a) Both the frog and rabbit have a homologous trait. Frogs are the largest group of the amphibian class. They live all over the world, and require to live near water sources to be able to reproduce. They are characterized by their abilities to jump, make croaking sounds, having slimy skin, and bulging eyes. Also, frogs have four limbs folded under their body, webbed feet, no tail, range in many different colors, and some are toxic. Rabbits are mammals that live in various habitats. They are herbivores with long ears, short tails, strong hind legs, and long rear feet. Also, they have fur of different color, depending if they are domestic or wild. The wild rabbits usually have brown or tan fur so they can camouflage, and domestic ones are usually black, white, or spotted. Rabbits are characterized by a great sense of sight, hearing, and great ability to run and jump.
b) The forelimbs of frogs and rabbits are homologs. The forelimbs of frogs are constructed of the humerus, ulna, radius, and carpal bones.The forelimbs are mainly used to move and balance themselves. They support the stout body of the frog when they sit or walk. These front legs also help to absorb the impact when they land from a jump. On the other hand, rabbits mainly use their forelimbs for the claws that grow on them. They also use them to hold on to things, especially food, with the paws. This forelimb is divided into an upper arm (brachium), middle forearm (antebrachium), and distal hand (manus). They use their claws on the forelimb to dig the ground and build their home, known as burrows. The rabbit evolved its front legs to use as a digging tool, for the need to hide from predators and have a place to live.
c) The common ancestor of the frog and rabbit is a fish (Eusthenopteron), which lived more than 385 million years ago. The similar structure of forelimbs, for the frog and rabbit, that is traced back to this fish shows that they share an evolutionary origin.
2. Analogous Traits:
a) Two species that possess an analogous trait are worms and snakes. Worms and snakes have many physical similarities. They are both long and legless creatures. Worms are part of invertebrate phyla. There are various types of worms but most share a cylindrical and tubular body shape. They can live in wet or dry habitats, so they are a key in the food chains of many ecosystems. Also, some are parasites and other are free-living. Snakes are carnivores and also have lots of different species. They do not have movable eyelids, limbs, ear openings, and a bladder. Snakes are amniote vertebrates covered in scales.
b) The shape of the snake and worm are analogous. The snake and worm evolved this shape to dig into the ground. The ground is their main habitat and they use their digging abilities to protect themselves from predators.
c) In reality, the snake evolved to be able to dig and build its underground tunnels. They did not evolve from a type of worm. Snakes are more related to the Komodo dragon. They evolved from a reptile, like lizard, and happened to get a body/shape like a worm.
Homology: Great opening description of your two species. Thorough.
ReplyDeleteGood description of the function of these forelimbs (though I would suggest that the rabbit also uses the forelimb for landing after a jump) but how is the difference in function reflected in structure, beyond the presence or absence of claws? How does the underlying bone structure differ? Are the bones lighter or heavier, longer or shorter, thinner or broader or shaped differently? We are looking to see how the structure changed from that common ancestor due to differences in environment and function. That needed to be addressed here.
Do we need to go all the way back to a fish for a common ancestor? And if the common ancestor is supposed to possess the general ancestral trait in question, how does that work with a limbless fish? Rabbits are mammals, who arose from reptiles, who arose from amphibians. Since frogs are also amphibians, the common ancestor was an archaic amphibian who DID possess the skeletal limb structure in question. This is what we needed to know to confirm the common genetic origin of a homologous trait.
Analogy: Good opening description.
I've never heard of this particular comparison before. Do you have evidence to back up the claim that snakes evolved this body shape specifically for digging in the ground? Seems like keeping limbs and claws would have been a better path for this.
So, did a quick search and it appears that the long, limbless body shape is advantageous for *burrowing*, not digging. They are more easily able to move through existing holes and tunnels, dug by other organisms (who have limbs). I'm willing to be this is true for the worm as well. They don't "dig". They "burrow" through loose dirt and existing holes.
https://www.wienslab.com/Publications_files/Evolution_of_Limblessness.pdf
For the ancestry section, you need to provide some evidence that the trait arose independently in at least one of the species. I'm not familiar with worm evolution but we know quite a bit about snake evolution. The elongated, limbless body shape has evolved independently several times in reptiles, long after any possible split with a distant common ancestor with the worm. That is the evidence we need to confirm analogy here.
Good images.
I really enjoyed reading your post for the homogolous trait as I hadn't thought to compare a frog to a rabbit and I thought that was a great example of how they're limbs are similar for jumping. You shared lots of good information about their similarities and how their common ancestor was a fish. Good job!
ReplyDeleteI think it's interesting how snakes and worms have limbless bodies in comparison to other animals like groundhogs, moles and rabbits who use thier limbs to dig out burrows for themselves. You did a great job describing how the snake is related to the komodo dragon. It had never crossed my mind that they were related even in the sence that they both use thier tongues for sampling the air. That was a great animal of choice to use as a comparison.
ReplyDeleteVery detailed post. I too chose a frog as my analogous animal as well. Not only do frogs share a big passion of mine because of my childhood, frogs are one of the most preferred animal to refer. Unique animals in our ecology, rabbits are very smart and also have a very rapid heart beat and must not be scared or they could have a serious heart attack. Snakes and worms are also two great choices and I hope that reading the biology I can get familiar with the wilderness and hopefully not get bit or have a poisonous outbreak.
ReplyDeleteYour response was very interesting had many details. Choosing worms and snakes for your analogous example was interesting. While they are obviously very much in common by appearance, they have a lot of distinct features as well. It is interesting how those two species do not have limbs in their bodies; it makes me wonder on how evolution brought them to be. Your photos were very helpful in understanding your response as well.
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