Are there interactive effects of mate availability and predation risk on life history and defence in a simultaneous hermaphrodite?

Relyea

2009

Biol. Lett.

While much attention has been paid to the effects of inbreeding on fitness, this has mostly come from a genetic perspective. Consequently, the interaction between inbreeding and the environment is less well understood. To understand the effects of inbreeding in natural populations where environmental conditions are variable, we need to examine not only how the effects of inbreeding change among environments but also how inbreeding may affect the ability to respond to environmental conditions (i.e. phenotypic plasticity). We reared selfed and outcrossed hermaphroditic snails (Physa acuta) in the presence and absence of chemical cues from predatory crayfish and quantified expression of an inducible defence, an adaptively plastic response to predation risk. Overall, inbred snails exhibited reduced defences, but more importantly, inbreeding reduced the expression of predator-induced adaptive plasticity. Inbreeding depression in defensive morphology was 26 per cent and inbreeding depression in the plasticity of this trait was 48 per cent. Inbreeding depression in adaptive plasticity may be important to understanding the effects of inbreeding in nature.

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Inbreeding depression in adaptive plasticity under predation risk in a freshwater snail

Relyea

2009

Biol. Lett.

“…Predation risk is a potential stress that may alter the effects of isolation and inbreeding. While the effects of predation risk on isolation have recently been discussed (Auld and Relyea 2008), the effects of predation risk on inbreeding depression have not received any empirical attention (to our knowledge; Steets et al 2007).…”

Section: Introductionmentioning

confidence: 99%

“…Due to the role that the mating system plays in determining genetic structure and directly affecting fitness (Jarne 1995;Charlesworth 2003), understanding the basis of this variation is central to understanding evolution in natural populations. While we know that traits related to the mating system (e.g., the age at first reproduction, sex allocation) and the effects of various mating systems (e.g., the fitness consequences of inbreeding) often change among environments (e.g., Carr and Eubanks 2002;Stephenson et al 2004;Armbruster and Reed 2005;Waller et al 2008;Auld and Relyea 2008), a functional understanding of how these components combine to affect cumulative lifetime fitness is lacking in most systems.…”

Section: Introductionmentioning

confidence: 99%

“…During this waiting time, individuals should allocate resources to growth and therefore initiate reproduction at a larger size (Tsitrone et al 2003a). Size-specific predation risk may affect the waiting time because individuals must balance investment in growth, reproduction and defense (Auld and Relyea 2008). Previously, we examined whether predation risk and mate availability interact to affect the waiting time and longevity in a simultaneously hermaphroditic snail (Auld and Relyea 2008).…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Life-history plasticity and inbreeding depression under mate limitation and predation risk: cumulative lifetime fitness dissected with a life table response experiment

Relyea

2010

Evol Ecol

Environmental effects on the evolution of mating systems are increasingly discussed, but we lack many examples of how environmental conditions affect the expression and consequences of alternative mating systems. Variation in mate availability sets up a trade-off between reproductive assurance and inbreeding depression, but the consequences of both mate limitation and inbreeding may depend on other environmental conditions. Predation risk is common under natural conditions, and known to affect allocation to reproduction, but we know little about the effects of isolation and inbreeding under predation risk. We reared selfed and outcrossed hermaphroditic freshwater snails (Physa acuta) in four environments (predator cues present or absent crossed with mating partners available or not) and quantified life-history traits and cumulative lifetime fitness. Our results confirm that isolation from mates can increase longevity and growth, resulting in higher lifetime fecundity. Thus, we observed no evidence for mate limitation of reproduction. However, reproduction under isolation (i.e., selfing) resulted in inbreeding depression, which should counteract the benefits of selfing. Inbreeding depression in fitness occurred in both predator and no-predator environments, but there was no overall change in inbreeding depression with predator cues. This represents, to our knowledge, the first empirical estimate of the effect of predation risk on inbreeding depression in an animal. Cumulative fitness was most influenced by early survival and especially early fecundity. As predation risk and inbreeding (both ancestral and due to a lack of mates) reduced early fecundity, these effect are predicted to have important contributions to population growth Electronic supplementary material The online version of this article (under natural conditions. Therefore life-history plasticity (e.g., delayed reproduction) is likely to be very important to overall fitness.

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

Henkel

2014

Ecology and Evolution

Reproductive success is a critical fitness attribute that is directly influenced by resource availability. Here, we investigate the effects of diet-based resource availability on three interrelated aspects of reproductive success: a change in mating system based on mate availability, consequent inbreeding depression, and the deterioration of reproductive efficiency with age (senescence). We employed a factorial experimental design using 22 full-sib families of the hermaphroditic freshwater snail Physa acuta to explore these interactions. Individual snails were reared in one of two mate-availability treatments (isolated [selfing] or occasionally paired [outcrossing]) and one of two diet treatments (boiled lettuce or Spirulina, an algae that is rich in protein, vitamins, and minerals). Spirulina-fed snails initiated reproduction at a 13% earlier age and 7% larger size than lettuce-fed snails. Spirulina also resulted in a 30% reduction in the time delay before selfing. Compared to lettuce, a diet of Spirulina increased inbreeding depression by 52% for egg hatching rate and 64% for posthatching juvenile survival. Furthermore, Spirulina led to a 15-fold increase in the rate of reproductive senescence compared with a diet of lettuce. These transgenerational, interactive effects of diet on inbreeding depression and reproductive senescence are discussed in the context of diet-induced phenotypic plasticity.