood •  Larva = lancelet like •  •  •  •  Lamprey skeleton •  Has car<lage notochord, like hagfishes •  Also has car<lage tube surrounding notochord Nerve cord Endoskeletal elements Notochord –  Some projec<ons extend Centra upward to par<ally Lamprey (jawless surround nerve cord vertebrate) –  May be what an early stage of the vertebral Gnathostome column looked like (jawed vertebrate) dorsal ventral Centra (singular, centrum) = “vertebral bodies” develop into main bodies of vertebrae dorsal ventral Sea lamprey invasion of the Great Lakes •  •  •  sea lamprey (Petromyzon marinus) ‐ na<ve to Atlan<c Ocean Invaded Great Lakes in 1830s (but may be na<ve to Lake Ontario); canals (Erie, Welland) facilitated spread through en<re Great Lakes caused crashes of na<ve fish popula<ons in Western Great Lakes in the mid 20th Century –  •  •  •  Lake Superior including important sport fish: lake trout, lake whitefish, and others decreases in these predatory fish caused a massive increase in alewife popula<ons, (which are prey of trout and other top predators affected by lampreys) various control efforts have been launched (including barriers to prevent their dispersal from shallow waters where they breed and chemical "lampricides") these programs have been somewhat successful, par<ally restoring the sport fishery sea_lamprey/tech_assistance.html Evolu<on of the jaw ‐from skeletal supports of pharyngeal slits Diversifica@on of jawed vertebrates (Gnathostomes) lampreys Sharks and rays (Chondrichthyes) Bony fishes (Osteichthyes) Tetrapods Bony fishes include: Ray‐finned fishes Coelacanths Lungfishes ...
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