BIOL 330 - Vertebrates

Traditional binominal nomenclature is based…

mainly on anatomical features

Limitations of traditional binominal nomenclature

1. species are static

2. Which similarities between species are more significant than others? (e.g. Paired limbs vs. mammary glands)

3 Goals of scientific naming of species

1. Uniqueness = no two species can share the same name

2. Universality = everyone agrees to use the same name

3. Stability = a species name cannot be changed once it is properly named

Phylogenetic systematics

classifying organisms based on shared ancestry

Cladistics

classifying organisms within phylogenetic systematics that is characterized by its use of shared derived characteristics.

parsimony

Any change in a structure is an unlikely event, so the most plausible phylogeny is the one requiring the fewest number of changes

apomorphy

features that have evolved and are different from the ancestral or primitive traits.

synapomorphy

shared, derived trait found in multiple species that was inherited by a recent common ancestor

Plesiomorphies

ancestral characteristics that are shared between all members of a clade (does not reveal anything about the relatedness of the taxa within the clade)

Homoplasy

analogous trait (similarities in characters that are not indicative of a common ancestry)

parallel evolution

Convergent evolution (similar characteristics that have evolved independently in separate evolutionary lineages)

Homology

similarity in traits due to shared ancestor

3 Synapomorphies of Chordata

1) Notochord-dorsal stiffening rod

2) Dorsal hollow neural tube

3) Segmented, postanal tail

2 subdivisions of shark mesoderm (developed from coelem)

pericardial cavity & peritoneal cavity

2 subdivisions of salamander coelom

4 subdivisions of cat coelom

Mineralized connective tissue is made up of

collagen and crystals of calcium hydroxyapatite

Chondrocranium function

protects the brain, nose, inner ear

Dermatocranium function

protects the brain, anchors teeth, provides attachment sites for muscles

Splanchnocranium function

functions in feeding and respiration

Osteognathostomata

all vertebrates with bone

Odontodes

small, toothlike elements in the skin consisting of projections of dentine from a bony base covered with an outer layer of enamel in early vertebrates

advantages of mineralized tissues in vertebrates

1. Protection from predators

2. Storage and regulation of phosphorus and calcium

3 pieces of evidence for the marine origin of vertebrates

1. Earliest vertebrate fossils are from marine sediments

2. Invertebrate deuterostomes are exclusively marine, and have body fluids with about the same osmolal concentration as their surroundings

3. Hagfishes (early vertebrates) have concentrated body fluids like surrounding seawater

flowthrough ventilation

water is drawn into the mouth and pumped out over the gills (buccal pumping)

tidal ventilation

water is drawn in and expelled it out through the gill openings using muscles associated with their gill slits.

which lampreys use flowthrough ventilation

Larval lamprey and adults of nonparasitic species

which lampreys use tidal ventilation

Adult parasitic lampreys

anadromous/anadromy

adults lampreys live in the ocean

potamodromous/potamodromy

adults lampreys live in large lakes

4 stages of lamprey life cycle

1. emergence of larva from stream bed and metamorphosis

2. migration of adults into lakes or oceans

3. migration of adults into streams

4. death of adults after spawning

4 new behaviours due to the development of jaws

1. Grasping and cutting prey & herbivory

2. Grasping of mates during courtship

3. Grasping of juveniles during parental care

4. Refuge and nest building

4 uses of paired fins (pectoral, pelvic) in gnathostomes

1. Improved locomotion for predation (braking, tilting, thrust)

2. Anti-predator defenses (e.g. spines)

3. Visual signals to mates & predators

4. Reproduction

secondary lamellae

microscopic projections from gill filaments for gas exchange

What do fish living in low oxygen environments use to supplement oxygen needs

lungs or accessory respiratory structures (vascularized ‘labyrinth’ chambers)

Why do fish maintain neutral buoyancy (same density as water)?

1. Reduces energy consumption when ascending/descending

2. Weightless body requires less energy to move at a given speed

how do fish maintain neutral buoyancy

swim bladders

how do fish go deeper in water

added pressure compresses gas, bladder becomes smaller, buoyancy reduced – fish secretes gas into bladder

how do fish go shallower in water

relaxed pressure expands gas, bladder becomes larger, buoyancy increased - fish removes gas

Two types of swim bladders

Physostomes & Physoclists

Physostomes

Retain a connection between the gut and bladder (pneumatic duct)

Permits gulping of air to fill bladder and burping to empty it E.x Basal teleosts

Physoclists

Increase gas bladder volume by secreting gas from blood into the bladder

Decrease gas bladder volume by absorbing gas from the bladder and releasing it at the gills

Rete mirabile moves oxygen from the blood into the gas bladder

Ovale allows oxygen to diffuse into the blood when the ovale sphincter muscle is open

how do Cartilaginous fishes maintain buoyancy?

they use their liver to create neutral buoyancy