Unit II: Population Ecology Flashcards
What is a survivorship curve?
graph of the number of surviving population members versus the relative age of the member
What is a survivorship curve used for?
It is used to visualize and compare life histories
Exponential Growth is density ___________.
independent
What is Exponential Growth?
accelerating growth pattern seen in populations under conditions where resources are NOT limiting
Exponential growth has an _____ population growth rate.
accelerating
What is Population Growth Rate?
number of organisms added in each reproductive generation
When does exponential growth occur?
It happens in nature when there is NO intraspecific competition, such as:
- new population
- after a bottleneck
- increase in resources
- decrease in predation
How do you calculate exponential growth rate?
dN/dT = rN
(r = intrinsic rate of increase
N = population size
T = time
d = derivative)
What do the values of r mean?
neg: decreasing N
0: zero population growth
pos: increasing N
Why does the potential for growth vary among species?
This is because of the variation in Life History traits.
- high potential growth rate: r - selection strategy
- low potential growth rate: K - selection strategy
What is Biotic Potential (max)?
maximal potential growth rate of a species
How do you calculate maximum growth for a species?
dN/dT = rmaxN
What is Logistic Growth?
leveling off of exponential growth due to limiting resources
What is Carrying Capacity?
(K) number of individuals of a species that can be supported by the limited resources of a habitat
As N approached K, the growth of the population ___.
slows
On a graph, the Malthusian catastrophe passes the carrying capacity of the population size.
True
How do you calculate logistic growth?
dN/dT = rmaxN * (K-N)/K
All individuals have an _______, which shapes how individuals survive and reproduce
energy budget
What is an Energy Budget?
allocation of energy resources for body maintenance, reproduction, and parental care
Can you have both fecundity AND parental care?
no
What is Fecundity?
potential reproductive capacity of an individual, which is usually measured in females due to asymmetry of sexes
What is Parental Care?
investment by parents in the production, survival, and reproduction of offspring
What are the typically trade-offs in life history traits (fecundity, parental care)?
you can have few offspring with high parental care or lots of offspring with low parental care
What is the Type I survivorship curve?
high in seed/offspring size but low in seed/offspring amount/number
What is the Type III survivorship curve?
low in seed/offspring size but high in seed/offspring amount/number
What trade-off issues does the time of reproduction present?
Early Reproduction
- allocate lots of energy to growth
- greater chance that you survive to reproductive age
Late Reproduce
- slower growth, need to survive longer before reproducing
- but if individuals survive to reproductive age they are more “mature”
Reproduction is costly in terms of lifetime fitness as reproducing more offspring now reduces the ability to survive and reproduce later. True or False?
True
There is no variation in how species allocate their energy budget to the number of times they breed. True or False?
False, there is variation.
What is Semelparity?
life history strategy characterized by a single reproductive event followed by death
What is Iteroparity?
life history strategy characterized by a multiple reproductive events during the lifetime of a species
Describe r - selection life history (Type III survivorship).
- high fecundity
- low parental care
- fast maturity
- small body size
- low disease/predator resistance
- low survivorship/lifespan
Describe K - selection life history (Type I survivorship).
- low fecundity
- high parental care
- slow maturity
- large body size
- high disease/predator resistance
- high survivorship/lifespan
