Week 4 Flashcards
What is evolution ?
Descent with modification
What is a trait in evolution
Trait: Characteristics or attributes of an organism that are expressed by genes and/or influenced by the environment.
Name some behavioral traits
: care invested in offspring, mating behaviours,
foraging (food search) methods, etc.
Name some physical traits
hair colour, leaf shape, size at maturity, etc.
What do the mechanisms of evolution act on ?
The traits of organisms
What are some key traits that mammals have in common
“Warm blooded” – use metabolism to regulate
their own temperature.
Give birth to live young (no externally laid eggs)
Nurse young with mother’s milk
They originated (first evolved) on land!
Name some cetacean traits
Dolphins
Streamlined
Powerful tails
Up and down movement
Blowhole draws in air for oxygen
extraction
Long muscles run the length of their
bodies
Birth live young
Feed young with mammary glands
Name some fish traits
Streamlined
Powerful tails
Side to side movement
Gills pump in water for oxygen
extraction
Short sets of muscles form vertical
blocks
Births vary
No mammary glands
What is a pakicetus
Earliest cetacean, first
terrestrial whale known.
Lived 50 million years ago
Found in Pakistan geological
formation from Eocene (56-
34 mya)
Surrounding rocks indicated
dry landscape
Involucrum (unique ear
bone) present
What is ambulocetus
One of the earliest
whales
Lived 47- 49 million
years ago
Short legs and massive
feet
Great example of a
transitional species
What was present in the ambulocetus skeleton ?
Involucrum (pakicetus had it too)
Complete legs
What happened to whales overtime ?
◦ Moved from strictly
terrestrial to
partially, and then
to fully aquatic.
◦ Traded nostrils for a
blowhole on the top
of the head.
◦ Lost their legs and
fur.
What happens in embryonic development in dolphins from weeks 4-9
Forelimb buds go on to develop into fins
Hindlumb buds stop growing and dissapear as the embryo grows
All of life on earth is the product of………..?
………….evolution from one common ancestor
What is the tree of life
Traces the history of life
on Earth
How do evolutionary biologist identify how species diverged from a common ancestor ?
◦ Anatomical traits are
compared
◦ DNA and protein
sequences are
compared
What do close relatives share more than distant relatives ?
Close relatives share more inherited traits, and more DNA
sequences, than distant relatives
Name the fundamental principles of evolution
A. Organisms inherit traits from their ancestors
B. These traits are passed on in the form of DNA
molecules
C. Cells use DNA as a recipe book for building proteins
and other organic molecules
D. New copies of DNA are made for offspring
E. Mistakes in copying are called mutations
F. Mutations may be harmful, neutral, or beneficial…
most mutations are neutral, or harmful.
What are mistakes in copying called ?
mutations
What can mutations be ?
They may be harmful, neutral, or beneficial,, most mutations are neutral or harmful
What is the only source of novel traits ?
mutation
What do the effects of mutation depend on ?
◦ All the other genes in an organism
◦ The organism’s environment
What are the effects of a beneficial mutation ?
A beneficial mutation in a gene may help an organism
survive or reproduce more than others in the same group
at the same time.
If so, more of the organism’s genes are passed on through
reproduction to the next generation.
What is natural selection ?
The nonrandmom spread of beneficial genes. Non random does not equal intentional, its just the environment
Is it possible for traits to become harmful rather than beneficial ?
Yes, Natural selection may favor the exact same
mutation, and trait, in one environment but
not in another.
Ex; ◦ Large complex brain makes childbirth much more
dangerous for humans than other female primates
◦ Brain also requires a huge energy supply- 1 out of
every 5 calories you eat
How does evolution occur ?
Evolution does not invent things from scratch, evolution occurs through modifications of genes and traits that already exist.
What are homologous structures and how did they evolve
Homologous structures have evolved divergently from a structure of a common ancestor.
For example, the forelimbs of humans, bats, and whales are homologous, even though they have evolved for different functions (grasping, flying, and swimming, respectively).
What are analogous structures and how did they evolve
Analogous structures have evolved convergently but not from a common ancestor.
For instance, the wings of birds and insects are analogous structures—both used for flight, but they evolved separately in different lineages.
What is lost when a species goes extinct
The genetic potential of
a species is lost when it
goes extinct.
What caused many whale species to go extinct ?
Nineteenth century whaling nearly drove many
species to extinction, reducing genetic diversity.
Name threats to whales today
Whales reproduce slowly
Diseases
Pollution
Little genetic variability
What is natural selection
Natural selection is the differential survival
and reproduction of individuals due to differences in heritable traits
What is a non random mechanism of evolution that leads to adaptation
Natural selection
Does evolution invent new genes from scratch ?
Evolution does not invent things from scratch,
evolution occurs through modifications of
genes and traits that already exist.
