Sperm utilization in subadult and adult simultaneous hermaphrodite snails mating in the wild

2011 ◽  
Vol 89 (11) ◽  
pp. 1041-1049 ◽  
Author(s):  
Sandra Kupfernagel ◽  
Bruno Baur
Keyword(s):  
Sperm Competition ◽  
Egg Production ◽  
Shell Growth ◽  
Land Snail ◽  
Snail Species ◽  
Simultaneous Hermaphrodite ◽  
Young Females ◽  
Short Period ◽  
In The Wild ◽  
Previous Mating

In species with multiple mating and long-term sperm storage, males are expected to show a preference for mating with virgin and young females to reduce the risk of sperm competition. In various simultaneous hermaphrodite land snail species, sperm production precedes egg production by 2–4 weeks, resulting in a short period of protandric hermaphroditism before shell growth is completed. In a natural population, we collected copulating pairs of the simultaneous hermaphrodite land snail Arianta arbustorum (L., 1758) consisting either of two adults, of two subadults, or of one adult and one subadult snail, and determined the paternity of their hatchlings that emerged from subsequently deposited eggs. Adult snails used sperm received from subadult mating partners for egg fertilization in the same frequency as sperm from adults, indicating that subadult and adult snails do not differ in male function. Furthermore, an unfinished shell is not a reliable indicator for virginity, because 35% of the subadult individuals had already sperm stored from previous mating(s). Compared with adults, young individuals exhibited a lower risk of sperm competition, indicated by a higher last mate sperm precedence. However, subadult snails produced fewer eggs than adult snails, counteracting the evolutionary advantage of preferring a young partner with low sperm competition risk.

Behavioural aspects of microhabitat segregation of different age stages in the wetland land snail Vertigo moulinsiana (Eupulmonata: Vertiginidae) in the laboratory

2020 ◽  
Vol 86 (3) ◽  
pp. 228-232
Author(s):  
Zofia Książkiewicz-Parulska
Keyword(s):  
High Temperature ◽  
Land Snail ◽  
Snail Species ◽  
High Humidity ◽  
Short Period ◽  
Temperature And Humidity ◽  
In The Wild ◽  
Different Response ◽  
Behavioural Aspects ◽  
Microhabitat Segregation

ABSTRACT This laboratory study investigated behavioural differences between adults and juveniles of the wetland land snail species Vertigo moulinsiana with respect to temperature and humidity. Juveniles of V. moulinsiana, for example, tend to remain within the shaded, humid and cool layer of the litter, while adults usually climb above wet vegetation to a height of over 2 m. Adults are thus exposed to greater variation in temperature and humidity than juveniles. My experiments showed that adults of V. moulinsiana remain active longer than juveniles when subject to high temperature (36 °C) and low relative humidity (RH 30%). Conversely, juveniles stay active longer than adults in high humidity (22 °C, RH 100%). A short period of starvation lengthened the time needed for the juveniles to become active after dormancy, possibly indicating a different response between adults and juveniles to lack of nutritional reserves. These behavioural differences to food availability and the risk of water loss correspond to the microhabitat differences observed between adults and juveniles in the wild.

scholarly journals Cost of autotomy drives ontogenetic switching of anti-predator mechanisms under developmental constraints in a land snail

2012 ◽  
Vol 279 (1748) ◽  
pp. 4811-4816 ◽  
Author(s):  
Masaki Hoso
Keyword(s):  
High Efficiency ◽  
Shell Growth ◽  
Land Snail ◽  
Life History Strategies ◽  
Body Parts ◽  
Developmental Constraint ◽  
Developmental Constraints ◽  
Evolution Of Life ◽  
Snake Range ◽  
In The Wild

Autotomy of body parts offers various prey animals immediate benefits of survival in compensation for considerable costs. I found that a land snail Satsuma caliginosa of populations coexisting with a snail-eating snake Pareas iwasakii survived the snake predation by autotomizing its foot, whereas those out of the snake range rarely survived. Regeneration of a lost foot completed in a few weeks but imposed a delay of shell growth. Imprints of autotomy were found in greater than 10 per cent of S. caliginosa in the snake range but in only less than 1 per cent out of it, simultaneously demonstrating intense predation by the snakes and high efficiency of autotomy for surviving snake predation in the wild. However, in experiments, mature S. caliginosa performed autotomy less frequently. Instead of the costly autotomy, they can use defensive denticles on the inside of their shell apertures. Owing to the constraints from the additive growth of shells, most pulmonate snails can produce these denticles only when they have fully grown up. Thus, this developmental constraint limits the availability of the modified aperture, resulting in ontogenetic switching of the alternative defences. This study illustrates how costs of adaptation operate in the evolution of life-history strategies under developmental constraints

scholarly journals Husbandry of the Carnivorous Land Snail, Powelliphanta augusta (Gastropoda: Pulmonata: Rhytdidae)

2021 ◽  
Author(s):  
◽  
Thomas Edward Allan
Keyword(s):  
Weight Gain ◽  
Body Condition ◽  
Egg Production ◽  
Captive Breeding ◽  
Calcium Supplementation ◽  
Stocking Density ◽  
Land Snail ◽  
Captive Population ◽  
Mammalian Predators ◽  
In The Wild

<p>Key aspects of the captive husbandry of Powelliphanta augusta, a newly-described New Zealand land snail are investigated: how they should be managed and fed to provide individuals for release, and how a long-term captive population can be maintained as an insurance against extinction in the wild. This project arises from almost all members of this species having been brought into captivity due to their displacement in the wild by an opencast coalmine. Powelliphanta (F: Rhytididae) is a genus of endemic carnivorous snails, which includes 10 species, 27 subspecies and numerous undescribed taxa. As well as its diversity, Powelliphanta is renowned for the large size of its members (up to 90mm diameter) and their attractively-patterned shells. Most taxa are threatened due to habitat loss and predation by introduced mammalian predators. The study commences with a literature review to refine husbandry methods and to assess requirements for captive breeding of snails. From this review investigations are made into stocking densities, substrate, reproductive biology, body condition and growth of the P. augusta captive population. To determine an appropriate stocking density for P. augusta groups of six snails were kept at two densities; with either 720cm2, or 1440cm2 per group. Survival and weight gain were compared over 52 weeks. There was no difference in weight gain between treatments, but survival was significantly reduced at the highest density. The agent responsible for mortality was not identified, but previous studies on snails implicate disease. The effect of calcium supplementation on reproductive output was assessed by introducing limestone chip to the captive substrate of sphagnum moss. The experiment was aborted after eight months because of the apparently lethal effects of treatment. Egg production during this time was negligible, probably due to the lack of appropriate environmental cues. P. augusta showed evidence of size-specific fecundity, with a significant increase in clutch size with parental shell volume. Size-specific fecundity is predicted to cause size-assortative mating, but experiments determined that mate-choice is random with respect to shell size.Body condition was studied using the residuals from a regression of mass and size at time of capture. Condition in the wild showed strong seasonal variation, with a high in December and January. Body condition in captive snails remained stable, at a level equivalent to the peak of condition in the wild. The growth of captive snails was modeled using a Gompertz curve. Using a 30mm shell diameter as a reproductive indicator, snails hatching in captivity are predicted to reach maturity in approximately eight years. The study concludes by discussing the implications of the research for husbandry. Updates and expansions to the analyses are suggested, as well as methods for effectively monitoring the captive population.</p>

scholarly journals Husbandry of the Carnivorous Land Snail, Powelliphanta augusta (Gastropoda: Pulmonata: Rhytdidae)

2021 ◽  
Author(s):  
◽  
Thomas Edward Allan
Keyword(s):  
Weight Gain ◽  
Body Condition ◽  
Egg Production ◽  
Captive Breeding ◽  
Calcium Supplementation ◽  
Stocking Density ◽  
Land Snail ◽  
Captive Population ◽  
Mammalian Predators ◽  
In The Wild

<p>Key aspects of the captive husbandry of Powelliphanta augusta, a newly-described New Zealand land snail are investigated: how they should be managed and fed to provide individuals for release, and how a long-term captive population can be maintained as an insurance against extinction in the wild. This project arises from almost all members of this species having been brought into captivity due to their displacement in the wild by an opencast coalmine. Powelliphanta (F: Rhytididae) is a genus of endemic carnivorous snails, which includes 10 species, 27 subspecies and numerous undescribed taxa. As well as its diversity, Powelliphanta is renowned for the large size of its members (up to 90mm diameter) and their attractively-patterned shells. Most taxa are threatened due to habitat loss and predation by introduced mammalian predators. The study commences with a literature review to refine husbandry methods and to assess requirements for captive breeding of snails. From this review investigations are made into stocking densities, substrate, reproductive biology, body condition and growth of the P. augusta captive population. To determine an appropriate stocking density for P. augusta groups of six snails were kept at two densities; with either 720cm2, or 1440cm2 per group. Survival and weight gain were compared over 52 weeks. There was no difference in weight gain between treatments, but survival was significantly reduced at the highest density. The agent responsible for mortality was not identified, but previous studies on snails implicate disease. The effect of calcium supplementation on reproductive output was assessed by introducing limestone chip to the captive substrate of sphagnum moss. The experiment was aborted after eight months because of the apparently lethal effects of treatment. Egg production during this time was negligible, probably due to the lack of appropriate environmental cues. P. augusta showed evidence of size-specific fecundity, with a significant increase in clutch size with parental shell volume. Size-specific fecundity is predicted to cause size-assortative mating, but experiments determined that mate-choice is random with respect to shell size.Body condition was studied using the residuals from a regression of mass and size at time of capture. Condition in the wild showed strong seasonal variation, with a high in December and January. Body condition in captive snails remained stable, at a level equivalent to the peak of condition in the wild. The growth of captive snails was modeled using a Gompertz curve. Using a 30mm shell diameter as a reproductive indicator, snails hatching in captivity are predicted to reach maturity in approximately eight years. The study concludes by discussing the implications of the research for husbandry. Updates and expansions to the analyses are suggested, as well as methods for effectively monitoring the captive population.</p>

scholarly journals Toxicity And Accumulation of Lead And Cadmium In The Land Snail, Archachatina Papyracea In A Tropical Alfisol From Southwestern Nigeria

2021 ◽  
Author(s):  
Olugbenga John Owojori ◽  
Michael Awodiran ◽  
Oluwadunsin Ajana ◽  
Olukayode Jegede
Keyword(s):  
Food Chain ◽  
Weight Change ◽  
Egg Production ◽  
Land Snail ◽  
Human Consumption ◽  
Snail Species ◽  
Southwestern Nigeria ◽  
Visceral Mass ◽  
Lc50 Value ◽  
Lead And Cadmium

Abstract Snails are an important link in the transfer of contaminants, especially metals in the food chain. Yet, few studies have examined the toxicity and accumulation of metals in snails in the tropics. This study assessed the toxicity and accumulation of two non-essential metals (cadmium and lead) to the tropical snail Archachatina papyracea. Specimens of the snail A. papyracea were exposed in a loamy soil collected from Ile-Ife, Nigeria and spiked with varying concentrations of Cd and Pb over 28 days. Survival and weight change of snails were monitored weekly while tissue accumulation was assessed at the end of the 28-day period. Survival was a more sensitive endpoint than the weight change of snails. The Cd median lethal concentration (LC50) value was 93 ± 4.4 mg/kg, while the median effect concentration (EC50) for snail weight change was 131 ± 41mg/kg. For Pb, LC50 value was 1121 ± 457 mg/kg while the EC50 value for weight change was higher at 4541 ± 1180 mg/kg. Therefore, Cd was a factor of about 10 to 30 more toxic than Pb, consistent with findings on the relative toxicity of Cd and Pb to other soil organisms, including earthworms, springtails, and mites. Although not included initially as an endpoint, egg production in the snails decreased with increasing Cd and Pb concentrations in the substrate. Metal analysis of the foot and visceral mass of surviving snails showed progressive accumulation of Cd and Pb as concentration increased, showing the tendency to use body residue of A. papyracea as an indicator of metal pollution. It further suggests the role of this snail species in above-ground metal transfer in the food chain and highlights the potential danger for human consumption.

scholarly journals Premating barriers in young sympatric snail species

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Arina L. Maltseva ◽  
Marina A. Varfolomeeva ◽  
Arseniy A. Lobov ◽  
Polina O. Tikanova ◽  
Egor A. Repkin ◽  
...  
Keyword(s):  
Gene Flow ◽  
Snail Species ◽  
Sympatric Populations ◽  
Gastropod Species ◽  
Shell Size ◽  
Closely Related Species ◽  
Partial Canonical Correspondence Analysis ◽  
In The Wild ◽  
Isolation Index

AbstractSympatric coexistence of recently diverged species raises the question of barriers restricting the gene flow between them. Reproductive isolation may be implemented at several levels, and the weakening of some, e.g. premating, barriers may require the strengthening of the others, e.g. postcopulatory ones. We analysed mating patterns and shell size of mates in recently diverged closely related species of the subgenus Littorina Neritrema (Littorinidae, Caenogastropoda) in order to assess the role of premating reproductive barriers between them. We compared mating frequencies observed in the wild with those expected based on relative densities using partial canonical correspondence analysis. We introduced the fidelity index (FI) to estimate the relative accuracy of mating with conspecific females and precopulatory isolation index (IPC) to characterize the strength of premating barriers. The species under study, with the exception of L. arcana, clearly demonstrated preferential mating with conspecifics. According to FI and IPC, L. fabalis and L. compressa appeared reliably isolated from their closest relatives within Neritrema. Individuals of these two species tend to be smaller than those of the others, highlighting the importance of shell size changes in gastropod species divergence. L. arcana males were often found in pairs with L. saxatilis females, and no interspecific size differences were revealed in this sibling species pair. We discuss the lack of discriminative mate choice in the sympatric populations of L. arcana and L. saxatilis, and possible additional mechanisms restricting gene flow between them.

scholarly journals Deep genetic structure at a small spatial scale in the endangered land snail Xerocrassa montserratensis

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Cristina Català ◽  
Vicenç Bros ◽  
Xavier Castelltort ◽  
Xavier Santos ◽  
Marta Pascual
Keyword(s):  
Genetic Structure ◽  
Land Snail ◽  
Snail Species ◽  
Small Spatial Scale ◽  
Geographic Ranges ◽  
Genetic Groups ◽  
Species Of Conservation Concern ◽  
Conservation Actions ◽  
Conservation Concern ◽  
Single Locality

AbstractSpecies with small geographic ranges do not tend to have a high genetic structure, but some land snail species seem to be an exception. Xerocrassa montserratensis, an endangered land snail endemic to Catalonia (northeastern Iberian Peninsula), is an excellent model to study the processes affecting the phylogeography of specialized species of conservation concern. This species is restricted to xerophilous stony slopes and occurs within a small and fragmented area of ca. 500 km2. We sequenced the COI barcode region of 152 individuals from eight sites covering the entire range of the species. We found four genetic groups mostly coincident with their geographic distribution: a central ancestral group containing shared haplotypes among five localities and three groups restricted to a single locality each. Two of these derived groups were geographically and genetically isolated, while the third and most differentiated group was not geographically isolated. Geomorphologic and paleoclimatic processes during the Pleistocene can explain the divergence found between populations of this low dispersal species with historical fragmentation and secondary contacts. Nonetheless, recent passive large dispersal through streams was also detected in the central group. Overall, our study uncovered four evolutionary units, partially matching morphologically described subspecies, which should be considered in future conservation actions.

Organ- and species-specific accumulation of metals in two land snail species (Gastropoda, Pulmonata)

2013 ◽  
Vol 449 ◽  
pp. 470-481 ◽  
Author(s):  
Magdalena Boshoff ◽  
Kurt Jordaens ◽  
Thierry Backeljau ◽  
Suzanna Lettens ◽  
Filip Tack ◽  
...  
Keyword(s):  
Land Snail ◽  
Snail Species ◽  
Specific Accumulation ◽  
Accumulation Of Metals ◽  
Species Specific

Introduction of the Predatory Land Snail Species Poiretia delesserti (Spiraxidae) in France

Malacologia ◽  
2021 ◽  
Vol 63 (2) ◽  
Author(s):  
Bernhard Hausdorf ◽  
Stephan Solvery
Keyword(s):  
Land Snail ◽  
Snail Species

Effects of some crop management practices on reproduction of Meloidogyne javanica on Brassica napus

Nematology ◽  
2002 ◽  
Vol 4 (3) ◽  
pp. 381-386
Author(s):  
Christopher Steel ◽  
John Kirkegaard ◽  
Rod McLeod
Keyword(s):  
Brassica Napus ◽  
Soil Temperature ◽  
Egg Production ◽  
Management Practices ◽  
Seedling Emergence ◽  
Meloidogyne Javanica ◽  
Egg Laying ◽  
Infested Soil ◽  
Young Females ◽  
Soil Temperatures

AbstractThe effects of seed treatments with pesticides, soil temperature at sowing, cutting of plants with and without glyphosate herbicide, root disruption and age of crop at inoculation on reproduction of Meloidogyne javanica on Brassica napus were investigated. When inoculated at sowing, plants grown from fodder rape cv. Rangi seed treated with fenamiphos (0.35 g a.i. per 100 g) and from fodder swede cv. Highlander seed with a coating including imidacloprid had fewer galls than plants from seed untreated or treated with omethoate (0.7 g a.i. per 100 g). When nematode inoculation was delayed until 4 weeks after sowing, omethoate and the imadacloprid treatments had no effect while fenamiphos (0.7 g a.i. per 100 g seed) suppressed galling but also impaired seedling emergence and induced chlorosis. Green manure rape plants cvs Rangi and Humus transplanted into infested soil in the field in mid-autumn (soil temperature 17°C) remained nematode and gall-free, but tomato cv. Grosse Lisse plants were heavily galled. All three cultivars were gall-free when transplanted and grown in early winter (soil temperatures 8-14°C). Cutting off the tops of cv. Rangi plants at from 6 to 11 weeks after sowing and inoculation had no effect on egg production compared to that on intact plants. Predominant nematode stages in cut plants ranged from developing juveniles to egg-laying females. Application of glyphosate to freshly cut stems had no effect on egg production at any stage. Infesting soil with roots of cv. Rangi, finely chopped while nematodes in them were still juveniles, resulted in a low incidence of infection of bioassay tomato plants compared with infesting soil with rape roots chopped later, when females and females with eggs predominated. Young females in tomato roots laid eggs despite fine chopping of the roots. When cv. Rangi plants were inoculated at 3, 5 and 7 weeks after sowing, the 7-week-old plants were the least invaded and fewer eggs were produced on the 5 and 7-week-old plants than on the 3-week-old ones.

Sign in / Sign up

Export Citation Format

Share Document