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DiRenzo, GV, Tunstall TS, Ibanez R, deVries MS, Longo AV, Zamudio KR, Lips KR.  2018.  External reinfection of a fungal pathogen does not contribute to pathogen growth. Ecohealth. 15:815-826.   10.1007/s10393-018-1358-x   AbstractWebsite

Chytridiomycosis is an emerging infectious disease of amphibians caused by the fungal pathogen Batrachochytrium dendrobatidis (Bd), which has led to devastating declines in amphibian populations worldwide. Current theory predicts that Bd infections are maintained through both reproduction on the host's skin and reinfection from sources outside of the host. To investigate the importance of external reinfection on pathogen burden, we infected captive-bred individuals of the highly susceptible Panamanian Golden Frog, Atelopus glyphus, and wild-caught glass frogs, Espadarana prosoblepon, with Bd. We housed the animals in one of three treatments: individually, in heterospecific pairs, and in conspecific pairs. For 8 weeks, we measured the Bd load and shedding rate of all frogs. We found that Atelopus had high rates of increase in both Bd load and shedding rate, but pathogen growth rates did not differ among treatments. The infection intensity of Espadarana co-housed with Atelopus was indistinguishable from those housed singly and those in conspecific pairs, despite being exposed to a large external source of Bd zoospores. Our results indicate that Bd load in both species is driven by pathogen replication within an individual, with reinfection from outside the host contributing little to the amplification of host fungal load.

deVries, MS.  2017.  The role of feeding morphology and competition in governing the diet breadth of sympatric stomatopod crustaceans. Biology Letters. 13   10.1098/rsbl.2017.0055   Abstract

Competition for food drives divergence and specialization in feeding morphology. Stomatopod crustaceans have two kinds of highly specialized feeding appendages: either elongate spear-like appendages (spearers) used to ambush soft-bodied evasive prey or hammer-like appendages (smashers) that produce extremely high forces used both to break hard-shelled prey and to capture evasive prey. To evaluate associations between appendage type and feeding ecology, the diet of two small smasher and spearer species (size range: 21–27 mm) that co-occur were compared. Stable isotope analysis and the Bayesian mixing model MixSIAR were used to estimate the proportional contributions of prey types to the diet. Both species had relatively wide diets that included hard-shelled and soft-bodied prey, albeit in different proportions; the smasher consumed a greater proportion of hard-shelled prey, and the spearer consumed mostly soft-bodied prey. Appendage kinematics in stomatopods is known to scale linearly across species. These two small species may produce similar kinematics allowing them both to capture evasive prey and hammer hard-shelled prey, thereby widening their diets. Yet, the spearer species is more highly adept at capturing evasive prey, indicating that small spearers are stronger competitors for soft-bodied prey. These findings suggest that a smasher's ability to access hard prey reduced competition for soft prey, and therefore conferred an important benefit favouring the evolution of the impressive smashing strike.

deVries, MS, Webb SJ, Tu J, Cory E, Morgan V, Sah RL, Deheyn DD, Taylor JRA.  2016.  Stress physiology and weapon integrity of intertidal mantis shrimp under future ocean conditions. Scientific Reports. 6(38637 )   10.1038/srep38637  
deVries, MS, Stock BC, Christy JH, Goldsmith GR, Dawson TE.  2016.  Specialized morphology corresponds to a generalist diet: linking form and function in smashing mantis shrimp crustaceans. Oecologia.   10.1007/s00442-016-3667-5   Abstract

Many animals are considered to be specialists because they have feeding structures that are fine-tuned for consuming specific prey. For example, "smasher" mantis shrimp have highly specialized predatory appendages that generate forceful strikes to break apart hard-shelled prey. Anecdotal observations suggest, however, that the diet of smashers may include soft-bodied prey as well. Our goal was to examine the diet breadth of the smasher mantis shrimp, Neogonodactylus bredini, to determine whether it has a narrow diet of hard-shelled prey. We combined studies of prey abundance, feeding behavior, and stable isotope analyses of diet in both seagrass and coral rubble to determine if N. bredini's diet was consistent across different habitat types. The abundances of hard-shelled and soft-bodied prey varied between habitats. In feeding experiments, N. bredini consumed both prey types. N. bredini consumed a range of different prey in the field as well and, unexpectedly, the stable isotope analysis demonstrated that soft-bodied prey comprised a large proportion (29-53 %) of the diet in both habitats. Using a Bayesian mixing model framework (MixSIAR), we found that this result held even when we used uninformative, or generalist, priors and informative priors reflecting a specialist diet on hard-shelled prey and prey abundances in the field. Thus, contrary to expectation, the specialized feeding morphology of N. bredini corresponds to a broad diet of both hard-shelled and soft-bodied prey. Using multiple lines of study to describe the natural diets of other presumed specialists may demonstrate that specialized morphology often broadens rather than narrows diet breadth.

deVries, MS, del Rio CM, Tunstall TS, Dawson TE.  2015.  Isotopic incorporation rates and discrimination factors in mantis shrimp crustaceans. Plos One. 10   10.1371/journal.pone.0122334   AbstractWebsite

Stable isotope analysis has provided insights into the trophic ecology of a wide diversity of animals. Knowledge about isotopic incorporation rates and isotopic discrimination between the consumer and its diet for different tissue types is essential for interpreting stable isotope data, but these parameters remain understudied in many animal taxa and particularly in aquatic invertebrates. We performed a 292-day diet shift experiment on 92 individuals of the predatory mantis shrimp, Neogonodactylus bredini, to quantify carbon and nitrogen incorporation rates and isotope discrimination factors in muscle and hemolymph tissues. Average isotopic discrimination factors between mantis shrimp muscle and the new diet were 3.0 +/- 0.6% and 0.9 +/- 0.3% for carbon and nitrogen, respectively, which is contrary to what is seen in many other animals (e.g. C and N discrimination is generally 0-1% and 3-4%, respectively). Surprisingly, the average residence time of nitrogen in hemolymph (28.9 +/- 8.3 days) was over 8 times longer than that of carbon (3.4 +/- 1.4 days). In muscle, the average residence times of carbon and nitrogen were of the same magnitude (89.3 +/- 44.4 and 72.8 +/- 18.8 days, respectively). We compared the mantis shrimps' incorporation rates, along with rates from four other invertebrate taxa from the literature, to those predicted by an allometric equation relating carbon incorporation rate to body mass that was developed for teleost fishes and sharks. The rate of carbon incorporation into muscle was consistent with rates predicted by this equation. Our findings provide new insight into isotopic discrimination factors and incorporation rates in invertebrates with the former showing a different trend than what is commonly observed in other animals.

deVries, MS, Murphy EAK, Patek SN.  2012.  Strike mechanics of an ambush predator: the spearing mantis shrimp. Journal of Experimental Biology. 215:4374-4384.   10.1242/Jeb.075317   AbstractWebsite

Ambush predation is characterized by an animal scanning the environment from a concealed position and then rapidly executing a surprise attack. Mantis shrimp (Stomatopoda) consist of both ambush predators ('spearers') and foragers ('smashers'). Spearers hide in sandy burrows and capture evasive prey, whereas smashers search for prey away from their burrows and typically hammer hard-shelled, sedentary prey. Here, we examined the kinematics, morphology and field behavior of spearing mantis shrimp and compared them with previously studied smashers. Using two species with dramatically different adult sizes, we found that strikes produced by the diminutive species, Alachosquilla vicina, were faster (mean peak speed 5.72 +/- 0.91 ms(-1); mean duration 3.26 +/- 0.41 ms) than the strikes produced by the large species, Lysiosquillina maculata (mean peak speed 2.30 +/- 0.85 ms(-1); mean duration 24.98 +/- 9.68 ms). Micro-computed tomography and dissections showed that both species have the spring and latch structures that are used in other species for producing a spring-loaded strike; however, kinematic analyses indicated that only A. vicina consistently engages the elastic mechanism. In the field, L. maculata ambushed evasive prey primarily at night while hidden in burrows, striking with both long and short durations compared with laboratory videos. We expected ambush predators to strike with very high speeds, yet instead we found that these spearing mantis shrimp struck more slowly and with longer durations than smashers. Nonetheless, the strikes of spearers occurred at similar speeds and durations to those of other aquatic predators of evasive prey. Although counterintuitive, these findings suggest that ambush predators do not actually need to produce extremely high speeds, and that the very fastest predators are using speed to achieve other mechanical feats, such as producing large impact forces.

Staaterman, ER, Clark CW, Gallagher AJ, Claverie T, deVries MS, Patek SN.  2012.  Acoustic ecology of the California mantis shrimp (Hemisquilla californiensis). Effects of Noise on Aquatic Life. 730:165-168.   10.1007/978-1-4419-7311-5_37   AbstractWebsite

Acoustic communication plays a major role in the behavioral ecology of various marine organisms (Busnel 1963), especially marine mammals and fish. However, little attention has been given to acoustic communication in marine crustaceans (Popper et al. 2001). Furthermore, the interplay between anthropogenic noise and the acoustic ecology of marine crustaceans remains virtually unexplored. In this study, we investigated the acoustic environment of a benthic stomatopod crustacean, the California mantis shrimp (Hemisquilla californiensis, Crustacea, Stomatopoda).

Staaterman, ER, Clark CW, Gallagher AJ, deVries MS, Claverie T, Patek SN.  2011.  Rumbling in the benthos: acoustic ecology of the California mantis shrimp Hemisquilla californiensis. Aquatic Biology. 13:97-105.   10.3354/Ab00361   AbstractWebsite

Although much research has focused on acoustic mapping and exploration of the benthic environment, little is known about the acoustic ecology of benthic organisms, particularly benthic crustaceans. Through the use of a coupled audio-video system, a hydrophone array, and an autonomous recording unit, we tested several hypotheses about the field acoustics of a benthic marine crustacean, Hemisquilla californiensis. Living in muddy burrows in southern California, these large mantis shrimp produce low frequency 'rumbles' through muscle vibrations. First, we tested whether acoustic signals are similar in the field and in the laboratory, and discovered that field-produced rumbles are more acoustically and temporally variable than laboratory rumbles, and are typically produced in rhythmic series called 'rumble groups.' Second, we verified if the sounds were indeed coming from mantis shrimp burrows and explored whether rumble groups were produced by multiple individuals. Our results suggest that during certain time periods, multiple mantis shrimp in the vicinity of the hydro phone produce sounds. Third, we examined the relationship between behavioral and acoustic activity, and found that H. californiensis is most active during crepuscular periods. While these crustaceans make a substantial contribution to the benthic soundscape, omnipresent and acoustically overlapping boat noise may threaten their acoustic ecology.

deVries, MS, Wainwright PC.  2006.  The effects of acute temperature change on prey capture kinematics in Largemouth Bass, Micropterus salmoldes. Copeia. :437-444.   10.1643/0045-8511(2006)2006%5B437:TEOATC%5D2.0.CO;2   AbstractWebsite

The effects of temperature on prey capture kinematics were investigated in the Largemouth Bass, Micropterus salmoides. Five individuals were first acclimated to 22 C and then acutely exposed to temperatures of 15, 20, 25, and 30 C. At each temperature, feeding events were recorded using high-speed video at 500 frames s(-1). An analysis of variance on the five fastest feeding events from each individual at each temperature resulted in a significant trend for the fastest feeding events to occur at 25 C. This effect confirmed the expectation of thermal dependence of mouth opening movements, which was based on an inverse relationship between water viscosity and temperature and the assumption that temperatures outside optimum decrease muscular power and contraction rates. However, the Q(10) value between 15-25 C was only 1.28, well below the minimum expected value of 2.0. Thus, we suggest the possibility that Largemouth Bass partially compensate for the effects of acute temperature changes by recruiting additional motor units at lower temperatures. The capacity of Largemouth Bass to mitigate the impact of acute temperature change on muscle physiology and the physical properties of water may represent a physiological adaptation to a predatory lifestyle in a thermally variable environment.