Vestigial Structures
Some humans are genetically determined to have 4, some 3, some 2, some 1, and some none.
What are wisdom teeth?
Organisms with homologous structures share those structures because of this.
What is a common ancestor?
Organisms with analogous structures share those structures because of this.
What is a similar environment?
True or false: every living thing has DNA that can be used to compare to the DNA of every other living thing.
What is true?
In the Embryology of Vertebrates part of your handout, which stage was the earliest stage of development?
What is Stage 1?
This forearm muscle is vestigial and, if present, one of the first used by cosmetic surgeons.
What is the palmaris longus?
We looked at this part of animals' bodies (including our own) in order to understand homologous structures.
What is forelimb (arms, legs, limbs)?
We looked at this part of organisms' bodies in order to understand analogous structures.
What is wings?
These random changes in DNA can be used to estimate how recently two organisms share a common ancestor.
What are mutations?
These two features are present in all Stage 2 embryos.
What are limb buds and tails?
Rarely, a mutation occurs and human babies are born with this evidence of evolution that is normally programmed to disappear during development.
What is a tail?
The various colors used in the images of homologous structures (in the slides you looked at) represent these.
What are bones?
What is a common ancestor?
When determining common ancestry, the differences in DNA sequences between two organisms is indicative of their relatedness. More differences indicates this.
What is a more distant common ancestor (they are less closely related)?
Normally developed humans have this feature during embryonic development but lose it before birth
What is a tail?
Experiments demonstrate that vestigial muscles continue to try to move these body parts in response to sound.
What are ears?
Differences in organisms with homologous structures come about because of this (these).
What are different environments?
Select the correct pair of organisms with ANALOGOUS structures:
Pair #1: bat leg and duck-billed platypus leg
Pair #2: duck bill and duck-billed platypus bill
What is Pair #2: duck bill and duck-billed platypus bill?
The less evolutionary time that passes between two different organisms branching off from a common ancestor, the less time there is for changes in their DNA to occur. Therefore, those two organisms tend to be...?
What is more similar (more closely related, more genetically related)?
These are the creatures from Part 7 (Embryology of Vertebrates) of the handout that have tails as embryos and also after birth.
What is all other than humans (fish, salamander, tortoise, chick, hog, calf, rabbit).
Vestigial structures are evidence of this. Provide a specific example.
What is evidence of structures in ancestors that were once useful but are no longer so they are being gradually lost over evolutionary time.
Homologous structures are evidence of this. Provide a specific example.
What is common ancestry (in genetic/physical form) that is then shaped over evolutionary time and by random mutations to "fit" different environments. Appropriateness of example discretion of Ms. M
Analogous structures are evidence of this. Provide a specific example.
What is the convergence over evolutionary time and via random mutations towards a similar shape or form to "fit" similar environments, without a common ancestor providing any underlying genetic/physical relatedness? Appropriateness of example discretion of Ms. M
In the cladogram that Ms. M shows you, which group of organisms has the more recent common ancestor?
Group #1: Rodents & rabbits and primates
Group #2: Dinosaurs & birds and crocodiles
What is they all share the same most recent common ancestor?
All the organisms in this part of the handout (including humans) have limb buds and tails during embryonic development, but humans are the only ones to lose their tails before birth. Additionally, it was likely quite challenging for you to sort the Stage 1 and Stage 2 images. Explain the significance of these facts.
What is humans share a great deal of embryological development with other creatures, demonstrating that we have close common ancestors with them, and likely only recently in evolutionary time lost our tails before birth?