Population Abundance
What are the three things that determines habitat suitability?
Abiotic features, biotic features, disturbance
Define fecundity, mortality
Fecundity: Number of offspring
Mortality: Death
Define Density independent and dependent factors
Density independent factors: affect birth/death rates no matter the population size
Density dependent factors: cause birth, death, dispersal to change based on population size
What is the difference between a community and a population?
Community: Group of interacting species that occur together at the same place and time
Population: a group of individuals of the same species in the same area that interact with each other
Define the intermediate disturbance hypothesis
species diversity is greatest in communities that experience intermediate levels of disturbance
What are the two different kinds of dispersal? Give me an example of each.
Passive: Seeds stuck to a dog's coat
Active: A bird flying to a new location
If r(or lambda) is greater than 0(1) what is happening to the population?
If r(or lambda) is less than 0(1) what is happening to the population?
If r(or lambda) is equal to 0(1) what is happening to the population?
growing
shrinking
staying the same
Define a metapopulation
spatially isolated populations that are linked to each other by dispersal
What is the difference between species richness, total abundance, relative abundance, and species evenness
Species richness (s): total # of species
Total abundance: total number of individuals (across all species)
Relative abundance: a species’ proportion of total abundance
Species evenness: distribution of individuals across different species in the community
The _____ overlap between species, the more partitioning and less competition will occur
Less
What is an ecological niche?
What's the difference between a fundamental niche and a realized niche?
Ecological niche : biotic AND abiotic conditions that a species needs to grow, survive, reproduce
Fundamental: The whole area a species can occupy
Realized: The actual area a species does occupy
A population at time 1 is 20 individuals. At time 2 it is 32 individuals. What is the geometric growth rate? How many individuals will be in the population in 10 years?
Growth Rate: 1.6
Population at year 10: 2,199
What happens to survival/birth rates when a population is increasing in
A) negative density dependence
B) Positive density dependence
A) negative density dependence: decreases
B) Positive density dependence: increases
What are three ways disturbances can be characterized?
What are the two types of succession? Define each.
extent, severity, frequency
Primary: Colonization and establishment of a community in habitats virtually devoid of life
Secondary: Reestablishment of community in which some but not all organisms were destroyed
Define stability. What are two ways to maintain stability?
–retaining structure and function
1. resistance: resisting change
2. resilience: bouncing back after change
Describe the 3 different kinds of dispersal. What are each affected by?
Clumped: resources are clumped together
Random: equal chance of resource
Regular/Spaced: Territoriality or competition
Define the following terms in a life-table:
x
n(x)
l(x)
S(x)
F(x)
x age class (age of organism at start of the interval)
nx number of individuals alive at the start of x, where n0 = # of individuals in the population at time 0 (‘initial’ population size)
lx survivorship - proportion of initial population alive at the start of x.
Sx survival rate - proportion of individuals surviving from x to x+1
Fx fecundity – avg number of offspring per female of age class x
What are the two factors that determine extinction rates among metapopulation patches? Describe how each factor works.
1. Distance – Habitat patches located far away are less likely to be colonized
2. Size – Larger patches more likely to be colonized vs. smaller ones
Name and define the three models of succession
Facilitation: One species can increase the probability that second species can grow
Tolerance: Some species are not influenced by interactions with other species
Inhibition: Individuals of one species can inhibit the presence of the other
Define resource partitioning.
What are two different ways species can resource partition?
use of resources by members of a community in different ways
Space or Time
What are the two ways we discussed doing population estimates?
Describe how you would perform them.
1. Area-based counts:
-Calculate average abundance across quadrats
-Multiply by total area (area of interest) to estimate population size
2. Mark-Recapture:
–Sample of the population is caught, marked, and released
–Sample of the population is taken again and a ratio of marked to unmarked individuals is used to estimate the population
Complete a life-table from the following information:
50 garlic mustard plants were alive at the start of the study, 30 at the start of year 1, and none at the start of year 2. Each plant produced 10 offspring the reproductive year 1.
What is happening to the population? (Hint: net reproductive rate R0)
nx lx Fx lx*Fx
0 50 1.0 0 0
1 30 0.6 10 6
2 0 0 0 0
Population is increasing b/c R0 is greater than 1
What are the five ways a small population can go extinct?
1 Environmental stochasticity
2 Natural catastrophe
3 Demographic stochasticity
4 Genetic Drift
5 Inbreeding
Shannon-Wiener Biodiversity
Species Abundance pi ln(pi)
Red 13
Green 12
Blue 3
Purple 7
Species Abundance pi ln(pi) pi*ln(pi)
Red 13 .37 -.99 -0.37
Green 12 .34 -1.08 -0.37
Blue 3 .09 -2.41 -0.21
Purple 7 .2 -1.61 -0.32
H = 1.27
What are the 4 major hypotheses of the positive diversity-function? Define each
1.Complementarity: Each species has an equal effect
2. Redundancy: The functional contribution of each species increases to a threshold
3. Driver and passenger: Some species (drivers) are more influential on ecosystem function
4. Driver and passenger with overlap: Same as the driver passenger hypothesis except that there is overlap between species function