Why are metapopulations so rare?

Levins (1970) introduced the term 'metapopulation' to describe the concept of a population of populations. A metapopulation describes a set of subpopulations linked by rare dispersal events allowing for recolonizations after extinctions (Fronhofer et al. 2012). Interest in the metapopulation concept has increased substantially since the 1980s and since the mid-2000s c.400 articles relating to metapopulations have been published each year.

The metapopulation theory as defined by Levin (1969) has been frequently applied to conservation biology because two of its basic parameters are extinctions and recolonizations. The term has been used in a broad sense and despite the application to conservation biology very few empirical examples conform to the strict classical metapopulation model (CM) defined by Levins (Fronhofer et al. 2012).

Fronhofer et al. (2012) use the term spatially structured populations (SSP) to encompass metapopulations and other population structures such as mainland-island systems, source-sink and patchy populations. The group discussed the use of this terminology in ecology and how terms can be picked up by other disciplines and used in such a way that their meaning becomes vague or too broad. Hanski & Gilpin (1991) stated that ecology is afflicted with inconsistencies in the use of terms and concepts. Vague use of terms leads to grouping or splitting of ecological phenomena and can hinder attempts at understanding the real world.

Interestingly there was a lag phase in the uptake of the metapopulation theory. The theory of island biogeography dominated ecological thinking up to the late 1980s. The theory of island biogeography is related to the metapopulation concept in having the same fundamental processes: colonization and extinction (Hanski & Gilpin, 1991). The island biogeography theory looks at communities whereas the metapopulation theory relates to single species. One reason put forward for this lag by the discussion was that early work done on metapopulations were model driven. Empirical studies were difficult and time consuming to do. Social changes in the late 1980s brought environmental issues such as rainforest destruction to the fore. Metapopulation theory research was seen as a way of determining the consequences of habitat fragmentation. It also came to the forefront in the discussions on reserve design.

The importance of using the correct term was questioned: Does it matter if the term metapopulation or spatially structured population is used? The paper we discussed did address this question by suggesting assumptions may lead to resources being invested incorrectly leading to biodiversity loss. Management decisions for conservation have been based on the metapopulation theory but examples of the CM are rare in nature. The paper discussed states the CM concept is applicable to populations which are on the brink of extinction. These populations may already be too far down the track of extinction to save. The emphasis is on determining the type of SSP that is being conserved so the correct management decisions can be made (Fronhofer et al. 2012).

Does ecology need a system to create consistent definitions for ecological terminology?

Is the metapopulation concept relevant to applied areas such as conservation biology?

Is the individual-based modelling approach a useful tool for determining management strategies for conservation?

References

Fronhofer, E. A., Kubisch, A., Hilker, F. M., Hovestadt, T., & Poethke, H. J. (2012). Why are metapopulations so rare? Ecology, 93(8), 1967-1978.

Hanski, I., & Gilpin, M. (1991). Metapopulation dynamics: brief history and conceptual domain. Biological Journal of the Linnean Society, 42, 3-16.

Levins, R. (1969). Some demographic and genetic consequences of environmental heterogeneity for biological control. Bulletin of the Entomological Society of America, 15, 237-240.

Levins, R. (1970). Extinction. In M. Gerstenhaber (Ed.), Lectures on mathematics in the life sciences (Vol. 2). Providence, Rhode Island: American Mathematical Society.