Behavioral Ecology
What's the difference between a proximate and ultimate hypothesis?
Proximate - HOW; focus on the immediate stimulus and mechanism (genetic, physiological, anatomical) for the behavior
Ultimate - WHY; explore how the behavior contribute to survival and reproduction. Why did it evolve?
r represents the per capita growth rate, dN/dt represents population growth rate
According to the competitive exclusion principle, two species cannot occupy the same ___.
When a predator is in the presence of a town of prairie dogs, one prairie dog will let out an alarm call to alert the rest of the town to take cover. As a result, the prairie dog that releases the alarm will be killed by the predator, but the rest of the town gets away. Give an explanation for this behavior.
Kin selection; the town is more likely to survive if one prairie dog draws attention away from the town by calling attention to itself
Where is the per capita growth rate the lowest in an exponential growth model?
Trick question! The per capita growth rate stays the same in an exponential growth model
What is a collection of organisms that belong to different populations but all live in the same area and interact with each other?
Community
Imagine you're a beekeeper located in Eugene, and you're checking on your bees at 8:00am (so the sun is directly east of the hive). You open the hive and observe a worker bee performing a waggle dance on the hive's vertical face. After watching for a while, you determine that each waggle lasts about 5 seconds and is pointed straight down.
What direction was the flower patch located that the bee was waggling for, and approximately how far away was the flower patch that she was foraging in?
West, 5 km
Describe an instance in which the carrying capacity of a population could change.
Many possible answers! Examples include changing seasons, natural disasters, human activity, anything that changes the availability of resources
In a given meadow, deer eat both invasive plant species and native plant species.
A. What is the name of the interaction between the deer and both plant species?
B. What type of competition is occurring between the invasive and native plants?
A. Consumption of plants by deer
B. Apparent competition - two plant types competing over survival from the deer predator
How many of her own offspring would a worker bee need to raise to get the same indirect fitness benefit as raising 15 of her sisters that had a different dad and 7 of her sister had the same dad?
rhalf-sibs = 0.25 bhalf-sibs = 15
rfull-sibs = 0.75 bfull-sibs = 7
roffspring = 0.5 boffspring = ?
rb(half-sibs): 0.25 * 15 = 3.75
rb(full-sibs): 0.75 * 7 = 5.25
rb(siblings) = 3.75 + 5.25 = 9
9 = roffspring * boffspring
9 = 0.5boffspring boffspring = 9 / 0.5
boffspring = 18 offspring
What causes growth rate to decline when a population increases in size?
Density-dependent limiting factors --> effect depends on the population size; have the potential to cause the growth rate to decline as the population increases in size
Examples --> competition, predation, food availability, disease, and parasitism
Synthetic fertilizers cause excess resources in groundwater, which runs off into oceans and causes harmful algal blooms. Daphnia are an aquatic species which feed on algae. Zooplanktivore feed on the Daphnia. Conservationists propose the introduction of Piscivores, which eat the Zooplanktivores as means as control of the algae.
Is this a bottom-up or top-down means of controlling the algae?
Top down - you're adding a predator to control the Zooplanktivore population, which would increase algal-consuming Daphnia, therefore decreasing the algae population
Describe what each variable represents in the expression br > c, and what this expression means in terms of evolution.
b = benefit (# of offspring produced) to recipient
c = cost (# of offspring not produced) to altruist
r = coefficient of relatedness (how close the altruist and recipient are related)
When br>c, a gene coding for cooperation evolves
A population of ladybugs has a carrying capacity of 500 and an rmax of 0.1 ladybugs/ladybug/month. What is the maximum possible population growth rate for the given population, and what are the units?
rmax = 0.1
Maximum population growth rate occurs at N = K/2; K = 500, so N = 250
dN/dt = rmax * (K-N)/K * N
dN/dt = 0.1 * (500-250)/500 * 250
dN/dt = 12.5 individuals/month
Niche differentiation is realized when niche overlap becomes costly to the species. What are the differences between the fundamental and realized niches?
fundamental niche = niche that could theoretically be occupied by a species, large, no limiting factors
realized niche = portion of the fundamental niche, post-competition niche that the species actually occupies, small
A bacteria population growing exponentially doubles in size every 38 minutes. How long will it take a population of 50 bacteria to reach a size of 6,000?
Part A: Finding r
td = 38 min
0.69 / td = r
r = 0.69 / 38
r = 0.018 bacteria/bacteria/minute
Part B: Finding t
N0 = 50 Nt = 6,000 r = 0.018 t = ?
Nt = N0ert
6,000 = 50e0.018t
120 = e0.018t
ln(120) = 0.018t
ln(120) / 0.018 = t
t = 266 minutes