Photoluminescence in mammal fur: 111 years of research.

Photoluminescence in the pelage of mammals, a topic that has gained considerable recent research interest, was first documented in the 1700s and reported sporadically in the literature over the last century. The first detailed species accounts were of rabbits and humans, published 111 years ago in 1911. Recent studies have largely overlooked this earlier research into photoluminescent mammalian taxa and their luminophores. Here we provide a comprehensive update on existing research on photoluminescence in mammal fur, with the intention of drawing attention to earlier pioneering research in this field. We provide an overview on appropriate terminology, explain the physics of photoluminescence, and explore pigmentation and the ubiquitous photoluminescence of animal tissues, before touching on the emerging debate regarding visual function. We then provide a chronological account of research into mammalian fur photoluminescence, from the earliest discoveries and identification of luminophores to the most recent studies. While all mammal fur is likely to have a general low-level photoluminescence due to the presence of the protein keratin, fur glows luminously under ultraviolet light if it contains significant concentrations of tryptophan metabolites or porphyrins. Finally, we briefly discuss issues associated with preserved museum specimens in studies of photoluminescence. The study of mammal fur photoluminescence has a substantial history, which provides a broad foundation on which future studies can be grounded.

The consistency of exploration behaviours across life stages in a native Australian rodent, the fawn-footed mosaic-tailed rat Melomys cervinipes.

Many species show inter-individual variation in exploratory behaviours that are consistent over time, reflecting a personality. Differences in exploration can affect how individuals acquire resources and use their environment. However, few studies have considered whether exploratory behaviours are consistent across developmental life stages, such as when individuals disperse out the natal territory or when they become sexually mature. We therefore investigated the consistency of exploration behaviours towards a novel object and novel environment in a native Australian rodent, the fawn-footed mosaic-tailed rat Melomys cervinipes across development. Individuals were tested in an open field test and novel object test for five trials across four different life stages (pre-weaning, recently weaned, independent juvenile, sexually mature adult). We found that individual mosaic-tailed rats were consistent in their exploration of novel objects over these life stages, as these behaviours were repeatable and did not change across testing replicates. However, how individuals explored novel environments was not repeatable and changed across development, with exploration peaking during the independent juvenile stage. These results suggest that the way an individual interacts with novel objects may be somewhat constrained by genetic or epigenetic effects early in development, whereas spatial exploration could be more flexible to facilitate developmental shifts, such as dispersal. The life stage of an animal should therefore be taken into consideration when assessing personality in different species.

The effects of antibiotics and illness on gut microbial composition in the fawn-footed mosaic-tailed rat (Melomys cervinipes).

The gut microbiota are critical for maintaining the health and physiological function of individuals. However, illness and treatment with antibiotics can disrupt bacterial community composition, the consequences of which are largely unknown in wild animals. In this study, we described and quantified the changes in bacterial community composition in response to illness and treatment with antibiotics in a native Australian rodent, the fawn-footed mosaic-tailed rat (Melomys cervinipes). We collected faecal samples during an undiagnosed illness outbreak in a captive colony of animals, and again at least one year later, and quantified the microbiome at each time point using 16s ribosomal rRNA gene sequencing. Gut bacterial composition was quantified at different taxonomic levels, up to family. Gut bacterial composition changed between time periods, indicating that illness, treatment with antibiotics, or a combination affects bacterial communities. While some bacterial groups increased in abundance, others decreased, suggesting differential effects and possible co-adapted and synergistic interactions. Our findings provide a greater understanding of the dynamic nature of the gut microbiome of a native Australian rodent species and provides insights into the management and ethical well-being of animals kept under captive conditions.

Both age and experience are important for successful problem solving in juvenile fawn-footed mosaic-tailed rats Melomys cervinipes.

Problem solving ability is affected by many factors, including physiology, personality, and cognition. However, how age and experience influence problem-solving ability during development is harder to untangle. We tested how age and experience affected problem solving in a native Australian rodent, the fawn-footed mosaic-tailed rat Melomys cervinipes. Juveniles were divided into two groups (different ages at start of testing) and then received a food-baited cardboard matchbox every 10 days for a total of three tests. We compared the problem-solving ability of individuals from both groups, which allowed us to separate the effects of age and experience. Juveniles with more experience solved the task faster than juveniles with less experience. Furthermore, inexperienced older juveniles interacted with the problems more than inexperienced younger juveniles. Previous solving experience may be important for short-term solving success, while age, in the absence of experience, might be associated with increased exploration, leading to increased investigation of novel problems. Previous experience at manipulating objects generally may also be important for problem-solving success, which likely provides an advantage as resources and habitats change seasonally and annually.

Problem solving in fawn-footed mosaic-tailed rats Melomys cervinipes is not significantly influenced by maternal care or genetic effects.

Innovative problem solving is thought to be a flexible trait that allows animals to adjust to changing or challenging environmental conditions. However, it is not known how problem solving develops during an animal's early life, or whether it may have a heritable component. We investigated whether maternal genetic and nongenetic effects influenced problem-solving ability in a native Australian rodent, the fawn-footed mosaic-tailed rat Melomys cervinipes. We measured direct (time spent grooming and huddling), indirect (time spent nesting), and total amount of maternal care received across pup development (postnatal Days 1-13). We measured problem solving in juveniles using matchbox tasks, and in mothers and adult offspring using six tasks of varying complexity (matchbox, cylinder, obstruction, pillar, tile, and lever tasks). We found no relationship between any maternal care measures and problem-solving abilities across multiple tests, suggesting limited (if any) maternal nongenetic effects. We also found that, as shown by low heritability estimates, problem solving only had a small heritable component in some tasks, but this was nonsignificant and requires further investigation. These results suggest that problem solving is unlikely to be constrained by maternal effects experienced during early development, and is, instead, more likely to be influenced by other factors (e.g., experience) later in an individual's lifetime.

Memory enhances problem solving in the fawn-footed mosaic-tailed rat Melomys cervinipes.

Problem solving is important for survival, allowing animals to access novel food resources or escape from predators. It was originally thought to rely on an animal's intelligence; however, studies examining the relationship between individual cognitive ability and problem solving performance show mixed results, and studies are often restricted to only one cognitive and one problem solving task. We investigated the relationship between general cognitive ability and problem solving across multiple tasks in the fawn-footed mosaic-tailed rat Melomys cervinipes. We measured general cognitive ability across different domains (memory in an odour learning association task, recognition in a novel object recognition task, size discrimination using different sized pieces of food, and learning across multiple presentations of a food-baited activity board). We also measured problem solving across different contexts (food-baited puzzle boxes in home cage, obstruction task, and food-baited activity board in a novel arena). Mosaic-tailed rats showed a general cognitive ability, with average problem solving latency, memory ability, and learning in the tile task being correlated. As such, individuals that were able to remember an association and learned to solve the tile task solved the problems faster than individuals that could not remember or learn. Our results suggest that problem solving in mosaic-tailed rats likely relies on some forms of simple cognition, particularly memory, but could also depend on other traits, such as an individual's persistence.

Resolving phylogenetic and classical nomenclature: A revision of Seraphsidae Jung, 1974 (Gastropoda: Neostromboidae).

This revision demonstrates that an integrated taxonomic approach to classical taxonomic practice can lead to increased internal cladistic resolution within a clade, including the recognition of new taxa at all nomenclatural levels. In particular, this revision has two aims: 1) to complete an α-taxonomic revision of Seraphsidae (Stromboidea); and 2) to resolve the infrafamilial relationships within Seraphsidae using morphological cladistics. An annotated synonymy was generated for each taxon, the precedence of names determined, and revised descriptions formulated. Character sets that reflect the synapomorphies within the major subclades of Seraphsidae were coded and a cladogram generated using maximum likelihood within the tnt program with default settings. Four forms of material and evidence were used in this systematic review: 1) the type material for each taxon; 2) non-type physical material; 3) published images; and 4) literary references for specimen localities without illustration. The current morphologically-based classification of Seraphsidae was found to be sound in terms of current species delimitations. Regardless of this, the use of an integrated taxonomy improved understanding of the internal cladistic relationships within Seraphsidae, which led to higher resolution of the internal cladistic arrangements and taxonomic delimitation. Furthermore, this increased resolution is now reflected in the family nomenclature. Two new subfamilies are proposed, Seraphsinae and Pseudoterebellinae, which are used to distinguish the two clades within Seraphsidae based on form: members of Seraphsinae are involute, while members of Pseudoterebellinae are evolute. Pseudoterebellum is proposed as a new genus to show the discontinuity in the fossil record and highlight the structural differences between it and Terebellum. A new species from Jamaica, Seraphs kaindraperi, is described, being the first record from that location and that geological period and is morphologically distinct from other described taxa. This revision included Mauryna within Seraphsidae on the grounds that it provides a basal link to the Seraphsidae sister taxa Semiterebellum and Terebellopsis, all of which are currently contained within Rostellariidae, and all three clades may in time be brought together under one family. All clades have been constructed to be in compliance with both the ICZN and PhyloCode. It was not possible within the context of this revision to test the results of the α-taxonomic findings against phylogenies generated with molecular data. This was due to the high number of extinct taxa within the Seraphsidae.

Problem Solving in Animals: Proposal for an Ontogenetic Perspective.

Problem solving, the act of overcoming an obstacle to obtain an incentive, has been studied in a wide variety of taxa, and is often based on simple strategies such as trial-and-error learning, instead of higher-order cognitive processes, such as insight. There are large variations in problem solving abilities between species, populations and individuals, and this variation could arise due to differences in development, and other intrinsic (genetic, neuroendocrine and aging) and extrinsic (environmental) factors. However, experimental studies investigating the ontogeny of problem solving are lacking. Here, we provide a comprehensive review of problem solving from an ontogenetic perspective. The focus is to highlight aspects of problem solving that have been overlooked in the current literature, and highlight why developmental influences of problem-solving ability are particularly important avenues for future investigation. We argue that the ultimate outcome of solving a problem is underpinned by interacting cognitive, physiological and behavioural components, all of which are affected by ontogenetic factors. We emphasise that, due to the large number of confounding ontogenetic influences, an individual-centric approach is important for a full understanding of the development of problem solving.

Corticosterone Metabolite Concentration Is Not Related to Problem Solving in the Fawn-Footed Mosaic-Tailed Rat Melomys Cervinipes.

Animals can respond physiologically, such as by adjusting glucocorticoid hormone concentrations, to sudden environmental challenges. These physiological changes can then affect behavioural and cognitive responses. While the relationships between adrenocortical activity and behaviour and cognition are well documented, results are equivocal, suggesting species-specific responses. We investigated whether adrenocortical activity, measured using corticosterone metabolite concentration, was related to problem solving in an Australian rodent, the fawn-footed mosaic-tailed rat (Melomys cervinipes). Mosaic-tailed rats live in complex environments that are prone to disturbance, suggesting a potential need to solve novel problems, and have been found to show relationships between physiology and other behaviours. We measured problem solving using five food-baited puzzles (matchbox and cylinder in the home cage, and activity board with pillars to push, tiles to slide and levers to lift in an open field), and an escape-motivated obstruction task in a light/dark box. Faecal samples were collected from individuals during routine cage cleaning. Adrenocortical activity was evaluated non-invasively by measuring faecal corticosterone metabolites using an enzyme immunoassay, which was biochemically and biologically validated. Despite varying over time, adrenocortical activity was not significantly related to problem solving success or time spent interacting for any task. However, as adrenocortical activity is reflective of multiple physiological processes, including stress and metabolism, future studies should consider how other measures of physiology are also linked to problem solving.

Sons benefit from paternal care in African striped mice.

Mammalian paternal care is rare and is often linked to enhanced fitness under particular ecological conditions. The proximate consequences of paternal care on offspring are lacking, however. Here, we tested whether levels of paternal care predict the behavioural, cognitive and physiological development of sons in the naturally paternal African striped mouse (Rhabdomys pumilio). We focused on sons raised in two treatments: biparental (both parents) or uniparental (mother alone) families. We recorded levels of interactions between pups with both parents, and later assessed the behaviour, cognition and physiology of sons at three developmental stages: juvenile, sub-adult and adult (sexual maturity). Sons from biparental families showed (a) reduced anxiety as juveniles; (b) greater exploration and social interaction at different stages; (c) better cognition; and (d) reduced corticosterone concentrations than sons from uniparental families. In contrast, sons from uniparental families showed greater levels of paternal care, although prolactin concentrations did not differ between treatments. Paternal care in striped mice enhances fitness of males. Here, we also show that sons benefit psychologically and physiologically through interactions with their fathers. However, sons also trade-off such benefits against their own paternal care behaviour, suggesting that fathers influence the development of their son's phenotype in complex ways.

Decision-making by bushveld gerbils (Gerbilliscus leucogaster).

Decision-making reflects an individual's behavioral motivation, shaped by intrinsic and extrinsic factors. We investigated the motivation and decision-making to forage in captive bushveld gerbils (Gerbilliscus leucogaster) using an individually tailored experimental protocol. Individual gerbils were subjected to 4 experiments, where we assessed behavior and decision-making in response to: (a) food quality when resources were clumped (Experiment 1), (b) food quality when resources were scattered (Experiment 2), (c) changing food distribution (clumped vs. scattered; Experiment 3), and (d) predation risk. Each experiment comprised 4 treatments, where both cost (a weighted door) and incentive (preferred vs. nonpreferred seeds; clumped vs. scattered seeds) varied according to the mass and personal preferences of individual gerbils. We counted the number of seeds eaten, assessed the frequency of door usage, and measured the duration of exploration, vigilance, and foraging (as a proportion of total time) of gerbils in each experiment. Gerbils showed individual preferences for different seed types although all preferred sunflower or sorghum seeds. Generally, gerbils ate more seeds and used the door more frequently when the costs were low. Similarly, gerbils tended to forage more when the costs were low and predation risk was low. We also found that males, in general, were more vigilant than females in Experiments 3 and 4, likely because of risk of intrasexual competition over a high-resource patch. There was considerable individual variation in behavior, but there was also consistency in most behaviors, indicating that individual gerbils perform consistently differently to other gerbils. (PsycInfo Database Record (c) 2021 APA, all rights reserved).

The Role of Olfactory Genes in the Expression of Rodent Paternal Care Behavior.

Olfaction is the dominant sensory modality in rodents, and is crucial for regulating social behaviors, including parental care. Paternal care is rare in rodents, but can have significant consequences for offspring fitness, suggesting a need to understand the factors that regulate its expression. Pup-related odor cues are critical for the onset and maintenance of paternal care. Here, I consider the role of olfaction in the expression of paternal care in rodents. The medial preoptic area shares neural projections with the olfactory and accessory olfactory bulbs, which are responsible for the interpretation of olfactory cues detected by the main olfactory and vomeronasal systems. The olfactory, trace amine, membrane-spanning 4-pass A, vomeronasal 1, vomeronasal 2 and formyl peptide receptors are all involved in olfactory detection. I highlight the roles that 10 olfactory genes play in the expression of direct paternal care behaviors, acknowledging that this list is not exhaustive. Many of these genes modulate parental aggression towards intruders, and facilitate the recognition and discrimination of pups in general. Much of our understanding comes from studies on non-naturally paternal laboratory rodents. Future studies should explore what role these genes play in the regulation and expression of paternal care in naturally biparental species.

Innovation in a native Australian rodent, the fawn-footed mosaic-tailed rat (Melomys cervinipes).

Innovation is the ability to use a new behaviour, or use an existing behaviour in a new context. Innovation, as an aspect of behavioural flexibility, could be important for allowing animals to cope with rapid environmental changes. Surprisingly, few studies have focused on how innovation ability is affected by task complexity. We investigated innovation ability across multiple tasks of varying complexity in a native Australian rodent, the fawn-footed mosaic-tailed rat (Melomys cervinipes). We predicted that mosaic-tailed rats would be capable of innovating because they live in complex habitats and can exploit disturbed and changing environments. However, we also predicted that the success rate of innovating would decrease as task complexity increased. Mosaic-tailed rats were exposed to six novel problems: cylinder, matchbox, obstruction test, pillar, tile and lever (the last three presented in a Trixie dog activity board), which represented increasing complexity. We counted the number of individuals that could solve at least one task, compared individuals for solving efficiency and latency to solve, and compared the solving success of each task. All mosaic-tailed rats could innovate. However, solving success differed between individuals, with some solving every task and others only solving one. Solving success rate was significantly higher in the simplest task (pillar) compared to the most complicated task (lever). There was no effect of sex or sampling condition on innovation. This study is the first to demonstrate innovation ability across task complexity in an Australian rodent and provides promising avenues for future studies of innovation.

Recognising and defining a new crown clade within Stromboidea Rafinesque, 1815 (Mollusca, Gastropoda).

This paper defines a new crown clade Neostromboidea to separate the Strombidae, Rostellariidae, and Seraphsidae from their sister families Struthiolariidae and Aporrhaidae. There is significant value to understanding evolutionary processes within Stromboidea to recognise the universal similarity in the position of the eye on the end of peduncles and a diminished cephalic tentacle that arises from the middle to the end on that peduncle. This is in contrast to other members of the Stromboidea where the eye is located at the base of the cephalic tentacle. These physiological differences represent two set of organisms with divergent and independent evolutionary life histories and therefore these differences need to be identifiable within the nomenclature to bring meaning to the way we name things.

Laevistrombus Abbott 1960 (Gastropoda: Strombidae): Indian and southwest Pacific species.

Here we evaluate the taxonomy of the marine gastropod genus Laevistrombus Abbott, 1960 and determine that there are five extant species within this genus, three of which occur in the southwest Pacific. Comparative analyses of this complex have been problematic due to the lack of designated type material. Therefore, we present the type material for L. canarium Linnaeus, 1758; L. taeniatus Quoy Gaimard, 1834; and L. vanikorensis Quoy Gaimard, 1834. Current taxonomy has L. vanikorensis absorbed within the L. canarium complex. L. taeniatus is generally held to be a synonym of L. turturella Röding, 1789. We demonstrate that both L. taeniatus and L. vanikorensis are distinct species and reinstate both to species level. Our revision also notes the significant variability in early teleoconch structure within the geographic range of L. vanikorensis, and highlights the need for a greater revision of Laevistrombus, given the diversity in early teleoconch morphology present in southwest Pacific species.

RESILIENCE TO DROUGHTS IN MAMMALS: A CONCEPTUAL FRAMEWORK FOR ESTIMATING VULNERABILITY OF A SINGLE SPECIES.

ABSTRACT The frequency and severity of droughts in certain areas is increasing as a consequence of climate change. The associated environmental challenges, including high temperatures, low food, and water availability, have affected, and will affect, many populations. Our aims are to review the behavioral, physiological, and morphological adaptations of mammals to arid environments, and to aid research- ers and nature conservationists about which traits they should study to assess whether or not their study species will be able to cope with droughts. We provide a suite of traits that should be considered when making predictions about species resilience to drought. We define and differentiate between general adaptations, specialized adaptations, and exaptations, and argue that specialized adaptations are of little interest in establishing how nondesert specialists will cope with droughts. Attention should be placed on general adaptations of semidesert species and assess whether these exist as exaptations in nondesert species. We conclude that phenotypic flexibility is the most important general adaptation that may promote species resilience. Thus, to assess whether a species will be able to cope with increasing aridity, it is important to establish the degree offlexibility of traits identified in semidesert species that confer afitness advantage under drying conditions.

Separation at weaning from the family is stressful for naturally group-living, but not solitary-living, male African striped mice Rhabdomys.

Early separation from a family is stressful for young mammals, but might be more stressful for group-living than solitary species. Using juvenile males of three African striped mice Rhabdomys taxa that are either group (R. pumilio) or solitary (R. dilectus dilectus and R. d. chakae) living, we predicted greater separation anxiety in R. pumilio than R. dilectus because group-living could reduce anxiety in R. pumilio. Three brothers from each of 10 litters per taxon were randomly assigned soon after natural weaning (25 days) to one of three treatments for 10 days: (1) remained with the family (philopatric); (2) separated from the family by a wire mesh barrier (separated); and (3) isolated from the family (isolated). Males were individually tested in a four-arm maze to assess their anxiety responses and sampled for corticosterone concentrations 20 mins and 10 days later. Compared to R. dilectus males, R. pumilio males showed a greater treatment response to separation: philopatric males used the light arms of the maze less and had higher corticosterone concentrations compared to isolated males, which spent the most time in the light arms and had the lowest corticosterone concentrations overall; separated males showed an intermediate behavioural response, but had similar corticosterone concentrations to philopatric males. Thus, separation from a family group is more stressful in group-living Rhabdomys and this stress response dissipates with time. Philopatry and group-living may be more important for young R. pumilio, whereas dispersal at weaning is an important life history event for solitary R. dilectus.

Maternal care in the African striped mouse Rhabdomys pumilio: a behaviorally flexible phenotype that is modified by experience.

The development of maternal care in mammals can be influenced by the type and quality of maternal care received. Using biparental striped mice Rhabdomys pumilio, we investigated whether development of maternal care is influenced by the mother during early rearing and by an adult female's experience and that of her mate. Offspring were raised in one of three treatments, by: both parents; mothers alone; and mothers separated from the father with a barrier. Since female striped mice increase their care when raising litters alone, which influences expression of parental care of their adult sons, we expected daughters to respond like sons. However, there was no treatment effect in the development of maternal care in daughters. In subsequent experiments, experienced and inexperienced females decreased care when raising their offspring with experienced but not inexperienced males. Therefore, maternal care in striped mice is modulated in response to prevailing environmental and social conditions.

Behavioural divergence, interfertility and speciation: a review.

Behavioural compatibility between mates is fundamental for maintaining species boundaries and is achieved through appropriate communication between males and females. A breakdown in communication will lead to behavioural divergence and reduced interfertility. In this review, we summarise the current knowledge on male signals and female perception of these signals, integrating the literature from several taxa. We advocate that signaller-perceiver coevolution, which is usually under strong stabilising selection to enable mating, forms the basis of species-specific mate recognition systems. The mechanisms (phylogeny, geography, ecology, biology) shaping signaller-perceiver systems are briefly discussed to demonstrate the factors underpinning the evolution of signaller-perceiver couplings. Since divergence and diversification of communication systems is driven by changes in the mechanical properties of sensory pathways and morphology of sensory organs, we highlight signal modalities (auditory, olfactory, visual, tactile) and their importance in communication, particularly in mate selection. Next, using available examples and generating a stylised model, we suggest how disruption (biological, ecological, stochastic) of signaller-perceiver systems drives behavioural divergence and consequently results in reduced interfertility and speciation. Future studies should adopt an integrative approach, combining multiple parameters (phylogeny, adaptive utility of communication systems, genetics and biomechanical/biochemical properties of signals and perception) to explore how disruption of signaller-perceiver systems results in behavioural divergence and reduced interfertility. Finally, we question the impact that rapid environmental change will have on disruption of communication systems, potentially interfering with signaller-perceiver couplings.