BI111 Chapter Notes - Chapter #9: Synapomorphy, Comparative Anatomy, Cladistics

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19 Feb 2018

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Biologists use characteristics of organisms to figure out their relationships. Similarities can possibly suggest a shared ancestor. However only some similarities are actually useful. Characters are anatomical, physiological, or molecular features that make up organisms. Characters have several observed conditions called character states. A character can be present or absent. All species contain some character stated that are shared with other members of their group and some that are unique. Characters that are similar because of descent from a common ancestor are said to be homologous. Similarities due to independent adoption by different species are said to be analogous and are the result of convergent evolution. Shared derived characters enables biologists to reconstruct evolutionary history: Only homologies and analogies are useful in constructing phylogenetic trees. Shared same derived characters are called synapomorphies. Phylogenetic reconstruction on the basis of synapomorphies is called cladistics. The simplest tree is often favoured among multiple possible trees:

Related Questions

What problems does horizontal gene transfer cause for evolutionary biologists?

It can make reconstruction of phylogenetic trees difficult because it can obscure phylogenetic relationships.

It can cause physiological problems in some organisms, making it hard to study them.

It can make breeding between different individuals of the same species difficult.

Because it is transfer of genes between the same species, it can make individuals look more similar than they actually are.

All of the above

Which statement best describes the maximum parsimony approach to the reconstruction of phylogenetic trees?

A pathway is constructed that requires the minimum number of changes to arrive at the modern species from a common ancestor.

The tree is based on relationships that show the maximum probability of obtaining a set of characteristics.

Relationships on the tree are based on overall similarity between species.

Branches on the tree are constructed from the predicted date of speciation, measured in millions of years.

The best phylogeny is selected by comparing models representing random mutation and adaptive radiation.

ambermouse112

The Cambrian explosion is a prime example of ________________.

		mass extinction
		evolutionary stasis
		a large meteor impact
		adaptive radiation

1 points

QUESTION 2

Most animals are viviparous.

True

False

1 points

QUESTION 3

The first phylum with ganglia in their nervous system are the ________________________.

		Mollusca
		Nematoda
		Bivalvia
		Platyhelminthes

1 points

QUESTION 4

The last common ancestor of all animals was probably a _____________________.

		a unicellular worm
		multicellular algae
		flagellated protist
		multicellular fungus

1 points

QUESTION 5

You are given an unknown organism to identify. It is unicellular and heterotrophic. It is motile by use of many short extensions of the cytoplasm. It has well-developed organelles and two nuclei, one large, one small. The organism is most likely to be a ______________.

		foraminifera
		radiolarian
		ciliate
		flagellate

1 points

QUESTION 6

Which of the following organisms would you expect to have the largest surface-area-to-volume ratio? Assume that all of the following are the same total length.

		A mollusc
		A nematode
		A platyhelminth
		Not enough information to determine.

1 points

QUESTION 7

If the animal is a hermaphrodite, it is said to be _______________.

		dioecious
		eutelic
		monoecious
		trioecious

1 points

QUESTION 8

A terrestrial animal species is discovered with the following larval characteristics: exoskeleton, system of tubes for gas exchange and segmentation. A knowledgeable zoologist should predict that the adults of this species would also feature ____________.

		eight legs
		two pairs of antennae
		a sessile lifecycle
		an open circulatory system

1 points

QUESTION 9

The Phylum Echinodermata exhibits metamerism.

True

False

1 points

QUESTION 10

The existence of evolutionary trends, such as increasing body sizes among horse species, is evidence that _____.

		a larger volume-to-surface area ratio is adaptive in many mammals
		evolution generally progresses toward some goal
		evolution tends toward increased complexity or increased size
		in particular environments, similar adaptations can be beneficial to more than one species

The Cambrian explosion is a prime example of ________________.

		mass extinction
		evolutionary stasis
		a large meteor impact
		adaptive radiation

1 points

QUESTION 2

Most animals are viviparous.

True

False

1 points

QUESTION 3

The first phylum with ganglia in their nervous system are the ________________________.

		Mollusca
		Nematoda
		Bivalvia
		Platyhelminthes

1 points

QUESTION 4

The last common ancestor of all animals was probably a _____________________.

		a unicellular worm
		multicellular algae
		flagellated protist
		multicellular fungus

1 points

QUESTION 5

		foraminifera
		radiolarian
		ciliate
		flagellate

1 points

QUESTION 6

Which of the following organisms would you expect to have the largest surface-area-to-volume ratio? Assume that all of the following are the same total length.

		A mollusc
		A nematode
		A platyhelminth
		Not enough information to determine.

1 points

QUESTION 7

If the animal is a hermaphrodite, it is said to be _______________.

		dioecious
		eutelic
		monoecious
		trioecious

1 points

QUESTION 8

		eight legs
		two pairs of antennae
		a sessile lifecycle
		an open circulatory system

1 points

QUESTION 9

The Phylum Echinodermata exhibits metamerism.

True

False

1 points

QUESTION 10

The existence of evolutionary trends, such as increasing body sizes among horse species, is evidence that _____.

		a larger volume-to-surface area ratio is adaptive in many mammals
		evolution generally progresses toward some goal
		evolution tends toward increased complexity or increased size
		in particular environments, similar adaptations can be beneficial to more than one species

1 points

QUESTION 11

Suppose you are a researcher fro a pest-control company and you develop a chemical that inhibits the develpment of an embryonic mosquito's endodermal cells. Which of the following would cause the pesticide to work?

		The mosquito would develop a weak exoskeleton, making it easy prey.
		The mosquito's gut would not function properly and it would starve.
		The mosquito would not have a properly functioning muscular system.
		Nothing would happen and your experiment would be a failure.

1 points

QUESTION 12

Holometabolis refers to complete metamorphosis.

True

False

1 points

QUESTION 13

Which of these conditions are always true of populations evolving due to natural selection?
Condition 1: The population must vary in traits that are heritable.
Condition 2: Some heritable traits must increase reproductive success.
Condition 3: Individuals pass on most traits that they acquire during their lifetime.

		Condition 1 only
		Condition 2 only
		Conditions 1 and 2
		Conditions 2 and 3

1 points

QUESTION 14

Scientific theories _____. 22.3

		are nearly the same things as hypotheses
		are supported by, and make sense of, many observations
		cannot be tested because the described events occurred only once
		are predictions of future events

1 points

QUESTION 15

The evolution of animal species and their diversity is a result of the evolution of new and different ways to _______________.

		reproduce
		arrange their cells into tissues
		become symmetrical
		form an embyro and establish a basic body plan

BI111 Chapter Notes - Chapter #9: Synapomorphy, Comparative Anatomy, Cladistics

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