BIO 301 unit 2 exam

1-22 chap6 Chondrichthyes; 23-39 chap7 Osteichthyes and Actinopterygii; 40-55 chap8 Sarcopterygii and the Origins of Tetrapods; 56-61 chap9 Origins of Lissamphibia and Amniota; 62-70 chap10 Mesozoic; - chap11

Describe three synapomorphies of Chondrichthyes.

Cartilaginous skeleton, placoid scales, pelvic claspers

List the synapomorphies of Elasmobranchs

Hyostylic jaw suspension - jaw can be extended and retracted during feeding

Describe the diversity and basic characteristics of Holocephali

• ~60 extant species

• primarily deep water fish

• rabbit-like head attached to long body (aka ratfish, rabbit fish, ghost sharks, chimeras)

• enlarged pectoral fins

• rostral extensions contain lots of lateral line organs and electroreceptors

• holostylic jaw (jaw is fused to chondrocranium)

• Reproductive ecology

  • males have cephalic clasper

  • annual mating meet up btwn sexes (stay separated by depth most of time, females deeper)

  • Oviparous (female deposits egg outside body)

  • few offspring per year, delayed onset of sexual maturity, low reproductive rates

• dorsal spine for defense, many have venom gland

Describe the diversity and basic characteristics Selachii

• ~570 extant species across two major groups

• range in feeding niches and size

• mostly streamlined fusiform shape

• ram ventilation (O2 intake through mouth by swimming)

• buoyancy with oily liver

Describe the diversity and basic characteristics Squalomorphii

• cold, deep ocean waters

• more primitive (smaller brain)

• ~170 extant species

• feeding specialists

  • cookie cutter shark takes chunks out of large prey

Describe the diversity and basic characteristics Galeomorphii

• ~350 species

• top carnivores of shallow, warm seas. can also be in cold water

• hammerheads, great whites, mako

• includes specialized filter feeding species like whale shark (largest living fish)

• generally larger but some smaller (horn shark 1m)

Describe the diversity and basic characteristics Batomorphii

• ~700 species: skates, rays, sawfish, etc

• dorsoventrally flattened

• eyes and spiracle on dorsal surface

• many ambush specialists (lie in wait in sand)

• pectoral fins enlarged, fused to chondrocranium, undulate for swimming, increased surface area for ampullae of lorenzini

Contrast the skeletons of cartilaginous fish with other vertebrates

Skeletons mineralized with same mineral as osteichthyan bones

• Calcium hyrdoxapatite

Deposited differently—forms calcified cartilage instead of bone

Describe the potential benefits and limitations of a cartilaginous skeleton.

pros: lighter, more buoyant, increased mobility.

cons: minerals are not as metabolically active, harder to repair than bone.

Explain the structure and function of tooth whorls.

series of teeth arranged in curled lines, flexible attachment to jaw (dispersal of biting force), allows rapid replacement of teeth (speed dependent on shark and environmental factors)

Determine whether this group exhibits internal or external fertilization.

internal fertilization

Describe the three reproductive strategies present in Chondrichthyes and identify which strategy is found in each subgroup.

Oviparity - lay eggs outside of body (ex. chimeras, many sharks like chain catshark)

Non-Placental Viviparity - pups get all nutrients from egg, lecithotrophy, egg is protected internally (dog-fish shark)

Placental Viviparity - live birth with matrotrophy (lemon shark)

Contrast lecithotrophy and matrotrophy.

Lecithotrophy - pups get all nutrients from egg

Matrotrophy - nutrients provided by reproductive tract of mother

Contrast holostylic and hyostylic jaws and identify which group has each type of jaw.

holostylic jaws are fused to chondrocranium - allow for crushing of prey, used by holocephalii

hyostylic jaws are must fused - allow for extension and grabbing of prey, used by selachii

Describe the sensory mechanisms in sharks and explain when they are likely to use each during the hunting process.

olfaction for detecting, lateral line (mechanoreception) for tracking, vision for orienting for attack, electroreception, lateral line, and touch for attacking

Explain why teeth might be especially important for sharks when they are hunting prey that is dangerous/difficult to subdue.

bite and hold until dead, frequently bite and release more dangerous prey, teeth are maximize severity of bite, encourage blood loss

Explain endothermal heterothermy.

What is it?

In which species does it occur?

Describe the general mechanism of this process.

What are the benefits of this process?

ability to maintain body temperature in different parts of the body

occurs in mackerel sharks, mako sharks, and white sharks

generate heat from muscle contractions, warmed blood passes close to cold oxygenated blood, heat exchange occurs by the time blood reaches the muscles.

swimming muscles and eyes are warmer than rest of body

may improve speed and performance and detection in areas with dim lights. allows them to occupy a wider rang of habitats

Define biofluorescence and explain its significance in sharks.

Definition: absorb one wave length and re-emit in a different wave length

enhances skin patterns, species specific and sexually dimorphic

intraspecific communication btwn sharks

Describe how the population dynamics of sharks and other cartilaginous fish make them vulnerable to disturbance.

Delayed offspring, few offspring and breeding period, infrequent reproduction. and long gestation.

Describe the current status of global shark populations.

36% of elasmobranchs are listed as threatened or worse, 70% of large predator sharks. Some species especially (hammerheads)

Explain the body plan of Batomorphs.

pectoral fins enlarged, fused to chondrocranium, undulate for swimming, increased surface area for ampullae of lorenzini

Explain the difference between skates and rays.

• Skates

  • long thick tail w/ two dorsal fins, usually small, oviparious

• Rays

  • whiplike tail w/ dorsal fins replaced by venomous spines, range of sizes, some species electric, viviparous

Describe four synapomorphies of Osteichthyes

1) Ossified endochondral bone 2) Addition of maxilla, premaxilla, dentary bones 3) Opercular Bone 4) Gas-filled sac(s) serving as lungs (aka ventral lungs on exam)

Explain which taxa fall into Osteichthyes clade

Includes all vertebrates EXCEPT cartilaginous fish, hagfish, lampreys

Osteichthyes split into two clades in the Silurian. Name the two clades and explain which vertebrates fall into each of these groups.

Actinopterygii (Ray-finned fish) - 34,000 species—More than any other group

Sarcopterygii (Lobe-finned fish) - Tetrapod lineage

Explain why Actinopterygii are known as ray-finned fish. Contrast the fins of early members of this group with later members of the group.

bony fin ray extend from radials in fins, these make up most of fins

Describe why Bichirs/Reedfish (Polypteriformes) are considered to be basal members of the Actinopterygii clade.

Exhibit many basal traits: Ganoid scales (armored scales), lungs ventral to gut and used for respiration, basals still present in fins, heterocercal tail (like sharks)

Compare the sturgeon (Acipenseriformes) to the bichirs (Polypteriformes) in terms of its lungs and caudal fin. What (if anything) has changed between these two basal lineages?

Lungs are dorsal to gut in sturgeons, still have heterocercal tail. loss of endochondral ossification (dermatocranium cartilagnous) scales are plate-like armor called scutes

What other unique traits do Sturgeons have? Know the general ecology of this group and why it is threatened.

Bottom dwelling fish, harvested for caviar and meat, high price for roe drives market for wild caught sturgeon

Describe the four synapomorphies of teleost fish and explain how these traits effect their ecology/behavior.

1) Homocercal Tail - caudal tail is very flexible

2) Scales are ctenoid or cycloid - overlapping shingles and part is exposed, thinner lighter scales, body more flexible during swimming

3) Mobile premaxilla - reduced cheek bones, allows oral cavity to rapidly open, suction effect

4) Lung evolves into swim bladder - not respiratory, buoyancy only, maintains position in water column → frees up paired fins from generating lift, reduction of basals and radials (mostly just fin rays), fins have more diverse uses (social, courtships, sound production)

Clupeomorpha: Herrings, sardines, anchovies

• silvery, mainly marine teleosts that feed on plankton

• most species are anadromous

• Anadromous: migrating from sea water to freshwater to spawn

• adult shad spawn in rivers; offspring live in freshwater for a summer then will live in sea water.

• many species, like sardines, form schools often called a "sardine run"

Characiformes: Tetras, piranhas, etc

• Found in South America and in Africa

  • Very important Amazonian food fish

• Pacus (herbivores famous for grinding their teeth) use their teeth to crack Brazil nuts

  • Piranhas have sharp teeth that aid their carnivorous diet

• Tetras are very popular for the aquarium-keeping hobby (large aquariums often feature piranhas)

Salmoniformes: Trout, Salmon, etc

• Salmoniformes and Esociforms resulted from the first branch of euteleosts

• Approximately 225 extant species

• Salmonids are important commercial and game fishes

  • Native to the Northern Hemisphere

  • Introduced and cultivated for aquaculture worldwide

• Many species of salmonids are anadromous

  • They spend their adult lives at sea, and make epic journeys up freshwater rivers to spawn

Contrast the three swimming styles described: Anguilliform, Carangiform and Ostraciform. Explain benefits/limitations to each style as noted and provide an example fish for each swim style.

Anguilliform: body bends more than half sinusoidal wavelength. substantial drag. ex. eels

Carangiform: body bends less than half of wavelength, reduces yaw (lateral head movement) increased speed and maneuverability, ex. herring

Ostraciform: bends caudal fin only, fused body scales and reduced # of vertebrae to prevent anterior contractions, slow swimmers, ex. pufferfish

Explain which reproductive modes are used by teleosts and note which is most common.

Oviparity, non-placental viviparity, placental viviparity. oviparity most common

Contrast reproduction in marine versus freshwater teleosts.

Marine: Pelagic eggs (tiny eggs that float in water column due to small oil droplet), bony fish only, large number of eggs, hatch into small larvae that drift in currents and feed on plankton, go on to metamorphize and settle to appropriate habitat

Freshwater: small number of eggs, yolk rich, demersal eggs that rest on floor, usually buried, parental care is possible (male guarding common)

Describe advantages/disadvantages of producing many tiny pelagic eggs.

advantages: less predators present, larvae hatch in nutrient rich areas, increased chance of colonizing new suitable habitats, widespread dispersal → less vulnerable to local environmental events, less vulnerable to extinction

disadvantages: eggs and larvae have a prolonged period of risk, many gametes are wasted

Define gonochorism and the prevalence of this trait in teleost fish

gonochorism: sex remains constant throughout life (88% of teleosts)

Explain the difference between protandry, protogyny, and simultaneous hermaphroditism in teleost fish. Provide an example of each from class or your textbook.

Protandry: started as male and eventually become female, clownfish

Protogyny: begin as females and eventually develop into males, blue-head wrasse

simultaneous hermaphroditism: have both functional male/female organs at same time, harlequin sea bass

Describe the extant groups of sarcopterygians (common names), comparing diversity

among these groups

2 species of coelacanths

6 species of lungfish

rest are tetrapods

Describe the ecology of coelacanths and how it relates to their rediscovery

Shelter in caves during the day, feed at night along slopes of underwater reefs and canyons

viviparous, likely internal fertilization

Name three unique traits of coelacanth anatomy and explain how swimming occurs in this group

unique rostral electroreceptor organ

diphycercal caudal tail

• symmetrical with vertebral column extending to tip

fat filled lung for buoyency

swims by moving pectoral and pelvic fins in pairs (similar to terrestrial tetrapods)

Explain how lungfish have a mix of terrestrial and aquatic traits

Ampullae for electroreception, lateral line, and large olfactory like fish

vomeronasal system (terrestrial), and able to perceive sound in both terrestrial and aquatic environments

Define aestivation. Explain how it relates to lungfish ecology

Aestivation: period of dormancy due to heat/drought

lungfish are able to survive droughts

explain why there are many fossils from Devonian Euramerica

sediment washing from steep slopes in north eastern america

Contrast the fins of Actinopterygian fish and Sarcopterygian fish

1) long fin rays and multiple basals

2) shorter fin rays, one basal

Contrast the following: monobasic fin of a lungfish, fin of a basal tetrapodomorph, tetrapod limb.

1) monobasic, single basal w/ radials braanching off

2) one-two bone pattern, reduced radials and mesomeres

3) one bone, two bone, lots of bones pattern

Explain how the following fossils enhance our understanding of tetrapod evolution. Be

able to explain which traits they posses that are fish-like versus tetrapod-like. You

should also be able to differentiate which ones are considered tetrapodomorphs vs.

tetrapods.

• Osteolepis

• Panderichthys

• Tiktaalik

• Acanthostega

• Ichthyostega

Tetrapodamorphs:

• Osteolepis

  • cylindrical body (fish)

  • heterocercal caudal fin (fish)

  • dorsal fins (fish)

  • Choana presesnt (tetrapod)

• Panderichthyes

  • loss of dorsal fins (tetrapod)

  • body flattened (tetrapod)

  • able to push up on fins

  • shallow water

• Tiktaalik

  • bones connecting head & pectoral girdle absent (tetrapod)

  • loss of opercular bone covering gills (tetrapod)

  • creates a neck (tetrapod)

  • pelvic and pectoral girdle similar sizes (tetrapod)

  • finger-like bones

  • fin rays, gills with soft tissue covering, pelvic girdle does not articulate with vertebral column (fish)

Tetrapods:

• Acanthostega

• Ichthyostega

Explain why terrestriality requires changes to the axial skeleton of vertebrates and describe the two key changes that occur between early tetrapodomorphs and tetrapods, including the function of these changes.

gravity is not major deal in water

changes to axial skeleton

• pectoral girdle not attached to cranial skeleton (form neck)

  • greater mobility of head

• attachment of pelvic girdle to vertebral column by sacral vertebrae

  • supports more weight and generate forward propulsion

Describe the components of the tetrapod limb

Stylopodium (humerus/femur) - derived from basal

Zuegopodium (radius/ulna + tibula/fibula) - derived from mesomere and proximal radial

Autopodium (carpals and digits)

Explain 5 potential benefits to terrestriality

1) reduced competition

2) evade predation

3) thermoregulation

4) dispersal

5) managing intertidal/water level fluctuations (ability to move over mud flats)

Discuss how the conditions of the Devonian Period relate to the evolution of terrestrial life

terrestrial habitat increasing → new niches to fill, lower global temps

Name the synapomorphy of Sarcopterygii

monobasic fin

List three synapomorphies of Tetrapodomorpha

choana, 1-2 bone pattern, loss of dermal bone

List three synapomorphies of Tetrapods

pelvic girdle attached to sacral vertebrae, vertebral zygapopphyes, true limbs

What is crown tetrapoda? What features are found in crown tetrapoda that are absent in earlier tetrapods like Acanthostega

last common ancestor to living groups of tetrapods (amphibians and amniotes)

have pentadactyle limbs, more mobile neck (occipital condyle)

Explain the evolutionary origins of Lissamphibia and Tetrapoda—when did they occur and what were the conditions like

split in the early carboniferous, covered in rainforests, dense swamps, and high humidity

Name extant groups in Lissamphibia and Amniota

Lissamphibia- caellians, salamanders, frogs

Amniota - mammals, reptiles, birds

Explain the benefits and challenges of an amniotic egg, explaining where appropriate the evolutionary strategies to overcome them

Benefits:

• resistant to dessication

• protects embryo from pathogens

• permits development w/o gilled larval stage

• calcium deposits in egg can be absorbed

Challenges

• prevents external fertilization (favors copulation)

• gas and waste management more complex

What is temporal fenestration? What is the evolutionary advantage of fenestrae?

Temporal fenestration: skull openings

provide room for jaw muscles to hinge

Contrast anapsid, synapsid, and diapsid skulls and be able to name which group has this skull type.

Anapsid: no fenestrae, no temporal arch, primitave, modern turtles

synapsid: one fenestrae, modern mammals

diapsid: two fenestrae, lepidosaurs (lizards, snakes, tuatara) anf archosaurs (crocs, birds, “dinos”

Contrast the geography and climate of the Triassic, Jurassic, and Cretaceous Periods, knowing key changes that occur in each period

Triassic:

• Pangea fully formed, all land is straddling the equator (equator is arid and too hot, animals are mostly in temperate areas.

• climate is hot and humid but unstable, mini extinctions from volcanic eruptions

• ends with Pangea breaking up, may have triggered more volcanic eruptions, temps rose 4 degrees C, one of the 5 big extinctions

Jurassic

• Pangea continues to split into Gondwana and Laurasia, epicontinental seas and extensive coastal environments

• Mostly warm, high CO2

Cretaceous

• Major continents are either in or approaching modern positions. Atlantic ocean expands

• Warm at the start, cools at the end

Describe the terrestrial ecosystems of the Triassic, Jurassic, and Cretaceous Periods

• Know key new groups that develop in these periods as well as dominant players during each period

Triassic:

• First teleosts, frog-like lissamphibians, early mammals, crocodilians, turtles

• Many ecosystems destroyed by Permian Extinction Event

• Late Permian food webs were modern—carnivores, herbivores, etc.

• Early Triassic faunas contain modest diversity of mammal-like reptiles (= non-mammalian synapsids)

  • Many herbivorous low-browsers

  • Some carnivorous species

Jurassic:

• Warm shallow seas create extensive habitat for coral reefs, Teleosts are radiating, We see a return to aquatic environments for many tetrapods, Lineages of marine reptiles that began evolving in Triassic are now dominant apex predators alongside sharks

• Period of low O2 that resulted from Triassic Mass Extinction may have set the stage for Archosaurs (lineage that includes crocs, dinos) to dominate over non-mammal synapsids

• First lizards and salamanders appear by the end of this period

• Radiations of dinosaurs including first birds and herbivorous and carnivorous dinosaurs (Sauropods, stegosaurs, and therapods)

Cretaceous:

• Angiosperm plants appear and diversify, arthropod pollinators and herbivores follow, all extant tetrapods present (birds, snakes, and all three major groups of living mammals (monotremes, marsupials, eutherians))

Explain the Mesozoic Marine Revolution, including

• What is it?

• What factors led to it (e.g., geographically, environmentally)

• How it influenced the evolution of marine life during this Era

• By Jurassic, ocean is crowded with predators of many sizes

• High number of shelled invertebrate prey due to increasing habitat and availability of calcium carbonate

• Evolutionary arms race takes off in Jurassic and continues for rest of Era

• Invertebrate prey—Selection for thicker shells to resist crushing by vertebrates

• Vertebrate predators evolving specialized adaptations for crushing shells

• Vertebrate predators continue to increase in size through this period and the Cretaceous

Explain why Archosaurs may have had an edge over non-mammal synapsids during the Jurassic Period

Archosaurs have more efficient respiratory system and can function in low O2 environments

Provide an example of niche partitioning among dinosaurs

Herbivores splitting into high-browsing and low-browsing feeders to create more niches

Describe the ecology/general characteristics of Sauropods, Stegosaurs, and Theropods

Sauropods: long-necked herbivores, large high-browsing herbivores, feed on foliage in tree tops

Stegosaurs: large low browsers, feed on low branches/shrubs

Theropods: bipedal with short arms, carnivorous, many are small, availability of large herbivores supports large members

Explain the Cretaceous Terrestrial Revolution, including—what it was, what ecological factors may have contributed to it, when it occurred

First time terrestrial diversity > marine diversity, diversification of plant life and additional niches to fill may have contributed, during the cretaceous

Contrast the causes of the two mass extinction events during this Era

End of Triassic: ends with Pangea breaking up, may have triggered more volcanic eruptions, temps rose 4 degrees C, one of the 5 big extinctions

K-Pg Extinction (end of cretaceous): Meteoroid impact in yucatan, mexico; widespread destruction in immediate area, tidal waves and fires, Hell’s Creek Formation in North Dakota, Dust cloud → global cooling, reduction of sunlight, diminished rainfall

Describe the impacts of the K-Pg extinction event on various vertebrate groups

43% of tetrapods go extinct

high imapact: all non-avian dinosaurs and 75% of birds, many marine reptiles (plesiosaurs), Metatherians (mammal lineage related to marsupials)

Moderate impact on crocs/turtles and other mammals

Low impact on amphibians, lizards, snakes, many fish asided from large predators