Papers by Mauricio Gamboa
Does phylogeny drive penguin diving characteristics?
Gayana (Concepción), 2019
The geographic range of a species is often limited by sampling approaches, underestimating the ac... more The geographic range of a species is often limited by sampling approaches, underestimating the actual distribution. This is likely the case of Dromiciops gliroides (Microbiotheria), an endemic marsupial from southern South America. We used camera-traps to record D. gliroides for the first time in Chaitén and Futaleufú (southern Chile), expanding its known distribution 100 km to the south. Climate and forest composition in this area differs from the typical Valdivian rainforest. Activity assessments show a narrow activity patterns compared to northern populations.
PeerJ, 2016
BackgroundProviding the context for the evolution of life-history traits, habitat features constr... more BackgroundProviding the context for the evolution of life-history traits, habitat features constrain successful ecological and physiological strategies. In vertebrates, a key response to life’s challenges is the activation of the Stress (HPA) and Gonadal (HPG) axes. Much of the interest in stress ecology is motivated by the desire to understand the physiological mechanisms in which the environment affects fitness. As reported in the literature, several intrinsic and extrinsic factors affect variability in hormone levels. In both social and non-social animals, the frequency and type of interaction with conspecifics, as well as the status in social species, can affect HPA axis activity, resulting in changes in the reproductive success of animals. We predicted that a social environment can affect both guanaco axes by increasing the secretion of testosterone (T) and Glucocorticoid (GCs) in response to individual social interactions and the energetic demands of breeding. Assuming that pr...
Reproductive biology and behavior during incubation of black necked swan (cygnus melanocoryphus)
ORNITOLOGIA NEOTROPICAL
Animal Behaviour, 2015
The outcome of sexual selection acting on a given sexual trait depends on the interaction between... more The outcome of sexual selection acting on a given sexual trait depends on the interaction between the strength, direction and form of both inter-and intrasexual selection processes. Therefore, determining female choice and maleemale competition is necessary to gain a better understanding of how sexual selection acts on sexual traits. Anuran males produce advertisement vocalizations to attract females and to maintain other males at distance, providing a convenient opportunity to test the combined effect of inter-and intrasexual selection. Our main objective was to test experimentally potential effects of female choice and maleemale competition and their interaction when acting as selective agents on the advertisement vocalizations of the rosy ground frog, Eupsophus roseus. We performed phonotaxis experiments on females and males and determined their behavioural responses to artificial signals synthesized based on the distribution of natural calls. The main results suggest that females' preference would favour vocalizations having lower frequencies and a harmonic composition in which the main harmonics of vocalizations have similar amplitudes. These preferences suggest that females could exert negative directional sexual selection on the frequency and stabilizing selection on the amplitude ratio. The responses of males were variable, suggesting that this type of maleemale competition may not result in intrasexual selection favouring specific values of advertisement vocalizations. The occurrence of no clear preferences in males may result in a decrease in the potential effect of females' preferences, which could further contribute to variability in spectral components of calls.
Revista chilena de historia natural, 2009
Human-carnivore conflict has been recognized as one of the main threats to carnivore conservation... more Human-carnivore conflict has been recognized as one of the main threats to carnivore conservation. When small livestock or poultry are available, small carnivores will likely prey upon them. Centinela -a rural area located in Southern Chile where chillas (Lycalopex griseus Gray) and small farmers coexist-was chosen as a study site. To understand potential conflicts we conducted interviews to assess local knowledge, experiences, and attitudes toward this fox and small stock management. Almost a third of the interviewed people reported the loss of poultry during the last year due to chillas, which was confirmed by dietary analysis in a parallel study. Consequently, most research participants (67.4 %) had negative attitudes toward the chilla. Management appeared to be related to poultry losses, since no losses were reported when poultry was confined in henhouses, suggesting that continuous confinement was an effective measure to prevent the conflict. The negative attitudes are further reflected in that most people reported to have killed at least one chilla.
Communal nesting and kinship in degus (Octodon degus)
Naturwissenschaften, 2004
Communal nesting is a fundamental component of many animal societies. Because the fitness consequ... more Communal nesting is a fundamental component of many animal societies. Because the fitness consequences of this behavior vary with the relatedness among nest mates, understanding the kin structure of communally nesting groups is critical to understanding why such groups form. Observations of captive degus (Octodon degus) indicate that multiple females nest together, even when supplied with several nest boxes. To determine whether free-living degus also engage in communal nesting, we used radiotelemetry to monitor spatial relationships among adult females in a population of O. degus in central Chile. These analyses revealed that females formed stable associations of > 2-4 individuals, all of whom shared the same nest site at night. During the daytime, spatial overlap and frequency of social interactions were greatest among co-nesting females, suggesting that nesting associations represent distinct social units. To assess kinship among co-nesting females, we examined genotypic variation in our study animals at six microsatellite loci. These analyses indicated that mean pairwise relatedness among members of a nesting association (r=0.25) was significantly greater than that among randomly selected females (r=-0.03). Thus, communally nesting groups of degus are composed of female kin, making it possible for indirect as well as direct fitness benefits to contribute to sociality in this species.
Journal of Mammalogy, 2011
In the late 1990s and early 2000s it was recognized that behavioral ecologists needed to study th... more In the late 1990s and early 2000s it was recognized that behavioral ecologists needed to study the sociality of caviomorph rodents (New World hystricognaths) before generalizations about rodent sociality could be made. Researchers identified specific problems facing individuals interested in caviomorph sociality, including a lack of information on the proximate mechanisms of sociality, role of social environment in development, and geographical or intraspecific variation in social systems. Since then researchers have described the social systems of many previously understudied species, including some with broad geographical ranges. Researchers have done a good job of determining the role of social environments in development and identifying the costs and benefits of social living. However, relatively little is known about the proximate mechanisms of social behavior and fitness consequences, limiting progress toward the development of integrative (evolutionarymechanistic) models for sociality. To develop integrative models behavioral ecologists studying caviomorph rodents must generate information on the fitness consequences of different types of social organization, brain mechanisms, and endocrine substrates of sociality. We review our current understanding and future directions for research in these conceptual areas. A greater understanding of disease ecology, particularly in species carrying Old World parasites, is needed before we can identify potential links between social phenotypes, mechanism, and fitness.
Hormones and Behavior, 2005
Social interactions are important factors determining and regulating individual behaviors. Testos... more Social interactions are important factors determining and regulating individual behaviors. Testosterone has been related to agonistic interactions, while glucocorticoids have been related to social stress, especially during interactions of dominance. We compared testosterone and cortisol concentrations in male degus (Octodon degus, Rodentia) under laboratory conditions without male social interactions, with data from wild males in nature. Under natural conditions, males should present higher levels of testosterone during the breeding season due to social interactions (Challenge Hypothesis). Alternatively, intense social instability could act as a stressing environment, raising glucocorticoids, which inhibit testosterone concentrations. Our results show a significant increase in agonistic interactions between males during the breeding season, and disappearance of non-agonistic male interactions during this period. Hormone levels in breeding season show nonsignificant differences between laboratory groups, but testosterone concentrations in field males were significantly higher than in laboratory males. Testosterone levels were similar among pre-breeding and breeding periods, but in field animals the concentration was ~30% higher than in laboratory degus. In field animals, we found two different mating strategies: resident males, with territorial behavior, and transient males, displayed an opportunistic approach to females. Finally, cortisol presents a similar pattern in both laboratory and field animals; pre-breeding values of cortisol are higher than during the breeding season. This suggests that social interactions in O. degus activate a rise in testosterone, supporting the Challenge Hypothesis, and could be considered as partial support of the Social Stress Hypothesis.
The Condor, 2000
We examined grit consumption in the facultative granivorous Rufous-collared Sparrow (Zonotrichia ... more We examined grit consumption in the facultative granivorous Rufous-collared Sparrow (Zonotrichia capensis). Grit consumption fluctuated seasonally and was significantly correlated with morphological changes in the digestive tract, and with seed size. The highest values of grit consumption and digestive tract mass were observed during winter. Laboratory experiments suggested that grit consumption was a voluntary behavior rather than the result of accidental ingestion, and favored digestibility. Grit consumption 1
Blood biochemistry reveals malnutrition in black-necked swans (Cygnus melanocoryphus) living in a conservation priority area
Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, 2007
The application of clinical biochemical techniques to determine the products of intermediary meta... more The application of clinical biochemical techniques to determine the products of intermediary metabolism has proved to be a reliable approach for the study of the physiological state of animals in nature. More specifically, the determination of plasma metabolites, such as glucose, total proteins (PRO), albumin (ALB), globulins (GL), urea, uric acid, triglycerides (TG) and beta-hydroxy-butyrate (BHB), and plasma enzymes such as creatine kinase (CK) and aspartate aminotransferase (AST) in wild animals is a valuable possibility for a non-destructive assessment of health in endangered populations. Since August 2004 to January 2005, we conducted a temporal study in a conservation priority site, the "Carlos Anwandter Nature Sanctuary" to determine blood biochemistry of a wild population of black-necked swans (Cygnus melanocoryphus). This population was experiencing a drastic reduction, according to the actual knowledge about yearly fluctuations in numbers and breeding pairs. In six months, we periodically sampled about 12 swans (a total of 122 individuals), which exhibited a reduction near 30% in body mass (body mass corrected by total length). Our results showed reductions in most plasma biochemical parameters (glucose, PRO, ALB, uric acid, TG) and increase in BHB, which taken together indicated signs of chronic malnutrition. Also, the increase in AST and CK that we found, together with additional evidences of sub-lethal hepatic damage (in dead individuals), and iron pollution in aquatic plants and water confirmed that water pollution was the ultimate cause of this population reduction.
Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, 2007
Living organisms are continuously faced with several forms of environmental perturbation, one of ... more Living organisms are continuously faced with several forms of environmental perturbation, one of the most important being human activity. In this scenario, the role of physiological studies on wildlife has proved to be important given that in vivo physiological variables reflect a great deal how sensitive animals are to acute environmental changes. We studied the haematological parameters in black-necked swans (Cygnus melanocoryphus) at the Ramsar site at the Carlos Anwandter Sanctuary, which were experiencing a drastic population decrease. Through seven months, body mass (body mass corrected by total length) was reduced 30%, which was followed by significant reductions of haemoglobin concentration, haematocrit and red blood cell count. Mean cell volume and mean cell haemoglobin concentration did not change with time, whereas there was a significant increase of the white blood cells and heterophile / lymphocyte ratio. Our results, together with the published evidence, suggests that the proximal factors associated with the mass mortality and emigration of the black -necked swan population at the "Carlos Anwandter Sanctuary" was a drastic nutritional deficiency, and the potentially toxic effects of iron pollution in the waters of the Ramsar site.
Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, 2004
Hystricomorph rodents are a group of species that belong to the suborder Hystricognathi. They mai... more Hystricomorph rodents are a group of species that belong to the suborder Hystricognathi. They mainly inhabit South American (caviomorph) and African (phiomorph) habitats. This group of rodents has a divergent insulin structure. For example, insulin in this group of rodents exhibits only 1-10% of biological activity in comparison to other mammals. Therefore, hystricomorph rodents may hypothetically be unable to regulate blood glucose concentration as nonhystricomorph mammals. In this work we evaluated blood glucose concentration in nine species of caviomorph rodents, with emphasis on species belonging to the families Abrocomidae, Ctenomyidae and Octodontidae. Specifically we: (1) measured glucose concentrations after a fasting period; and (2) conducted a glucose tolerance test. In the latter assay we used Octodon degus as a representative species of the genus Octodon. Results showed that blood glucose concentration values after fasting, and in the glucose tolerance test, were within the expected range for mammals. We postulate that this group of rodents has compensatory traits that may permit the maintenance of standard values of plasma glucose.
Behavioural Processes, 2013
Social life involves costs and benefits mostly associated with how individuals interact with each... more Social life involves costs and benefits mostly associated with how individuals interact with each other. The formation of hierarchies inside social groups has evolved as a common strategy to avoid high costs stemming from social interactions. Hierarchical relationships seem to be associated with different features such as body size, body condition and/or age, which determine dominance ability ('prior attributes' hypothesis). In contrast, the 'social dynamic' hypothesis suggests that an initial social context is a determinant in the formation of the hierarchy, more so than specific individual attributes. Hierarchical rank places individuals in higher positions, which presumably increases resource accessibility to their benefit, including opportunities for reproduction. We evaluate the maintenance of hierarchy in a family group of guanacos (Lama guanicoe) and evaluate the possible mechanisms involved in the stability of these interactions and their consequences. We estimate the linearity of social hierarchy and their dynamics. We find evidence of the formation of a highly linear hierarchy among females with males positioned at the bottom of the hierarchy. This hierarchy is not affected by physical characteristics or age, suggesting that it is established only through intra-group interactions. Rank is not related with calves' weight gain either; however, subordinated females, with lower rank, exhibit higher rates of allosuckling. We found no evidence of hierarchical structure in calves suggesting that hierarchical relationship in guanacos could be established during the formation of the family group. Hence, our results suggest that hierarchical dynamics could be related more to social dynamics than to prior attributes. We finally discuss the importance of hierarchies established by dominance and their role in minimizing social costs of interactions.
Tamaño celular y tasa metabólica basal en picaflores
Revista chilena de historia …
... We captured five individuals of Rhodopis vesper in Arica (18°29´ S, 70°19´ W), five Oreotroch... more ... We captured five individuals of Rhodopis vesper in Arica (18°29´ S, 70°19´ W), five Oreotrochilus estella in Chusmiza (19°40´ S, 69°10´ W), three Sephanoides sephaniodes in San Carlos de Apoquindo (33°23´ S, 70°31´ W), and four individuals of Patagona gigas in El Pangue ...
Intraspecific variation in alarm calls of a social subterranean rodent, Spalacopus cyanus
eco.confex.com
Intraspecific variation in alarm calls of a social subterranean rodent, Spalacopus cyanus. Monica... more Intraspecific variation in alarm calls of a social subterranean rodent, Spalacopus cyanus. Monica L. Stewart, Biology, University of Louisiana at Monroe, Monroe, LA, Loren D. Hayes, Department of Biology, The University of Louisiana ...
Revista Chilena de Historia Natural, 2019
Background Behavior and activity patterns largely determine animal’s fitness and their ecological... more Background Behavior and activity patterns largely determine animal’s fitness and their ecological roles. Those patterns depend on many factors, being body mass, sex and age the most relevant in mammals. Particularly, those factors altogether with environmental conditions could influence movement behavior of mammals that hibernate, such as the Monito del monte (Dromiciops gliroides). Methods To evaluate its movement behavior and activity we radio-tracked D. gliroides 12 individuals (8 females and 4 males, corresponding to 5 adults and 7 sub-adults) during the austral summer. With the estimated locations we estimated home ranges, core areas and their relationship with body mass. We also assessed movement speed during early (19:00 to 01:00 h), peak (01:00 to 03:00 h) and late (03:00 to 07:00 h) activity periods. This study was conducted at the San Martín experimental forest (Valdivia, southern Chile). Results Estimated home range areas were 1.04 ± 0.20 ha, and core areas were 0.27 ± 0....
MOESM1 of Movement behavior of the Monito del monte (Dromiciops gliroides): new insights into the ecology of a unique marsupial
Additional file 1: Supporting Information associated to this article contains: Accumulation curve... more Additional file 1: Supporting Information associated to this article contains: Accumulation curves showing the effect on increasing number of locations on home range and core area estimations (Figure S1.), home range (Figure S2.) and core areas (Figure S3.) of tracked Dromiciops gliroides individuals; core area overlap between adult males and females (Figure S4.) and between adults and sub-adults (Figure S5.); detailed GLM results of: body mass comparison between males and females, and between adults and sub-adults (Table S1.), home range and core area comparisons between males and females, and between adults and sub-adults (Table S2.), home range and core area vs. body mass relationships (Table S4.), home range and core area vs. number of locations relationships (Table S5.), and movement speed among activity periods (Table S5.).
Data from: Movement behaviour of the monito del monte (Dromiciops gliroides): new insights into the ecology of a unique marsupial
Original dataset from:<br>Franco, L.M., F.E. Fontúrbel, G. Guevara & M Soto-Gamboa. 2019. M... more Original dataset from:<br>Franco, L.M., F.E. Fontúrbel, G. Guevara & M Soto-Gamboa. 2019. Movement behaviour of the monito del monte (Dromiciops gliroides): new insights into the ecology of a unique marsupial. Revista Chilena de Historia Natural (2019).<br>
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Papers by Mauricio Gamboa