flashcards

Question 1

What is a population?

Answer 1

A group of interacting organisms of the same species living in the same place at the same time.

Question 2

What four general factors can bind a population together?

Answer 2

Geography, behavior, resources, and convenience.

Question 3

What is meant by a population’s ‘biotic structure’?

Answer 3

It includes the number of individuals, density, and age classes within the population.

Question 4

What aspects are included in a population’s ‘spatial structure’?

Answer 4

Geographic distribution, habitat arrangement, dispersion of individuals, and movement patterns.

Question 5

According to Hutchinson, a niche is an n-dimensional hyper-volume where ‘n’ equates to what?

Answer 5

The number of environmental factors important to the survival and reproduction of a species.

Question 6

What is a ‘limiting resource’ in the context of population ecology?

Answer 6

A resource that establishes the maximum population size.

Question 7

Distinguish between a fundamental niche and a realized niche.

Answer 7

The fundamental niche is the full hypervolume of conditions a species can tolerate, while the realized niche is the portion it actually occupies due to interactions like competition.

Question 8

The geographic area in which a species occurs is known as its _____.

Answer 8

Geographic Range.

Question 9

What factors can constrain a species’ geographic range?

Answer 9

Geographic barriers, distance, physical features, and competition.

Question 10

How does climate indirectly influence species distributions?

Answer 10

By affecting food production, water supply, habitat, and the incidence of parasites, pathogens, and competitors.

Question 11

A species with a geographically widespread distribution is called a(n) _____ species.

Answer 11

Ubiquitous or Cosmopolitan.

Question 12

What is an endemic species?

Answer 12

A species with a geographically restricted distribution, often due to specialized habitat requirements.

Question 13

Define population density.

Answer 13

The number of individuals per unit area.

Question 14

What is the difference between population abundance and population density?

Answer 14

Abundance is the actual total number of organisms, while density is the number of organisms per unit area.

Question 15

What is ‘dispersion’ in a population context?

Answer 15

The spacing of individuals with respect to one another within the geographic range of a population.

Question 16

What is clustered dispersion (also called clumped or aggregated)?

Answer 16

individuals are aggregated in discrete groups.

Question 17

What factors typically lead to a clustered dispersion pattern?

Answer 17

Heterogeneous resource distribution, mutual attraction between individuals, and weak dispersal tendencies.

Question 18

An evenly spaced dispersion pattern is one in which each individual maintains a(n) _____ between itself and its neighbors.

Answer 18

uniform distance.

Question 19

What factors often cause an evenly spaced (uniform) dispersion pattern?

Answer 19

Aggressive behaviors, competition for limited but homogeneous resources, and strong dispersal tendencies.

Question 20

What is a random dispersion pattern?

Answer 20

position of each individual is independent of the position of other individuals.

Question 21

Under what conditions does a random dispersion pattern typically occur?

Answer 21

When resources are randomly distributed and not limiting, and there is a lack of strong social or interactive forces.

Question 22

What is the key difference between dispersal and migration?

Answer 22

Dispersal is a one-way movement away from a habitat, while migration is an annual or seasonal round-trip movement.

Question 23

What are the primary drivers of migration?

Answer 23

Local climate, seasons, food availability, and variations in the life cycle.

Question 24

What factors can drive the dispersal of individuals?

Answer 24

Reproduction, resource availability, competition, and changing environmental conditions.

Question 25

What is 'dispersal limitation' in conservation biology?

Answer 25

The absence of a population from suitable habitat because of barriers to dispersal.

Question 26

A strip of favorable habitat located between two large patches of habitat that facilitates dispersal is known as a(n) _____.

Answer 26

habitat corridor.

Question 27

How is a population's growth rate calculated?

Answer 27

It is the number of new individuals produced (births + immigration) minus the number of individuals that die (deaths + emigration).

Question 28

What is the intrinsic growth rate ($r_0$) of a population?

Answer 28

The highest possible per capita growth rate for a population under ideal conditions.

Question 29

Geometric growth is an appropriate model for populations with _____ generations and _____ reproduction.

Answer 29

non-overlapping; discrete.

Question 30

What is the formula for geometric population growth?

Answer 30

$N_t = N_0\lambda^t$, where $N_0$ is initial size, $\lambda$ is the geometric rate of increase, and t is time.

Question 31

What is the formula for exponential population growth?

Answer 31

$N_t = N_0e^{r_0t}$, where $N_0$ is initial size, e is the base of natural logs, $r_0$ is the intrinsic growth rate, and t is time.

Question 32

Exponential growth is an appropriate model for populations with _____ generations and _____ reproduction and death.

Answer 32

overlapping; continuous.

Question 33

How can the intrinsic rate of increase ($r$) be calculated from the geometric rate of increase ($\lambda$)?

Answer 33

The formula is $r = \ln(\lambda)$.

Question 34

What is the key characteristic of density-dependent factors that limit population growth?

Answer 34

Their intensity is influenced by the density of the population.

Question 35

Provide three examples of density-dependent factors.

Answer 35

Disease, resource competition, and predation.

Question 36

What defines a density-independent factor in population regulation?

Answer 36

It controls population size with no relation to the population's density.

Question 37

Provide three examples of density-independent factors.

Answer 37

Natural disasters (fires, floods), temperature, and precipitation.

Question 38

The concept that regulation and density dependence imply competition among individuals for limited resources is called _____ competition.

Answer 38

intraspecific.

Question 39

What is the name for the S-shaped population growth curve that accounts for environmental limits?

Answer 39

Logistic population growth.

Question 40

What does the carrying capacity (K) of an environment represent?

Answer 40

The maximum number of individuals of a population that the environment can support.

Question 41

What is the differential equation for logistic population growth?

Answer 41

$\frac{dN}{dt} = r_0N(1 - \frac{N}{K})$

Question 42

In the logistic growth model, at what population size (relative to K) is the actual number of individuals added per unit time (dN/dt) maximized?

Answer 42

At half the carrying capacity, or $N = K/2$.

Question 43

What is the 'self-thinning curve' in plant populations?

Answer 43

It shows how decreases in population density over time lead to increases in the mass of each individual in the population.

Question 44

What is the Allee effect?

Answer 44

A density-dependent mechanism that reduces birthrate and survival when a population is at a very low density.

Question 45

Name two potential causes of the Allee effect.

Answer 45

Difficulty in finding a mate and breakdown of social structures like pack hunting.

Question 46

What is the difference between a cohort life table and a static life table?

Answer 46

A cohort life table follows individuals born at the same time, while a static life table records the age at death of individuals at a single point in time.

Question 47

What are the three ecologically important age classes a population can be divided into?

Answer 47

Prereproductive, reproductive, and postreproductive.

Question 48

What does the net reproductive rate ($R_0$) represent?

Answer 48

The total number of female offspring that an average female is expected to produce over her lifetime.

Question 49

If a population's net reproductive rate ($R_0$) is greater than 1.0, what is happening to the population?

Answer 49

The population is growing.

Question 50

What does a net reproductive rate ($R_0$) of less than 1.0 indicate about a population?

Answer 50

The population is declining.

Question 51

For a species with non-overlapping generations, the geometric rate of increase ($\lambda$) is equal to what other demographic parameter?

Answer 51

The net reproductive rate ($R_0$).

Question 52

For species with overlapping generations, how is the per capita rate of increase ($r_0$) estimated from the net reproductive rate ($R_0$) and generation time (T)?

Answer 52

The formula is $r_0 = \frac{\ln(R_0)}{T}$.

Question 53

What is competition, in an ecological sense?

Answer 53

Any use or defense of a resource by one individual that reduces the availability of that resource to other individuals.

Question 54

Differentiate between intraspecific and interspecific competition.

Answer 54

Intraspecific competition is among individuals of the same species, while interspecific competition is among individuals of different species.

Question 55

What is Liebig's law of the minimum?

Answer 55

A law stating that a population increases until the supply of the most limiting resource prevents it from increasing further.

Question 56

What is the Competitive Exclusion Principle, as formulated by Gause?

Answer 56

Two species competing for the same limiting resource cannot coexist indefinitely; one will eventually exclude the other.

Question 57

Tansley's experiments with bedstraw (Galium spp.) suggested that interspecific competition restricts the _____ of each species.

Answer 57

realized niche.

Question 58

In the Lotka-Volterra competition model, what is represented by the competition coefficient $\alpha$?

Answer 58

The effect of an individual of species 2 on the rate of population growth of species 1.

Question 59

The Lotka-Volterra model predicts coexistence of two species when, for both species, _____ competition is weaker than _____ competition.

Answer 59

interspecific; intraspecific.

Question 60

What is allelopathy?

Answer 60

A type of interference competition where organisms use chemicals to harm their competitors.

Question 61

What is character displacement?

Answer 61

The divergence in characteristics of two similar species where their ranges overlap, caused by the selective effects of competition.

Question 62

What is the expected evolutionary result of strong interspecific competition on the niches of the competing species?

Answer 62

Directional selection for reduced niche overlap.

Question 63

What is the difference between an exotic species and an invasive species?

Answer 63

An exotic species is found outside its normal range, while an invasive species is an exotic species that spreads rapidly and has negative effects.

Question 64

The introduction of the moth Cactoblastis cactorum to Australia to control the prickly pear cactus is an example of what practice?

Answer 64

Biological control.

Question 65

What two main factors are believed to drive the population cycles of snowshoe hares and lynx?

Answer 65

Fluctuations in the food supply for hares and predation by lynx and other predators.

Question 66

What did Gause's experiments with Paramecium and Didinium demonstrate about the requirements for stable predator-prey cycling?

Answer 66

Stable cycling requires both refuges for the prey and immigration.

Question 67

What is the Red Queen Hypothesis as it applies to predator-prey relationships?

Answer 67

It suggests that predators and prey are in a constant co-evolutionary race, where each must continually evolve just to maintain its current fitness level relative to the other.

Question 68

What is aposematic coloration?

Answer 68

Warning colors, often combined with chemical defenses, that advertise an organism's unpalatability or toxicity to predators.

Question 69

What is Batesian mimicry?

Answer 69

A form of mimicry where a harmless species evolves to imitate the warning signals of a harmful or noxious species.

Question 70

What is Mullerian mimicry?

Answer 70

A form of mimicry where two or more noxious or well-defended species evolve to resemble each other.

Question 71

How does 'predator satiation' work as a prey defense?

Answer 71

Prey reduce their individual probability of being eaten by living and emerging in extremely dense populations, overwhelming the feeding capacity of predators.

Question 72

What is 'masting' in trees, and how does it relate to predator satiation?

Answer 72

Masting is the synchronous, widespread production of seeds and fruit, which satiates seed predators and allows more seeds to survive.

Question 73

How can large body size function as a refuge from predation?

Answer 73

If predators ignore individuals above a certain size, growing large provides protection, as the large prey may be less profitable to pursue.