The ethics of fish welfare

The topic of fish welfare in the context of commercial fisheries is a difficult one. From traditionally anthropocentric or human‐centred perspectives, fishes are simply objects for humans to use as they see fit. When it is argued that anthropocentrism is arbitrary, it may appear that a strong animal rights position is the only recourse, with the result that humans ought not to use animals in the first place, if it is at all possible. It can be argued that both positions fail to view human beings as part of the natural world. If human beings are viewed as part of the world from which they live, then it has to be asked what it means to be respectful of the animals which humans use and from which they live. From this perspective, concern for the welfare of the fishes humans eat is simply what should be expected from humans as good citizens in the community of living creatures.     

Philosophical background of attitudes toward and treatment of invertebrates

People who interact with or make decisions about invertebrate animals have an attitude toward them, although they may not have consciously worked it out. Three philosophical approaches underlie this attitude. The first is the contractarian, which basically contends that animals are only automata and that we humans need not concern ourselves with their welfare except for our own good, because cruelty and neglect demean us. A second approach is the utilitarian, which focuses on gains versus losses in interactions between animals, including humans. Given the sheer numbers of invertebrates-they constitute 99% of the animals on the planet- this attitude implicitly requires concern for them and consideration in particular of whether they can feel pain. Third is the rights-based approach, which focuses on humans-treatment of animals by calling for an assessment of their quality of life in each human-animal interaction. Here scholars debate to what extent different animals have self-awareness or even consciousness, which may dictate our treatment of them. Regardless of the philosophical approach to invertebrates, information and education about their lives are critical to an understanding of how humans ought to treat them.     

Do we expect natural selection to produce rational behaviour?

We expect that natural selection should result in behavioural rules which perform well; however, animals (including humans) sometimes make bad decisions. Researchers account for these with a variety of explanations; we concentrate on two of them. One explanation is that the outcome is a side effect; what matters is how a rule performs (in terms of reproductive success). Several rules may perform well in the environment in which they have evolved, but their performance may differ in a 'new' environment (e.g. the laboratory). Some rules may perform very badly in this environment. We use the debate about whether animals follow the matching law rather than maximizing their gains as an illustration. Another possibility is that we were wrong about what is optimal. Here, the general idea is that the setting in which optimal decisions are investigated is too simple and may not include elements that add extra degrees of freedom to the situation.     

Behavioral adaptations to parasites: an ethological approach.

Wild vertebrate animals must live in an environment with the ever present threat of internal and external parasites. This threat by macroparasites is responsible for the natural selection of an array of behavioral adaptations that, together with the immune system and other physiological forms of resistance, enable the animals to survive and reproduce in this environment. Several lines of research, some quite recent, illustrate that specific behavioral patterns can be effective in helping animals or their offspring avoid or control macroparasites that can affect adversely the animal's fitness. These behavioral patterns fall under the general strategies of avoidance behavior and mate selection.     

Natural History of Innate Host Defense Peptides

Host defense peptides act on the forefront of innate immunity, thus playing a central role in the survival of animals and plants. Despite vast morphological changes in species through evolutionary history, all animals examined to date share common features in their innate immune defense strategies, hereunder expression of host defense peptides (HDPs). Most studies on HDPs have focused on humans, domestic and laboratory animals. More than a thousand different sequences have been identified, yet data on HDPs in wild-living animals are sparse. The biological functions of HDPs include broad-spectrum antimicrobial activity and immunomodulation. Natural selection and coevolutionary host-pathogen arms race theory suggest that the extent and specificity of the microbial load influences the spectrum and potency of HDPs in different species. Individuals of extant species—that have lived for an extended period in evolutionary history amid populations with intact processes of natural selection—likely possess the most powerful and well-adapted “natural antibiotics”. Research on the evolutionary history of the innate defense system and the host in context of the consequences of challenges as well as the efficacy of the innate immune system under natural conditions is therefore of immediate interest. This review focuses on evolutionary aspects of immunophysiology, with emphasis on innate effector molecules. Studies on host defense in wild-living animals may significantly enhance our understanding of inborn immune mechanisms, and help identify molecules that may assist us to cope better with the increasing microbial challenges that likely follow from the continuous amplification of biodiversity levels on Earth.     

Genetic variation in natural populations: patterns and theory.

Allozymic variation in natural populations of plants, animals, and humans based on studies published prior to early 1976 and involving 243 species, in which 14 or more loci were tested, is herein reviewed. Explanatory models are compared and contrasted in view of the evidence to see which theories best explain genetic variation in natural populations. The analysis suggests that the amounts of genetic polymorphism and heterozygosity vary nonrandomly between loci, populations, species, habitats, and life zones, and are correlated with ecological heterogeneity. Natural selection, in some form, may often be the major determinant of genetic population structure and differentiation. Yet precise critical experiments must be designed to test possible alternative hypotheses, to establish direct cause-effect relationships between ecological and genetic profiles, and to assay the contribution of single and multilocus structures to fitness.     

Serotonergic Chemosensory Neurons Modify the C. elegans Immune Response by Regulating G-Protein Signaling in Epithelial Cells

The nervous and immune systems influence each other, allowing animals to rapidly protect themselves from changes in their internal and external environment. However, the complex nature of these systems in mammals makes it difficult to determine how neuronal signaling influences the immune response. Here we show that serotonin, synthesized in Caenorhabditis elegans chemosensory neurons, modulates the immune response. Serotonin released from these cells acts, directly or indirectly, to regulate G-protein signaling in epithelial cells. Signaling in these cells is required for the immune response to infection by the natural pathogen Microbacterium nematophilum. Here we show that serotonin signaling suppresses the innate immune response and limits the rate of pathogen clearance. We show that C. elegans uses classical neurotransmitters to alter the immune response. Serotonin released from sensory neurons may function to modify the immune system in response to changes in the animal''s external environment such as the availability, or quality, of food.     

Gorilla ecology and behavior

Many factors influence the evolution of primate grouping patterns, including phylogeny, demographic and life-history variables, and ecological factors such as access to food, predation pressure, and avoidance of infanticide. The interaction between these factors determines social organization.¹ Because western lowland and mountain gorillas differ so dramatically in their habitats and foraging strategies, they provide a valuable opportunity to assess how changes in ecology influence this balance. Mountain gorillas live in high-altitude montane forests, are herbivorous, and live in stable and cohesive groups. Western lowland gorillas live in lowland rainforest and are much more frugivorous than mountain gorillas. It is not yet clear to what extent incorporating significant quantities of fruit in the diet influences western lowland gorilla sociality because they have been studied much less than have mountain gorillas. However, what is known about their behavior hints that there may also be considerable differences in their social organization, including changes in group size and cohesion and in the frequency and type of intergroup encounters. Gorillas thus provide a unique opportunity to reevaluate proposed models of ecological influences on social organization in African apes.© 1998 Wiley-Liss, Inc.     

From the Cell to the Ecosystem: The Physiological Evolution of Symbiosis

Living organisms constantly interact with their habitats, selectively taking up compounds from their surroundings to meet their particular needs but also excreting metabolic products and thus modifying their environment. The small size, ubiquity, metabolic versatility, flexibility, and genetic plasticity (horizontal transfer) of microbes allow them to tolerate and quickly adapt to unfavorable and/or changing environmental conditions. The consumption of resources and the formation of metabolic products by spatially separated microbial populations constitute the driving forces that lead to chemical gradient formation. Communication and cooperation, both within and among bacterial species, have produced the properties that give these organisms a selective advantage. Observations of a wide range of natural habitats have established that bacteria do not function as individuals; rather, the vast majority of bacteria in natural and pathogenic ecosystems live in biofilms, defined as surface-associated, complex aggregates of bacterial communities that are attached to solid substrates and embedded in a polymer matrix of their own production. The spatial configurations of biofilms reach levels of complexity nearing those of multicellular eukaryotes. Microbial consortia have played important roles throughout the history of life on Earth, from the microbial mats (a type of biofilm) that were probably the first ecosystems in the early Archean, to the complex microbiota of the intestinal tract of different animals.     

Different strokes: Can managing behavioral types increase post-release success?

Re-introduction programs for endangered animals operate under the hope that protected habitats can sustain viable populations that rely little on humans. The goal of these programs is to supply animals with the resources and skills they need to succeed in the modern wild. However, predicting the set of skills necessary to respond to unpredictable selection events is difficult and efforts sometimes fail as animals respond inappropriately to environmental variation because they lack behavioral flexibility. Population resilience to environmental change may be enhanced if all members of a population do not exhibit the same response when selection pressures change. In many species individual animals express behavioral types that exhibit alternative responses to the same stimuli. Yet when animals are prepared for release to the wild, there is rarely consideration of consistent behavioral variation between individuals. Since experience influences both behavioral and physiological responses to varied stimuli and can shape the future behavioral type of captive animals, pre-release environmental enrichment may be successful in facilitating the expression of varied behavioral types in populations slated for release. This approach to environmental enrichment requires a departure from a ‘one size fits all’ strategy and may also involve exposure to increased challenge and competition. In addition, there is a need for empirical evidence to better understand the role of environmental enrichment and behavioral types on post-release success. The zoo environment provides an excellent arena for examining the development and expression of behavioral types and for taking a novel functional approach to environmental enrichment research that may prove to be very important to re-introduction efforts.     

Effects of an anthropogenic diet on indicators of physiological challenge and immunity of white ibis nestlings raised in captivity

When wildlife forage and/or live in urban habitats, they often experience a shift in resource availability and dietary quality. Some species even use human handouts, such as bread, as well as human refuse, as a large part of their new diets; yet the influences of this nutritional shift on health and survival remain unclear. American white ibises are increasingly being seen in urban areas in Florida; they collect handouts, such as bread and other food items, from humans in parks, and are also found foraging on anthropogenic sources in trash heaps. We hypothesized that the consumption of these new anthropogenic food sources may trigger increases in indicators of physiological challenge and dampen immune responses. We tested this experimentally by raising 20 white ibis nestlings in captivity, and exposing 10 to a simulated anthropogenic diet (including the addition of white bread and a reduction in seafood content) while maintaining 10 on a diet similar to what ibises consume in more natural environments. We then tested two indicators of physiological challenge (corticosterone and heat shock protein 70), assessed innate immunity in these birds via bactericidal assays and an in vitro carbon clearance assay, and adaptive immunity using a phytohemagglutinin skin test. The anthropogenic diet depressed the development of the ability to kill Salmonella paratyphi in culture. Our results suggest that consuming an anthropogenic diet may be detrimental in terms of the ability to battle a pathogenic bacterial species, but there was little effect on indicators of physiological challenge and other immunological measures.     

Coevolutionary networks: a novel approach to understanding the relationships of humans with the infectious agents

Human organism is interpenetrated by the world of microorganisms, from the conception until the death. This interpenetration involves different levels of interactions between the partners including trophic exchanges, bi-directional cell signaling and gene activation, besides genetic and epigenetic phenomena, and tends towards mutual adaptation and coevolution. Since these processes are critical for the survival of individuals and species, they rely on the existence of a complex organization of adaptive systems aiming at two apparently conflicting purposes: the maintenance of the internal coherence of each partner, and a mutually advantageous coexistence and progressive adaptation between them. Humans possess three adaptive systems: the nervous, the endocrine and the immune system, each internally organized into subsystems functionally connected by intraconnections, to maintain the internal coherence of the system. The three adaptive systems aim at the maintenance of the internal coherence of the organism and are functionally linked by interconnections, in such way that what happens to one is immediately sensed by the others. The different communities of infectious agents that live within the organism are also organized into functional networks. The members of each community are linked by intraconnections, represented by the mutual trophic, metabolic and other influences, while the different infectious communities affect each other through interconnections. Furthermore, by means of its adaptive systems, the organism influences and is influenced by the microbial communities through the existence of transconnections. It is proposed that these highly complex and dynamic networks, involving gene exchange and epigenetic phenomena, represent major coevolutionary forces for humans and microorganisms.     

From humans to hydra: patterns of cancer across the tree of life

Cancer is a disease of multicellularity; it originates when cells become dysregulated due to mutations and grow out of control, invading other tissues and provoking discomfort, disability, and eventually death. Human life expectancy has greatly increased in the last two centuries, and consequently so has the incidence of cancer. However, how cancer patterns in humans compare to those of other species remains largely unknown. In this review, we search for clues about cancer and its evolutionary underpinnings across the tree of life. We discuss data from a wide range of species, drawing comparisons with humans when adequate, and interpret our findings from an evolutionary perspective. We conclude that certain cancers are uniquely common in humans, such as lung, prostate, and testicular cancer; while others are common across many species. Lymphomas appear in almost every animal analysed, including in young animals, which may be related to pathogens imposing selection on the immune system. Cancers unique to humans may be due to our modern environment or may be evolutionary accidents: random events in the evolution of our species. Finally, we find that cancer‐resistant animals such as whales and mole‐rats have evolved cellular mechanisms that help them avoid neoplasia, and we argue that there are multiple natural routes to cancer resistance.     

Ecological validity of social interaction tests in rats and mice

Different rat and mouse models are used in studies of social interactions. Simple behavioral measures, which are commonly used in the laboratory, allow to perform relatively short experiments and to use multiple brain manipulation techniques. However, too much focus on the simplest behavioral models generates a serious risk of reducing ecological validity or even studying phenomena which would never happen outside of the laboratory. In this review, we discuss the suitability of mice and rats as model organisms for studying social behaviors, with focus on social transmission of fear paradigms. First, we briefly introduce the concept of domestication and what impact it had on laboratory rodents. Then, we present two aspects of social behaviors, sociability and dominance, which are crucial for social organization in these species. Finally, we present experimental models used for studying how animals transmit information about danger between each other, and how these models may reflect what happens in the natural environment. We discuss the difficulties that arise from our limited knowledge of rat and mouse ecology, especially their social life. We also explore the subject of balancing ecological validity and controllability in rodent models of social behaviors, the latter being particularly important for studying brain activity. Although it is very challenging, an efficient program for social neuroscience research should, in our opinion, aim at bridging the gap between laboratory and field studies.     

Further role of zoos in conservation: Monitoring wildlife use and the dilemma of receiving donated and confiscated animals

The role of zoos in conservation has evolved. Additional roles that zoos can play in conservation include monitoring live wildlife use (one of the main threats for many species). Zoos in many parts of the world are offered animals by the public and are required to receive animals confiscated by the authorities. By quantifying these animals, zoos can monitor live wildlife use rates and trends and obtain relevant information on the environment of a region which can assist in situ conservation management. Zoos are sometimes forced to receive unwanted animals from the public or the authorities. Receiving these animals is a burden for zoos. Agreements between zoos and governments are important to take care of these animals and to optimize the use of conservation resources. It is not possible or desirable to maintain all donated and seized animals. The International Union for Conservation of Nature and Natural Resources provides useful guidelines on what to do with them. In all cases, species conservation should take precedence over individual animal welfare. These issues are illustrated with data collected at Zoológico Regional Miguel Alvarez del Toro (ZOOMAT) in Chiapas, southern Mexico. Zoo Biol 24:115–124, 2005. © 2005 Wiley‐Liss, Inc.     

Great tits take greater risk toward humans and sparrowhawks in urban habitats than in forests

Urban animals often take more risk toward humans than their non‐urban conspecifics do, but it is unclear how urbanization affects behavior toward non‐human predators. Responses to humans and non‐human predators may covary due to common mechanisms enforcing a phenotypic correlation. However, while increased tolerance toward humans may be advantageous for urban animals, reduced vigilance toward non‐human predators that can pose actual threat may be costly. Therefore, urban animals may benefit from showing specific responses to different threat levels, such as humans versus non‐human predators, or hostile versus non‐hostile humans. To test these alternatives, we compared responses (latencies to return to nest) of urban and forest‐breeding great tits (Parus major) to familiar hostile and unfamiliar humans as well as one of their common predators, the sparrowhawk (Accipiter nisus). We found that urban birds were more risk‐taking toward both humans and sparrowhawk than forest birds. However, responses to sparrowhawk did not correlate with responses to humans either within or across habitats. This suggests that higher risk‐taking of urban compared to forest‐dwelling great tits toward sparrowhawk may be threat‐specific response to lower predation risk rather than a spillover effect of increased tolerance to humans. Furthermore, birds responded similarly to unfamiliar and familiar (potentially dangerous) humans in both habitats, suggesting that great tits may not adjust their risk‐taking to the threat represented by individual humans. These findings indicate that urban birds may flexibly adjust their risk‐taking to certain, but not all, types of threat.     

Common and divergent psychobiological mechanisms underlying maternal behaviors in non-human and human mammals

Maternal interactions with young occupy most of the reproductive period for female mammals and are absolutely essential for offspring survival and development. The hormonal, sensory, reward-related, emotional, cognitive and neurobiological regulators of maternal caregiving behaviors have been well studied in numerous subprimate mammalian species, and some of the importance of this body of work is thought to be its relevance for understanding similar controls in humans. We here review many of the important biopsychological influences on maternal behaviors in the two best studied non-human animals, laboratory rats and sheep, and directly examine how the conceptual framework established by some of the major discoveries in these animal “models” do or do not hold for our understanding of human mothering. We also explore some of the limits for extrapolating from non-human animals to humans. We conclude that there are many similarities between non-human and human mothers in the biological and psychological factors influencing their early maternal behavior and that many of the differences are due to species-characteristic features related to the role of hormones, the relative importance of each sensory system, flexibility in what behaviors are exhibited, the presence or absence of language, and the complexity of cortical function influencing caregiving behaviors.     

Markedly Elevated Antibody Responses in Wild versus Captive Spotted Hyenas Show that Environmental and Ecological Factors Are Important Modulators of Immunity

Evolutionary processes have shaped the vertebrate immune system over time, but proximal mechanisms control the onset, duration, and intensity of immune responses. Based on testing of the hygiene hypothesis, it is now well known that microbial exposure is important for proper development and regulation of the immune system. However, few studies have examined the differences between wild animals in their natural environments, in which they are typically exposed to a wide array of potential pathogens, and their conspecifics living in captivity. Wild spotted hyenas (Crocuta crocuta) are regularly exposed to myriad pathogens, but there is little evidence of disease-induced mortality in wild hyena populations, suggesting that immune defenses are robust in this species. Here we assessed differences in immune defenses between wild spotted hyenas that inhabit their natural savanna environment and captive hyenas that inhabit a captive environment where pathogen control programs are implemented. Importantly, the captive population of spotted hyenas was derived directly from the wild population and has been in captivity for less than four generations. Our results show that wild hyenas have significantly higher serum antibody concentrations, including total IgG and IgM, natural antibodies, and autoantibodies than do captive hyenas; there was no difference in the bacterial killing capacity of sera collected from captive and wild hyenas. The striking differences in serum antibody concentrations observed here suggest that complementing traditional immunology studies, with comparative studies of wild animals in their natural environment may help to uncover links between environment and immune function, and facilitate progress towards answering immunological questions associated with the hygiene hypothesis.     

Relationship of weight loss to ambient humidity of birds eggs during incubation

Summary Eggs of birds nesting in wet and dry habitats, have been artificially incubated at controlled humidity white weight loss of the eggs and shell water vapour conductance have been determined. Eggs of species from wet habitats loose weight at a higher rate than those from drier habitats at a given relative humidity.It is suggested that the conductance of the egg shell to water vapour is adapted to the conditions of humidity in the environment such that weight loss varies little (and less than predictable) in relation to the relative humidity at the nesting sites.The relative humidity surrounding eggs during natural incubation was found to be in the range of 30–50% in 4 different species. Humidity in the nest during natural incubation was found to be higher than what would result if ambient air was heated to incubation temperature indicating that the sitting bird conserves humidity around the eggs.