Guided Response: Read your classmates’ posts and respond to at least three of them. Add to their reflections by making connections or suggestions. Share specific examples from your own personal and

Week 6- Phylogeny (NEED TO FINISH PART 1-3)

Part 1- Introduction

Read the information and use your own and no other cited to answer the question and make some response. You Can use ‘I (Around 100-150 words)

Read Stephen J. Gould's classic essay, The Panda's Thumb. (It is often cited as an example of clear writing. If you disagree, there's a summary at the bottom of this page.) Then, as a group, discuss the following:

Why is it adaptive for panda's to have thumbs (why do they need them)?
Why is it surprising that they have thumbs?
Panda's have 5 fingers and a thumb. Why?
What is "descent with modification"?
What is "a contrivance" in the context of this essay?
What was Gould's point about the panda's thumb?
Did you learn anything else that is relevant to this course?
Please answer only one question and try to avoid repeating points that have already been made. To keep the discussion organized, you might repeat the question at the top of your post. If you wish to elaborate on a question that has already been answered, reply to that post.

Part 2 A – Finish the MC Choice

We've been looking at how natural selection can explain an animal's behavior. A complete explanation based on natural selection needs to address both the behavior's function and its phylogeny. A functional explanation shows why the behavior is adaptive. A phylogenetic explanation shows the evolutionary history behind the behavior. This week, we're going to look more closely at phylogeny. Phylogenies are often represented as trees, and the branches of the tree correspond to species. You've encountered the term species many times before, I know, but let's define it now. The simplest definition of a species is a group of animals that mate together. The animals within a species don't necessarily look similar, https://www.youtube.com/watch?v=O4STc1r-nVs&list=PLElB7nLNHZvjCQHR0R_0lEQAoWpzAxPek&index=17

the only requirement is that they can and do mate and produce viable offspring. Because the animals within a species intermix, they form a single pool of genes. (There are some exceptions to this definition, but it is good enough for our purposes. Check this video https://www.youtube.com/watch?v=dnfaiJJnzdE

if you want a more thorough explanation.)

This historical relationship between species is often illustrated with a "tree of life", which organizes living things based on their relatedness. The science behind the tree of life used to be based on the observable traits of organisms (phenotypes). Nowadays, phylogenetics is based on similarities in DNA (genotypes). This video provides a good introduction. https://www.youtube.com/watch?v=rdZOwyDbyL0

Watch the 3 youtubes https://www.youtube.com/watch?v=rdZOwyDbyL0 , https://www.youtube.com/watch?v=dnfaiJJnzdE , https://www.youtube.com/watch?v=O4STc1r-nVs&list=PLElB7nLNHZvjCQHR0R_0lEQAoWpzAxPek&index=17 and answer Q1-3

If having long legs makes an animal faster, then why don't all lizards have long legs?

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A: It is more adaptive to move slowly in extreme heat

B : Long legs are less stable on narrow surfaces (e.g. twigs)

C : Males find it easier to catch slower females.

What causes the reproductive isolation of the different anole species?

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A : females of different species are attracted to dewlaps of different colors

B : the anoles are separated by a mountain range

C : each species has unique pheromones

The scientist used similarities in DNA to make a phylogenetic tree for the anoles. The tree indicates that the most closely related species are

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A : similar in shape and color

B : occupy similar habitats

C : are on the same island

Watch https://www.pbs.org/wgbh/nova/labs/video_popup/6/36/ , In a phylogenetic tree, a branching point represents

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A : a speciation event (the splitting of one species into two)

B : the last common ancestor for the species on the two branches

C : an event that occurred in the past

D : all of the above

Watch https://www.youtube.com/watch?time_continue=3&v=fObmcBGMm9I , Which arachnid split off first (is most different from the others)

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A : horseshoe crabs

B : scorpions

C : ticks

D : spiders

reading an article about the phylogeny of bird penises. https://www.youtube.com/watch?v=qwjEeI2SmiU Most bird species don't have a penis, and that raises two questions: (1) why don't most birds have penises, and (2) how do they...

So, how do they?

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A : They just rub against each other (a "cloacal kiss").

B : The females have a penis.

C : They transfer the sperm with a specialized feather.

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Part 2 B – Check points answer

Checkpoint Question (This may seem hard, but it's not. Really.)
Below is the phylogenetic tree of three current species (A, B and C) that evolved from a common ancestral species (at the base of the tree). Under the tree are corresponding sequences of DNA for the current and ancestral species. You don't have enough information to match each sequence with a species, but you can compare the sequences to determine which of the following matches is most likely.

Ancestral Species

Ancestral Species

A T A C G G G T C A G C Current Species.

A A A C G G G T C A C T
2 A A T A C G G T G T G C
3. A A A C G G G T C A G T

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A : A = 1; B = 2; C = 3

B : A = 2; B = 3; C = 1

C : A = 3; B = 1; C = 2

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How did you arrive at your answer?

Part 3 –Use part 2 video and use your own word to write the response for below question

The anole video gave examples of both divergent and convergent evolution. Divergent evolution occurs when a population splits into two species (speciation). Convergent evolution occurs when different species evolve similar traits. Discuss the processes that caused divergent evolution and convergent evolution in the anole populations in the Caribbean.
If your group exhausts all of the relevant information in the video, then you can discuss convergent and divergent evolution in other species. The focus should be less on examples of divergent and convergent evolution and more on the forces that cause these two types of evolution.

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