Population & Community Ecology Flashcards
—: a group of individuals of a single species living in the same general area
*Defined by their — (natural or artificial) and their —
- Population
- Boundaries
- Size
——: the study of population in relation to the environment
* Focuses in factors affecting —— over time
- Population Ecology
2. Population size
—: the number of individuals per unit area or volume
Density
—: the pattern of spacing among individuals within the boundaries of the population
Dispersion
In most cases, it is impractical or impossible to — all individuals in a population
Count
Sampling techniques can be used to estimate densities and total population sizes, for example by:
* Extrapolating from —— (e.g., number of trees in randomly located 100 x 100 m plots) * Using an indicator of —— (e.g., number of nests, burrows, tracks or fecal droppings) * ———
- Small samples
- Population size
- Mark-recapture method
Mark Recapture Method:
Scientists —,—, & — a random sample of individual in a population
- Capture
- Tag
- Release
Mark Recapture Method:
— individuals are given time to mix back into the —
- Marked
2. Population
Mark Recapture Method:
A — sample of individuals are — and the number that are marked is notes
- Second
2. Captured
Mark Recapture Method:
Population size is estimated by the equation: —=—/—
N= sn/x
S=individuals
n= second sample individuals
X= number marked
N= population size
Density is the result of an interplay between processes that — & — individuals to/from a —
- Add
- Remove
- Population
—: the influx of new individuals from other areas
Immigration
—: the movement of individuals out of a population
Emigration
Local densities within a population’s geographic range can — and create — of —
- Differ
- Patterns
- Dispersion
Spacing can be influenced by both — and — factors
- Environmental
2. Social
Individuals aggregate in —
Patches
—— is the most common pattern
Clumped Dispersion
Clumped Dispersion may be influenced by:
- — availability
- mating — & group —
- Resource
- Behavior
- Defense
Uniform Dispersion:
Individuals are ——
Evenly distributed
Uniform dispersion:
May be influenced by social interactions such as —, the defense of a bounded space against other individuals
Territoriality
Random Dispersion:
Position of each individual is — of others
Independent
Random Dispersion:
Occurs in Absence of strong — or —
- Attractions
2. Repulsions
Patterns of Dispersion:
Dispersion patterns tend to be highly dependent on the —— of the observer
Spatial scale
—: the study of the vital statistics of a population and how they change over time
Demographics
— and — factors influence birth, death, and migration rates of populations
- Biotic
2. Abiotic
Life Tables:
An — specific summary of the survival and reproductive rates within a population
*Often made by following the fate of a —, a group of individuals of the same age, from birth until all have died
*— are often ignored when studying sexually reproducing species because only — produce offspring
*E.g., Belding’s ground squirrels
- Age
- Cohort
- Males
- Females
——:
Graphic way of representing the data in a life table
* Belding’s ground squirrels show relatively constant death rates
Survivorship Curves
Sensorship Curves:
Type 1: — death rates during early and middle life, then an —in death rates among older age groups
- Low
2. Increase
Survivorship Curves:
Type 2: death rate is — over the organisms life span
Constant
Survivorship Curves:
Type 3: — death rates for the young, then a — death rate for survivors
- High
2. Slower
Survivorship Curves:
Many species are — to the curves
Intermediate
Reproductive rate for sexual organisms, measured as the average number of — offspring produced by the — in an —group
- Females
- Females
- Age
Age-specific reproductive rates — considerable by —
- Vary
2. Species
2 models are commonly used by ecologists to estimate population growth under ideal or limiting conditions:
- —— describes population growth in an idealized, unlimited environment
- —— describes how a population grows more slowly as it nears its carrying capacity associated with limiting resources
- Exponential model
2. Logistic model
Exponential growth Model:
Helps is understand the capacity of species to increase and the conditions that may facilitate this growth
* Population increases at an exponential rate(r), ————
* Results in a —— curve
- Intrinsic rate of increase
2. J-shaped
Exponential Growth Model:
Characterizes some populations introduced in a new — or ——
* E.g. elephant population in South Africa grew exponentially after hunting was banned
- Environment
2. Rebounding populations
Logistic Growth Model:
Exponential growth cannot be — for — in any population
- Sustained
2. Long
Logistic Growth Model:
A more realistic population model limits growth by incorporating ——
Carrying capacity
Carrying Capacity (K): — population size the environment can — * varies with the abundance of ——
- Maximum
- Support
- Limiting resources
Rate of increase declines as —— is reached
* Produces a — curve
- Carrying Capacity (K)
2. Sigmoid (s-shaped)
The growth of laboratory populations of paramecium fits an —— curve
* these organisms are grown in a constant environment lacking — & —
- S-shaped
- Predators
- Competitors
Some populations:
- overshoot K before settling down to a relatively stable —
- Fluctuate greatly, making it difficult to define —
- Density
2. K
The logistic model fits few ——, but is useful as a starting point for thinking about how ——
- Real populations
2. Populations grow
Th logistic model and real populations: Can be used to: * Predict rates of —— * estimate sustainable —— * Estimate size below which population may become —
- Population recovery
- Harvest rates
- Extinct
An organisms —— comprises the traits that affect its schedule of reproduction and survival
Life history
Life history entails 3. Key components:
- The age at which — begins
- How much and how often an organism —
- Amount of investment in ——
- Reproduction
- reproduces
- Parental care
—, or ———: produce many offspring once and die
- favored in highly variable or unpredictable environment where survival rates is —
- E.g. salmon, agave plant
- Semelparity
- Big-bang reproduction
- Low
—-, or ——: produce offspring repeatedly
Z8Favored in more stable or predictable environments where survival is more —
E.g., sea turtle, bur oak
- Iteroparity
- Repeated Reproduction
- Likely
Organisms vary widely in the number of offspring they —
Produce
Species that produce one or few offspring may — them better than species that produce many offspring
Provision
Organisms have — resources, which may lease to —— between survival and reproduction
* e.g. trade off between survival; and parental care in European kestrels
- Finite
2. Trade-offs
—— can also influence trade off between number and size of offspring
Selective Pressure
If young are likely to —, may produce — small offspring
*Some plants produce a large number of small seeds, ensuring that at least some of them will grow and eventually reproduce
- Die
2. Many
Greater —— in one or a few offspring enhances survival chances
* Some plants produce a moderate number of large seeds that provide a large store of energy that will help seedlings become established
Parental investment
——: selects for life history traits that are advantageous at high population densities
- Populations living at a density near carrying capacity, K
* E.g., mature trees in old growth forests
K-Selection
——: selects for life history traits that are advantageous at low population densities
- Populations living well below carrying capacity, such that the intrinsic rate of increase (r) is maximized
- E.g., weeds colonizing abandoned agricultural field
R-selection
2 important questions about regulation of population growth:
- What —— stop a population from — indefinitely?
- Why are some populations fairly — in —, while others are not?
- Environmental Factors
- Growing
- Stable
- Size
———: birth rate and death rate do not change with population density
Density-independent popualtions
———: birth rates fall and death rates increase with rising population density
density dependent populations
Population change and population density:
— sometimes exist
Combinations
Density-dependent birth and death rates are an example of ——that regulates population growth and are affected by many factors, such as:
- Competition for —
- —
*— - —
- — factors
* — wastes
- Negative Feedback
- Resources
- Territoriality
- Disease
- Predations
- Intrinsic
- Toxic
In crowded populations, — population — intensifies competition for resources and results in a lower ——
- Increasing
- Density
- Reproductive Rate
Territoriality:
Can limits —— when individuals compete for limited space
Population density
Disease:
- Population density can influence the — and — of organisms
- In dense populations, — can spread more rapidly
- Health
- Survival
- Pathogens
Predation:
As a prey population build up, — may feed preferentially on that —
- Predators
2. Species
Intrinsic Factors:
For some populations, intrinsic(physiological) factors appear to regulate ——
Population size
Toxic Wastes:
Accumulation of toxic wastes can contribute to —— regulation of population size
Density dependent
Population Dynamics:
Focuses on the complex interactions between — and — factors that cause — in population size
- Biotic
- Abiotic
- Variation
—: entry of individuals to an area
Immigration
—: exit of individual from an area
* Often increases when
~ a population becomes —
~ Competition for resources —
- Emigration
- Crowded
- Increases
Metapopualtions:
Local populations that are linked by — and —
* Occupy patches of — habitat surrounded by — habitat
*Those lost through extinctions can be — by immigration from other patches
- Immigration
- Emigration
- Suitable
- Unsuitable
- Recolonized
The Global Human Popualtion:
Increase relatively — until about 1650 and then began to grow —
- Slowly
2. Exponentially
The Global Human Population:
No longer growing — but is still — rapidly
- exponentially
2. Increasing
To maintain population stability, a regional human population can exist in one of 2 configurations:
- Zero population growth = — birth rate – — death rate
- Zero population growth =— birth rate – —death rate
- High
- High
- Low
- Low
——: the move from the first state to the second state
*Associated with an increase in quality of —— and improved access to —
- Demographic Transition
- Health Care
- Education
Global Carrying Capacity:
* Population ecologists predict a global population of ~— billion people in 2050
~ The carrying capacity of Earth for humans is —
- 10
2. Uncertain
Global Carrying Capacity: Scientists have estimates on: - — growth models - area of —— - — availability
- Logistic
- Habitable Land
- Food
Our carrying capacity could potentially be limited by —, —, —, nonrenewable resources, buildup of wastes, — change, plagues and war
- food
- water
- Space
- Climate
Unlike other organisms, we can regulate our population growth through ——
Social changes
