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Population viability analysis for plants: practical recommendations and applications
Södertörn University, School of Life Sciences. Stockholms universitet, Botaniska institutionen.
2006 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Population viability analysis (PVA) is commonly used in conservation biology to predict population viability in terms of population growth rate and risk of extinction. However, large data requirements limit the use of PVA for many rare and threatened species. This thesis examines the possibility of conducting a matrix model-based PVA for plants with limited data and provides some practical recommendations for reducing the amount of work required. Moreover, the thesis applies different forms of matrix population models to species with different life histories. Matrix manipulations on 37 plant species revealed that the amount of demographic data required can often be reduced using a smaller matrix dimensionality. Given that an individual’s fitness is affected by plant density, linear matrix models are unlikely to predict population dynamics correctly. Estimates of population size of the herb Melampyrum sylvaticum were sensitive to the strength of density dependence operating at different life stages, suggesting that in addition to identifying density-dependent life stages, it is important to estimate the strength of density dependence precisely. When a small number of matrices are available for stochastic matrix population models, the precision of population estimates may depend on the stochastic method used. To optimize the precision of population estimates and the amount of calculation effort in stochastic matrix models, selection of matrices and Tuljapurkar’s approximation are preferable methods to assess population viability. Overall, these results emphasize that in a matrix model-based PVA, the selection of a stage classification and a model is essential because both factors significantly affect the amount of data required as well as the precision of population estimates. By integrating population dynamics into different environmental and genetic factors, matrix population models may be used more effectively in conservation biology and ecology in the future.

Place, publisher, year, edition, pages
Stockholm: Botaniska institutionen , 2006. , 15 p.
Keyword [en]
demography, matrix population models, population viability analysis, population growth rate, stochastic models
National Category
Biological Sciences
Identifiers
URN: urn:nbn:se:sh:diva-31511ISBN: 91-7155-192-1OAI: oai:DiVA.org:sh-31511DiVA: diva2:1059524
Public defence
2006-04-01, MA 231, Alfred Nobels allé 7, Huddinge, 13:00
Opponent
Supervisors
Available from: 2016-12-22 Created: 2016-12-22 Last updated: 2016-12-22Bibliographically approved
List of papers
1. Matrix dimensionality in demographic analyses of plants: when to use smaller matrices?
Open this publication in new window or tab >>Matrix dimensionality in demographic analyses of plants: when to use smaller matrices?
2005 (English)In: Oikos, ISSN 0030-1299, E-ISSN 1600-0706, Vol. 111, no 3, 563-573 p.Article in journal (Refereed) Published
Abstract [en]

Large data requirements may restrict the use of matrix population models for analysis of population dynamics. Less data are required for a small population matrix than for a large matrix because the smaller matrix contains fewer vital rates that need to be estimated. Smaller matrices, however, tend to have a lower precision. Based on 37 plant species, we studied the effects of matrix dimensionality on the long-term population growth rate (lambda) and the elasticity of lambda in herbaceous and woody species. We found that when matrix dimensionality was reduced, changes in lambda were significantly larger for herbaceous than for woody species. In many cases, lambda of woody species remained virtually the same after a substantial decrease in matrix dimensionality, suggesting that woody species are less susceptible to matrix dimensionality. We demonstrated that when adjacent stages of a transition matrix are combined, the magnitude of a change in lambda depends on the distance of the population structure from a stable stage distribution, and the difference in the combined vital rates weighted by their reproductive values. Elasticity of lambda to survival and fecundity usually increased, whereas elasticity to growth decreased both in herbaceous and in woody species with reduced matrix dimensionality. Changes in elasticity values tended to be larger for herbaceous than for woody species. Our results show that by reducing matrix dimensionality, the amount of demographic data can be decreased to save time, money, and field effort. We recommend the use of a small matrix dimensionality especially when a limited amount of data is available, and for slow-growing species having a simple matrix structure that mainly consists of stasis and growth to the next stage.

National Category
Natural Sciences
Identifiers
urn:nbn:se:sh:diva-6046 (URN)10.1111/j.0030-1299.2005.13808.x (DOI)000233306800016 ()2-s2.0-29144529096 (ScopusID)
Available from: 2011-02-07 Created: 2011-02-07 Last updated: 2016-12-22Bibliographically approved
2. Among-Population Variation in the Ability of Fitness Components to Predict Population Viability in an Annual Herb
Open this publication in new window or tab >>Among-Population Variation in the Ability of Fitness Components to Predict Population Viability in an Annual Herb
(English)Manuscript (preprint) (Other academic)
National Category
Biological Sciences
Identifiers
urn:nbn:se:sh:diva-31512 (URN)
Note

Som manuskript i avhandling. As manuscript in dissertation.

Available from: 2016-12-22 Created: 2016-12-22 Last updated: 2016-12-22Bibliographically approved
3. Importance of correlations among matrix entries in stochastic models in relation to number of transition matrices
Open this publication in new window or tab >>Importance of correlations among matrix entries in stochastic models in relation to number of transition matrices
2005 (English)In: Oikos, ISSN 0030-1299, E-ISSN 1600-0706, Vol. 111, no 1, 9-18 p.Article in journal (Refereed) Published
Abstract [en]

Stochastic matrix models are used to predict population viability and the risk of extinction. Different stochastic methods require different amounts of estimation effort and may lead to divergent estimates. We used 16 transition matrices collected from ten populations of the perennial herb Primula veris to compare population estimates produced by different stochastic methods, such as selection of matrices, selection of vital rates, selection of matrix elements, and Tuljapurkar's approximation. Specifically, we tested the reliability of the methods using different numbers of transition matrices, and examined the importance of correlations among matrix entries. When correlations among matrix entries were included in the models, selection of vital rates produced the lowest and Tuljapurkar's approximation produced the highest estimates of mean population growth rates. Selection of matrices and matrix elements often produced nearly similar population estimates. Simulations based on incompletely estimated correlations among matrix entries considerably differed from those based on all correlations estimated, particularly when correlations were strong. The magnitude of correlations among matrix entries depended on the number of matrices, which made it difficult to generalize correlations within a species. Given that selection of vital rates or matrix elements is used, correlations among matrix entries should usually be included in the model, and they should preferably be estimated from the present data rather than according to other information of the species.

National Category
Natural Sciences
Identifiers
urn:nbn:se:sh:diva-6058 (URN)10.1111/j.0030-1299.2005.13940.x (DOI)000231864900002 ()2-s2.0-26444600781 (ScopusID)
Available from: 2011-02-07 Created: 2011-02-07 Last updated: 2016-12-22Bibliographically approved
4. Sensitivity of Population Estimates to Density Dependence in an Annual Plant, Melampyrum sylvaticum
Open this publication in new window or tab >>Sensitivity of Population Estimates to Density Dependence in an Annual Plant, Melampyrum sylvaticum
(English)Manuscript (preprint) (Other academic)
National Category
Biological Sciences
Identifiers
urn:nbn:se:sh:diva-31513 (URN)
Note

Som manuskript i avhandling. As manuscript in dissertation.

Available from: 2016-12-22 Created: 2016-12-22 Last updated: 2016-12-22Bibliographically approved
5. Demographic consequences of pollen limitation and inbreeding depression in a gynodioecious herb
Open this publication in new window or tab >>Demographic consequences of pollen limitation and inbreeding depression in a gynodioecious herb
2007 (English)In: International journal of plant sciences, ISSN 1058-5893, E-ISSN 1537-5315, Vol. 168, no 4, 443-453 p.Article in journal (Refereed) Published
Abstract [en]

In a gynodioecious plant population, where female and hermaphroditic plants co- occur, females must produce more seeds or better- quality offspring than hermaphrodites to be maintained. Further, differences in the magnitude of pollen limitation and inbreeding depression between females and hermaphrodites may affect the relative fitness of the gender morphs and consequently population dynamics. We integrated demographic data into data on pollen limitation and inbreeding depression in a gynodioecious herb. Using a matrix model approach, we then examined the effects of pollen limitation and inbreeding depression on population growth rate and sex ratio. Hermaphrodites tended to contribute more to population growth rates than females. Because of the insensitivity of population growth rates to variation in annual fecundity, pollen limitation of either females or hermaphrodites had a negligible effect on population sex ratio. Inbreeding depression expressed simultaneously in three fitness components of the offspring produced by hermaphrodites reduced stochastic population growth rate and increased female frequency. Given that population growth rates are insensitive to fecundity transitions and that hermaphrodites have moderate selfing rates, our results suggest that inbreeding depression plays a larger role in the maintenance of females in gynodioecious populations than pollen limitation.

National Category
Biological Sciences
Identifiers
urn:nbn:se:sh:diva-14227 (URN)10.1086/512040 (DOI)000245945800007 ()2-s2.0-34247641057 (ScopusID)
Note

Som manuskript i avhandling. As manuscript in dissertation.

Available from: 2011-12-19 Created: 2011-12-19 Last updated: 2016-12-22Bibliographically approved

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