Evolution Exam 1

What is evolution?

Change in allele frequency of a population over time

What is biological fitness?

an organism’s ability to survive and reproduce in its environment, passing on its genes to the next population

what is the flow of genetic information

DNA → RNA → protein → phenotype

Adaptation definition

inherited trait that increases an organism’s fitness in its environment and has arisen through natural selection for its current function

Exaptation definition

trait that originally served one function but has been co-opted for another purpose

example of adaptation

webbed feet in aquatic birds for swimming

example of exaptation

feathers initially evolved for temperature regulation, but were later co-opted for flight

Do you believe in evolution?

I accept evolution on the basis of the evidence

explain HIV and drug resistance

treatments like AZT work by interfering with HIV’s reverse transcriptase, however HIV’s reverse transcriptase mutates over time, allowing it to develop a resistance. This leads to eventual failure

How did HIV influence human evolution?

It applied selective pressure on the population. Some people carry the resistant allele, which would allow them to survive better

How did HIV originate?

zoonotic transmissions from nonhuman primates - HIV-1=chimps, HIV-2 = sooty manabeys

Why is HIV lethal?

Higher viral loads lead to the progression of AIDS which is lethal

How to root an unrooted tree

identify a node that would best represent the common ancestor of all taxa in the tree by using an outgroup

polytomy definition

point on a tree where multiple lineages branch off from a single node, indicating uncertainty in their relationships

monophyletic group definition

ancestor and all its descendants

Geography and Evolution

Geographic distribution can explain how species evolve in different environments due to varying selective pressures

synapomorphies definition

shared derived traits

symplesiomorphies definition

shared ancestral traits, found in multiple lineages but inherited from a distance common ancestor

which is more useful? synapomorphies or symplesiomorphies?

synapomorphies because they indicate recent evolutionary changes

paraphylitic definition

a grouping that consists of the grouping's last common ancestor and some but not all of its descendant lineages

polyphyletic definition

derived from more than one common evolutionary ancestor or ancestral group and therefore not suitable for placing in the same taxon