Source–sink dynamics

This coral reef in the Phoenix Islands Protected Area provides habitat for numerous marine species.

Theoretical model used by ecologists to describe how variation in habitat quality may affect the population growth or decline of organisms.

- Source–sink dynamics

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A metapopulation consists of a group of spatially separated populations of the same species which interact at some level.

Metapopulations are important in fisheries. The local population (1.) serves as a source for hybridization with surrounding subspecies populations (1.a, 1.b, and 1.c).The populations are normally spatially separated and independent but spatial overlap during breeding times allows for gene flow between the populations.
E. coli metapopulation on a chip.

The development of metapopulation theory, in conjunction with the development of source–sink dynamics, emphasised the importance of connectivity between seemingly isolated populations.


Set of interacting communities which are linked by the dispersal of multiple, potentially interacting species.

Biodiversity of a coral reef. Corals adapt to and modify their environment by forming calcium carbonate skeletons. This provides growing conditions for future generations and forms a habitat for many other species.

These are the patch dynamics, species sorting, source–sink dynamics (or mass effect) and neutral model frameworks.

Potassium deficiency (plants)

Plant disorder that is most common on light, sandy soils, because potassium ions are highly soluble and will easily leach from soils without colloids.

A potassium-deficient grape leaf

Potassium also functions in other physiological processes such as photosynthesis, protein synthesis, activation of some enzymes, phloem solute transport of photoassimilates into source organs, and maintenance of cation:anion balance in the cytosol and vacuole.

Oxygen cycle

Oxygen cycle refers to the movement of oxygen through the atmosphere (air), Biosphere (plants and animals) and the Lithosphere (the earth’s crust).

Main reservoirs and fluxes — in biosphere (green), marine biosphere (blue), lithosphere (brown), and atmosphere (grey).
The major fluxes between these reservoirs are shown in colored arrows, where the green arrows are related to the terrestrial biosphere, blue arrows are related to the marine biosphere, black arrows are related to the lithosphere, purple arrow is related to space (not a reservoir, but also contributes to the atmospheric O2. 
The value of photosynthesis or net primary productivity (NPP) can be estimated through the variation in the abundance and isotopic composition of atmospheric O2. 
The rate of organic carbon burial was derived from estimated fluxes of volcanic and hydrothermal carbon.

Processes within the oxygen cycle are considered to be biological or geological and are evaluated as either a source (O2 production) or sink (O2 consumption).

Population genetics

Subfield of genetics that deals with genetic differences within and between populations, and is a part of evolutionary biology.

The logarithm of fitness as a function of the number of deleterious mutations. Synergistic epistasis is represented by the red line - each subsequent deleterious mutation has a larger proportionate effect on the organism's fitness. Antagonistic epistasis is in blue. The black line shows the non-epistatic case, where fitness is the product of the contributions from each of its loci.
Drosophila melanogaster
Gene flow is the transfer of alleles from one population to another population through immigration of individuals. In this example, one of the birds from population A immigrates to population B, which has fewer of the dominant alleles, and through mating incorporates its alleles into the other population.
The Great Wall of China is an obstacle to gene flow of some terrestrial species.
Current tree of life showing vertical and horizontal gene transfers.

It can be used to infer the relationships between species (phylogenetics), as well as the population structure, demographic history (e.g. population bottlenecks, population growth), biological dispersal, source–sink dynamics and introgression within a species.

Natural landscaping

Use of native plants, including trees, shrubs, groundcover, and grasses which are indigenous to the geographic area of the garden.

Natural landscaping using pine, redbud, maple, and American sweetgum with leaf litter.
Natural landscaping with pine leaf litter mulch
Banksia spinulosa, a Sydney local plant which attracts wildlife
A small prairie garden.

Plants in a garden or maintained landscape often form a source population from which plants can colonize new areas.

Cross-boundary subsidy

Cross-boundary subsidies are caused by organisms or materials that cross or traverse habitat patch boundaries, subsidizing the resident populations.

Alaskan boreal forest in Yukon National Wildlife Refuge
Figure 1. Conceptual model of cross-boundary subsidies of insect predators from agricultural to adjacent wildland patches. a. Habitat specialization, the boundary is a hard edge to predators such that they do not disperse to the wildland patch. b. Differences in productivity, increased productivity in the agricultural patch allows a generalist insect predator to disperse to the lower productivity wildland patch. This is an example of a directional positive edge response. c. Complementary resource use, insect predator abundance is highest near the edge because they need resources present in both patches. This is an example of a reciprocal positive edge response. Redrawn from Rand et al. 2006.

The idea of a subsidy of materials or organisms across a patch boundary affecting resident populations has clear parallels with source-sink dynamics (Fagan et al. 1999).

Xiphinema americanum

Species of plant pathogenic nematodes.

Life cycle of the black rot pathogen, Xanthomonas campestris pathovar campes

Xiphinema americanum is a plant parasite that lives entirely in the soil and is attracted to young, growing roots due to source–sink dynamics.

Occupancy–abundance relationship

Relationship between the abundance of species and the size of their ranges within a region.

Fig. 1. EOO for Lawrencia densiflora using 140 GBIF dataponits (21 August 2018), and, giving an EOO of 841836.564 square kilometres, and an AOO of 384 square kilometres - IUCN categories "LC" and "EN", respectively.)
Fig 2. Lawrencia densiflora Area of Occupancy (AOO) plot using a 30 km x 30 km grid. There are 81 occupied cells,giving an AOO of 81 x 900 (72900) square kilometres (and illustrating the dependence of AOO on scale or grid size).

For species exhibiting this pattern, dispersal into what would otherwise be sub-optimal habitats can occur when local abundances are high in high quality habitats (see Source–sink dynamics), thus increasing the size of the species geographic range.

Refuge (ecology)

Concept in ecology, in which an organism obtains protection from predation by hiding in an area where it is inaccessible or cannot easily be found.

Biodiverse coral reef community

In human-managed systems like these, heavily hunted areas act as a sink in which animals die faster than they reproduce, but are replaced by animals migrating from the protected nature reserve area.