a. Humans and Dolphins
b. dolphin's pectoral fins have a similar bone structure to the human arm and hand sharing the same bones: Humerus, ulna, radius, carpals, metacarpals, and phalanges. However, the function of the human arm and hand and the dolphin pectoral fin are vastly different with the human arm and hand being used for things like writing, eating, constructing objects, making gestures, self defense, etc. while the dolphin's pectoral fins are used for balance, and help a dolphin steer and stop while swimming.
c. Humans descend from primates, while dolphins descend from a land mammal due to their need for air and the bone structure of their fins greatly resembling the bone structure of land mammals.
d.
2. Two species with an analogous trait
a. Platypus and ducks
b. both species possess bills however while a duck's bill is used for eating and anything relating to eating food like filtering out extra water or inedible things a platypus's bill is used detect smaller prey while it swims under water through electrolocation, which is being able to sense an object through a weak electrical field, in addition to use its bill to eat.
c. the common ancestors of both species may have possessed similar traits but given how platypus are mammals and ducks are birds they would most likely have had different ancestors thus their traits would still be analogous as a result.
d.
"Describe" means more than "identify". The initial section should have been expanded and more complete. (Applies to the first part of your analogous section as well.)
ReplyDeleteI agree that there are skeletal similarities between the human and dolphin limb and that there are functional differences. The question is, how are those functional differences reflected in the skeletal system? That is what you need to explain to help support your claim that these are homologous traits.
Both humans and mammals descended from land mammals that possessed the ancestral limb structure. You needed to make that connection to demonstrate that these structures arose from common descent and are therefore homologous traits.
Okay on your description of the bills in the platypus and duck as your analogous trait pairing.
In order for these bills to be analogous, the common ancestor did not pass the trait onto both organisms. It had to arise independently in at least one of these organisms. In this case, with the platypus being a mammal and the duck being a bird, the common ancestor was a reptile, which was likely bill-less. That means the trait arose independently in both species, but it helps that we know about the evolution of both the platypus and the duck and understand how their bills evolved, which confirms that these are indeed analogous traits.