Diet alters delayed selfing, inbreeding depression, and reproductive senescence in a freshwater snail

Auld, Josh R.; Henkel, John F.

doi:10.1002/ece3.1146

Cited by 13 publications

(18 citation statements)

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“…Theory predicts an optimal waiting time before commencing self-fertilization, related to the intensity of inbreeding depression in the progeny, the ability to re-allocate reproductive resources to later fecundity and the probability of finding a partner versus dying as the individual ages (Tsitrone et al, 2003a). Empirical evidence for delayed selfing in line with these predictions comes from a variety of hermaphroditic organisms, including plants (Kalisz et al, 1999;Qu et al, 2007), freshwater snails (Tsitrone et al, 2003b;Auld & Henkel, 2014; but see Escobar et al, 2007), cestodes (Schjørring, 2004, but see Schärer & Wedekind, 1999 and the flatworm M. hystrix, which delays reproduction for up to 50% of the average age at first outcrossing, when forced to self (Ramm et al, 2012).…”

Section: Introductionmentioning

confidence: 68%

Self-fertilization, sex allocation and spermatogenesis kinetics in the hypodermically-inseminating flatworm Macrostomum pusillum

Giannakara

Ramm

2017

Journal of Experimental Biology

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The free-living flatworm genus Macrostomum is an emerging model system for studying the links between sex allocation, sexual selection and mating system evolution, as well as the underlying developmental and physiological mechanisms responsible for wide intra-and inter-specific variability in reproductive phenotypes. Despite compelling comparative morphological evidence of sexual diversity, detailed experimental work on reproductive behaviour and physiology in Macrostomum has so far been largely limited to just two species, M. lignano and M. hystrix, an obligate and a preferential outcrosser, respectively. In this study, we establish that a third species, M. pusillum, exhibits a combination of reproductive traits strikingly different from both of its congeners. Unlike M. lignano, we demonstrate that M. pusillum does not adjust sex allocation or the speed of spermatogenesis to the prevailing social group size. Macrostomum pusillum's relatively simple sperm morphology likely explains the short spermatogenesis duration we report, and is linked to a hypodermically inseminating mode of fertilization, which we show also means that these worms are capable of self-fertilization. Surprisingly, and unlike M. hystrix, selfing in isolated worms commences after only a short (if any) delay compared with the onset of reproduction in grouped individuals, with little evidence of differential inbreeding depression in 'isolated' progeny. These combined results suggest that, in nature, M. pusillum may be regularly selfing, in contrast to the congeners studied to date. Our findings highlight the rapid and correlated evolution of reproductive traits, and reinforce the utility of the genus Macrostomum for understanding the evolutionary and developmental mechanisms responsible for this diversity.

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Section: Introductionmentioning

confidence: 68%

Self-fertilization, sex allocation and spermatogenesis kinetics in the hypodermically-inseminating flatworm Macrostomum pusillum

Giannakara

Ramm

2017

Journal of Experimental Biology

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“…Mean ages at first reproduction, last reproduction, and death (±1 SE ) for Physa acuta reared under two different diets (Lettuce or Spirulina) and two different mate treatments (mated or isolated). Age at first reproduction was reported and discussed in Auld and Henkel () and is redrawn here for comparison. The difference between the age at last reproduction (ALR) and the age at first reproduction (AFR) is the reproductive life span (RL), the difference between age at death at ALR is the post‐reproductive life span (PRL)…”

Section: Resultsmentioning

confidence: 99%

“…When individuals have more access to mating partners they initiate reproduction early and their life span in shortened, but the relative duration of reproductive life span is unknown. When individuals are not given access to mating partners, they delay the onset of reproduction (i.e., delayed self‐fertilization; Auld, , Auld & Henkel, ), and we can expect a consequent delay in the onset of reproductive senescence. Previous work evaluating the effects of mating system on relative rate of reproductive senescence has shown that reproductive function of mated snails tends to senesce faster than in unmated snails (Auld & Henkel, ), but this comparison is only based on the first few reproductive events.…”

Section: Introductionmentioning

confidence: 99%

“…When individuals are not given access to mating partners, they delay the onset of reproduction (i.e., delayed self‐fertilization; Auld, , Auld & Henkel, ), and we can expect a consequent delay in the onset of reproductive senescence. Previous work evaluating the effects of mating system on relative rate of reproductive senescence has shown that reproductive function of mated snails tends to senesce faster than in unmated snails (Auld & Henkel, ), but this comparison is only based on the first few reproductive events. Furthermore, diet is known to affect individual condition where individuals fed a higherquality diet exhibit an earlier onset of reproduction and much more rapid reproductive senescence compared to snails reared on a lower‐quality diet (Auld & Henkel, ).…”

Section: Introductionmentioning

confidence: 99%

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The effects of diet and mating system on reproductive (and post‐reproductive) life span in a freshwater snail

Auld

2018

Ecology and Evolution

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The length of the reproductive life span, along with the number/frequency/magnitude of reproductive events, quantifies an individual's potential contribution to the next generation. By examining reproductive life span, and distinguishing it from somatic life span, we gain insight into critical aspects of an individual's potential fitness as well as reproductive and somatic senescence. Additionally, differentiating somatic and reproductive life spans can provide insight into the existence of a post‐reproductive period and factors that shape its duration. Given the known importance of diet and mating system on resource allocation, I reared individual freshwater snails (Physa acuta) from 22 full‐sib families under a 2 × 2 factorial design that crossed mate availability (available [outcrossing] or not [selfing]) and diet (Spirulina or lettuce) and quantified aspects of the entire life history enabling me to distinguish reproductive and somatic life spans, determine the total number of reproductive events, and evaluate how the reproductive rate changes with age. Overall, mated snails experienced shorter reproductive and somatic life spans; a diet of Spirulina also shortened both reproductive and somatic life spans. A post‐reproductive period existed in all conditions; its duration was proportional to somatic but not reproductive life span. I evaluate several hypotheses for the existence and duration of the post‐reproductive period, including a novel hypothesis that the post‐reproductive period may result from an increase in reproductive interval with age. I conclude that the post‐reproductive period may be indicative of a randomly timed death occurring as the interval between reproductive events continues to increase. As such, a “post‐reproductive” period can be viewed as a by‐product of a situation where reproductive senescence outpaces somatic senescence.

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“…; Auld et al. ), and that reproductive senescence is affected by diet (Auld and Henkel ). While considerably less is known about the physiological effects of predation risk in mollusks, snails do exhibit stress hormone responses involving corticotropin (Ottaviani et al.…”

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confidence: 99%

Age-dependent effects of predation risk on reproductive success in a freshwater snail

Auld

Houser

2015

Evolution

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Reproductive performance is often age-dependent, showing patterns of improvement and/or senescence as well as trade-offs with other traits throughout the lifespan. High levels of extrinsic mortality (e.g., from predators) have been shown to sometimes, but not always, select for accelerated actuarial senescence in nature and in the lab. Here, we explore the inductive (i.e., plastic) effects of predation risk (i.e., nonlethal exposure to chemical cues from predators) on the reproductive success of freshwater snails (Physa acuta). Snails were reared either in the presence or absence of chemical cues from predatory crayfish and mated early in life or late in life (a 2 × 2 factorial design); we measured egg hatching and early post-hatching survival of their offspring. Both age and predation risk reduced reproductive success, illustrating that predation risk can have a cross-generational effect on the early survival of juveniles. Further, the decline in reproductive success was over three times faster under predation risk compared to the no-predator treatment, an effect that stemmed from a disproportionate, negative effect of predation risk on the post-hatching survival instead of hatching rate. We discuss our results in terms of a hypothesized consequence of elevated stress hormone levels.

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Diet alters delayed selfing, inbreeding depression, and reproductive senescence in a freshwater snail

Cited by 13 publications

References 51 publications

Self-fertilization, sex allocation and spermatogenesis kinetics in the hypodermically-inseminating flatworm Macrostomum pusillum

Self-fertilization, sex allocation and spermatogenesis kinetics in the hypodermically-inseminating flatworm Macrostomum pusillum

The effects of diet and mating system on reproductive (and post‐reproductive) life span in a freshwater snail

Age-dependent effects of predation risk on reproductive success in a freshwater snail

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