9.2 Establishing Phylogenetic Relationships Flashcards
What does phylogeny establish?
Phylogeny establishes evolutionary relationships among species and groups of species.
How can cladograms be produced?
Cladograms can be produced by examining shared derived characters.
Where does evidence of hominid evolution come from?
Evidence of hominid evolution comes from the fossil record.
Phylogeny definition
the evolutionary development and history of a species or group
Phylogenetic tree
branching diagram that represents evolutionary relationships among species or groups
Clade definition
an evolutionary branch in a phylogenetic tree
Cladistics definition
a method of determining the sequence of branches in a phylogenetic tree
Cladogram definition
a phylogenetic diagram that specifies the derived characters of clades
Derived characteristics
homologous structures that are common to all the organisms in a clade (e.g. amniotic egg)
What is one of the best clues to assess how closely related organisms are?
Homologous structures are one of the best clues to assess how closely related organisms are
(e.g. human and chimpanzee skulls)
What can hide homologous structures?
Adaptations can hide homologous structures
(e.g. wing of a bat and flipper of a whale)
What can produce analogous structures that can be mistaken for homologous structures?
convergent evolution
How can the relatedness of species be measured?
Relatedness of species can be measured by comparing their genes and the proteins that genes code for
The more similar the _____ are, the more closely the species are related
The more similar the genes the more closely the species are related
-e.g. fossil data indicates whales are closely
related to hippos, cows, deer, and pigs.
-Molecular data now also supports this.
Phylogeny & HIV Evolution
Case Study: Libyan bioterrorism case
-HIV mutates at a fast rate (it’s a virus)
-HIV can evolve into 5 new strains per year
-All infected children were infected by the same
strain
-2 possible scenarios:
-HIV developed from a single strain AFTER 1998
- Medics could have infected the children
-HIV not similar enough to have a common
ancestor after 1998 (this the lineages split
BEFORE 1998)
- Medics could NOT have caused the
infection
conclusions on Libyan case
-Looking at the rate of mutation, scenario 2 was proven
-The strains had been diverging before the medics arrived at the hospital
-HIV was blamed on tainted needles and poor hygiene practices by the hospital, not the medics
Which group were one of the first placental mammals to evolve about 65 mya?
primates
What also occurred 65 million years ago?
dinosaur extinction
Prosimians
group of primates that include lemurs, lorises, tarsiers
Anthropoids
group of primates that include new-world monkeys, old-world monkeys, hominoids
Hominoids
the great apes: gibbons, orangutans, gorillas, chimpanzees and humans*
characteristics of primates
-Grasping hands and feet
-Opposable first digits (thumbs)
-Forward facing eyes or binocular vision (provide depth perception)
-prosimians – lemurs, lorises, tarsiers
-anthropoids – new-world monkeys, old-world monkeys, hominoids
characteristics of hominoids
-Large brains
-Lack tails
-Swinging arms
-gibbons, orangutans, gorillas, chimps, and humans
Hominids
Humans and all their ancestral species that arose after the split from ancestral chimpanzees
Hominoids vs. Hominids
hominoids- primate group that includes gibbons, orangutans, gorillas, chimps, and humans
hominids- humans
Early primates gave rise to two distinct lines:
Prosimians
Anthropoids