lec 4- macroevolution Flashcards
how do we know whales are mammals?
they share several synapomorphies with others in the order Mammalia
what are the traits whales share with mammals?
-mammary glands and milk production
-three middle ear bones
-hair
-ankle bone and more
what is an example of convergent evolution that a whale has with sharks and fish?
-general body plan
-both have fins
-both have tails
what are archaeocetes?
the early ancestors of whales, share synapomorphies with current whales
what is the archaeocete that was found 50 mya on land?
Pakicetus
what was the archaeocete that was found 40 mya in the ocean and its body features?
Dorudon, had reduced legs and more streamline body
what features did dorudon and pakicetus share with one another and current whales?
they had very thick involucrum (inner ear capsule) which is only seen in whales and other cetaceans
what is the other archaeocete that was found on land during the eocene?
Indohyus
which taxonomic group and clade do whales fall into?
Artiodactyla (even toed ungulates, even hooved animals)
what group were whales in before?
cetaceans, now added into artiodactyla
what is the whales closest relative?
hippos, four unique DNA homologies are synapomorphies Linking them
what is the ankle bone that links the cetaceans to artiodactyls and what structure does it have?
astragalus, double pulley structure only found in artiodactyls
what whale ancestor lived both in the land and water, acting as the missing link?
ambulocetus
what did whales lose over time and what remained?
they lost their hindlimbs, the small hind limb bones remained but the socket in the femur disappeared, making legs useless
what caused hindlimb loss?
changes in gene expression
do hindlimbs begin to form in the embryo but then inactivate in dolphin embryos?
yes
what are the two paths of evolution that can lead to the changes seen in cetaceans and other organisms?
evolution:
genetic variation (population) –> natural selection (certain gene frequencies) –> adaptive change
genetic variation –> genetic drift (random changes in gene frequencies) –> non-adaptive change
what are some forms of evidence used for the evolution of whales?
fossils, DNA, archaeology, vestigial features, transitional forms, cladistic analysis, radiometric dating
is the origin of turtles known?
no
what was the transitional fossil of the turtle called? what were its features?
Odontochelys, it had a fully formed shell shielding its belly, but an incomplete upper shell made of fused ribs
will the fossil record ever be complete?
no, it will always have organisms and fossils we never found
what is creationism?
belief that the universe and living organisms originated from specific acts of divine creation
what is the difference between science and religions?
science looks at evidence and data to make biological sense of things, religion relies on scriptures for knowledge
what is the difference between theists, atheists, and agnostics?
theists = believe in god
atheists = don’t believe in god
agnostic = not knowing if god exists, unsure
can science and religion work together?
yes, some things can be brought to light by the help of both
