Population and Community Ecology Exam 1

stable stage distribution

Under the asymptotic dynamics, the distribution of individuals (i.e., proportion) among stages remains constant

Stage-structured populations

- Developmental stages - Size classes - Geographic locations

Population Dynamics

Change in the state of a population

Dynamics

Changes in the state of something

(sensitivity)

Changes in vital rates by the same magnitude

Reproductive value

Relative contribution of individuals to the future population abundance/growth

all arrows in a lifecycle graph...

have the same unit time

Sensitivity matrix shows measures of...

how important vital rates (a.k.a. transition rates) are to the asymptotic population growth rate

longitudinal data

identified individuals are followed over time

what is lambda?

population growth rate

per-capita survival rate equation

s = 1-d (1 - per-capita mortality rate)

Elasticity

sensitivity to proportional changes in vital rates

per-population rates

snt, dnt, and bnt are the number of survived individuals, the number of dead individuals, and the number of births in a population,

state variables

variables representing the state of a population (ex. population density)

why does population density fluctuate over time (i.e. why doesn't it always change exponentially)?

vital rates are not constant

Unit of Organisms in Practice (3)

1. Evolutionary Significant Unit (ESU) 2. Distinct Population Segment (DPS) 3. Stock

(elasticity)

Proportional change in vital rates

Leslie matrix

(age structured)

reproduction

(fecundity per parent x survival of offspring over one unit time)

Anadromous

(live mostly in the ocean and spawn in a river)

Fecundity

(number of offspring per parent)

Simpson's Paradox

- A phenomenon in which a trend appears in several groups of data but disappears or reverses when the groups are combined. (Wikipedia.com) - In the right whale example, there may not be any trend in each group, but when groups are combined the trend might appear.

why can a growing population can have a reduced survival rate?

-because stage distribution may be different! -because the population may consist of more individuals in a stage with lower survival rate (e.g. younger individuals).

definition of population (various)

1. A group of individuals of one species that live in a particular geographic area (textbook by N. Campbell 1987) 2. A collection of inter-breeding organisms of a particular species (Wikipedia.com)

Measures of the state of a population (4)

1. Population abundance 2. Population density (number of individuals per unit area) 3. Biomass 4. Incidence (presence-absence)

Three things you can calculate from constant population projection matrix

1. asymptotic population growth rate (lambda) 2. stable stage distribution (w) 3. reproductive value (v)

Why is grouping individuals into a population important in conservation?

1. because it will affect the unit of management (e.g. the area of management). 2. because it will affect the status of the population(s). - Populations with a small number of individuals have a greater chance of going extinct.

Unstructured population

All individuals are the same regardless of their age, size, developmental stage, etc.

Sensitivity Analysis

How sensitive is λ to changes in population parameters (i.e., transition rates)

Fertility

Number of offspring that are born and survive one time unit (e.g. one year) produced per individual parent (under pre-breeding count)

Lefkovitch matrix

Population matrix associated with a stage-structured population (i.e. not age-structured)

Population is... a. a group of individuals of one species that live in a particular geographic area b. a collection of multiple species interacting with each other c. a concept equivalent to species d. all of the above

a. a group of individuals of one species that live in a particular geographic area

geometric/exponential growth results from... a. constant per-capita survival and per-capita birth rate b. constant per-population survivals and per-population birth rate

a. constant per-capita survival and per-capita birth rate

what is the shape of a graph representing population density if both per-capita birth rate and per-capita death rates are constant over time (but b>d)? a. exponentially increasing density b. linearly increasing density c. no change in population density

a. exponentially increasing density

you administer medication to individuals and keep track of their symptoms/fate over time (a record for each individual is kept). the data are... a. longitudinal data b. census data c. count data d. cellular data

a. longitudinal data

case mortality rate (i.e. the mortality rate of people with symptoms) appears to be declining. it is still plausible that disease is becoming worse (according to Simpson's Paradox) because... a. more younger people (who previously did not develop symptoms before) are developing symptoms and they tend to recover b. we are simply not detecting mortalities accurately c. we do not care much about mortalities, and we are only really concerned about infection rate

a. more younger people (who previously did not develop symptoms before) are developing symptoms and they tend to recover

the proportion of individuals died over one year is 0.8. this value represents: a. per-capita death/mortality rate b. per-population death/mortality rate

a. per-capita death/mortality rate

Which of the following is a state variable? a. population density b. survival rate c. reproductive rate d. all of the above

a. population density

when you learned a geometric/exponential growth, lambda was called... a. population growth rate b. survival rate c. death rate d. interest rate

a. population growth rate

what does reproductive value measure? a. relative contribution of individuals in a given stage to the future population abundance b. number of eggs produced by a female c. number of offspring that survive over one year d. number of offspring produced by a population per year

a. relative contribution of individuals in a given stage to the future population abundance

the average survival rate for a population can decline when a population abundance is increasing (assuming no immigration and emigration). a. true b. false

a. true

the number of rows of a Leslie matrix and the number of component of an associated population vector must be the same. a. true b. false

a. true

the sensitivity in the matrix population model analysis models how sensitive lambda is to the same magnitude changes in vital rates, whereas the elasticity measures how sensitive lambda is to the same proportional changes in vital rates a. true b. false

a. true

Suppose a population of frogs consisted of 100 individuals on March 1, 2021 and 94 individuals on April 1, 2021. We know there was no birth (because it is not a reproductive season). We also know there was no immigration and emigration because the population is isolated. Which of the following is the best answer? a. The monthly mortality rate was 0.6. b. The monthly mortality rate was 0.06. c. The monthly survival rate was 0.6. d. The monthly survival rate was 0.06. e. None of the above is correct because the population might have experienced something unexpected.

b. The monthly mortality rate was 0.06.

what is the shape of a graph representing population abundance if the same proportion 0.3 of individuals (30%) dies and each individual in the population contributes to the birth of 0.2 individuals on average (e.g. one in five reproduce one offspring) and these per-capita rates remain constant? a. exponentially increasing density b. exponentially decreasing density c. no change in population density

b. exponentially decreasing density

The vital rates in an age-structured population (a.k.a. in the lecture) must have the same time unit (e.g. one year) with in the same population matrix; however, the vital rates in a stage-structured population can be different. a. true b. false

b. false

the asymptotic population growth rate and stable stage distribution are the properties of age-structured population, but they are not the properties of stage-structured population. a. true b. false

b. false

Fertility rate (as defined during the lecture) for a matrix population model is... a. the sum of offspring and adults b. the product of fecundity per parent and the survival rate of offspring c. the number of eggs/larvae produced by female d. the proportion of females that are mature

b. the product of fecundity per parent and the survival rate of offspring

which one of the statements is NOT true? a. in population dynamics, variables are often density, abundance, biomass, or incidence b. there is no variable in statistical analysis c. data frame in R contains variables d. R is statistical software, but it can be used for other computations

b. there is no variable in statistical analysis

the first step to build a population matrix is... a. to write a population vector b. to draw a lifecycle graph c. to write down vital rates

b. to draw a lifecycle graph

vital rates (4)

birth rate, death (mortality) and/or survival rate, immigration rate, and emigration rate

How does population abundance change?

births, deaths, immigration, and emigration "Fundamental Law of Population Ecology" (prof's definition)

suppose we were to conduct many experiments. in each experiment, we start with the same number of individuals in each stage and introduce two additional individuals (either 2 adults or 2 juveniles). on average, which will have the greater number of individuals in the future? a. populations with two additional adults b. populations with two additional juveniles

both answers are correct

why do we need to structure a population based on age? a. because survival rate may be different among stage classes b. because reproductive rate may be different among age classes c. both A and B

c. both A and B

if all of the per-capita rates (birth rate, death rate, developmental rate) are constant over time, population density should change... a. linearly with time b. logistically with time c. exponentially with time

c. exponentially with time

Suppose you survey deer in a national park (all of the individuals in the population is in the park) and count how many individuals died in a given year. The total number of death is... a. a per-capita annual death rate b. a per-capita annual survival rate. c. not sufficient information to calculate a per-capita annual death rate. d. equivalent to one minus the total number of survivors.

c. not sufficient information to calculate a per-capita annual death rate.

what does lambda equaling 0.95 mean? a. population expected to increase by 95% per year on average b. population expected to decrease by 95% per year on average c. population expected to decrease by 5% per year per average d. population is fluctuating (going up and down)

c. population expected to decrease by 5% per year per average

per-capita rate

change in a state per individual per time

per-population rate

change in a state per population per time

Count data (a.k.a. Census Data)

count individuals (often along with some characteristics of the individuals).

Semelparous means... (read all potential answers!) a. individuals reproduce to one individual at a time. b. there is only one season for reproduction per year. c. all individuals reproduce exactly once and die. d. individuals reproduce at most once in their life time.

d. individuals reproduce at most once in their life time.

what is the shape of a graph representing population abundance against time if five individuals are born and three individuals die each year (same number of births and deaths)? a. exponentially increasing abundance b. exponentially decreasing abundance c. no change in population abundance d. none of the above

d. none of the above

the size of Leslie matrix for a population is determined by... a. the length of study period b. the time of speciation c. the age of the first reproduction d. the oldest individuals in the population

d. the oldest individuals in the population

lifecycle graph tells us...

the number of stages/age classes and how individuals can transition among them