Macroevolution Flashcards
What is a synapomorphy?
a derived trait shared with a group of animals and their CA, and not found in any other group
What are some synapomorphies from the group Mammalia?
- milk production and mammary glands
- 3 middle ear bones
- hair in embryos
What synapomorphy do archaeocetes (early relatives of cetaceans) share with the clade?
- teeth shape
- similar ankle bones
- involucrum (thick inner ear bone)
Name some archaeocetes and their brief anatomy
- indohyus and pakicetus (terrestrial, quadrapedal, dense bones suggest somewhat aquatic lifestyle)
- ambulocetus (amphibious, webbed feet and reduced limb size suggests paddling lifestyle)
- dorudon (aquatic, jaws and teeth more adapted for active aquatic diet, hind legs almost completely reduced for fully swimming lifestyle)
What are the two modern clades of cetaceans?
odontocetes (toothed) and mysticetes (filter feeding)
Which historical figure supported the idea of extinction and recognized the similarities of ancient fossils?
George Cuvier
What were some of Lamarck’s beliefs?
correct:
- complex life originated from simpler microbes
incorrect:
- adaptation occurs through inheritance of well used traits and the loss of unused traits (i.e giraffe necks got longer because they needed to reach higher)
- early life spontaneously appeared
What is epigenetics and one of its critiques?
- the change in gene expression as a result of environmental cues
- clashes with evolutionary theory as some changes can be reversible/last only a few generations (not long enough for evolution)
Explain Darwin’s idea of descent with modification
- all species share a common ancestry with earlier life
- all life has variations that can be inherited
- changes occur via natural selection as a result of variation
What is a homologous structure?
traits similar due to inheritance from a common ancestor
What were Darwin’s 4 observations?
1) there is variation within individuals of the same species
2) traits can be passed down from parent to offspring (inheritance)
3) more individuals are born into a population than can be steadily supported
4) individuals compete for resources and only those with suitable traits can survive
