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Resource competition between genetically varied and genetically uniform populations of Daphnia pulex (Leydig): does sexual reproduction confer a short-term ecological advantage?

Record type: Article

Small competitive advantages may suffice to compensate for a large disadvantage in intrinsic growth capacity. This well-known principle from ecology has recently been applied to the enduring question of how sexual reproduction can persist in the face of invasion by female-only parthenogens. Small competitive advantages resulting directly from sexual reproduction are predicted to cancel a two-fold disadvantage in intrinsic growth capacity caused by males (which do not themselves produce offspring) comprising half the sexual population. In this paper we test the principal assumption of this theory, that the genetic variation produced by sexual reproduction confers a competitive advantage over self-identical asexual invaders. We set up competition between a diverse clonal assembly of Daphnia pulex and genetically uniform populations from single clones. At young ages, the population comprising genetically varied Daphnia had significantly higher birth rates in competition with populations of genetically uniform Daphnia than in competition with itself, indicating competitive release and a Lotka-Volterra competition coefficient ?12 < 1. No such difference was apparent under conditions of greater food stress, possibly due to individuals channelling more energy into survival, or for old-aged populations, possibly as a result of reduced selective pressures for high reproduction in old females. Mean birth rates differed between the clones at all ages in the presence of competition, providing evidence of variation in life history traits between clones. A Lotka-Volterra model predicted empirical estimates of ?12 = 0.896 (genetically uniform on varied) and ?21 = 1.010 (varied on uniform), which permits immediate coexistence of a sexual population of D. pulex even with an asexual lineage having twice the intrinsic growth capacity.

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Citation

Tagg, Nikki, Doncaster, C. Patrick and Innes, David J. (2005) Resource competition between genetically varied and genetically uniform populations of Daphnia pulex (Leydig): does sexual reproduction confer a short-term ecological advantage? Biological Journal of the Linnean Society, 85, (1), pp. 111-123. (doi:10.1111/j.1095-8312.2005.00475.x).

More information

Published date: May 2005

Identifiers

Local EPrints ID: 66487
URI: http://eprints.soton.ac.uk/id/eprint/66487
ISSN: 0024-4066
PURE UUID: 051ccddd-946e-4c5a-9801-a311838c645f
ORCID for C. Patrick Doncaster: ORCID iD orcid.org/0000-0001-9406-0693

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Date deposited: 24 Jun 2009
Last modified: 19 Jul 2017 00:24

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Contributors

Author: Nikki Tagg
Author: David J. Innes

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