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Timothy C. Sparkes - One of the best experts on this subject based on the ideXlab platform.
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FEMALE RESISTANCE AND MATING OUTCOMES IN A STREAM-DWELLING ISOPOD: EFFECTS OF MALE ENERGY RESERVES AND MATING HISTORY
Behaviour, 2020Co-Authors: Timothy C. Sparkes, Daniel P. Keogh, Tyler H. OrsburnAbstract:In the stream-dwelling isopod, Lirceus fontinalis, conspicuous mating contests occur between males and females prior to pair formation. Our previous work has shown that female resistance during contests determines contest outcomes. Here we examined whether female resistance could act as a mechanism of choice in which females discriminate against males with low energy (glycogen) reserves. We manipulated male glycogen levels by chasing males around a race-track then exposed females to males that differed in glycogen levels. We found that high-glycogen males were more successful than low-glycogen males and that this effect appeared to be due to increased female resistance towards low-glycogen males. We then examined one potential benefit to females of energy-based mate discrimination. In L. fontinalis, male mating history and levels of glycogen reserves are correlated, i.e. recently mated males are glycogen-depleted due to energy costs associated with mating. We examined whether recently mated males were also costly mates, and thus should be avoided by females. We quantified the relationship between male mating history and female fertilization success and found that females suffered an 18% reduction in fertilization success by mating with a male that had recently inseminated another female. We propose that female resistance could act as a mechanism of choice in which males with low energy reserves are avoided and that one benefit of this discrimination is that females increase fertilization success be avoiding males that have recently mated.
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Survival Benefit to Antipredator Behavior in the Amphipod Gammarus minus (Crustacea: Amphipoda) in Response to Injury‐released Chemical Cues from Conspecifics and Heterospecifics
Ethology, 1999Co-Authors: Brian D. Wisenden, Alecia Cline, Timothy C. SparkesAbstract:A wide range of aquatic taxa use environmental chemical cues for the assessment of predation risk. We examined whether Gammarus minus (Crustacea: Amphipoda) exhibit antipredator behavior in response to injury-released chemicals from conspecifics or heterospecifics (Crustacea: Isopoda). We then examined whether behavioral responses to these cues conferred survival benefits to the amphipods. In the first part of this study, we tested the behavioral response of G. minus to the following treatments: 1. water containing injury-released cues of conspecifics; 2. water containing injury-released cues of a sympatric isopod crustacean, Lirceus fontinalis; or 3. water containing no cues (control). Relative to the control, Gammarus responded to the conspecific cue by moving to the substratum and decreasing activity. In contrast, Gammarus responded to the heterospecific cue by moving up into the water column and increasing activity. In the second part of this study, we tested if the behavioral response to these cues confers a survival benefit to Gammarus when exposed to a predator. A green sunfish (Lepomis cyanellus) was retained behind a partition in the test tanks. Two minutes after the introduction of the chemical cues in the first test, the barrier was lifted and predation events recorded. Relative to the control, the time to the first attack increased for Gammarus exposed to conspecific cues and decreased for those exposed to heterospecific cues. These data indicate that Gammarus distinguish between chemical cues from conspecific and heterospecific crustaceans, and that the antipredator response to conspecific cues confers a fitness benefit (i.e. increased survival due to increased time to the first attack).
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The effects of size-dependent predation risk on the interaction between behavioral and life history traits in a stream-dwelling isopod
Behavioral Ecology and Sociobiology, 1996Co-Authors: Timothy C. SparkesAbstract:In field surveys, laboratory observations and field-based assays of behavior, I examined the effects of size-dependent predation risk on the interaction between size at reproductive maturity and maternal care behavior in the stream-dwelling isopod, Lirceus fontinalis . L. fontinalis exhibit population-specific sizes at reproductive maturity which result in population differences in predation risk during the adult phase. Females from streams containing salamander larvae (that prefer small prey) mature at large sizes and then become relatively safe from predation. Females from streams containing fish (that consume all size classes of prey equally) mature at small sizes and remain at risk. I tested whether these differences in expected survival were reflected in the behavior of females during the maternal phase (i.e., the period during which females exhibit maternal care). Female L. fontinalis carry developing juveniles inside a brood pouch. I simulated predatory attacks on gravid female L. fontinalis from the different population types and found that female behavior correlated with population differences in risk. When “attacked”, females from streams with predatory fish (that experience high risk to adult females) released juveniles from the brood pouch, whereas females from populations with predatory salamander larvae (that pose relatively little risk to adult females) did not release juveniles. I discuss the results with reference to the joint evolution of behavioral and life history traits.
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Energetic costs of mate guarding behavior in male stream-dwelling isopods
Oecologia, 1996Co-Authors: Timothy C. Sparkes, Daniel P. Keogh, Rose A. ParyAbstract:In the stream-dwelling isopod Lirceus fontinalis , males and females engage in a precopulatory mate guarding phase prior to mating. We examined the energetic costs of mate guarding behavior in males by separately assaying glycogen and lipid content at different time increments following mating. We found that males that had recently mated possessed reduced glycogen reserves and that these reserves were fully replenished within 36 h. Conversely, we found that male lipid reserves were unaffected by time since mating. We concluded that precopulatory mate guarding behavior is energetically costly to males and that glycogen is the energy source utilized to pay that cost. We also examined whether food deprivation during the mate guarding phase affected male energy reserves (glycogen) at the end of that phase. We found that males that were held in the laboratory and starved during mate guarding possessed reduced glycogen at the termination of the phase when compared to fed males. This reduced quantity was equivalent to the glycogen reserves of recently mated males collected from the field. We propose that food deprivation during the mate guarding phase explains the reduction in glycogen reserves at the termination of that phase. We discuss these results with reference to patterns of refuge use behavior during the mate guarding phase.
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Effects of predation risk on population variation in adult size in a stream-dwelling isopod
Oecologia, 1996Co-Authors: Timothy C. SparkesAbstract:I used a combination of laboratory experiments and field surveys to examine the role that population-specific predation risk may play in shaping the life history strategy of a stream-dwelling isopod Lirceus fontinalis . Two focal populations were identified that were exposed to different predator types. The first population was exposed to larvae of the streamside salamander ( Ambystoma barbouri ) and the second to banded sculpin ( Cottus carolinae ). A laboratory experiment, in which different size classes of prey were offered simultaneously to individual predators, revealed that L. fontinalis suffered greatest mortality risk at small sizes with A. barbouri . Alternatively, with C. carolinae the risk of mortality was independent of size. Life history theory predicts that L. fontinalis from populations exposed to the gape-limited salamander larvae should be larger at maturity relative to individuals from populations exposed to C. carolinae . Field surveys on the two focal populations both within 1 year and across 4 years supported this prediction. Four other populations, two exposed to streamside salamander larvae and two to fish, provided additional support for the prediction. I concluded that L. fontinalis exhibited an adaptive response in size at maturity in response to population-specific predation risk. I then used gut content assays of the major predators to assess whether the population-specific life history strategies adopted by L. fontinalis were successful in avoiding predation.
K. E. Haskins - One of the best experts on this subject based on the ideXlab platform.
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Female resistance and male preference in a stream-dwelling isopod: effects of female molt characteristics
Behavioral Ecology and Sociobiology, 2000Co-Authors: T. C. Sparkes, D. P. Keogh, K. E. HaskinsAbstract:In the stream-dwelling isopod, Lirceus fontinalis , mating contests between males and females occur prior to pair formation. We examined the relative contribution of male preference and female resistance to contest outcomes. We first quantified male and female behavior during typical mating interactions and examined the relationship between time until molt (TTM) and mating outcomes. We then examined the role of male preference and female resistance in determining mating outcomes when females differed in molt type (growth, egg deposition) and appeared to differ in TTM (due to hormone applications). Both male preference and female resistance contributed to different components of the mating sequence but female resistance ultimately determined whether or not pair formation occurred. Males expressed a preference for females that appeared to be close to molt, using variation in levels of molt hormone as a cue. However, males did not discriminate between females based on molt type.
Allison T. Davidson - One of the best experts on this subject based on the ideXlab platform.
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Long-term maintenance requirements of the riparian isopod, Lirceus sp.
Hydrobiologia, 2017Co-Authors: Erika V. Iyengar, Chad I. Schwartz, Allison T. DavidsonAbstract:Riparian isopods possess many traits that make them ideal candidates for a wide range of ecological and evolutionary studies, but they are under-utilized because long-term maintenance under laboratory conditions has been largely unsuccessful. We explored a variety of experimental conditions to determine those necessary to maintain captive populations. Our studies demonstrated that starting colonies with water from the natal stream, filtering the water in a way that causes agitation at the surface of the water, maintaining colonies in full-spectrum light at room temperature or colder, lining the bottom of containers with a coarse benthos, and providing a leaf pack that contains Norway maple leaves are important criteria for successful maintenance of individuals of Lirceus sp. colonies for periods of over 6 weeks in the laboratory. Water changes do not require addition of water from the natal stream, whether the containers are glass or plastic is inconsequential, aeration does not need to be high-powered, and refrigeration of colonies is not necessary for this species of riparian isopod. We expect identifying the minimum husbandry needs will facilitate research using these organisms.
Joseph R Holomuzki - One of the best experts on this subject based on the ideXlab platform.
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indirect effects of fish on foraging behaviour and leaf processing by the isopod Lirceus fontinalis
Freshwater Biology, 1992Co-Authors: Terry M Short, Joseph R HolomuzkiAbstract:SUMMARY 1. We examined whether the isopod, Lirceus fontinalis, an important facultative shredder in low-order streams in the eastern United States, responded to chemical cues of the skin mucus of five fish species varying in relatedness and feeding habits, and if fish-induced alterations in the foraging activity of isopods indirectly affected leaf processing. 2. In the laboratory, isopods generally responded to the presence of fish mucus by reducing their activity. Isopods were most responsive in water containing the skin mucus of predatory sunfish (Lepomis) and least responsive in water treated with mucus from algivorous stonerollers (Campostoma anomalum). 3. Rates of leaf disc breakdown by isopods in the laboratory were significantly reduced when isopods were exposed to chemical cues of confined green sunfish (L. cyanellus). 4. The rate of leaf processing in a fishless reach of a headwater stream was four to five times greater by isopods 7—10mmTL (total length) than those ≤ 5mm TL. Rates of leaf processing by isopods in low-order streams may be affected directly by the size structure of the isopod population and indirectly by the presence of fish.
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Ontogenetic shifts in habitat use and activity in a stream‐dwelling isopod
Ecography, 1990Co-Authors: Joseph R Holomuzki, Terry M ShortAbstract:We examined ontogenetic changes in diel patterns of habitat use and activity of the lotic isopod Lirceus fontinalis in relation to differences in predation risk from green sunfish, Lepomis cyanellus. Juveniles are ≤5 mm total length (TL), individuals 6-9 mm TL are mature females (c. 90%) and immature males, and mature males are ≥10 mm TL. Isopods of all sizes were far more dense in Cladophora, a filamentous green algae, than in open silt/sand substrates in fish pools. Densities of each size did not increase in open areas at night in fish pools when risk of predation presumably decreases. Few individuals of any size class occurred in open silt/sand areas in fish pools. However, habitat use did not depend on fish presence. Densities and relative abundances of all sizes were similar between algal and open habitats in fishless pools both day and night, except for mature males which were more abundant in open areas during daylight. All sizes of isopods were significantly more dense in fishless versus fish pools, and density of a size class was influenced by fish presence. Densities of size classes were typically juveniles > individuals 6-9 mm TL > mature males. Green sunfish are size selective feeders on isopods, thus demography of isopods within pools may be partially influenced by the size structure of the fish population. Isopods reduced their activity, as measured by captures in benthic traps, in the presence of caged green sunfish only at night. This behavior coupled with relatively high activity levels during daylight regardless of fish presence suggests other predators or factors may influence diel activity. Mature males were overrepresented in traps relative to their occurrence in fish runs, indicating high activity levels. Mature males were also more active than gravid and nongravid females and juveniles in the presence of fish in laboratory aquaria. Number of male encounters with nongravid females depended on activity level.
T. C. Sparkes - One of the best experts on this subject based on the ideXlab platform.
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Female resistance and male preference in a stream-dwelling isopod: effects of female molt characteristics
Behavioral Ecology and Sociobiology, 2000Co-Authors: T. C. Sparkes, D. P. Keogh, K. E. HaskinsAbstract:In the stream-dwelling isopod, Lirceus fontinalis , mating contests between males and females occur prior to pair formation. We examined the relative contribution of male preference and female resistance to contest outcomes. We first quantified male and female behavior during typical mating interactions and examined the relationship between time until molt (TTM) and mating outcomes. We then examined the role of male preference and female resistance in determining mating outcomes when females differed in molt type (growth, egg deposition) and appeared to differ in TTM (due to hormone applications). Both male preference and female resistance contributed to different components of the mating sequence but female resistance ultimately determined whether or not pair formation occurred. Males expressed a preference for females that appeared to be close to molt, using variation in levels of molt hormone as a cue. However, males did not discriminate between females based on molt type.