Density-dependence and within-host competition in a semelparous parasite of leaf-cutting ants
<p>Abstract</p> <p/> <p>Background</p> <p>Parasite heterogeneity and within-host competition are thought to be important factors influencing the dynamics of host-parasite relationships. Yet, while there have been many theoretical investigations of how these factor...
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| Format: | Article |
| Language: | English |
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BMC
2004-11-01
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| Series: | BMC Evolutionary Biology |
| Online Access: | http://www.biomedcentral.com/1471-2148/4/45 |
| _version_ | 1818890744708988928 |
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| author | Thomsen Lene Pedersen Dorthe Ugelvig Line V Petersen Klaus S Hughes William OH Poulsen Michael Boomsma Jacobus J |
| author_facet | Thomsen Lene Pedersen Dorthe Ugelvig Line V Petersen Klaus S Hughes William OH Poulsen Michael Boomsma Jacobus J |
| author_sort | Thomsen Lene |
| collection | DOAJ |
| description | <p>Abstract</p> <p/> <p>Background</p> <p>Parasite heterogeneity and within-host competition are thought to be important factors influencing the dynamics of host-parasite relationships. Yet, while there have been many theoretical investigations of how these factors may act, empirical data is more limited. We investigated the effects of parasite density and heterogeneity on parasite virulence and fitness using four strains of the entomopathogenic fungus, <it>Metarhizium anisopliae </it>var. <it>anisopliae</it>, and its leaf-cutting ant host <it>Acromyrmex echinatior </it>as the model system.</p> <p>Results</p> <p>The relationship between parasite density and infection was sigmoidal, with there being an invasion threshold for an infection to occur (an Allee effect). Although spore production was positively density-dependent, parasite fitness decreased with increasing parasite density, indicating within-host scramble competition. The dynamics differed little between the four strains tested. In mixed infections of three strains the infection-growth dynamics were unaffected by parasite heterogeneity.</p> <p>Conclusions</p> <p>The strength of within-host competition makes dispersal the best strategy for the parasite. Parasite heterogeneity may not have effected virulence or the infection dynamics either because the most virulent strain outcompeted the others, or because the interaction involved scramble competition that was impervious to parasite heterogeneity. The dynamics observed may be common for virulent parasites, such as <it>Metarhizium</it>, that produce aggregated transmission stages. Such parasites make useful models for investigating infection dynamics and the impact of parasite competition.</p> |
| first_indexed | 2024-12-19T17:29:47Z |
| format | Article |
| id | doaj.art-0693c6264d1446a289effde7d3abb25c |
| institution | Directory Open Access Journal |
| issn | 1471-2148 |
| language | English |
| last_indexed | 2024-12-19T17:29:47Z |
| publishDate | 2004-11-01 |
| publisher | BMC |
| record_format | Article |
| series | BMC Evolutionary Biology |
| spelling | doaj.art-0693c6264d1446a289effde7d3abb25c2022-12-21T20:12:28ZengBMCBMC Evolutionary Biology1471-21482004-11-01414510.1186/1471-2148-4-45Density-dependence and within-host competition in a semelparous parasite of leaf-cutting antsThomsen LenePedersen DortheUgelvig Line VPetersen Klaus SHughes William OHPoulsen MichaelBoomsma Jacobus J<p>Abstract</p> <p/> <p>Background</p> <p>Parasite heterogeneity and within-host competition are thought to be important factors influencing the dynamics of host-parasite relationships. Yet, while there have been many theoretical investigations of how these factors may act, empirical data is more limited. We investigated the effects of parasite density and heterogeneity on parasite virulence and fitness using four strains of the entomopathogenic fungus, <it>Metarhizium anisopliae </it>var. <it>anisopliae</it>, and its leaf-cutting ant host <it>Acromyrmex echinatior </it>as the model system.</p> <p>Results</p> <p>The relationship between parasite density and infection was sigmoidal, with there being an invasion threshold for an infection to occur (an Allee effect). Although spore production was positively density-dependent, parasite fitness decreased with increasing parasite density, indicating within-host scramble competition. The dynamics differed little between the four strains tested. In mixed infections of three strains the infection-growth dynamics were unaffected by parasite heterogeneity.</p> <p>Conclusions</p> <p>The strength of within-host competition makes dispersal the best strategy for the parasite. Parasite heterogeneity may not have effected virulence or the infection dynamics either because the most virulent strain outcompeted the others, or because the interaction involved scramble competition that was impervious to parasite heterogeneity. The dynamics observed may be common for virulent parasites, such as <it>Metarhizium</it>, that produce aggregated transmission stages. Such parasites make useful models for investigating infection dynamics and the impact of parasite competition.</p>http://www.biomedcentral.com/1471-2148/4/45 |
| spellingShingle | Thomsen Lene Pedersen Dorthe Ugelvig Line V Petersen Klaus S Hughes William OH Poulsen Michael Boomsma Jacobus J Density-dependence and within-host competition in a semelparous parasite of leaf-cutting ants BMC Evolutionary Biology |
| title | Density-dependence and within-host competition in a semelparous parasite of leaf-cutting ants |
| title_full | Density-dependence and within-host competition in a semelparous parasite of leaf-cutting ants |
| title_fullStr | Density-dependence and within-host competition in a semelparous parasite of leaf-cutting ants |
| title_full_unstemmed | Density-dependence and within-host competition in a semelparous parasite of leaf-cutting ants |
| title_short | Density-dependence and within-host competition in a semelparous parasite of leaf-cutting ants |
| title_sort | density dependence and within host competition in a semelparous parasite of leaf cutting ants |
| url | http://www.biomedcentral.com/1471-2148/4/45 |
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