Adaptive Radiation Flashcards
What was the significance of the Burgess Shale?
It was an avalanche of fine mud that preserved soft parts of animals in fossils as well as hard
What were common characteristics of Precambrian Fauna?
Small
Soft bodied - jellyfish, sponges, etc.
Radially symmetrical
What are the characteristics of Cambrian Fauna?
Large, complex and bilateral
Most extant phyla appeared
Many morphological innovations and ecological adaptations appeared - limbs, shells, swimming, burrowing
What was the statement made by Jonathan Wells about the Cambrian explosion? Is it valid?
That textbooks fail to cover the explosion and that it contradicts the tree of life. It is note valid as each premise in the statement is incorrect.
Most major animal phyla appear, but all species that appeared are now extinct. It was primarily marine animals with no land animals developing
What is the effect of micro-evolution on a macro-evolutionary scale?
There may be an initial burst in diversification but it is followed by a much lower rate and enters stasis because of adaptation
Explain the example of adaptive radiation in Cichilids
One lake in Africa had all niches occupied by cichlids, and another lake that was empty was colonized.
This lake saw a selective advantage (no competition) to occupying the empty niches, and caused rapid diversification
What radiation happened after the dinosaurs went extinct?
Niches were left empty when dinosaurs went extinct, and they were filled by mammals
What is the difference between stem and crown lineages?
Stem lineages were present before adaptive radiation
Crown lineages begin at radiation and experience rapid divergence
What was the “fuel” of the Cambrian explosion?
Changing environments allowed diversification of crown lineages
Oxygen allowed larger sizes and more complex body plans - maybe
What is the difference between mutation and substitution?
Mutation is a random base pair change that introduces a new allele into the population
Substitution is when a new mutation goes to fixation so the new allele is present in EVERY individual. It is not random and depends on selection
How do mutations lead to species with novel characteristics in functions? Give an example
Single mutations lead to continuous traits. These can be selected for and lead to novel functions. Breeding can cause speciation that include more new functions of the trait
Front legs used for walking, leading to catching prey, led to net made of feathers, led to gliding wings, led to flight powered by wings
