Ecology - Week 9

Question 1

What two requirements are required in order for a behaviour to be an adaptation?

Answer 1

• be heritable

- increase fitness in the current environment

Question 2

What is a proximate answer?

Answer 2

the immediate, mechanistic cause of a phenomenon (answering the question of how it happens)

• deals with the immediate mechanisms resulting in a trait (how did this particular instance of the trait come to be?)

Question 3

What is an ultimate answer?

Answer 3

the reason that a trait is thought to have evolved (why it happens)

• deals with larger scale, long-term mechanisms resulting in the trait (why does this trait (in general) exist?)

Question 4

What is aggression?

Answer 4

an example of behaviour that can have heritable basis

alleles that affect neural tube development → reduced brain size → low aggression

Question 5

What is indirect fitness?

Answer 5

individuals can pass on their alleles to the next generation by producing their own offspring AND by helping close relatives produce more offspring

• help each other, some risk
• help your relatives, some risk

Question 6

What are reproductive cheaters?

Answer 6

benefit, no risk

Question 7

What is reproductive cooperation?

Answer 7

help each other, some risk

Question 8

How is cooperation maintained?

Answer 8

• give individuals a reason to cooperate (create opportunities for reciprocity, identify as one time and maintain trust, make sure everyone has a chance to win)
• give individuals a reason not to defect (punish cheaters, make others aware of what is at risk)

Question 9

What are intraspecific interactions?

Answer 9

interactions within a single species (between conspecifics)

Question 10

What are conspecifics?

Answer 10

members of the same species

Question 11

What are the 3 intraspecific interactions?

Answer 11

• cooperative (+/+)
• competitive (-/-)
• exploitative (+/-): cheating

Question 12

What are interspecific interactions?

Answer 12

interactions between species (between heterospecifics)

Question 13

What are heterospecifics?

Answer 13

members of different species

Question 14

What are the 3 interspecific interactions?

Answer 14

• mutualistic (+/+)
• competitive (-/-)
• exploitative (+/-): parasitism and predation

Question 15

What is parasitism?

Answer 15

where the parasite lives on or in another organism (host), which results in some harm

Question 16

What is predation?

Answer 16

where the predator kills and eats another organism (prey)

Question 17

What does + mean?
What does - mean?
What does 0 mean?

Answer 17

+: increases fitness

• : decreases fitness
  0: no effect on fitness

Question 18

What is commensalism?

Answer 18

(+/0)

Question 19

What is ammensalism?

Answer 19

(-/0)

Question 20

What are neutral interactions?

Answer 20

(0/0)

interactions that have little or no effect on fitness of either party
- will generally be less important in the context adaptations and community dynamics

Question 21

How are species interactions classified?

Answer 21

according to how the interaction impacts the fitness of both parties

• if we only measure the fitness of one party, we can’t know for sure what type of interaction is going on
  ie. if we observe that an interaction increases the fitness of one party (ie. living inside a sea anemone increases the fitness of the clownfish), we still won’t know whether we are observing a case of mutualism, commensalism, or parasitism/predation

Question 22

How can we explain the distribution of species?

Answer 22

• dispersal
• abiotic factors (climate: seasonal variation in temperature, humidity, etc.)
• biotic factors (resource distribution: habitat, producers, prey, etc, AND species interactions: competition, predation, etc.)

Question 23

What is success defined as?

Answer 23

survival and reproductive success

Question 24

How successful will a species be in a given environment?

Answer 24

• abiotic factors (climate: seasonal variation in temperature, humidity, etc.)
• biotic factors (resource distribution: habitat, producers, prey, etc. AND species interactions: competition, predation, etc.)

note: dispersal is not included here - in most cases, the probability that a species will disperse to a particular location is independent of the probability that it will be successful at that location

Question 25

How does an interaction affect fitness?

Answer 25

fitness with vs. without the interaction

only way we can determine how an interaction affects an individual’s fitness is to measure:

• the individual’s fitness when the interaction occurs
• the individual’s fitness when the interaction doesn’t occur

and then compare the two!