Classmates & Professor Rodriguez:
1. One common homologous trait that gorilla, a
mammal in the order of primates, has a bony skeleton. In reptile family, in the order of crocodilia,
crocodiles have bony skeletons as well. Vertebrates were their common ancestor.
They have four limbs in common, which they share with amphibians as well. They
are all tetrapods. Amphibians go a different course. Gorillas stand upright on
their skeletons, also have live births with offspring born in fetal sacks. Crocodiles, with shorter, yet sturdy legs, evolved
to lay eggs, their offspring are surrounded by amniotic fluids. Two more changes
in the evolutionary tree and crocodile reptiles separate from gorilla primates.
Gorillas developed hairy bodies, probably due to environmental pressures. Crocodiles,
living lower to the ground encountered different characters and grew a bonier
skull accommodating the eye sockets and openings behind the eyes. Natural
environments exerted pressures on the natural selection of their individual
species. Crocodiles’ natural habitat is water. They flourish in a tropical climate
historically. Gorillas, and man, live almost
exclusively on land.
2. An analogous trait
commonly shared by a dragonfly and a butterfly is their ability to fly. While they
arise from a common winged-ancestor each
developed similarities due to their environments and natural selection, not based on the ability to fly alone. They each
have wings, used for attracting the opposite sex, as well as for quick flight. Dragonflies, in the order of Ondonata, family
of Anisoptera, are predators, and their offspring are found only in water. The offspring
have gils to breath under water on their underbellys. Adult dragonflies are
found in every country and prefer temperate environments and the wings are used
for flying only. Dragonflies feed on mosquitos, flies, and rarely butterflies. Butterflies do not eat but take nutrition
through drinking through a straw like probiscus. A significant difference in
utilizing their wing structures is dragonflies hold their wings up and away
from their bodies, visually closed. Butterflies, in the order of Lepodoptra, and in order to attract mates and ward off predators, utilize their wings through vivid colors, prefer
living meadows, wetlands and rainforests. Their wings have developed a thicker
texture, while dragonflies wings are more paper-thin and suited to their
environment.
Debbie G.
Traits needed to be more specific. Skeletons in general are just shared traits. You needed to pick a specific part of that skeleton that differed in the two organisms. For instance, you could have discussed the different structure of the first phalange of the gorilla and an alligator (or other reptile). In the gorilla, it has evolved into a thumb for grasping. In alligators, it is not differentiated in that way and is just another digit for locomotion across the ground. Since both organisms inherited the ancestral trait from an early reptile, these would be homologous traits. The goal of this section was to demonstrate a genetic ancestry for these specific (the key is "specific") traits and to explain their differences through different environmental pressures.
ReplyDeleteAnalogous traits do NOT arise from a common ancestor. I'm not very familiar with insect evolution, but you would have to demonstrate that the wings of these two organisms arose independently, not from common descent, in order to confirm that these are analogs instead of homologs. The goal for this section was to demonstrate similarity in function, in spite of the absence of genetic ancestry, due to common evolutionary pressures.
Make sure you read through a few other student posts to help you understand the differences between homologs and analogs.
Missing images for both sets of traits?
After having read some other posts by students, I see what I didn't comprehend previously. I perceived images as mental images of the traits, not actual pictures of them. I will try to better grasp the intent of each lesson.
ReplyDeleteThanks again,
Debbie G