Population Ecology Flashcards
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It is the study of populations in relation to the environment.
Population ecology
It includes environmental influences on population density & distribution, age structure, & variations in population size.
Population ecology
What do dynamic biological processes influence?
Population density, dispersion, & demographics
It is a group of individuals of a single species living in the same general area.
Population
How are populations described?
By their boundaries & size.
It refers to the changes in a population over time.
Population dynamics
What are the four variables of population dynamics?
Density, dispersion, size, and age distribution
It refers to the amount of individuals in a population per unit habitat area.
Population density
Population density is also known as ___.
Ecological population density
Density depends upon what factors?
Social/population structure, mating relationships, and time of year
True or False: Mountain lions live in high density populations, while mice and cockroaches live in low density populations.
FALSE. Mice and cockroaches live in high density, while mountain lions live in low density.
It is the spatial pattern of distribution.
Population dispersion
What are the 3 main classifications of population dispersion?
Clumped, uniform, and random
This population dispersion is when individuals are clumped into groups.
Clumped
What are the causes of clumped population dispersion?
Resources that are clumped or social interactions
This population dispersion is when individuals are regularly spaced in the environment.
Uniform
What are the causes of uniform population dispersion?
Antagonism between individuals or regular spacing of resources
This population dispersion is when individuals are randomly dispersed in the environment.
Random
What are the causes of random population dispersion?
Random distribution of resources in the environment, or neither positive nor negative interaction between individuals
What is the order of population dispersion from most common to least common?
Clumped, Uniform, Random
Why is uniform population dispersion less common?
Because resources are evenly spread.
Why is random population dispersion rare?
Because the conditions needed for random population dispersion are rarely met.
What are some examples of clumped population dispersion?
Flocking birds, herbivore herds, patches of vegetation, wolf packs, schools of fish
What is an example of uniform population dispersion?
Creosote bush
What are some examples of random population dispersion?
Dandelions, plants with wind-dispersed seeds
What are the 4 reasons for clumping?
- Resources a species needs varies from place to place
- Better protection
- Predator species have a better chance of getting a meal if hunting in packs
- Temporary groups for mating and caring for young are sometimes formed
Why does uniform spacing benefit the creosote bush?
By having this pattern, they have better access to scarce water resources.
It dictates whether a population will grow, shrink, or stay the same size.
Age structure
How is age structure usually shown?
Graphically
What are the three divisions of age structure?
Pre-reproductives, reproductives, and post-reproductives
It refers to those not old enough to reproduce.
Prereproductives
It refers to those capable of reproduction.
Reproductives
It refers to those too old to reproduce.
Postreproductives
What type of population is presented if there are more prereproductives than reproductives and postreproductives?
Expanding population
What type of population is presented if there is an equal amount of prereproductives and reproductives, and fewer postreproductives?
Stable population
What type of population is presented if there are more postreproductives than reproductives and prereproductives?
Diminishing population
What does population growth depend upon?
Birth rates, death rates, immigration rates, and emigration rates?
What is being presented with the formula:
Pop(then) + (b + i) - (d + e)
Current population
What is being presented with the formula:
(b + i) - (d + e)
Change in population
What is being presented with the equation:
(b + i) = (d + e)
Zero population growth
What does it mean if a population is growing at a rate of 2% per year?
2 new individuals are added to the population for every 100 already present per year.
What are the two types of population growth?
Exponential growth and logistic growth
The increase is constant as the population grows.
Arithmetic growth
The increase changes as the population grows.
Exponential growth
What is the curve when exponential growth is presented graphically?
J-shaped curve
This type of growth is not limited by resources, species grow at their full biotic potential.
Exponential growth
True or False: Exponential growth begins slowly but quickly increases.
TRUE
What is an example of a species with exponential growth?
Houseflies (can produce 6,182,442,727,320 flies in one year)
This growth is when populations increase to some level, and then maintain that stable level (with minor oscillations).
Logistic growth
What is the shape of logistic growth when presented on a graph?
S-shaped curve
It is the capacity for growth without limits.
Biotic potential
It is the rate of growth with unlimited resources.
Intrinsic rate of increase
The limiting factors for population growth are also known as ___.
Environmental resistance
The size of the population of a particular species in a given place and time is determined by ___?
The interplay between its biotic potential and environmental resistance
It is the maximum number of species that can be sustained indefinitely in a given space.
Carrying capacity
How is carrying capacity determined?
Biotic potential + environmental resistance
True or False: All species enjoy exponential growth.
FALSE. The exponential growth of most populations ends at some point.
What are some causes of the end of exponential growth?
Overshoot, dieback/crash
What are the two types of factors that affect population growth?
Density-independent (D-I) factors and density-dependent (D-D) factors
They affect populations randomly (without respect to density).
Density-independent factors
They affect populations most when densities are high.
Density-dependent factors
True or False: Density-independent factors are poor regulators of populations.
TRUE. They have the ability to cause rapid increases or decreases in populations, but they are poor regulators of populations.
True or False: Density-dependent factors are bad regulators of populations.
FALSE. Density-dependent factors act to limit population growth only when populations are large, and are therefore good regulators of populations.
True or False: Density-independent factors are biotic, while density-independent factors are abiotic.
FALSE. D-I factors are abiotic, while D-D factors are biotic.
What are some examples of density-independent factors?
Hurricanes, tornadoes, fire, drought, floods
What are some examples of density-dependent factors?
Disease, competition, predation, parasitism
What kind of factors affect all populations with growth patterns?
Dependent-independent factors
Density-dependent factors cause populations to have what kind of growth?
Logistic growth
A severe freeze in late spring can kill many individuals in a plant population, regardless of density, is an example of what kind of factors?
Density-independent factors
Bubonic plague, which swept through densely populated European cities during the 14th century, is an example of what kind of factors?
Density-dependent factors
What are the four types of population fluctuation?
Stable, irruptive, cyclic, irregular
It is when population size fluctuates around carrying capacity (slightly above, slightly below).
Stable
It is typical of species in undisturbed tropical rainforests.
Stable
It is when population is normally fairly stable but occasionally explodes to peak then crashes to stable lower level (very low level)
Irruptive
Caused by factors (i.e. temp) that temporarily increases carrying capacity
Irruptive
What are some examples of irruptive fluctuations?
Raccoon, house mouse
It is chaotic behavior in population size with no apparent recurring pattern.
Irregular
May be due to chaos in system and poorly understood interactions.
Irregular
It is fluctuations in size that occur over a regular time period; most are poorly understood.
Cyclic
True or False: The goal of all individuals is to produce as many offspring as possible.
TRUE
True or False: Each individual has an unlimited amount of energy to put towards life and reproduction.
FALSE. Each individual has a limited amount of energy to put towards life and reproduction.
Natural selection has favored the production of what two main types of species?
r-strategists and k-strategists
The classification of whether species are r-strategists or k-strategists depends on what?
Their position on the s-shaped population growth curve and their reproductive patterns
The limited amount of energy of each individual leads to what trade-off?
Long life vs. high reproduction rate
True or False: Many K-selected species are prone to extinction.
TRUE. Especially those with long generation times and low reproductive rates like elephants, rhinoceroses, and sharks.
What are some examples of K-strategists?
Elephants, rhinoceroses, and sharks
What are some examples of r-strategists?
Algae, bacteria, rodents, annual plants (dandelions), and most insects
True or False: All species are strictly only either r-strategists or K-strategists.
FALSE. Most organisms have reproductive patterns between the extremes of r-selected species and K-selected species, or they change from one extreme to the other under certain environmental conditions.
True or False: The reproductive pattern of a species ma give it a temporary advantage. But the availability of suitable habitat for individuals of a population in a particular area is what determines its ultimate population size.
TRUE
What are the different types of survivorship curves?
Late loss population, constant loss population, early loss population
They typically have a high survivorship to a certain age, then high mortality.
Late loss population
They show a fairly constant death rate at all ages.
Constant loss population
Survivorship is low early in life.
Early loss population
Mammals such as elephants, rhinoceroses , and humans typically have a ___ survivorship curve.
Late loss population
What is the survivorship curve of most songbirds?
Constant loss population
Annual plants and many bony fish species have a ___ survivorship curve.
Early loss population
What are three examples of loss of genetic diversity?
Founder effect, demographic bottleneck, genetic drift
The establishment of a new population by a few original pioneers which carry only a small fraction of the total genetic variation of the parental population.
Founder effect
Genetic diversity loss that occurs as a result of a drastic reduction in population by an event having little to do with the usual forces of natural selection.
Demographic bottleneck
The process of change in the genetic composition of a population due to chance or random events rather than by natural selection, resulting in changes in allele frequencies over time.
Genetic drift
It occurs when a small group of individuals becomes isolated from a larger population and forms a new population, which may have different allele frequencies than the original.
Founder effect
It happens when a population experiences a drastic reduction in size due to a catastrophic event (e.g., natural disaster), leading to a loss of genetic diversity.
Demographic bottleneck
It refers to the random changes in allele frequencies in a population, especially in small populations, due to chance events.
Genetic drift
TheAmish populationin Pennsylvania descended from a small group of settlers who migrated from Europe. As a result, certain genetic traits, likeEllis-van Creveld syndrome(a rare form of dwarfism), are more common among the Amish than in the general population.
This is an example of what kind of loss of genetic diversity?
Founder effect
Thecheetah populationexperienced a severe population reduction about 10,000 years ago. Due to this event, cheetahs today have very low genetic variation, making them more vulnerable to diseases and environmental changes.
This is example of what kind of loss of genetic diversity?
Demographic bottleneck
In a small population ofwildflowers, if a few individuals with a rare flower color randomly do not reproduce (e.g., due to drought or other random events), the allele for that color might disappear entirely from the population, simply by chance.
This is an example of what kind of loss of genetic diversity?
Genetic drift
