1)    Why do rock pigeons have hooks on their beaks and how was this tested?

It helps reduce parasite loads (lice), keep warm, evade predators, and attract mates. Clayton gathered 26 pigeons, clipped their beaks, and saw a decrease in fitness. When 18 were allowed to regrow their hooked beaks, parasite loads fell.

Individuals in previous generations varied in their design, and the ones with the best designs passed on their genes in greater numbers.

To demonstrate that a trait is an adaptation, we need to determine what a trait is for and then show that individuals possessing the trait contribute more genes to future generations than individuals lacking it. 

Do oxpeckers eat ticks off ox?

Sometimes, but primarily they lick blood from wounds, probe the host’s ears for wax, and eat dead skin. 

How did removing oxpeckers affect tick loads on oxes?

Oxpeckers have no discernable effect on their hosts’ tick loads.

 Is every trait of an organism an adaptation?

No, much of the variation among individuals, populations, and species may be selectively neutral.

No, 

   Describe the experiment that green and colleauges did with Zonostema flies.  What did they find?  What were their methods.

5 experimental groups to test 3  hypotheses. Measured the responses of jumping spiders and other predators to the five types of experimental flies.  They starved 20 jumping spiders from 11 different species for 2 days, then presented one of each of the experimental fly types to each spider in random order.  Jumping spiders tended to retreat from flies that gave the wing-waving display with marked wings, but attacked flies that lacked either or both parts. Other predators had no preference on the flies.

  What two things does replication do for an experiment? 

1)   Reduce the amount of distortion in the estimate caused by unusual individuals or circumstances.

2)   Allow researchers to understand how precise their estimate is by measuring the amount of variation in the data.

  Are observational studies an experiment?  Why or why not?

Yes, if you have a hypothesis before hand.

    What were Huey et al.’s methods for demonstrating that garter snakes use behavioral thermoregulation?  

Snakes were implanted with radio transmitters. At night, they were almost always found under medium sized rocks.

   Does a scatter plot of two traits, if there is a positive correlation, show that the two traits are evolving in tandem (correlated evolution?). 

Maybe, if the data points are independent of one another. The species involved should not be closely related. Felsenstein’s method reconstructs ancestral nodes using averages to more accurately see correlations between groups. The method also accounts for branch length.

    Why do bats that live in large groups have larger testes, are these traits evolving in tandem? And if so, how was this demonstrated?

Large testes are an adaptation to sperm competition. Large testes and larger group size are evolving in tandem. Hoksen used Felsenstein’s method and found that there was a significant positive correlation between contrasts in relative testes size vs contrasts in group size.

 What is phenotypic plasticity, and how can this be a problem for testing whether a trait is an adaptation?

An individual’s genotype that is influenced by its environment and may see varying phenotypes.

    How did Daphnia phototactic behavior change in three lakes in Belgium, and how was this studied, and what effect did fish have on this?

In each of the lakes there was genetic variation in phototactic behavior (rising or sinking relative to light source). In Blankaart, Daphnia tended to submerge in the presence of fish, but populations in other lakes showed differently. De Meester studied this by placing individuals in a graduated cylinder, shining light at the top and seeing if the Daphnia sink or rise. Then, their behavior was recorded on a -1/+1 scale.

He was able to see that the phototactic behavior was an adaptation by hatching old daphnia eggs (that never had the predation pressure).

   Use Daphnia to explain the genotype by environment interaction.  

Some genotypes in each population of Daphnia alter their behavior more than others in the presence vs absence of fish.

 What is a reaction norm?

The genotype’s change in phenotype across a range of environments.

  What is the trade-off illustrated by Begonia male and female flowers? What kind of flowers do pollinators prefer?

Larger females are favored because they look more like males, but there is a trade-off between flower size and number. 

  Why aren’t female Begonia flowers enormous?

There would only be few of them which reduces potential seed production, and there may be selection in which bees favor inflorenscenes with more flowers.

 Why do Fuchsia flowers change color? Why don’t Fuchsia flowers abscise (fall off) immediately after fertilization?

They change color to alert pollinators that the flowers are no longer offering a reward. When pollinators forage efficiently they also transfer pollen efficiently.

The flowers don’t abscise immediately after fertilization because they need time for the pollen to reach the ovary. The process of dropping a flower cannot start until about 3 days after the flower is finished receiving pollen.

Why might there be a genetic constraint for host plant switching by herbivorous beetles?

There is not enough genetic variation for different beetle species to adapt to other hosts because the beetles don’t have the ability to degrade many toxins. Either to eat the plant itself in its various stages, avoid predation, win competition…

How did Clayton and Johnson suggest that body feather lice were constrained by dispersal ability on doves?

Body feather lice experienced less dispersal by flies and body to body contact than wing feather lice.

Describe some different levels of selection.

Individuals, populations, families, Organelles, mitochondrial DNA

   How could there be selection at the level of mitochondrial genotype in yeast?

LOF mitochondria do not undergo respiration (cost), but this allows them to replicate DNA faster (advantage). Within yeast cells, selction favors parasites (small pops). Among yeast cells within populations, selection favors yeast containing normal mitochondria (large pops).

  What is Apert’s syndrome, how is it inherited and is it dominant or recessive?

A genetic disease caused by a mutation in the gene for fibroblast growth factor receptor 2 (FGFR2). Side effects: premature fusion of suture joints in skull, facial malformation, fusion of fingers and toes. The condition is dominant. It is usually caused by new mutations. The mutant allele almost always comes from the father, and the mutation rate increases with father’s age. 

  How does the allele for Apert’s syndrome maintain in the human population?

The frequency in the human pop is determined by a balance between opposing patterns of selection acting at different levels. Selection acting at the cellular level causes the freq to increase, but selection acting at the level of individual babies causes the freq to fall. They are independent evolutionary events.

    Describe five strategies for asking interesting question in evolutionary biology.

1)   Study natural history

2)   Question conventional wisdom

3)   Question assumptions underlying a popular hypothesis or research technique

4)   Draw analogies that transfer questions from field to field or taxon to taxon

5)   Ask why not