Question

Looking at the antomy of: Bufffrog, Amphioxus, Lamprey, Perch, Dogfish and MudPuppy

i) List the characters of each organism listed above that will help in building a phylogenetic tree.

ii) Depict which characteristics that will be plesiomorphic and which will be apomorphic.

iii) From the information above, make a phylogenetic tree that illustrates the assumed relationship (phylogenetic) of the chordates listed above.

iv) In the form of an essay, utilize the anatomy of the six organisms above, justify your phylogenetic tree.

Answer 1

1)Buff frog- i really don,t know this name i think it is frog. Frogs have the characteristics of: two bulging eyes; strong, long, webbed hind feet that are adapted for leaping and swimming; and smooth or slimy skin (generally, frogs tend to like moister environments than toads).

Lamprey-A characteristic feature of these craniates is an anterior, rounded, sucker-like structure that is used to attach themselves to the body of their prey, from which the term “cyclostome” is derived

The yellow perch—Perca flavens—is an actinopterygians that are a huge success story, both in terms of diversity and numbers, with about 25,000 species known. The fins of actinopterygians are supported by slender, rod-like rays or lepidotrichia radiating from the base of the fin; the musculature controlling the fin is largely within the body wall. The perch belongs to Perciformes, a member of Acanthop­terygii, the spiny-finned fishes.

Dogfish- This long, slender dogfish has a pointed snout, large eyes, and spines in front of its two dorsal fins.

mudpuppy. The common mudpuppy, Necturus maculosus, is a member of Caudata, which together with Anura (frogs and toads) and Gymnophiona (caecilians or apodans) form Amphibia. Caudata, including the salamanders and newts, are the least specialized amphib­ians in the terms of body form and locomotion. The body is elon­gated and stout, with well-developed axial musculature and tail. Frogs are characterized by a shortened body and specialized saltatory locomotion and the limbless gymnophionans inhabit terrestrial to aquatic habitats.

2)All these terms have to do with identifying organisms, called taxa, into "family trees", according to identifying traits or characteristics.

Synapomorphy: a trait share by 2 or more taxa and their most recent common ancestor.

Symplesiomorphy (also known as plesiomorphy): A characteristic shared by 2 or more taxa also found in their earliest common ancestor.

Apomorphy: A characteristic believed to have evolved within a family tree; can be used to separate one group from the other.

All these terms provide valuable information, depending on how one is constructing the family tree or taxa. The first two, synapomorphy and symplesiomorphy, provide evidence among similarities between recent taxa and their ancestors. Apomorphy distinguishes differences between recent taxa and their ancestors, providing a breaking-off point that could be used to establish new groups or sub-groups.

3)

Echinodermata (sea stars, sea urchins) Deuterostomes Cephalochordata (lancelets) Chordates (notochord) Chordate ancestor (possessed notochord) Urochordata (tunicates) Myxini (hagfishes) Petromyzontida (lampreys) Craniata (head) Vertebrata (vertebral column) Chondrichthyes (sharks, rays, chimaeras) Gnathostomes (jaw) Actinopterygii (ray-finned fishes) Lungs Actinistia (coelacanths) Dipnoi (lungfishes) Four limbs Amphibia (frogs, salamanders) Tetrapods (four legs) Amniota (amniotic egg) Reptilia (turtles, snakes, crocodiles, birds) Mammals (milk) Mammalia (mammals)