scholarly journals Active foraging for toxic prey during gestation in a snake with maternal provisioning of sequestered chemical defences

2015 ◽  
Vol 282 (1798) ◽  
pp. 20142137 ◽  
Author(s):  
Yosuke Kojima ◽  
Akira Mori
Keyword(s):  
Chemical Cues ◽  
Chemical Defence ◽  
Stomach Contents ◽  
Direct Proportion ◽  
Chemical Defences ◽  
Y Maze ◽  
Maternal Provisioning ◽  
Behavioural Switching ◽  
Rhabdophis Tigrinus ◽  
Gravid Females

Many animals sequester dietary defensive compounds and incorporate them into the offspring, which protects the young against predation. One possible but poorly investigated question is whether females of such species actively prey upon toxic diets. The snake Rhabdophis tigrinus sequesters defensive steroids from toads consumed as prey; it also feeds on other amphibians. Females produce chemically armed offspring in direct proportion to their own level of toad-derived toxins by provisioning the toxins to their eggs. Our field observations of movements and stomach contents of radio-tracked R. tigrinus showed that gravid snakes preyed upon toads by actively foraging in the habitat of toads, even though toads were a scarce resource and toad-searching may incur potential costs. Our Y-maze experiments demonstrated that gravid females were more likely to trail the chemical cues of toads than were males or non-gravid females. These results showed behavioural switching in females and active foraging for scarce, toxic prey during gestation. Because exploitation of toads by gravid females results in their offspring being more richly endowed with prey-derived toxins, active foraging for toxic prey is expected to be an adaptive antipredator trait, which may enhance chemical defence in offspring.

Maternal provisioning of sequestered defensive steroids by the Asian snake Rhabdophis tigrinus

Chemoecology ◽  
2008 ◽  
Vol 18 (3) ◽  
pp. 181-190 ◽  
Author(s):  
Deborah A. Hutchinson ◽  
Alan H. Savitzky ◽  
Akira Mori ◽  
Jerrold Meinwald ◽  
Frank C. Schroeder
Keyword(s):  
Maternal Provisioning ◽  
Rhabdophis Tigrinus

scholarly journals Ocean acidification disrupts the orientation of postlarval Caribbean spiny lobsters

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Philip M. Gravinese ◽  
Heather N. Page ◽  
Casey B. Butler ◽  
Angelo Jason Spadaro ◽  
Clay Hewett ◽  
...  
Keyword(s):  
Ocean Acidification ◽  
Time Scales ◽  
Coastal Waters ◽  
Chemical Cues ◽  
Spiny Lobster ◽  
Episodic Acidification ◽  
Anthropogenic Inputs ◽  
Seawater Ph ◽  
Y Maze ◽  
The Caribbean

Abstract Anthropogenic inputs into coastal ecosystems are causing more frequent environmental fluctuations and reducing seawater pH. One such ecosystem is Florida Bay, an important nursery for the Caribbean spiny lobster, Panulirus argus. Although adult crustaceans are often resilient to reduced seawater pH, earlier ontogenetic stages can be physiologically limited in their tolerance to ocean acidification on shorter time scales. We used a Y-maze chamber to test whether reduced-pH seawater altered the orientation of spiny lobster pueruli toward chemical cues produced by Laurencia spp. macroalgae, a known settlement cue for the species. We tested the hypothesis that pueruli conditioned in reduced-pH seawater would be less responsive to Laurencia spp. chemical cues than pueruli in ambient-pH seawater by comparing the proportion of individuals that moved to the cue side of the chamber with the proportion that moved to the side with no cue. We also recorded the amount of time (sec) before a response was observed. Pueruli conditioned in reduced-pH seawater were less responsive and failed to select the Laurencia cue. Our results suggest that episodic acidification of coastal waters might limit the ability of pueruli to locate settlement habitats, increasing postsettlement mortality.

scholarly journals Florivory defence: are phenolic compounds distributed non-randomly within perianths?

2020 ◽  
Vol 131 (1) ◽  
pp. 12-25
Author(s):  
Saya Nakano ◽  
Michio Oguro ◽  
Tomoyuki Itagaki ◽  
Satoki Sakai
Keyword(s):  
Phenolic Compounds ◽  
Condensed Tannins ◽  
Total Phenolics ◽  
Chemical Defence ◽  
The Other ◽  
Chemical Defences ◽  
Herbivore Attack ◽  
Statistical Support ◽  
Angiosperm Species ◽  
Optimal Defence

Abstract Plants might allocate chemical defences unequally within attractive units of flowers including petals, sepals, and bracts because of variations in the probability of florivory. Based on optimal defence theory, which predicts that plants allocate higher chemical defences to tissues with higher probabilities of herbivore attack, we predicted that distal parts and sepals would have higher chemical defence allocations than proximal parts and petals. To test this prediction, we compared total phenolics and condensed tannins concentrations as well as presence of florivory within attractive units of ten angiosperm species. In agreement with the prediction, the overall results showed that the distal parts had higher total phenolics and condensed tannins than the proximal parts. On the other hand, contrary to the prediction, petals and sepals showed no tissue-specific variations. Florivory was more severe on the distal parts than the proximal parts, although statistical support for the variation was slightly weak, while the variations in presence of florivory between petals and sepals differed between the distal and proximal parts. These results may support the prediction of the optimal defence theory because distal parts of attractive units had higher presence of florivory and concentration of chemical defences.

Is headfirst ingestion essential in gape-limited predators? Prey-handling behavior of the anurophagous snake Rhabdophis tigrinus (Colubridae)

2006 ◽  
Vol 84 (7) ◽  
pp. 954-963 ◽  
Author(s):  
Akira Mori
Keyword(s):  
Simple Model ◽  
Laboratory Experiments ◽  
Buccal Cavity ◽  
Stomach Contents ◽  
Large Prey ◽  
Behavioral Trait ◽  
Hind Limbs ◽  
Rhabdophis Tigrinus ◽  
Prey Handling ◽  
Physical Resistance

Headfirst ingestion of prey is a common adaptive behavioral trait in gape-limited predators that swallow large prey whole. To ascertain this tendency during anurophagy, prey handling and direction of prey ingestion were investigated in Rhabdophis tigrinus (Boie, 1826), a snake that feeds mainly on anurans. Examinations of stomach contents of wild R. tigrinus revealed that this snake does not show a tendency for headfirst ingestion of large prey, unlike most other snake species. In the laboratory, direction of ingestion depended largely on initial bite position, and when R. tigrinus swallowed a frog rump-first, the snake grasped both hind limbs of the frog and aligned them side by side so that both were swallowed together simultaneously from their tips. A simple model test suggested that physical resistance in the buccal cavity incurred during transportation of frogs may not differ between headfirst and hind-first ingestion if the hind limbs of frogs are aligned and swallowed simultaneously. Laboratory experiments also demonstrated that ingestively naive hatchlings of R. tigrinus are able to perform the unique manipulation required to swallow frogs hind-first. It is suggested that this unique ingestion mode is an adaptation for anurophagy, and several possible functional advantages are discussed.

scholarly journals How to fight multiple enemies: target-specific chemical defences in an aposematic moth

2017 ◽  
Vol 284 (1863) ◽  
pp. 20171424 ◽  
Author(s):  
Bibiana Rojas ◽  
Emily Burdfield-Steel ◽  
Hannu Pakkanen ◽  
Kaisa Suisto ◽  
Michael Maczka ◽  
...  
Keyword(s):  
Chemical Defence ◽  
Single Species ◽  
Specific Chemical ◽  
Biologically Relevant ◽  
Chemical Defences ◽  
Defensive Strategies ◽  
Tiger Moth ◽  
Aversive Response ◽  
Show Evidence

Animals have evolved different defensive strategies to survive predation, among which chemical defences are particularly widespread and diverse. Here we investigate the function of chemical defence diversity, hypothesizing that such diversity has evolved as a response to multiple enemies. The aposematic wood tiger moth ( Arctia plantaginis ) displays conspicuous hindwing coloration and secretes distinct defensive fluids from its thoracic glands and abdomen. We presented the two defensive fluids from laboratory-reared moths to two biologically relevant predators, birds and ants, and measured their reaction in controlled bioassays (no information on colour was provided). We found that defensive fluids are target-specific: thoracic fluids, and particularly 2- sec -butyl-3-methoxypyrazine, which they contain, deterred birds, but caused no aversive response in ants. By contrast, abdominal fluids were particularly deterrent to ants, while birds did not find them repellent. Our study, to our knowledge, is the first to show evidence of a single species producing separate chemical defences targeted to different predator types, highlighting the importance of taking into account complex predator communities in studies on the evolution of prey defence diversity.

The influence of sex and reproductive state on diet preference in four terrestrial mammals of the French Guianan rain forest

1997 ◽  
Vol 75 (6) ◽  
pp. 929-935 ◽  
Author(s):  
O. Henry
Keyword(s):  
Stomach Contents ◽  
Reproductive Activity ◽  
Relative Energy ◽  
Feeding Strategies ◽  
Mammal Species ◽  
Protein Requirements ◽  
Terrestrial Mammals ◽  
Pregnant Females ◽  
Diet Preference ◽  
Gravid Females

The diets of males and pregnant and nonpregnant females were studied in four French Guianan mammal species, three rodents and one artiodactyl, illustrating a gradient of size, mass, and gestation, and thus of energy and protein requirements. In the rodents (Oryzomys capito, Proechimys cuvieri, Dasyprocta leporina), males were more frugivorous than females, whereas the reverse was the case in the artiodactyl (Tayassu tajacu). For all species, males ate the most pulp, while pregnant females focused on seeds or animal matter. Nevertheless, males and females appeared to be opportunistic foragers, with similar feeding strategies throughout the year. A comparative analysis of stomach contents showed that the diets of males and nonpregnant females were quite comparable, while significant differences occurred in gravid females (especially of the two smallest species). Intra-individual differences gradually decreased from O. capito to T. tajacu, possibly as a result of closer male and female cohabitation as well as lower relative energy and protein requirements for pregnant females of the larger species. Finally, for the two smallest species, reproductive activity was correlated with seed and (or) animal matter intake.

scholarly journals Are juvenile Caribbean spiny lobsters (Panulirus argus) becoming less social?

2015 ◽  
Vol 72 (suppl_1) ◽  
pp. i170-i176 ◽  
Author(s):  
Michael J. Childress ◽  
Katherine A. Heldt ◽  
Scott D. Miller
Keyword(s):  
Disease Transmission ◽  
Chemical Cues ◽  
Conspecific Attraction ◽  
Dominance Status ◽  
Future Studies ◽  
Movement Rates ◽  
Y Maze ◽  
Spiny Lobsters ◽  
Potential Benefits ◽  
Commercially Important

Abstract Caribbean spiny lobsters are one of the most commercially important fisheries due in large part to their highly gregarious nature that facilitates their harvest by the use of traps or aggregation devices containing conspecifics. Aggregation in this species has been shown to be due to strong attraction to conspecific chemical cues that influence movement rates, discovery of crevice shelters, and den sharing behaviours. Although aggregation has been shown to have many potential benefits (reduction in exposure time and predation risk), it may also have significant costs as well (increase in predator encounters, disease transmission, and fishing mortality). We compared the results of three published and three unpublished Y-maze chemical cue choice experiments from 1996 to 2012 to determine if there has been a decrease in conspecific attraction by early benthic juvenile Caribbean spiny lobsters (15–55 mm carapace length, CL). We found that attraction to conspecific chemical cues decreased since 2010 and was significantly lower in 2012. Lobsters showed individual variation in conspecific attraction but this variation was unrelated to size, sex, or dominance status. We also found localized regional variation in conspecific attraction with lobsters from high shelter/high disease areas showing significantly lower conspecific attraction than those from low shelter/low disease areas. Given that conspecific attraction varies among individuals and potentially increases mortality through either natural (increased disease transmission) or fishery-induced (attraction to traps) mechanisms, we should play close attention to this loss of conspecific attraction in juvenile lobsters. Future studies should investigate both the causation and the ecological significance of changes in conspecific attraction in regions that vary in intensity of disease (PaV1) and fishing pressure.

scholarly journals Phenotypic plasticity in chemical defence allows butterflies to diversify host use strategies

2020 ◽  
Author(s):  
Érika C. P. de Castro ◽  
Jamie Musgrove ◽  
Søren Bak ◽  
W. Owen McMillan ◽  
Chris D. Jiggins
Keyword(s):  
Phenotypic Plasticity ◽  
Host Plants ◽  
Niche Partitioning ◽  
Chemical Defence ◽  
Host Use ◽  
Insect Herbivores ◽  
Cyanogenic Glucosides ◽  
Chemical Defences ◽  
Biochemical Responses ◽  
Heliconius Cydno

AbstractHostplant specialization is a major force driving ecological niche partitioning and diversification in insect herbivores. The cyanogenic defences of Passiflora plants keeps most herbivores at bay, but not larvae of Heliconius butterflies, which can both sequester and biosynthesize cyanogenic compounds. Here, we demonstrate that both Heliconius cydno chioneus, a host plant generalist, and H. melpomene rosina, a specialist, have remarkable plasticity in their chemical defence. When feeding on Passiflora species with cyanogenic compounds they can readily sequester, both species downregulate the biosynthesis of these compounds. In contrast, when fed on Passiflora plants that do not contain cyanogenic glucosides that can be sequestered, both species increase biosynthesis. This biochemical plasticity comes at a significant fitness cost for specialist like H. m. rosina, as growth rates for this species negatively correlate with biosynthesis levels, but not for a generalist like H. c. chioneus. In exchange, H. m rosina has increased performance when sequestration is possible as on its specialised hostplant. In summary, phenotypic plasticity in biochemical responses to different host plants offers these butterflies the ability to widen their range of potential host within the Passiflora genus, while maintaining their chemical defences.

Biology and Management of Dogfish Sharks

2009 ◽  
Keyword(s):  
Sex Ratio ◽  
Stomach Contents ◽  
Spiny Dogfish ◽  
Depth Range ◽  
Female Embryo ◽  
Southwest Atlantic ◽  
Near Term ◽  
Gravid Females ◽  
Embryo Length ◽  
Trawl Surveys

Abstract.—Spiny dogfish <em>Squalus acanthias </em>is distributed in the Southwest Atlantic Ocean between 34°S and 55°S. Information on size, sex, stomach contents, presence of gravid females, oocyte size, embryo size, and sex ratio were collected from bottom trawl surveys in eight of the years between 1986 and 2004. The species was recorded from a depth range of 66 to 165 m, with maximum densities found between 86 and 105 m. Female length was in the range of 46 to 101 cm and male length from 48 to 94 cm. Gravid females had lengths between 69 and 98 cm, and contained 4 to 11 embryos each (mean = 7.8, SD = 1.7). In 1996 intrauterine embryo growth was observed between August (females: 19.9 cm; males: 19.9 cm) and November (females: 22.3 cm; males: 22.6 cm). The sex ratio of embryos was 1:1. Litter size and near-term embryo length increased with the size of the pregnant female. Embryo sizes were not significantly different with respect to sex. A 2-year gestation cycle appears consistent with the data. Dogfish is a top predator in the San Matías Gulf ecosystem, feeding on fish species important to local fisheries.

Chemical defences in embryos and juveniles of two common Antarctic sea stars and an isopod

2003 ◽  
Vol 15 (3) ◽  
pp. 339-344 ◽  
Author(s):  
JAMES B. MCCLINTOCK ◽  
ANDREW R. MAHON ◽  
KEVIN J. PETERS ◽  
CHARLES D. AMSLER ◽  
BILL J. BAKER
Keyword(s):  
Methanol Extract ◽  
Marine Invertebrates ◽  
Chemical Defence ◽  
Sea Star ◽  
Sea Stars ◽  
Methanol Extracts ◽  
Odontaster Validus ◽  
Chemical Defences ◽  
Organic Extracts ◽  
Antarctic Marine

The brooded embryos and/or juveniles of the sea stars Neosmilaster georgianus (Studer, 1885) and Lysasterias perrieri (Studer, 1885) and the isopod Glyptonotus antarcticus (Eights, 1853) were examined for their acceptability using the sympatric sea star Odontaster validus (Koehler, 1906) as a predator. Organic extracts were prepared from embryos of both sea stars and juveniles of Lyasterias perrieri and Glyptonotus antarcticus and tested in alginate food pellets to confirm whether lack of acceptability was chemically based. We found both intact whole embryos and juveniles of the sea star Neosmilaster georgianus were not acceptable to Odontaster validus. A methanol extract of the embryos was palatable. This could be the result of either the sequestration of deterrent chemicals within embryos or the presence of noxious compounds that were not extractable in methanol. Embryos and juveniles of the sea star Lysasterias perrieri were not acceptable to sea stars. Food pellets containing methanol extracts of unacceptable embryos were deterrent against sea stars, suggesting a chemical defence. Juvenile brooded isopods (Glyptonotus antarcticus) were also found to be unacceptable in sea star feeding bioassays. Significant rejection of alginate pellets containing a lipophilic dichloromethane methanol extract of juveniles indicated that this lack of acceptability was chemically based. Our study provides further support for chemical defences in the offspring of brooding lecithotrophic Antarctic marine invertebrates.

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