Lecture exam 1 Flashcards
Herpetology
Study of amphibians & non-avian reptiles **both groups were included within a single discipline for a long time because they were not known to be distantly related to one another.
How many living species of Amphibia are there?
~7080 living species
What are the 3 major extant clades included in Amphibia?
Anura (Salientia = stem based name) Caudata (Urodela = stem based name) Gymnophonia (Apoda = stem based name)
How many species are within the Anura clade?
Frogs & toads ~6250 species
How many species of Caudata are there?
Salamanders & Newts ~640 species
How many species of Gymnophiona are there?
Caecilians ~200 species
How many living species are in Reptilia?
~19,500 living species
What are the 5 major extant clades within Reptilia?
Chelonia Crocodylia Rhynchocephalia Squamata Aves (10,000 species) ~9500 sp. are non-avian
How many species of Chelonia are there?
Turtles ~ 320
How many species of Crocodylia are there?
Alligators, crocodiles, & caimans ~25 species
How many species of Rhynchocephalia are there?
Tautara ~2 species
How many species of Sqamata are there?
Lizards & Snakes ~ 9200 species
How are phylogenetic relationships inferred? What types of things are not used?
-infer phylogenetic relationships based on derived characters, or apomorphies -do not base relationships on plesiomorphies (ancestral or primitive characters)
What types of data can be used to determine phylogenetic relationships among taxa?
Morphology (osteology, external morphology, etc) , DNA sequences, others such as behavior, allozyme data, karyology, etc.
What methods can be used to determine phylogenetic relationships?
Cladistic analysis (parsimony; used for frequent method for morphology & non-DNA data), and Maximum likelihood & Bayesialn methods (used primarily DNA data and is a model-based analysis)
What is a monophyletic group? A paraphyletic group?
Monophyletic group- a common ancestor plus all of its decedents Paraphyletic group- a common ancestor plus some, but not all, of its decendents
What is a synapomorphy? A synplesiomorphy?
synapomorphy- a shared derived character, derived character exhibited by the common ancestor of a clade synplesiomorphy-a shared ancestral character **don’t use these to infer relationships**
Compare and contrast node-based names vs. stem based names.
Node based name is the most recent common ancestor of two or more groups and all of it’s descendants. Stem based names include all taxa more closely related to a particular group than to some alternative group. Similarities: Both are used to describe parts of a phylogeny and to communicate effectively with others about a specific phylogeny. Differences: They are used to describe different parts of a phylogeny. Stem based names are a more inclusive group and node-based names are used to describe the common ancestor of a particular group and all descendants.
Compare and contrast positive-pressure lung ventilation vs. negative-pressure lung ventilation.
Positive-pressure ventilation is applying pressure to move air into the lungs. Negative-pressure ventilation is expanding a space to create a vacuum to draw air into the lungs. Similarities: Both are methods of ventilating the lungs. Differences: One draws air in by creating a vacuum (negative-pressure) and the other physically pushes air into the lungs by applying a pressure to a sac (positive-pressure)
When naming node-based taxa, why do systematists generally use the more commonly used (traditional) name?
Commonly used names are restricted to node-based taxa because there is higher confidence in the construction of these groups. The reason for this is that often soft anatomy parts are used to identify extant taxa, and these parts do not fossilize well, so there is a little more uncertainty with groups that include only fossilized forms or extinct taxa. For this reason, when naming a node-based name, the more commonly used name is used to communicate certainty.
Describe the evidence that suggests that Ichthyostega was better adapted for terrestrial life than earlier forms of the early extinct osteolepids (ex Acanthostega)?
Earlier forms such as the Acanthostega possessed internal gills, relatively long limbs which would have been weak support for the body on land, had a pelvic girdle weakly attached to a poorly developed vertebral column, short thin ribs that would not have been able to protect the vital organs, and tail fin well suited for swimming but would have been mangled on land. The Ichthyostega had robust forelimbs with weight-bearing elbows (but weak hind limbs), a vertebral column with supporting zygapophyses, smaller supraneural arches on tail meaning less support for the tail fin, a massive rib cage that would have protected vital organs well on land, no evidence of internal gills. **The gills, larger forelimbs and ribs, and support for vertebral column, along with bending wrists and neck are all good evidence.
Why might some herbivorous reptiles (particularly those living in deserts) modify their consumption of plant material over a given season?
Sometimes in a hot desert eating plants may be the only way for a reptile to get any water. Of the few ways reptiles are able to obtain water for their survival, drinking or metabolic water intake may not be enough, so they may have to use the only other option, preformed water by food intake. If they are able to obtain more water from their environment by drinking it, they may not have to depend on their food, and may eat less.
Some desert reptiles may also stop feeding if the water content of a plant falls below a certain level because it costs more energy and water to digest the plant than what would actually be obtained from eating it. Chuckwallas (Sauromalus) is an example of this.
What is the biological reason that amphibians are generally thermoconformers?
The main reason amphibians are thermoconfomers is because of their permeable skin and evaporative cooling. The amphibians are unable to absorb heat from their environments by sitting in the sun like reptiles because they will lose more of their water through evaporation, and as this happens evaporative cooling will cool the overall body temperature.
Describe the mechanism used by crocodiles to ventilate their lungs.
The liver is involved with compressing and expanding the lungs in the crocodiles. The liver act as a plunger and is located behind the lungs. For exhalation, the muscles pull the liver forward to compress the lungs and push the air out (positive pressure). For inhalation the muscles pull the liver back, expanding the area of the lungs as this occurs, and causes a vacuum to suck air into the lungs (negative pressure).
