Week 9:Building Phylo Trees & A Tale of 3 Lice Flashcards
what is the Foramen Magnum
anatomical feature that allows the spinal cord to connect with the brain, forming the central nervous system
True or False: Fossils provide information about shared ancestry and relationships among taxa.
true
when did the human lineage and the chimp lineage diverged
6 million years ago
when did Homo sapiens evolve
200,000 years ago and were preceded by several other species of hominin.
what is a hominin?
any species that is more closely related to a human than a chimpanzee (e.g., members of the genera Australopithecus and Homo).
what are questions about hominins that the fossil record cannot answer
When did hominins lose their body hair?
When did hominins begin to wear clothes?
How can scientists go about answering “When did hominins lose their body hair?” and “When did hominins begin to wear clothes?”
study of lice
what are lice
Lice are highly specialized blood sucking parasites that live on a single host species.
how many lice species did each of our ape relatives hosts
one louse species
how many lice species do human host
humans host three types of lice
Name the three type of lice human host
Pediculus humanus capitus = The head louse
Phthirus pubis = The pubic louse
Pediculus humanus corporis = The body louse
what taxonomic rank do Human head lice and chimp lice belong to
genus
what was the possible origin hypothesis for head lice
Co-speciation hypothesis:
Human head lice and chimp lice lineages diverged at the same time that hominins and ancestral chimps diverged
how was the “Co-speciation hypothesis” tested
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.
what did the results of the head lice (Co-speciation hypothesis) test show
The last common ancestor of chimp lice and human head lice lived approximately:
6 million years ago, when ancestral chimps and hominins diverged.
what was the possible origin hypothesis for pubic lice
New niche hypothesis:
Human pubic and head lice lineages diverged because hominins lost their body hair and developed two hair niches.
how was the “New niche hypothesis” for pubic lice tested
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.
what were the results of the pubic lice (“New niche hypothesis “) test show
DNA comparison suggests the most recent common ancestor of human head lice and human pubic lice lived ~12 million years ago.
what is the closest relative of human pubic lice?
Human pubic lice are most closely related to gorilla lice.
look at slide 45
DNA comparisons show that human pubic lice and gorilla lice last shared a common ancestor ________million years ago.
3-4
Hominins might have picked up lice from early gorillas by:
Sleeping in nests recently used by early gorillas.
Preying on early gorillas.
* Lice are known to jump from prey to predator.
A possible origin of body lice:
Third niche hypothesis:
Human body lice arose because humans started to wear clothing.
Third niche hypothesis test:
First, estimate when body lice arose by identifying the most recent common ancestor of head and body lice.
Third niche hypothesis test results:
A DNA comparison suggests the most recent common ancestor of human body lice lived less than 72,000 years ago.