Patterns of sexual reproduction among parasitic platyhelminths

Nollen, Paul M.

doi:10.1017/s0031182000050861

Cited by 61 publications

(40 citation statements)

References 90 publications

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“…However, males seem to be extremely rare if not absent in Floridian populations (Holsinger 1991;Lubinski et al 1995), so another possibility not excluded by current data is that some of the outcrossing involves pairs of hermaphrodites. The mixed-mating strategy of selfing and outcrossing evidenced by the genetic architecture in natural populations of K. marmoratus bears analogy to the reproductive modes of various hermaphroditic (including gynodioecious and androdioecious) plants and invertebrate animals (Allard 1975;Nollen 1983;Selander & Ochman 1983;Holsinger 1991;Pannel 2002). Although key questions persist about the maintenance of mixed-mating systems (Goodwillie et al 2005), conventional wisdom and empirical evidence suggest that this reproductive tactic is adaptively significant especially in low-density colonizing species that occupy heterogeneous, ephemeral, or marginal habitats.…”

Section: Discussionmentioning

confidence: 99%

A mixed-mating strategy in a hermaphroditic vertebrate

et al. 2006

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Mixed-mating systems, in which hermaphrodites can either self-fertilize or outcross, are common in many species of plants and invertebrates and have been informative models for studying the selective forces that can maintain both inbreeding and outbreeding in populations. Here, we document a remarkable instance of evolutionary convergence to an analogous mixed mating system by a vertebrate, the mangrove killifish (Kryptolebias marmoratus). In this androdioecious species, most individuals are simultaneous hermaphrodites that characteristically self-fertilize, resulting in local populations that consist of (nearly) homozygous lines. Most demes are also genetically diverse, an observation traditionally attributed to de novo mutation coupled with high levels of inter-site migration. However, data presented here, from a survey of 35 microsatellite loci in Floridian populations, show that genotypic diversity also stems proximally from occasional outcross events that release 'explosions' of transient recombinant variation. The result is a local population genetic pattern (of extensive genotypic variety despite low but highly heterogeneous intra-individual heterozygosities) that differs qualitatively from the genetic architectures known in any other vertebrate species. Advantages of a mixed-mating strategy in K. marmoratus probably relate to this fish's solitary lifestyle and its ability to colonize new habitats.

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Section: Discussionmentioning

confidence: 99%

A mixed-mating strategy in a hermaphroditic vertebrate

et al. 2006

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“…A large group of simultaneous hermaphrodites are the parasitic platyhelminths (i.e. cestodes, trematodes, monogeneans) many of which can reproduce by both self-and cross-fertilisation (review in Nollen, 1983). Low or unpredictable population densities and limited control over access to mating partners are likely to be selecting for both simultaneous hermaphroditism and the ability for selffertilisation in this group of animals (Tomlinson, 1966;Ghiselin, 1969;Jarne and Charlesworth, 1993).…”

Section: Introductionmentioning

confidence: 99%

Lifetime reproductive output in a hermaphrodite cestode when reproducing alone or in pairs: a time cost of pairing

Schärer

Wedekind

1999

Evolutionary Ecology

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Abstract. The cestode Schistocephalus solidus is a facultatively self-fertilising simultaneous hermaphrodite. Here we test for di erences in the starting point, the rate, and the magnitude of egg production between individuals allowed to reproduce alone (only self-fertilisation possible) or in pairs (both self-and cross-fertilisation possible). Speci®cally, we want to distinguish between alternative processes responsible for the lower egg production in paired individuals observed in an earlier study (Wedekind et al., 1998). We designed an improved in vitro system, replacing the bird ®nal host that allows us to measure, with high temporal resolution, the timing and magnitude of lifetime egg production of worms in these two social situations. We found that the experimental groups did not di er signi®cantly in the starting point of egg production. However, the temporal pattern in egg production di ered between them, in that paired individuals had a lower rate of egg production. This, however, did not lead to a signi®cant reduction in lifetime egg production, as pairs compensated for the lower rate by producing eggs longer than single individuals. We argue that the lower rate of egg production may nevertheless lead to a time cost of pairing in the study species, and that this cost is likely to represent a cost of outcrossing due to sexual selection.

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“…Although mate-finding cues are common throughout Nematoda (14,15) and have been found in the hermaphroditic trematodes (flukes; refs. [16][17][18], it remains odd that no chemical communication has been demonstrated in bringing together Caenorhabditis elegans mating partners.…”

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confidence: 99%

Evidence of a mate-finding cue in the hermaphrodite nematode Caenorhabditis elegans

Simon

Sternberg

2002

Proc. Natl. Acad. Sci. U.S.A.

115

128

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When males of the roundworm Caenorhabditis elegans come into association with their hermaphroditic counterparts they cease foraging behavior and begin to mate. Here we detail several assays used to demonstrate that a diffusible cue is correlated with this process. This cue is sexually dimorphic, given off only by the hermaphrodite and eliciting a response only in the male. Males are attracted to, reverse direction of movement frequently, and remain in regions of agar conditioned with hermaphrodites. From our studies we suggest a form of kinesis that works by attracting males to their mating partners from a distance and functions, once males arrive, in holding attracted males in close proximity. The hermaphrodite vulva is not required for the cue. Males from general sensory mutants osm-5 and osm-6 fail to respond to the cue, whereas male-specific mutants lov-1 and pkd-2 respond. Finally, that males from multiple isolates of C. elegans also respond similarly to this cue indicates that this cue is robust and has been maintained during recent evolution.sensory behavior ͉ mating behavior ͉ kinesis M ate-location behavior depends on the ability of the nervous system to integrate incoming mate-specific cues and translate this information into appropriate responses in muscles and other effectors. Odorant cues have been studied extensively in fruit flies (1), other insects (2), fish (3, 4), and rodents (5), and less in reptiles (6, 7), birds (8), various mammals (9, 10), and primates including humans (11-13). Although mate-finding cues are common throughout Nematoda (14, 15) and have been found in the hermaphroditic trematodes (flukes; refs. 16-18), it remains odd that no chemical communication has been demonstrated in bringing together Caenorhabditis elegans mating partners.Although it has been suggested that some nontactile cue may work as a catalyst to a series of stereotyped steps by males resulting in successful reproduction (J. Sulston and E. Jorgensen, personal communication; see also ref. 19), no assays to address such a mate-finding cue have come into common practice (E. Jorgensen and R. Horvitz, personal communications; C. Song, K. Liu, and P.W.S., unpublished results). Moreover, other than for the fruit fly (20)(21)(22), simple, straightforward model systems in which to study the role of sensory organs and the underpinning genetic and neurologic machinery for processing of such sexrelated olfactory cues remain poorly described. Here we describe the design and results of several assays that provide evidence for a mate-finding cue in C. elegans. We also tested vulvaless hermaphrodites for their ability to condition agar and as well both general and specific male sensory mutants for their ability to respond. Last, we report cue-detection results from males of several C. elegans isolates from diverse locations. Materials and MethodsStrains. Unless indicated otherwise, all males come from the him-5(e1490) mutant, which segregates XO male progeny by X chromosome nondisjunction during meiosis (23). To construct cue ...

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Patterns of sexual reproduction among parasitic platyhelminths

Cited by 61 publications

References 90 publications

A mixed-mating strategy in a hermaphroditic vertebrate

A mixed-mating strategy in a hermaphroditic vertebrate

Lifetime reproductive output in a hermaphrodite cestode when reproducing alone or in pairs: a time cost of pairing

Evidence of a mate-finding cue in the hermaphrodite nematode Caenorhabditis elegans

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