#metapopulation

Population Ecology

A population that persists due to immigration despite high local extinction rates exemplifies:

“Core-satellite metapopulation” for a population that persists due to immigration despite high local extinction rates exemplifies. This relationship follows from the ecological mechanism represented by the terms in the item, not merely from an association between their names. At equilibrium, species identities can continue to turn over even when richness is approximately stable. The model predicts a balance of rates, not an absence of colonization or extinction. The remaining alternatives—“Classical metapopulation”, “Nonequilibrium metapopulation”, “Continuous population”—refer to different states, processes, or scales and therefore do not express the same causal relationship. Island biogeography explains species richness as a dynamic balance between immigration and extinction. Immigration generally declines as an island fills with species, whereas extinction rises as more species divide finite area and maintain smaller populations. The cited framing is therefore most useful when treated as a conditional biological claim, with assumptions about scale and environmental context kept explicit.

Ref: Campbell Biology, Urry et al., 12th Ed., Unit 8 Ecology

View Details

Population Ecology

In a metapopulation, subpopulations are interconnected through:

“Dispersal of individuals” for in a metapopulation, subpopulations are interconnected through. This relationship follows from the ecological mechanism represented by the terms in the item, not merely from an association between their names. Population ecology links individual births, deaths, immigration, and emigration to changes in abundance. Per-capita rates determine the direction of change, while density dependence creates feedback when crowding alters survival or reproduction. The remaining alternatives—“Genetic drift”, “Resource partitioning”, “Competitive exclusion”—refer to different states, processes, or scales and therefore do not express the same causal relationship. Interpretation must distinguish absolute population change from a per-capita rate and must state the time interval and population boundary. Age structure, dispersal, environmental variation, and delayed responses can all make observed trajectories depart from a simple model. Linking the wording to measurable consequences for fitness, abundance, or flux gives the conclusion its scientific meaning and prevents a purely mnemonic interpretation.

Ref: Campbell Biology, Urry et al., 12th Ed., Unit 8 Ecology

View Details

Population Ecology

Fragmented populations linked through dispersal constitute:

“A metapopulation” for fragmented populations linked through dispersal constitute. This relationship follows from the ecological mechanism represented by the terms in the item, not merely from an association between their names. Interpretation must distinguish absolute population change from a per-capita rate and must state the time interval and population boundary. Age structure, dispersal, environmental variation, and delayed responses can all make observed trajectories depart from a simple model. The remaining alternatives—“A deme”, “A single large population”, “An isolated group”—refer to different states, processes, or scales and therefore do not express the same causal relationship. Mechanistic support comes from showing how resource limitation, enemies, mate availability, or physiological stress changes demographic performance. A descriptive association alone does not establish regulation or causation. This distinction matters because similar surface patterns can arise through different mechanisms, whereas ecological prediction depends on identifying the mechanism that actually changes rates. The cited framing is therefore most useful when treated as a conditional biological claim, with assumptions about scale and environmental context kept explicit.

Ref: Campbell Biology, Urry et al., 12th Ed., Unit 8 Ecology

View Details

Population Ecology

Immigration prevents extinction in a patch; this phenomenon is called:

“Rescue effect” for immigration prevents extinction in a patch; this phenomenon is called. This relationship follows from the ecological mechanism represented by the terms in the item, not merely from an association between their names. Island biogeography explains species richness as a dynamic balance between immigration and extinction. Immigration generally declines as an island fills with species, whereas extinction rises as more species divide finite area and maintain smaller populations. The remaining alternatives—“Founder effect”, “Genetic drift”, “Colonization effect”—refer to different states, processes, or scales and therefore do not express the same causal relationship. Larger islands usually support more habitats and larger populations, lowering extinction risk; less isolated islands receive colonists more readily and may experience rescue effects. These mechanisms also apply to habitat fragments that function as ecological islands. This distinction matters because similar surface patterns can arise through different mechanisms, whereas ecological prediction depends on identifying the mechanism that actually changes rates.

Ref: Campbell Biology, Urry et al., 12th Ed., Unit 8 Ecology

View Details

Population Ecology

Which factor does NOT affect metapopulation persistence?

The keyed exception is “Genetic drift.” In the context of which factor does not affect metapopulation persistence, that statement differs from the governing ecological pattern and must be evaluated against the mechanism rather than accepted from wording alone. Mechanistic support comes from showing how resource limitation, enemies, mate availability, or physiological stress changes demographic performance. A descriptive association alone does not establish regulation or causation. The remaining alternatives—“Number of patches”, “Size of patches”, “Connectivity among patches”—refer to different states, processes, or scales and therefore do not express the same causal relationship. Population ecology links individual births, deaths, immigration, and emigration to changes in abundance. Per-capita rates determine the direction of change, while density dependence creates feedback when crowding alters survival or reproduction. The cited framing is therefore most useful when treated as a conditional biological claim, with assumptions about scale and environmental context kept explicit. Linking the wording to measurable consequences for fitness, abundance, or flux gives the conclusion its scientific meaning and prevents a purely mnemonic interpretation.

Ref: Campbell Biology, Urry et al., 12th Ed., Unit 8 Ecology

View Details

Population Ecology

A metapopulation is primarily defined as:

“A group of populations linked by immigration and emigration” for a metapopulation is primarily defined as. This relationship follows from the ecological mechanism represented by the terms in the item, not merely from an association between their names. Population ecology links individual births, deaths, immigration, and emigration to changes in abundance. Per-capita rates determine the direction of change, while density dependence creates feedback when crowding alters survival or reproduction. The remaining alternatives—“A single large population”, “A group of isolated individuals”, “A population living on a small island”—refer to different states, processes, or scales and therefore do not express the same causal relationship. Interpretation must distinguish absolute population change from a per-capita rate and must state the time interval and population boundary. Age structure, dispersal, environmental variation, and delayed responses can all make observed trajectories depart from a simple model. This distinction matters because similar surface patterns can arise through different mechanisms, whereas ecological prediction depends on identifying the mechanism that actually changes rates.

Ref: Campbell Biology, Urry et al., 12th Ed., Unit 8 Ecology

View Details

Density Dispersion Meta pop

Recolonization of a previously extinct patch is an example of:

The rescue effect and recolonization are related but distinct. Rescue occurs when immigrants enter a patch that is still occupied and prevent its local population from going extinct. Recolonization occurs after extinction, when dispersers establish a new population in an empty patch. Therefore, the wording “recolonization of a previously extinct patch” describes colonization following local extinction, not rescue in its strict ecological meaning. Movement of colonists is migration or dispersal, making that listed alternative closer to the mechanism, although “recolonization” itself would be the precise term if offered. This distinction matters in metapopulation models: rescue reduces the extinction probability of occupied patches, whereas recolonization increases the transition rate from empty to occupied. Both depend on landscape connectivity and sources of migrants. The preserved key conflates these processes and is scientifically inaccurate under standard definitions. A patch that has already lost every individual cannot be rescued from extinction; it can only be colonized again. Clear terminology helps separate persistence within patches from restoration of occupancy across the patch network.

Ref: Ecology: Concepts and Applications, Molles, 9th Ed., Ch. 9

View Details

Density Dispersion Meta pop

The term 'metapopulation' was coined by:

Richard Levins introduced the term and formal concept of a metapopulation in the late 1960s while developing models of populations occupying temporary habitat patches. His classic formulation tracked the fraction of suitable patches occupied, balancing colonization of empty patches against extinction of occupied ones. This abstraction showed how a species could persist regionally even when individual local populations repeatedly vanished. Robert MacArthur and E. O. Wilson developed island biogeography, a closely related theory balancing immigration and extinction in island species richness, but they did not coin “metapopulation.” Their work strongly influenced landscape and patch ecology, which may explain the plausible distractors. Levins’s model also established a threshold condition: colonization must be sufficiently strong relative to extinction for nonzero regional occupancy to persist. Modern metapopulation theory extends the framework by including patch area, isolation, habitat quality, rescue effects, demographic stochasticity, and explicit dispersal. The historical attribution matters because it connects the word to a specific theoretical shift—from treating populations as spatially continuous units to viewing them as networks of locally dynamic patches.

Ref: Ecology: Concepts and Applications, Molles, 9th Ed., Ch. 9

View Details

Density Dispersion Meta pop

The 'rescue effect' refers to:

The rescue effect occurs when immigrants enter a small, declining local population and reduce its probability of extinction. New arrivals add individuals directly, can increase reproduction by supplying mates, and may restore genetic variation or reduce inbreeding. The patch remains occupied throughout; immigration “rescues” it before abundance reaches zero. This differs from recolonization, which establishes a population in a patch after local extinction has already occurred. In metapopulation models, both processes depend on connectivity, but they affect occupancy in different ways: rescue lowers the local extinction rate, whereas recolonization raises the colonization rate of empty patches. Predator control and resource reallocation are management actions, not the defining mechanism. Increased reproduction may contribute after immigrants arrive, but immigration is the causal link between patches. Very high connectivity can also synchronize populations or spread disease, so more dispersal is not always beneficial. The rescue effect is strongest when donor populations provide migrants and the recipient patch remains suitable enough for those migrants to survive and reproduce.

Ref: Ecology: Concepts and Applications, Molles, 9th Ed., Ch. 9

View Details

Density Dispersion Meta pop

Core-satellite metapopulations are maintained by:

In a core–satellite, or mainland–island, metapopulation, a large persistent core population provides a continuing supply of emigrants to smaller peripheral populations. The core has low extinction risk because of its size or superior habitat quality, whereas satellite patches may frequently disappear and be recolonized. Regional persistence therefore depends heavily on propagule production from the core. Equal gene flow among all patches is not required; movement is often asymmetric from core to satellites. A high extinction rate in satellites may characterize the system but does not maintain it without compensating colonization. Mutation is not the ecological process supporting patch occupancy. The model differs from the classic Levins structure, which treats patches as more similar, and from a source–sink framework, although a core often functions as a demographic source. Protecting only satellites while degrading the core can therefore destabilize the entire network. Conversely, conserving the large persistent population and its dispersal routes can sustain otherwise transient local populations across a fragmented landscape.

Ref: Ecology: Concepts and Applications, Molles, 9th Ed., Ch. 9

View Details

Density Dispersion Meta pop

Which statement best describes a metapopulation?

A metapopulation consists of multiple local subpopulations occupying separate habitat patches and linked by dispersal. Each patch can have its own births, deaths, density, and risk of extinction, while emigrants connect local dynamics by colonizing empty patches or supplementing occupied ones. Regional persistence can therefore occur despite recurring local extinctions. A single local population lacks this explicit patch network, and a completely isolated group cannot undergo the colonization–extinction balance central to metapopulation theory. The subpopulations need not be genetically identical or clonal; gene flow may occur, but ecological connectivity is the key feature. Different structures include classic patch networks, mainland–island systems, source–sink systems, and core–satellite arrangements. Connectivity must be intermediate enough that patches retain some demographic independence yet movement still occurs. If dispersal is absent, populations are isolated; if it is overwhelming, the system may behave as one continuous population. Habitat fragmentation, corridor placement, and patch quality are therefore fundamental to understanding metapopulation viability and conservation.

Ref: Ecology: Concepts and Applications, Molles, 9th Ed., Ch. 9

View Details

Density Dispersion Meta pop

In metapopulations, extinction of a patch is balanced by:

Metapopulation persistence depends on a dynamic balance between local extinction and colonization. When a patch population disappears, dispersers from occupied patches can establish a new local population, a process called recolonization. If recolonization rates are sufficient relative to extinction rates, the species can persist regionally even though no particular patch is occupied continuously. In the classic Levins model, the fraction of occupied patches changes as colonization creates new occupancy and extinction removes it. Dispersal is the movement mechanism that makes recolonization possible, but recolonization is the demographic event that directly counterbalances extinction of an already empty patch. This differs from the rescue effect, in which immigrants reduce the probability that a still-occupied local population will go extinct. Speciation and aggregation do not restore occupancy on the relevant ecological timescale. Patch isolation, matrix hostility, propagule supply, and habitat quality all influence recolonization success. Conservation corridors can therefore support regional persistence by allowing colonists to reach vacant suitable habitat, even when local environmental fluctuations continue to cause extinctions.

Ref: Ecology: Concepts and Applications, Molles, 9th Ed., Ch. 9

View Details