Lec 13 Ecology Flashcards
Define population ecology:
studies how the populations of groups for the same species may change over time
Define community ecology
How interactions of different species affects their organization
Define ecosystem ecology
studies how energy flows and ecosystems affect organisms’ living and non-living resources
Define global ecology
How local/regional interactions affect global changes in energy and specie dynamics
Define population:
group of individuals that are of the same species and live in the same area
Define population ecology:
observation of population size and questions how or why they change over time
Define ecology:
interactions between organisms and their living/non-living environment
What is an example of an animal that helps our population ecosystem?
Vultures. They eat dead carcasses, thus minimizing disease. Without them, animals and humans risk of disease increases monumentally
How do we determine the number of individuals in a population without counting them?
Mark-recapture method
What is the mark-recapture method?
Capture and mark a set of individuals, release to population, use proportion of re-caught individuals in second capture to est. total population
Describe the mark-recapture method setup:
First, capture a set of the species population. Then, send them back into the total population of unknown size, Afterwards, capture another subset for a second time. Finally, assess the marking in probability of capture.
For the mark-recapture method, what explains the reason if you don’t recapture marked individuals a second time around?
- You have underestimated the population size; You didn’t mark enough individuals
- Trapping can traumatize animals, causing them to avoid cages. OR animals realize they don’t get hurt when they’re trapped but come for the snacks.
How can you estimate the Mark-Recapture population?
To find the population total (=N), the first number of individuals in the first capture (=s) are sent out. After a second recapture, calculate the mean number of marked individuals (=S). Calculate the total number of individuals caught in the second capture (=n).
Equation: x/n = s/N
Describe the mark-Recapture estimation calculation:
number marked 2nd time (x) / total caught in 2nd sample (n) = number marked in 1st sample (s) / size of whole population (N)
Equation: x/n = s/N
Describe patterns of population growth:
periodic monitoring of population sizes for assessment of changes in pop. size over time
What population growth would we expect to see if they’re growing with unlimited resources, no predators and no external factors limiting reproduction?
Exponential growth
What population growth would we expect to see if they’re growing with limited resources?
Linear growth
What variables control population size (what means are indiv. added to and removed from pop.) ?
Adds: Birth and Immigration
Removes: Death and Emigration
How can we establish change in population size?:
(Birth+immigration) - (death+emigration) = pop. change
Changes in population size are determined how?
It’s the number of inidivudals added to a population over time
What equation can we use to establish change in pop. size?
Change in number of individuals in a pop. / change in time
What does the change in pop. size = ?
Births-deaths
____ numbers of births and deaths is _____ to a _____ population:
Exact numbers of births and deaths is specific to a single population:
Average ____ of birth and death can be applied to populations of ____ _____
Average rate of birth and death can be applied to populations of any size
Define per capita birth rate (b):
number of offspring produced per individual per unit of time
Define per capita death rate (d):
number of individuals that died per individual member per unit of time
Equation for per capita birth rate (b):
b = b/n (number births/N)
Equation for per capita birth rate (d):
d = d/N
How do you calculate expected number of Births and Deaths?
B = b*N
How can you calculate change in pop/change in time? (N/T)
bN-dN
Define final model translation:
determining net births and deaths
What is a net effect?
the sum of both births and deaths
Define per capita population growth rate (r):
number of individuals added per pre-existing individual in pop. when accounting for both births and deaths
How do you calculate r?
r = b-d
What is final model simplification?
use b and d to calculate r
How can you find the per capita population growth rate in the population?
N/T = rN
You have a population of 2500 marmots. In a year, 315 marmot babies are born, 22 marmots die. Calculate r.
r = B-D
B = b/N = 0.126
D= d/N = 0.0088
0.126-0.0088 -> r = 0.117
You have a population of 2500 marmots. In a year, 315 marmot babies are born, 22 marmots die. For year 2, you have 9082 marmots in your population. How many marmots will be added to this population at the end of year 1? At the end of years 2 and 3?
r = 0.117 (constant), N = 9082
Year one: N/T = 9082*0.117 = 1,062.6 marmots added
Pop size at end of year 1: = 9082+1062.6 = 10,144.6 marmots for year 2
Year two: N/T = 10,144.6*0.117 = 1,186.9 marmots added
Pop size at end of year 2: 10,144.6+1186.9 = 11,331.6 marmots
Year 3: N/T 11,331.6 * 0.117 = 1,325.8 marmots added
Why are more marmots added each year than in the year before if per capita rate of population growth remained the same?
Per capita: per individual. N increased because we added more individuals. Multiplying it by a bigger number increases pop. value.
Pattern of population growth is exponential growth. Happens in populations with unlimited resources.
What is the Exponential Growth model?
number of individuals added over time increases as N increases with unlimited resources
Would exponential growth occur often in nature?
No. Having unlimited resources are uncommon. At least one resource is limited
What is the Logistic Population Growth model?
the population growth slows as it approaches carrying capacity (K)
What is carry capacity? (K)
the maximum population size a given environment can sustain
How do exponential growth and logisitc growth models compare?
Exponential model with forever increase, not having a limit for population growth. Logistic model has a carrying capacity, meaning it will stabilize over time
What limiting resources determine carrying capacity?
Resources can vary from year to year: shelter from predators, nesting sites, food, water
What is the exponential model equation?
△N/△t = bN - dN
What happens to the population when it reaches carrying capacity?
It slows in growth
What does a decrease in growth for Logistic models mean?
Fewer births (b) due to inadequate resources for pregnancy or increased fetal mortality.
Increased death (d) due to inadequate resources to support current population
What population growth model fits best for humans?
Exponential or Logistic?
Exponential
Define Survivorship
the percent of the population that survives a specific age cap
How do you calculate Survivorship?
of surviving individuals/total # individuals you started with
What is a survivorship curve?
Plots of the proportion of individuals still alive in each age
What can survivorship curves help us discover?
Lifetime patterns of survival are informative about species ecology (based on species characteristic)
Describe Type 1 Survivorship:
plot number of survivors on Y axis to the highest survival rates they can go (most can be old, causing it to go up in mortality for species to stay alive)
Define Type 2 Survivorship:
Roughly equal proportions die in each age class (roughly 50% in ea. group)
What traits do Type 1 Species have?
Relatively few offspring with high parental care with a lower death in early age
What are examples of Type 1 Species?
Humans, whales, elephants
What is an example of Type 2 Species?
Ground squirrels (constant av. of indiv. die across each age class)
Define Type 3 Survivorship:
Very high mortality in early life but low mortality for older age groups
What traits would you expect for Type 3 Species?
High reproduction rates/offspring but low parental care (on their own at birth)
What are examples of Type 3 Survivorship?
Sea turtles, Oak trees, 1000s of acorns
How can we study the human population?
With human survivorship curves in periods of time
How has the global fertility rate changed over time?
It has decreased from 5 to 2.5 per woman.
How is the fertility rate associated with poverty and education?
Fertility increases with poverty (poorer people have more children on average due to less contraceptives and family planning resources).
Fertility decreases with education (women and girls with greater access to education have less children). Women have jobs (less time to take care of kids) and less economic freedom (can’t provide independently). Want decisions for bodies.
How does fertility rate vary from country to country?
Developed countries typically have lower fertility rate than developing countries. Mainly due to socioeconomic predictors.
The per capita birth rate for humans globally has:
decreased (global fertility rate is basically a synonym for per capita birth rate)
