Week 9:Building Phylo Trees & A Tale of 3 Lice

Question 1

what is the Foramen Magnum

Answer 1

anatomical feature that allows the spinal cord to connect with the brain, forming the central nervous system

Question 2

True or False: Fossils provide information about shared ancestry and relationships among taxa.

Answer 2

true

Question 3

when did the human lineage and the chimp lineage diverged

Answer 3

6 million years ago

Question 4

when did Homo sapiens evolve

Answer 4

200,000 years ago and were preceded by several other species of hominin.

Question 5

what is a hominin?

Answer 5

any species that is more closely related to a human than a chimpanzee (e.g., members of the genera Australopithecus and Homo).

Question 6

what are questions about hominins that the fossil record cannot answer

Answer 6

When did hominins lose their body hair?

When did hominins begin to wear clothes?

Question 7

How can scientists go about answering “When did hominins lose their body hair?” and “When did hominins begin to wear clothes?”

Answer 7

study of lice

Question 8

what are lice

Answer 8

Lice are highly specialized blood sucking parasites that live on a single host species.

Question 9

how many lice species did each of our ape relatives hosts

Answer 9

one louse species

Question 10

how many lice species do human host

Answer 10

humans host three types of lice

Question 11

Name the three type of lice human host

Answer 11

Pediculus humanus capitus = The head louse

Phthirus pubis = The pubic louse

Pediculus humanus corporis = The body louse

Question 12

what taxonomic rank do Human head lice and chimp lice belong to

Answer 12

genus

Question 13

what was the possible origin hypothesis for head lice

Answer 13

Co-speciation hypothesis:

Human head lice and chimp lice lineages diverged at the same time that hominins and ancestral chimps diverged

Question 14

how was the “Co-speciation hypothesis” tested

Answer 14

Compare DNA of human head lice to DNA of chimp lice at one nuclear and one mitochondrial gene to estimate when they last shared a common ancestor.

Question 15

what did the results of the head lice (Co-speciation hypothesis) test show

Answer 15

The last common ancestor of chimp lice and human head lice lived approximately:

6 million years ago, when ancestral chimps and hominins diverged.

Question 16

what was the possible origin hypothesis for pubic lice

Answer 16

New niche hypothesis:

Human pubic and head lice lineages diverged because hominins lost their body hair and developed two hair niches.

Question 17

how was the “New niche hypothesis” for pubic lice tested

Answer 17

First, compare DNA of human pubic lice to human head lice at one nuclear and one mitochondrial gene to estimate when they last shared a common ancestor.

Question 18

what were the results of the pubic lice (“New niche hypothesis “) test show

Answer 18

DNA comparison suggests the most recent common ancestor of human head lice and human pubic lice lived ~12 million years ago.

Question 19

what is the closest relative of human pubic lice?

Answer 19

Human pubic lice are most closely related to gorilla lice.

look at slide 45

Question 20

DNA comparisons show that human pubic lice and gorilla lice last shared a common ancestor ________million years ago.

Answer 20

3-4

Question 21

Hominins might have picked up lice from early gorillas by:

Answer 21

Sleeping in nests recently used by early gorillas.

Preying on early gorillas.
* Lice are known to jump from prey to predator.

Question 22

A possible origin of body lice:

Answer 22

Third niche hypothesis:

Human body lice arose because humans started to wear clothing.

Question 23

Third niche hypothesis test:

Answer 23

First, estimate when body lice arose by identifying the most recent common ancestor of head and body lice.

Question 24

Third niche hypothesis test results:

Answer 24

A DNA comparison suggests the most recent common ancestor of human body lice lived less than 72,000 years ago.