BIO120H1 Chapter 3: COYNE CH3

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3 Mar 2011

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Chapter 3: remnants: vestiges, embryos, and bad design. There are features (vestigial) and genes that were once useful. Vestiges feature of species that was an adaptation in its ancestors but has lost its usefulness or has been adapted for other uses. Longer performs funct ion for wh ich i t evolved (not necessarily that it has no function). Example: ostrich wings not for flight but for balance, weaponry and mating. Bones of wings same in both flying and flightless birds. Why lose flight: flight is metabolically expensive and wings easily injured. If lack of predators on island or food abundant on ground, then makes sense to reserve energy. Still visible because a) has other uses b) actually in the middle of transition. Also, eyes in burrowers and cave dwellers: mutations over time can just accumulate if they neither harm nor help the animal.

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3. Some Caminalcules went extinct without leaving descendents. In the real world, what intrinsic factors (i.e., related to an organismâs basic reproductive biology, population biology, ecological niche, etc.) or extrinsic factors (e.g., ecological/environmental factors) might increase or decrease the probability of a species going extinct? PLEASE DO NOT REFER TO HUMAN-CAUSED EXTINCTIONS IN YOUR ANSWER.

4. Find two additional examples of convergent evolution among the modern-day Caminalcules. This means finding cases where two or more species have a similar characteristic that evolved

independently in each lineage. The wing of bats, birds and bees is an example of

convergence since the three groups did not inherit the characteristic from their common

ancestor. Write your answers in complete sentences (e.g.,âSpecies x and y both have ____

but their most recent common ancestor, z, did notâ). List two additional real-world examples

of convergent evolution (ones that we have not already talked about in class) and discuss

what might have caused the convergence.

5. a. Describe two examples of vestigial structures that you can find among the

Caminalcules. These are structures that have been reduced to the point that they are

virtually useless. Ear muscles and the tailbones are examples of vestigial structures in our

own species.

b. Explain how vestigial structures provide clues about a speciesâ evolutionary past.

Illustrate your argument with vestigial structures found in humans or other real species.

Kindly answer question 3 to 5 thank you.

apricotmallard604

An African monkey has a DNA sequence that is 96.66% similar to a human sequence. According to the molecular clock, about how long ago did the common ancestor for African monkeys and humans live?

2.5â3 million years ago

5â6 million years ago

13â16 million years ago

17â20 million years ago

Humans and chimpanzees have a common ancestor that lived approximately 5 million years ago. Scientists have amassed an impressive collection of fossils for ancestors to modern humans and placed these ancestors in chronological order to observe the changes that occurred as these organisms evolved more human-like characteristics. Which lines of evidence provide the basis for stating that humans and chimps have a common ancestor that lived approximately 5 million years ago?

homologous structures in humans and chimps

DNA sequence similarity

changes in bone structure

vestigial structures in humans

Which description applies to a vestigial structure or trait?

It is the result of convergent evolution.

It represents evidence supporting the common descent and separate types models for modern organisms.

It did not have a necessary function in more ancestral organisms, but it does in more evolved organisms.

It is a type of homologous trait that is found in diverse organisms.

Which organisms are most closely related?

Bears and raccoons, which are both in the order Carnivora

Cougar and lynx, which are both in the family Felidae

Bread molds and yeast, which are both in the kingdom Fungi

Woodpeckers and warblers, which are both In the class Aves

1. Features in two different groups of organisms that are sharedbecause they were inherited from a common ancestor are examples of:(One word. Case does not matter, but you must spell it exactlycorrect.) ____________

2. A phylogeny is:

	A.	A diagram showing the relationship between groups oforganisms
	B.	A list of the evolutionary innovations possessed by a singlegroup of organisms
	C.	A diagram of all the known ancestors in the fossil record for asingle species living today
	D.	A unit of time used in geology

Homoplasy refers to:

	A.	The tendency of closely related organisms to interbreed witheach other
	B.	Features that ancestors had that were later lost by theirdescendants
	C.	Features in different groups of organisms that are not inheritedfrom a common ancestor
	D.	Features that appear only in a single group of organisms

Archaeopteryx lithographica and Tiktaalikroseae are examples of:

	A.	Fossils that show early forms of multicellular life in thePrecambrian
	B.	Transitional fossils that document the origin of evolutionaryinnovations
	C.	Index fossils that are used to identify the age of rocks
	D.	Living species that retain primitive characteristics

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BIO120H1 Chapter 3: COYNE CH3

BIO120H1 Full Course Notes

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