chapter 8- adaptation

Question 1

adaptation is a trait

Answer 1

increases the fitness of the individual relative to individuals that do not possess the trait- arise by selection, but the process may be aided (or hindered) by drift

Question 2

Oxpeckers

Answer 2

• oxpeckers host on mammals. many believed they would stay on mammal and eat the ticks.
• win-win situation as the oxpeckers ate food, and mammals will be tick free
• weeks studied the oxpeckers and noticed that the oxpeckers were not able to digest tick parts
• he noticed that they would only sometimes eat ticks
• instead, the oxpeckers would licking blood from open wounds
• probing their hosts’ ears, apparently for wax;
• scissoring their beaks through their hosts’ hair, apparently gleaning and eating dead skin.
• set up an experiment, 2 groups, one where oxpeckers were there and another where oxpeckers were shooed away
• noticed that cattle w/ oxpeckers had much more and larger wounds and had had less ear wax
• concludes that oxpeckers were vampire like (drink blood) and eat ear wax
• concludes: All hypotheses must be tested. Explanations unconfirmed by hypothesis testing are best regarded as stories.

Question 3

All hypotheses must be tested. Explanations unconfirmed by hypothesis testing are best regarded as stories.

Answer 3

True

Question 4

Things to keep in mind when studying adaptations

Answer 4

1. Differences among populations are not always adaptations
2. Not every trait an organism possesses is adaptive
3. Not every adaptation is perfect

Question 5

Three methods to study adaptations:

Answer 5

1. Experimental studies
2. observational studies
3. comparative studies

Question 6

true or false If we observe a correlation between two variables, can we infer that one is the cause of the other

Answer 6

true

Question 7

The Tephritid fly Zonosemata and the Jumping Spider: Experimental Approach

Answer 7

• the fly when trying to scare its predator the jumping spider fly holds its wings perpendicular to its body and waves them up and down.
• this display seems to mimic the leg-waving, territorial threat display of jumping spiders
• Greene and colleagues proposed that the fly uses its wing-waving display to intimidate the jumping spiders themselves
  -this is just a hypothesis, needs to be tested
• first pose question: Do the wing markings and the wing waving of Zonose- mata vittigera mimic the threat displays that jumping spiders use on each other, and thereby allow the flies to escape predation?
• have 3 hypothesis
  1. The flies do not mimic jumping spiders. This is a distinct possibility, because other fly species have dark wing bands and wing-flicking displays that do not deter predators. In many species, the flies use their mark- ings and displays during courtship.
  2.The flies mimic jumping spiders, but the flies behave like spiders to deter other, nonspider predators. Other fly predators that might be intimidated by a jumping spider, or a jumping spider mimic, include other kinds of spiders, assassin bugs, praying mantises, and lizards.
  3.The flies mimic jumping spiders, and this mimicry functions specifically to deter predation by the jumping spiders themselves.
• found flies with some features of the original fly, cut the flies off the found fly and glued them on original fly
• the original fly was still able to fly and wave their wings normally
• five experimental groups:
  1. Zonosemata untreated: Test effect of wing markings plus wing waving
  2.Zonosemata with own wings cut and reglued:
  Control for effects of operation
  3. Zonosemata with housefly wings: Test effect of wing waving without wing markings
  4. Housefly with Zonosemata wings: Test effect of wing markings without wing waving
  5. Housefly untreated: Test effect of no wing markings and no waving
• Greene and coworkers had to measure the responses of jumping spiders and other predators to the five types of experimental flies.
• would they retreat, attack and/or stalk
• researchers starved 20 jumping spiders from 11 different species for two days. Then they presented one of each of the five 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 wing markings, wing waving, or both
• when experimented on other predators, the predators attacked 1. 3. and 5. with no hesitation
• this satisfies the third hypothesis