clades

Question 1

what is phylogeny?

Answer 1

study of evolutionary history of lineages of organisms

Question 2

what is a clade?

Answer 2

grouping species back to a common ancestor, including all the decedents of that ancestor.

Question 3

what rules are used to determine a clade? (5)

Answer 3

1. the larger a taxa is, the farther back in time one must go to find their common ancestor, 2. there must be a common ancestor in order for a clade to exist, 3. clades are drawn in an upward line with splits, every time a new lineage (species) forms, 4. the bottom line (or root line) shows the original ancestor (common to all species in the clade), 5 a species is most closely related to its most recent split on the cladogram

Question 4

What is a derived characteristic? Example

Answer 4

a trait that arose in the most recent common ancestor of a lineage. Ex. the most recent trait that arose in a lion is not its fur or its teeth, but rather its retractible claws (its most recent trait, creating a evolutionary split and putting it into the Felidae clade)

Question 5

Any species derived from the taxa tetrapoda has had 4 legs….can a species without 4 legs be in this clade?

Answer 5

yes…. but only if it once had 4 legs and then LOST this TRAIT (ex. snakes are reptiles which are in the tetrapoda taxon).

Question 6

Looking at a cladogram of a cat…which order would they have developed each trait/clade (fur, 4 legs, sheering teeth, retractable claws)?

Answer 6

To know the order, you must go from the root (trunk) of the cladogram to the most recent split: 4 legs originated first, then fur, then shearing teeth and finally the retractable claws (all 4 groups represent a new clade)

Question 7

How does a Linnaean group differ from a clade?

Answer 7

ALL the SPECIES in a CLADE must have a common descendent…NO exception.

Question 8

Give an example of a Linnaean group that is not a clade

Answer 8

Reptilia: it doesn’t include birds (but birds evolved from reptiles

Question 9

How do we figure out the common ancestors of species that don’t look at all alike?

Answer 9

DNA analysis. The more similar the genes, the closer our ancestry.

Question 10

Are clades based on hypothesis or on fact?

Answer 10

They are not final, only visual hypothesis

Question 11

What are 3 differences between the domain bacteria and domain archaea?

Answer 11

1. cell wall of bacteria contains peptidoglycan and archaea has cell wall without this substance, 2. archaea have unusual lipids in their cell membrane that bacteria lack. 3. archaea can survive without oxygen

Question 12

How many clades do the protists contain?

Answer 12

5 (most are unicellular except the brown algae)

Question 13

fungi have cell walls containing?

Answer 13

chitin (most are multicellular except yeasts)

Question 14

How could you draw a cladogram to show a more accurate picture of the full diversity of the evolution of life (beyond a simple tree)?

Answer 14

a circular model (like a death star except its a life star which includes many extinct species)