ISSN:0024-4066    

DOI:10.1111/j.1095-8312.1991.tb00547.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY

摘要:

We review the early development of metapopulation ideas, which culminated in the well‐known model by Levins in 1969. We present a survey of metapopulation terminology and outline the kinds of studies that have been conducted on single‐species and multispecies metapopulations. Metapopulation studies have important conceptual links with the equilibrium theory of island biogeography and with studies on the dynamics of species living in patchy environments. Metapopulation ideas play an increasingly important role in landscape ecology and conservation biol

ISSN:0024-4066    

DOI:10.1111/j.1095-8312.1991.tb00548.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY

摘要:

This paper outlines a conceptual and theoretical framework for single‐species metapopulation dynamics based on the Levins model and its variants. The significance of the following factors to metapopulation dynamics are explored: evolutionary changes in colonization ability; habitat patch size and isolation; compensatory effects between colonization and extinction rates; the effect of immigration on local dynamics (the rescue effect); and heterogeneity among habitat patches. The rescue effect may lead to alternative stable equilibria in metapopulation dynamics. Heterogeneity among habitat patches may give rise to a bimodal equilibrium distribution of the fraction of patches occupied in an assemblage of species (the core‐satellite distribution). A new model of incidence functions is described, which allows one to estimate species' colonization and extinction rates on islands colonized from mainland. Four distinct kinds of stochasticity affecting metapopulation dynamics are discussed with examples. The concluding section describes four possible scenarios of metapopulation extinct

ISSN:0024-4066    

DOI:10.1111/j.1095-8312.1991.tb00549.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY

摘要:

Stochastic models for metapopulations that consist of a finite number of local populations are discussed. A stochastic Levins model with two local slates (metapopulation level: a patch is occupied or empty) is compared with a detailed model at the level of local populations. The European badger is taken as an example to illustrate that the stochastic Levins model can form a satisfactory description for populations of real animals, even for those with complex social behaviour. The local population model is a Markov chain model with animals of two sexes and a 1‐year reproduction cycle. Both heuristic and mathematical arguments are given to show that the stochastic Levins model is a sufficiently accurate representation of the complex model. A more general application of this modelling strategy is suggested (or bird and mammal species with a fragmented distribution, yielding a tool for evaluating conservation measures for species threatened by fragmentation. The local population model can then be used to translate changes in population parameters (birth, death, dispersal) into processes on the metapopulation level (local extinction, colonization

ISSN:0024-4066    

DOI:10.1111/j.1095-8312.1991.tb00550.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY

摘要:

I develop models of metapopulation dynamics that describe changes in the numbers of individuals within patches. These models are analogous to structured population models, with patches playing the role of individuals. Single species models which do not include the effect of immigration on local population dynamics of occupied patches typically lead to a unique equilibrium. The models can be used to study the distributions of numbers of individuals among patches, showing that both metapopulations with local outbreaks and metapopulations without outbreaks can occur in systems with no underlying environmental variability. Distributions of local population sizes (in occupied patches) can vary independently of the total population size, so both patterns of distributions of local population sizes are compatible with either rare or common species. Models which include the effect of immigration on local population dynamics can lead to two positive equilibria, one stable and one unstable, the latter representing a threshold between regional extinction and persistence.

ISSN:0024-4066    

DOI:10.1111/j.1095-8312.1991.tb00551.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY

摘要:

Metapopulations are classically viewed as sets of populations persisting in a balance between local extinction and colonization. When this is true, regional persistence depends critically upon parameters influencing extinction and colonization rates, e.g. the number of habitat patches and populations, the rates and patterns of interpatch migration, and propagule establishment probabilities. A review of relevant empirical literature identifies few metapopulations which fit this description well. Instead, three qualitatively different situations are found to be more common: (1) mainland‐island and source‐sink metapopulations, in which persistence depends on the existence of one or more extinction‐resistant populations; (2) patchy populations, in which dispersal between patches or sub‐populations is so high that the system is effectively a single extinction‐resistant population; (3) non‐equilibrium metapopulations, in which local extinction occurs in the course of a species' overall regional decline. This suggests a modified view of metapopulation dynamics in which local extinction is more an incidental than a cent

ISSN:0024-4066    

DOI:10.1111/j.1095-8312.1991.tb00552.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY

摘要:

This paper reviews characteristics of dispersal that influence metapopulation functioning, such as releasing factors, density dependence, timing and types and health of dispersers. Economic thresholds, intraspecific conflicts and avoidance of inbreeding arc often regarded as the key ultimate or proximate (or both) causes of dispersal, but there is no consensus about the most important mechanisms. Dispersing individuals arc often considered to differ genetically from the residents but good supporting evidence has only been presented for some insect species. Sex and age differences in dispersal rates are most common in polygamous species and in long‐lived species with many litters per female. A bimodal distribution of dispersal distances, earlier thought to be a common pattern, is probably an artifact, caused by habitat heterogeneity and varying survival of settled individuals. Dispersal distances are longer in poor environments. Habitat specialists are more affected by boundaries during dispersal than generalists. Dispersal just before or during the early reproductive season is common in certain species occupying early successional habitats. Dispersal increased both population and metapopulation size and persistence in plants, insects and small mammal

ISSN:0024-4066    

DOI:10.1111/j.1095-8312.1991.tb00553.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY

摘要:

In metapopulation dynamics turnover of populations in isolated patches may be frequent. Regional survival of a species in such a system with frequent extinctions hinges on its colonization ability. Colonization is more than just dispersal; when a propagule reaches a new patch it faces higher extinction probabilities than does an established population. Extinction models as well as empirical data suggest that a large propagule with a potential for rapid increase in a varying environment,orwith a low mortality rate in an environment perceived as constant, has a higher probability of successful colonization. Large variation in population size when it is still small increases the risk of failure. Factors introducing such variation are demographic stochasticity and environmental variation. It is hard to single out demographic traits that ensure good colonizing ability, since colonization can be achieved in many different ways, but generalists and species with self‐fertilization seem to be superio

ISSN:0024-4066    

DOI:10.1111/j.1095-8312.1991.tb00554.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY

摘要:

Random dispersal direction is assumed in all current metapopulation models. This assumption is called into question by recent experiments demonstrating that some species disperse preferentially to sites occupied by conspecifies. We incorporate conspecific attraction into two metapopulation models which differ in type of dispersal, the Levins model and a two‐dimensional stepping‐stone model. In both models, conspecific attraction lowers the proportion of occupied habitat patches within a metapopulation at equilibr

ISSN:0024-4066    

DOI:10.1111/j.1095-8312.1991.tb00555.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY

摘要:

Loral extinction along the intrinsic isolation gradient within metapopulations is reviewed with particular reference to a study of the pool frog (Rana lessonaé) on the northern periphery of its geographical range. As in the pool frog, many other different tax a show significantly increased extinction probabilities with increased interpopulation distance. Present data imply that the relative impact of demographic and genetic factors in such stochastic extinctions depends on the genetic history of the metapopulation; data also imply that populations fluctuate more greatly in size than predicted from demographic models which have been commonly referred to. By mitigating such fluctuations and inbreeding, and compensating for emigration, immigration undoubtedly ‘rescues’ local populations from extinction. In this way, and not just in terms of recolonization, connectivity is concluded to be a key to metapopulation persistence. Implications for conservation are also prese

ISSN:0024-4066    

DOI:10.1111/j.1095-8312.1991.tb00556.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY