1,721,053 research outputs found
Sensory cues underlying competitive growth in the clown anemonefish (Amphiprion percula)
Full text linkIn some animal societies, access to breeding depends on the individual’s position in a hierarchy, which often depends on an individual’s size. In such societies, individuals may engage in competitive growth, trying to outgrow one another to attain a higher rank. This suggests that members of the hierarchy can track changes in the growth and size of potential competitors and respond accordingly. The clown anemonefish, Amphiprion percula, is one species known to exhibit competitive growth at the initiation of size hierarchies. Here, we use 5 combinations of sensory cues to determine which cues must be available to initiate competitive growth between size-matched individuals. Our results show that mechanosensory (pressure and/or touch) cues are used to assess size and initiate competitive growth. This study provides an understanding into the relationship between environment and phenotypic response in a social context
How do parents respond to changing ecological and social environments: insights from a coral reef fish with biparental care
Full text linkPhenotypic plasticity, the capacity of individuals to respond to changing environments by modifying traits, is critically important in allowing biological innovation in the face of environmental change. My dissertation used the clown anemonefish (Amphiprion percula) study system to explore plasticity in parenting strategies in response to variable ecological and social environments.
In Part I, I investigated plasticity in response to ecological environment. First, I explored how resource variation influences parenting strategies. I measured parental behaviors in A. percula under two feeding regimes in the laboratory. I demonstrated that clownfish exhibit plasticity in parental care, and that there is significant among individual variation, i.e., personality, in parenting strategies. Second, I tested how plasticity affects life history strategies in the field. I measured habitat, reproductive, and parental traits in a natural population and found positive correlations between resource availability (anemone size) and body size, reproduction, and parental care. I conducted an experimental manipulation of resource availability and found that reproduction and parental care are plastic, providing a causal link between habitat quality variation and reproductive success in natural populations.
In Part II, I investigated plasticity in response to social environment. In my third chapter, I explored how parents utilize social information to optimize their parental investment. I developed a game theory model that provides predictions for how power and punishment influence negotiations between parents over offspring care. The model predicts that the threat of punishment by a powerful parent will result in greater partner effort and, as a result, the offspring receive more total care when there is power and punishment in negotiations. Finally, I tested alternative models along with the model I developed, investigating how parents respond to each other to reach a negotiated settlement over offspring care. I experimentally handicapped one pair member and measured the response of the other parent. I found that anemonefish males and females do not respond directly to changes in their partner’s behavior, contrary to predictions of current negotiation models. Together, results from my dissertation extend our understanding of plasticity of parental care, providing a framework for understanding how parents will respond to changing environments
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Vertebrate growth plasticity in response to variation in a mutualistic interaction
Full text linkA fundamental question of evolutionary ecology is, what determines body size? In general, the body size of vertebrates is thought to be relatively inflexible, a product of their genes, food, environment, and stress. However, vertebrate growth can be plastic in response to population interactions such as predator-prey and competition. While these relationships can elicit plasticity of vertebrate growth, mutualistic relationships have yet to be investigated. An iconic example of mutualism involving a vertebrate is the relationship between anemone and anemonefish. In this interaction anemonefish size is often positively correlated with anemone size. Here, I test the hypothesis that anemonefish growth is a plastic response to variation in anemone size. Juvenile clownfish (Amphiprion percula) of relatively uniform size were paired with sea anemones (Entacmaea quadricolor) of variable size and monitored over three months. The average anemone size over the course of the month was then used to predict the fish growth each month. Mixed model analyses verified that anemone area is significantly associated with both change in fish standard length and change in fish body depth. Fish in larger anemones grew more than did fish in small anemones. Remarkably, individuals in large anemones achieved this despite receiving the same amount of food as individuals in small anemones. This clownfish growth plasticity in response to anemone size might be adaptive if anemone area is a good indicator of resource availability in the wild, because it would enable the fish to maximize their reproduction without compromising survival. This study extends the understanding of how plasticity of vertebrate species can be influenced by a wide variety of population interactions
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Lunar cycles of reproduction in the clown anemonefish Amphiprion percula: individual-level strategies and population-level patterns
Full text linkLunar cycles of reproduction are a widespread phenomenon in marine invertebrates and vertebrates. It is common practice to infer the adaptive value of this behavior based on the population level pattern. This practice may be flawed if individuals within the population are employing different reproductive strategies. Here, we capitalize on a long-term field study and a carefully controlled laboratory experiment of individually identifiable clown anemonefish, Amphiprion percula, to investigate the individual reproductive strategies underlying population-level patterns of reproduction. The field data reveal that A. percula exhibit a lunar cycle of reproduction at the population level. Further, the field data reveal that there is naturally occurring variation among individuals and within individuals in the number of times they reproduce per month. The laboratory experiment reveals that the number of times individuals reproduce per month is dependent on their food availability. Individuals are employing a conditional strategy, breeding once, twice or thrice per month, depending on resource availability. Breaking down the population level pattern by reproductive tactic, we show that each reproductive tactic has its own non-random lunar cycle of reproduction. Considering the adaptive value of these cycles, we suggest that all individuals, regardless of tactic, may avoid reproducing around the new moon. Further, individuals may avoid breeding in synchrony with each other, because of negative frequency dependent selection at the time of settlement. Most importantly, we conclude that determining what individuals are doing is a critical step toward understanding the adaptive value of lunar cycles of reproduction
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Nocturnal parental care and the role of parents in hatching their eggs in the clown anemonefish Amphiprion percula
Full text linkParental care is a critical component of many breeding systems that enhances both parent and offspring fitness. It is widely recognized that parental care varies in quality and quantity in response to variation in offspring need, parental condition, and ecological context. One context that has been underexplored, however, is the difference in parental care between day and night, with many parental care studies focused on diurnal care. To fully understand the evolution of parental care, the costs and benefits and the negotiations between parents, both diurnal and nocturnal care must be accounted for. Here, we show that nocturnal parental care exists in the clownfish Amphiprion percula, with males and females actively caring for offspring at night throughout embryo development and during hatching in a laboratory setting. At night, as during the day, males are the dominant caregivers and both parents increase care as embryos mature. At night, in contrast to the day, females provide substantially more care. This increase in energy expended by parents on care may be a mechanism to increase dissolved oxygen in the water at night, improving embryo survival. We also document the existence of three new nocturnal parental care behaviors, not previously seen during the day: vigorous fanning, vigorous mouthing, and anemone biting. These behaviors are particularly frequent during hatching, and although they are not necessary for hatching to occur, they may serve to enhance the embryos’ successful transition from the benthos to the water column. This study contributes to our understanding of parental care, demonstrating the importance of considering nocturnal care if we are to gain a complete understanding of the evolution of parental care.2023-03-16T00:00:00
Review and optimization of housing and husbandry of anemonefishes for use in research
Full text linkAs anemonefishes of the genus Amphiprion are emerging as a model organism for marine science, it is critical to have standardization in housing and husbandry protocols for research laboratories. Here, we conducted a literature review, a questionnaire survey, and two experiments regarding the housing and husbandry of anemonefishes for use in research. The literature review identified the need for standardization and optimization of multiple variables including tank volume, diet composition, and lighting type for the housing of broodstock pairs. The questionnaire survey was completed by 27 laboratories, with a 45% response rate, across 11 different countries in Europe, North America, Asia, and Australia. Results from the survey confirmed the need for standardization or optimization of laboratory protocols. The experimental manipulation of housing of Amphiprion percula was conducted over a 3-month period, where reproduction was monitored for 8 breeding pairs housed in large, 120-liter (30-gallon) tanks versus 7 breeding pairs housed in small, 9-liter (2-gallon) tanks. Results suggest that reproductive output was significantly reduced among breeding pairs in experimental 9-liter tanks when compared to those housed in standard 120-liter tanks. The experimental manipulation of husbandry of A. percula was conducted over a 3-month period, where reproduction was monitored across 19 breeding pairs on a high ration diet (1 mL scoop of pellets) versus 15 breeding pairs on a low ration diet (0.5 mL scoop of pellets). Results suggest that reproductive output was significantly reduced among breeding pairs on a low ration diet when compared to those on a high ration diet. Although the experimental 9-liter tanks were likely below the optimum for reproductive output, the fact that reproduction still occurred suggests that the fish will reproduce in tanks smaller than 120 liters and that 20-75 liter tanks may be the best option for housing large numbers of A. percula and similar species. The reproductive output of broodstock pairs fed a high ration diet is similar to that seen in the wild, and provision of higher quality foods (e.g., cuttlefish, shrimp, fish eggs, etc.) beyond commercial pellets may enhance survival of larvae. In conclusion, our research suggests that the anemonefish research community should be discussing the optimization and standardization of housing and husbandry or, minimally, recognize that housing and husbandry influence a wide range of traits and will influence the results and conclusions drawn from experiments
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