Poecilogony in an estuarine opisthobranch: planktotrophy, lecithotrophy, and mixed clutches in a population of the ascoglossan Alderia modesta

Krug, Patrick J.

doi:10.1007/s002270050414

Cited by 80 publications

(115 citation statements)

References 39 publications

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“…Individual slugs were held overnight in dishes of 0.45μm filtered seawater (FSW) for oviposition. Lecithotrophic clutches were identified by egg size (Krug, 1998) and transferred to individual dishes of FSW. Clutches were held at room temperature (22-25°C), and FSW was changed every other day, until hatching (~5days).…”

Section: Collection Of Specimens and Larvaementioning

confidence: 99%

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Nitric oxide signaling differentially affects habitat choice by two larval morphs of the sea slugAlderia willowi: mechanistic insight into evolutionary transitions in dispersal strategies.

Romero

Phuong

Bishop

et al. 2012

Journal of Experimental Biology

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SUMMARYIn many marine animals, adult habitat is selected by lecithotrophic (non-feeding) larvae with a limited lifespan. In generalist species, larvae may increasingly accept sub-optimal habitat over time as energy stores are depleted (ʻdesperate larvaʼ hypothesis). If the fitness cost of suboptimal habitat is too high, larvae of specialists may prolong the searching phase until they encounter a high-quality patch or die (ʻdeath before dishonorʼ hypothesis). In generalists, starvation is hypothesized to lead to a decline in inhibitory nitric oxide (NO) signaling, thereby triggering metamorphosis. Here, we document alternative functions for identified signaling pathways in larvae having ʻdesperateʼ versus ʻdeath before dishonorʼ strategies in lecithotrophic clutches of a habitat specialist, the sea slug Alderia willowi. In an unusual dimorphism, each clutch of A. willowi hatches both non-selective larvae that settle soon after hatching and siblings that delay settlement in the absence of cues from the alga Vaucheria, the sole adult food. Pharmacological manipulation of NO signaling induced metamorphosis in non-selective but not selective stages. However, decreased NO signaling in selective larvae lowered the threshold for response to habitat cues, mimicking the effect of declining energy levels. Manipulation of cGMP or dopamine production induced metamorphosis in selective and non-selective larvae alike, highlighting a distinct role for the NO pathway in the two larval morphs. We propose a model in which NO production (1) links nitrogen metabolism with sensory receptor signaling, and (2) shifts from a regulatory role in ʻdesperate larvaʼ strategies to a modulatory role in ʻdeath before dishonorʼ strategies. This study provides new mechanistic insight into how the function of conserved signaling pathways may change in response to selection on larval habitat choice behaviors.

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Section: Collection Of Specimens and Larvaementioning

confidence: 99%

“…Slugs produce clutches of either planktotrophic larvae, which are long-lived and feeding, or short-lived lecithotrophic larvae, which can metamorphose without feeding (Krug, 1998). Moreover, lecithotrophic clutches hatch two larval types with differing settlement requirements.…”

Section: Introductionmentioning

confidence: 99%

Nitric oxide signaling differentially affects habitat choice by two larval morphs of the sea slugAlderia willowi: mechanistic insight into evolutionary transitions in dispersal strategies.

Romero

Phuong

Bishop

et al. 2012

Journal of Experimental Biology

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“…However, if shifts between planktonic and aplanktonic development are frequent and fully reversible, we would expect to see more populations in the midst of such shifts. Yet, documented cases of poecilogony are rare (Jablonski & Lutz 1983, Jablonski 1986, Levin & Bridges 1995, Chia et al 1996, Krug 1998; either the variation in reproductive patterns within populations has been poorly sampled, or the shifts between planktonic and aplanktonic modes do not happen frequently.…”

Section: Introductionmentioning

confidence: 99%

On the advantages and disadvantages of larval stages in benthic marine invertebrate life cycles

Pechenik¹

1999

Mar. Ecol. Prog. Ser.

590

424

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many benthic marine invertebrates develop by means of free-livlng, dispersive larval stages. The presumed advantages of such larvae include the avoidance of competition for resources with adults, temporary reduct~on of benthic mortality while in the plankton, decreased likelihood of inbreeding in the next generation, and increased ability to withstand local extinction However, the direct~on of evolutionary change appears generally b~a s e d toward the loss of larvae in many clades, implying that larvae are somehow disadvantageous. Poss~ble disadvantages include dispersal away from favorable habitat, mismatches between larval and luvenile physiological tolerances, greater susceptib~lity to env~ronmental stresses, greater susceptibihty to predation. and vanous costs that may be associated with n~etanlorphosing in response to specific chemical cues and postponing n~etamorphosis in the absence of those cues. Understanding the forces responsible for the present distribution of larval and non-larval (aplanktonlc) development among benthic marine invertebrates, and the potential influence of human activities on the direct~on of future evolutionary change in 1-eproductlve patterns, will require a better understanding of the following issues. the role of macro-evolutionary forces in selecting for or against dispersive larvae, the relative tolerances of encapsulated embryos and free-living larvae to salinity, pollutant, and other environmental stresses; the degree to which egg masses, e g g capsules, and brood chambers protect developing embryos from environmental stresses; the relative magmtude of predation by planktonic and benthic predators on both larvae and early juveniles; the way In which larval and juvenile size affect vulnerability to predators; the extent to w h~c h encapsulation and brooding protect against predators; the amount of genetic change associated with loss of larvae from invertebrate life cycles and the time required to accomplish that change; and the degree to which continued input of larvae from other populations deters selection against dispersive larvae The prominence of larval development in modern life cycles may reflect difficulties In loslng larvae from llfe cycles more than selection for their retention.

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“…Thus, the significant variation in offspring size we observed among mothers will result in differences in the dispersal profiles of the young of those mothers. It will be interesting to determine whether H. erythrogramma mothers that exist in poorquality habitats produce larger offspring than mothers in low-quality habitats and this increases the likelihood of those young dispersing to a better place (Krug, 1998;Krug, 2001). Given that offspring size also varies significantly within broods, mothers are effectively producing offspring with a range of dispersal profiles.…”

Section: Implications For Dispersalmentioning

confidence: 99%

Larval size and age affect colonization in a marine invertebrate

Marshall

Steinberg

2014

Journal of Experimental Biology

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The relationship between offspring size and performance determines the optimal trade-off between producing many small offspring or fewer large offspring and the existence of this relationship has become a central tenet of life-history theory. For organisms with multiple life-history stages, the relationship between offspring size and performance is determined by the effects of offspring size in each life-history stage. Marine invertebrates have long been a model system for examining the evolutionary ecology of offspring size, and whilst offspring size effects have been found in several life-history stages, the crucial stage of colonization has received less attention. We examined the effect of offspring size on the settlement response of sea-urchin larvae (Heliocidaris erythrogramma) to preferred and less preferred host plants, how these effects changed over the larval period and estimated the success of juveniles in the field on preferred and less-preferred host plants. We found that smaller larvae became competent to respond to preferred host plant cues sooner than larger larvae but larger larvae rejected less-preferred host plants for longer than smaller larvae. Overall, smaller H. erythrogramma larvae are likely to have less dispersal potential and are more likely to settle in less-preferred habitats whereas larger larvae appear to have an obligately longer dispersal period but settle in preferred habitats. Our results suggest that marine invertebrates that produce non-feeding larvae may have the potential to affect the dispersal of their offspring in previously unanticipated ways and that offspring size is subject to a complex web of selection across life-history stages.

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Poecilogony in an estuarine opisthobranch: planktotrophy, lecithotrophy, and mixed clutches in a population of the ascoglossan Alderia modesta

Cited by 80 publications

References 39 publications

Nitric oxide signaling differentially affects habitat choice by two larval morphs of the sea slugAlderia willowi: mechanistic insight into evolutionary transitions in dispersal strategies.

Nitric oxide signaling differentially affects habitat choice by two larval morphs of the sea slugAlderia willowi: mechanistic insight into evolutionary transitions in dispersal strategies.

On the advantages and disadvantages of larval stages in benthic marine invertebrate life cycles

Larval size and age affect colonization in a marine invertebrate

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