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The dynamics of a tephritid seed predator on Tripolium vulgare in a stochastic and heterogeneous environment

Riber Albrectsen, Benedicte (2000). The dynamics of a tephritid seed predator on Tripolium vulgare in a stochastic and heterogeneous environment. Diss. (sammanfattning/summary) Sveriges lantbruksuniv., Acta Universitatis Agriculturae Sueciae. Silvestria, 1401-6230
ISBN 91-576-5890-0
[Doctoral thesis]

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Abstract

In this thesis the factors regulating the interaction between the seed predatory fly Paroxyna plantaginis (Diptera: Tephritidae) and its host plant Tripolium vulgare, (former Aster tripolium, Asteraceae) are determined and evaluated. The host is patchily distributed on islands in the study area (the archipelago of Skeppsvik 63°44-48' N, 20°34-40'E) in northern Sweden. Possible factors that may cause the persistence of this system include direct density-dependent feedback processes, temporal and spatial heterogeneity, and the effect of stochasticity (chance). The impact of these forces is analysed through both pattern and process approaches, concentrating on the spatial and temporal distribution of the resource and the timing and dispersal of the fly, as well as the influence of stochasticity.

Relating attack frequencies to host density showed no strong indication of tight regulation between the specialist seed predator and its host plant (Paper I). Smaller plants and subpopulations were subject to the highest variation in attack frequency, suggesting that there is a strong element of chance influencing the risk of attack. There were, however, indications of a spatial effect at low fly densities, which seemed to break down at higher densities, implying that dispersal behaviour and strength may be related to adult fly density. The fragmented resource is more evenly used at higher attack frequencies (Paper II) : an effect which may be coupled directely to fly densities (Paper III). A mismatch between the phenology of the fly and the sea aster flowering phenology seems to benefit the first flowering flower heads, which are less often attacked in a normal year (Paper III) . However, it was experimentally shown that the flies compensate for the temporal and spatial unpredictability by a female-biased density-dependent dispersal (Paper IV). Density-independent water-borne dispersal during the puparia stage may also affect the dynamics of the tephritid (Paper V).

This system is an example of a highly persistent interaction, for which stochastic and spatial effects are of major importance. The density-dependent dispersal of females may act within generations in the spatially heterogeneous environment and this may be transformed from a local response to a mode of regulation that works between generations.

Authors/Creators:Riber Albrectsen, Benedicte
Title:The dynamics of a tephritid seed predator on Tripolium vulgare in a stochastic and heterogeneous environment
Year of publishing :2000
Number:156
Number of Pages:38
Publisher:Swedish University of Agricultural Sciences
ISBN for printed version:91-576-5890-0
ISSN:1401-6230
Language:English
Publication Type:Doctoral thesis
Article category:Other scientific
Version:Published version
Full Text Status:Public
Subjects:(A) Swedish standard research categories 2011 > 1 Natural sciences > 106 Biological Sciences (Medical to be 3 and Agricultural to be 4) > Ecology
Keywords:plant-animal interactions, population dynamics, regulation, densitydependence, stochasticity, temporal and spatial refuges, plant defence, dispersal, optimal patch use
URN:NBN:urn:nbn:se:slu:epsilon-p-107959
Permanent URL:
http://urn.kb.se/resolve?urn=urn:nbn:se:slu:epsilon-p-107959
ID Code:17687
Faculty:S - Faculty of Forest Sciences
Department:(S) > Institutionen för skoglig zooekologi
Deposited By: SLUpub Connector
Deposited On:05 Oct 2020 12:04
Metadata Last Modified:07 Oct 2020 10:30

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