| [the defense of the egg-laying site in the hood iguana (amblyrhynchus cristatus venustissimus)]. | | 1966 | 5994895 |
| progressive colonization and restricted gene flow shape island-dependent population structure in galápagos marine iguanas (amblyrhynchus cristatus). | marine iguanas (amblyrhynchus cristatus) inhabit the coastlines of large and small islands throughout the galápagos archipelago, providing a rich system to study the spatial and temporal factors influencing the phylogeographic distribution and population structure of a species. here, we analyze the microevolution of marine iguanas using the complete mitochondrial control region (cr) as well as 13 microsatellite loci representing more than 1200 individuals from 13 islands. | 2009 | 20028547 |
| phylogenetic analysis of the fecal microbial community in herbivorous land and marine iguanas of the galápagos islands using 16s rrna-based pyrosequencing. | herbivorous reptiles depend on complex gut microbial communities to effectively degrade dietary polysaccharides. the composition of these fermentative communities may vary based on dietary differences. to explore the role of diet in shaping gut microbial communities, we evaluated the fecal samples from two related host species-the algae-consuming marine iguana (amblyrhynchus cristatus) and land iguanas (li) (genus conolophus) that consume terrestrial vegetation. marine and li fecal samples were ... | 2011 | 21451584 |
| genomic fingerprinting and serotyping of salmonella from galápagos iguanas demonstrates island differences in strain diversity. | salmonella carriage patterns in wild and captive reptiles suggest that both geographical proximity and host ecological differences may determine bacterial diversity among reptile populations. in this study, we explore the relative importance of these factors on salmonella diversity in free-living galápagos iguanas. we isolated salmonella enterica from marine iguanas (amblyrhynchus cristatus) and land iguanas (conolophus subcristatus and c. pallidus) living on two islands (plaza sur and santa fe) ... | 2011 | 23761248 |
| human disturbance alters endocrine and immune responses in the galapagos marine iguana (amblyrhynchus cristatus). | anthropogenic disturbance is a relevant and widespread facilitator of environmental change and there is clear evidence that it impacts natural populations. while population-level responses to major anthropogenic changes have been well studied, individual physiological responses to mild disturbance can be equally critical to the long-term survival of a species, yet they remain largely unexamined. the current study investigated the impact of seemingly low-level anthropogenic disturbance (ecotouris ... | 2010 | 20708010 |
| island tameness: an altered cardiovascular stress response in galápagos marine iguanas. | island tameness is a widely documented phenomenon in which island species, particularly those that have evolved with no or few natural predators, show a greatly reduced behavioral response when faced with unfamiliar predators. this insufficient anti-predator response has led to widespread population declines among many island species exposed to novel predators, and has become a serious conservation problem. despite its prevalence, the underlying physiology of island tameness is not known. here w ... | 2010 | 20109476 |
| to breed or not to breed: physiological correlates of reproductive status in a facultatively biennial iguanid. | it is unusual for seasonal breeders to frequently skip opportunities for reproduction. we investigated the relationship between physiological state and reproductive decision-making in galápagos marine iguanas (amblyrhynchus cristatus), a species in which females typically reproduce biennially, although the proportion of breeding individuals varies significantly across years. nearly all adult-sized females initiated follicular development prior to the lekking period, but 38% of females resorbed a ... | 2010 | 19818354 |
| function of muscle-type lactate dehydrogenase and citrate synthase of the galápagos marine iguana, amblyrhynchus cristatus, in relation to temperature. | the galápagos marine iguana, amblyrhynchus cristatus, is unique among lizards in foraging subtidally, leading to activity across a broad range of ambient temperatures ( approximately 14-40 degrees c). to determine whether the marine iguana shows any biochemical changes consistent with maintaining enzyme function at both warm and cold body temperatures, we examined the function of the aerobic enzyme citrate synthase (cs) and the muscle isoform of the anaerobic enzyme lactate dehydrogenase (a(4)-l ... | 2008 | 18313960 |
| genetic impact of a severe el niño event on galápagos marine iguanas (amblyrhynchus cristatus). | the el niño-southern oscillation (enso) is a major source of climatic disturbance, impacting the dynamics of ecosystems worldwide. recent models predict that human-generated rises in green-house gas levels will cause an increase in the strength and frequency of el niño warming events in the next several decades, highlighting the need to understand the potential biological consequences of increased enso activity. studies have focused on the ecological and demographic implications of el niño in a ... | 2007 | 18074011 |
| behavioral and physiological adjustments to new predators in an endemic island species, the galápagos marine iguana. | for the past 5 to 15 million years, marine iguanas (amblyrhynchus cristatus), endemic to the galápagos archipelago, experienced relaxed predation pressure and consequently show negligible anti-predator behavior. however, over the past few decades introduced feral cats and dogs started to prey on iguanas on some of the islands. we investigated experimentally whether behavioral and endocrine anti-predator responses changed in response to predator introduction. we hypothesized that flight initiatio ... | 2007 | 17904141 |
| tameness and stress physiology in a predator-naive island species confronted with novel predation threat. | tame behaviour, i.e. low wariness, in terrestrial island species is often attributed to low predation pressure. however, we know little about its physiological control and its flexibility in the face of predator introductions. marine iguanas (amblyrhynchus cristatus) on the galapagos islands are a good model to study the physiological correlates of low wariness. they have lived virtually without predation for 5-15 myr until some populations were first confronted with feral cats and dogs some 150 ... | 2007 | 17476779 |
| diurnal and nocturnal differences in hypothalamic-pituitary-adrenal axis function in galápagos marine iguanas. | temporal modulation of the stress response is a ubiquitous characteristic of animals. here, we investigate possible mechanisms underlying daily changes in corticosterone release in an ectotherm model system. earlier work indicated that free-living galápagos marine iguanas (amblyrhynchus cristatus) have lower corticosterone concentrations during the night than during the day. this could result from: (i) a lower circadian secretion of adrenocorticotropic hormone (acth) as seen in mammals; (ii) fro ... | 2006 | 16263124 |
| biochemical and microbiological evidence for fermentative digestion in free-living land iguanas (conolophus pallidus) and marine iguanas (amblyrhynchus cristatus) on the galápagos archipelago. | herbivorous lizards are potentially capable of high digestive efficiency, but the presence of an indigenous microbial population has been implied from measurements of activity rather than directly studied. this study is the first to provide direct biochemical and microbiological evidence for fermentative digestion in free-living land iguanas (conolophus pallidus) and marine iguanas (amblyrhynchus cristatus) from the galapagos archipelago. in marine iguanas, the stomach and large capacious colon ... | 2004 | 15057723 |
| effect of tidal cycle and food intake on the baseline plasma corticosterone rhythm in intertidally foraging marine iguanas. | in most species, plasma levels of baseline glucocorticoids such as corticosterone (b) have a circadian rhythm. this rhythm can be entrained by both photoperiod and food intake and is related to aspects of energy intake and metabolism. marine iguanas (amblyrhynchus cristatus) offer a unique opportunity to better understand the relative importance of the light:dark cycle versus food intake in influencing the rhythm in baseline b in a natural system. compared to other species, food intake is not as ... | 2003 | 12812768 |
| the relationship between heart rate and rate of oxygen consumption in galapagos marine iguanas (amblyrhynchus cristatus) at two different temperatures. | to enable the use of heart rate (fh) for estimating field metabolic rate (fmr) in free-ranging galapagos marine iguanas amblyrhynchus cristatus, we determined the relationships between fh and mass-specific rate of oxygen consumption (svo2) in seven iguanas before and during exercise on a treadmill and during the post-exercise period. the experiments were conducted at 27 and 35 degrees c, which are the temperatures that represent the lowest and highest average body temperatures of these animals i ... | 2002 | 12077168 |
| a survey of the coccidian parasites of reptiles from islands of the galápagos archipelago: 1990-1994. | from 1990 through 1994, fecal samples were collected and examined for coccidian parasites from 26 giant land tortoises geochelone nigra, from 715 lava lizards tropidurus spp., from 139 land iguanas conolophus subcristatus, and from 128 marine iguanas amblyrhynchus cristatus, all of which inhabit various islands in the galápagos archipelago. none of the samples from a. cristatus or from c. subcristatus was infected with coccidia. only 1 of 26 (4%) g. nigra was infected with a single eimeria speci ... | 1996 | 8636848 |
| investigation of deaths in marine iguanas (amblyrhynchus cristatus) on galapagos. | large numbers of marine iguanas (amblyrhynchus cristatus bell) died on the galapagos between december 1982 and august 1983. gross and histopathological examination of five of these animals and comparison with three 1984 individuals indicated that the former had died of starvation. this was attributed to an inability to digest new species of algae which had flourished in the sea because of a rise in temperature associated with the el niño-southern oscillation event in 1982 to 83. in 1984 to 85, a ... | 1987 | 3597845 |
| comparative immunology of galapagos iguana hemoglobins. | the antigenic properties of the major hemoglobin component of the galapgaos iguanas were studied using second-approximation qualitative and quantitative immunochemical techniques. phylogenetic distances, relative to the galapagos marine iguana. amblyrhynchus cristatus, were established on the basis of immunological cross-reactions. | 1975 | 1182032 |
| genetic differentiation between marine iguanas from different breeding sites on the island of santa fe (galapagos archipelago). | we studied patterns of genetic diversity within and among 5 populations (318 individuals) of galápagos marine iguanas (amblyrhynchus cristatus) from the island santa fé. populations were separated by distances of 0.2 to 9.9 km. we sequenced 1182 base pairs of the mitochondrial control region and screened 13 microsatellite loci for variability. we also added data from 5 populations (397 individuals) sampled on 4 neighboring islands (santa cruz, floreana, espanola, and san cristobal). the 5 santa ... | 2010 | 20538757 |
| stress responsiveness predicts individual variation in mate selectivity. | steroid hormones, including glucocorticoids, mediate a variety of behavioral and physiological processes. circulating hormone concentrations vary substantially within populations, and although hormone titers predict reproductive success in several species, little is known about how individual variation in circulating hormone concentrations is linked with most reproductive behaviors in free-living organisms. mate choice is an important and often costly component of reproduction that also varies s ... | 2013 | 23524274 |
| alfred russel wallace and the destruction of island life: the iguana tragedy. | the galápagos islands (ecuador) are usually associated with the explorations and theoretical deductions of charles robert darwin (1809-1882), but alfred russel wallace (1823-1913) also investigated these islands and published several reports on the living world of this unique archipelago. in contrast to darwin, wallace described the destruction of natural ecosystems by humans and foresaw the resulting extinction of species. here, we outline two case studies pertinent to wallace's prediction. fir ... | 2013 | 23975644 |
| metagenomic-based study of the phylogenetic and functional gene diversity in galápagos land and marine iguanas. | in this study, a metagenome-based analysis of the fecal samples from the macrophytic algae-consuming marine iguana (mi; amblyrhynchus cristatus) and terrestrial biomass-consuming land iguanas (li; conolophus spp.) was conducted. phylogenetic affiliations of the fecal microbiome were more similar between both iguanas than to other mammalian herbivorous hosts. however, functional gene diversities in both mi and li iguana hosts differed in relation to the diet, where the mi fecal microbiota had a f ... | 2015 | 25524569 |
| blood gases, biochemistry and haematology of galápagos marine iguanas (amblyrhynchus cristatus). | the marine iguana, amblyrhynchus cristatus, is an iconic lizard endemic to the galápagos islands of ecuador, but surprisingly little information exists on baseline health parameters for this species. we analysed blood samples drawn from 35 marine iguanas captured at three locations on san cristóbal island. a portable blood analyser (istat) was used to obtain near-immediate field results for ph, lactate, partial pressure of o2, partial pressure of co2, bicarbonate (hco3 (-)), percentage o2 satura ... | 2015 | 27293719 |
| hybridization masks speciation in the evolutionary history of the galápagos marine iguana. | the effects of the direct interaction between hybridization and speciation-two major contrasting evolutionary processes--are poorly understood. we present here the evolutionary history of the galápagos marine iguana (amblyrhynchus cristatus) and reveal a case of incipient within--island speciation, which is paralleled by between-island hybridization. in-depth genome-wide analyses suggest that amblyrhynchus diverged from its sister group, the galápagos land iguanas, around 4.5 million years ago ( ... | 2015 | 26041359 |
| the complete mitochondrial genomes of the galápagos iguanas, amblyrhynchus cristatus and conolophus subcristatus. | the galápagos iguanas are among the oldest vertebrate lineages on the galápagos archipelago, and the evolutionary history of this clade is of great interest to biologists. we describe here the complete mitochondrial genomes of the marine iguana, amblyrhynchus cristatus (genbank accession number: kt277937) and the land iguana conolophus subcristatus (genbank accession number: kt277936). the genomes contain 13 protein-coding genes, 22 transfer rnas, and two ribosomal rnas genes, as well as a contr ... | 2016 | 26357924 |
| ecological and evolutionary influences on body size and shape in the galápagos marine iguana (amblyrhynchus cristatus). | oceanic islands are often inhabited by endemic species that have undergone substantial morphological evolutionary change due to processes of multiple colonizations from various source populations, dispersal, and local adaptation. galápagos marine iguanas are an example of an island endemic exhibiting high morphological diversity, including substantial body size variation among populations and sexes, but the causes and magnitude of this variation are not well understood. we obtained morphological ... | 2016 | 27041683 |
| endocrine-reproductive-immune interactions in female and male galápagos marine iguanas. | endocrine-immune interactions are variable across species and contexts making it difficult to discern consistent patterns. there is a paucity of data in non-model systems making these relationships even more nebulous, particularly in reptiles. in the present study, we have completed a more comprehensive test of the relationship among steroid hormones and ecologically relevant immune measures. we tested the relationship between baseline and stress-induced levels of sex and adrenal steroid hormone ... | 2017 | 27818221 |
| carriage of antibiotic-resistant enteric bacteria varies among sites in galapagos reptiles. | increased overlap between humans and wildlife populations has increased the risk for novel disease emergence. detecting contacts with a high risk for transmission of pathogens requires the identification of dependable measures of microbial exchange. we evaluated antibiotic resistance as a molecular marker for the intensity of human-wildlife microbial connectivity in the galápagos islands. we isolated escherichia coli and salmonella enterica from the feces of land iguanas (conolophus sp.), marine ... | 2012 | 22247374 |
| stress physiology as a predictor of survival in galapagos marine iguanas. | although glucocorticoid hormones are considered important physiological regulators for surviving adverse environmental stimuli (stressors), evidence for such a role is sparse and usually extrapolated from glucocorticoid effects under laboratory, short-term and/or non-emergency conditions. galápagos marine iguanas (amblyrhynchus cristatus) provide an excellent model for determining the ultimate function of a glucocorticoid response because susceptibility to starvation induced by el niño condition ... | 2010 | 20504812 |
| characterization and evolution of mhc class ii b genes in galápagos marine iguanas (amblyrhynchus cristatus). | major histocompatibility complex (mhc) class ii molecules play a key role in the adaptive immune system of vertebrates. class ii b genes appear to evolve in a very different manner in mammals and birds. orthology is commonly observed among mammal loci, while genes tend to cluster phylogenetically within bird species. here we present class ii b data from a representative of another major group of amniotes, the squamates (i.e. lizards, snakes, amphisbaenians), with the ultimate goal of placing mam ... | 2009 | 19454336 |
| characterization of a nonclassical class i mhc gene in a reptile, the galápagos marine iguana (amblyrhynchus cristatus). | squamates are a diverse order of vertebrates, representing more than 7,000 species. yet, descriptions of full-length major histocompatibility complex (mhc) genes in this group are nearly absent from the literature, while the number of mhc studies continues to rise in other vertebrate taxa. the lack of basic information about mhc organization in squamates inhibits investigation into the relationship between mhc polymorphism and disease, and leaves a large taxonomic gap in our understanding of amn ... | 2008 | 18682845 |
| are hotshots always hot? a longitudinal study of hormones, behavior, and reproductive success in male marine iguanas. | polygynous lek-mating systems are characterized by high reproductive skew, with a small number of males gaining a disproportionate share of copulations. in lekking species, where female choice drives male mating success and patterns of reproductive skew, female preferences for 'good genes' should lead to preferred males having high reproductive success in all years. here we investigate whether these 'hotshot' males have steroid hormone patterns that are consistent over time (between two mating s ... | 2008 | 18571171 |
| species-specific evolution of class i mhc genes in iguanas (order: squamata; subfamily: iguaninae). | over the last few decades, the major histocompatibility complex (mhc) has emerged as a model for understanding the influence of natural selection on genetic diversity in populations as well as for investigating the genetic basis of host resistance to pathogens. however, many vertebrate taxa remain underrepresented in the field of mhc research, preventing its application to studies of disease, evolution, and conservation genetics in these groups. this is particularly true for squamates, which are ... | 2008 | 18488213 |
| heterospecific alarm call recognition in a non-vocal reptile. | the ability to recognize and respond to the alarm calls of heterospecifics has previously been described only in species with vocal communication. here we provide evidence that a non-vocal reptile, the galápagos marine iguana (amblyrhynchus cristatus), can eavesdrop on the alarm call of the galápagos mockingbird (nesomimus parvulus) and respond with anti-predator behaviour. eavesdropping on complex heterospecific communications demonstrates a remarkable degree of auditory discrimination in a non ... | 2007 | 17911047 |
| high costs of female choice in a lekking lizard. | although the cost of mate choice is an essential component of the evolution and maintenance of sexual selection, the energetic cost of female choice has not previously been assessed directly. here we report that females can incur high energetic costs as a result of discriminating among potential mates. we used heart rate biologging to quantify energetic expenditure in lek-mating female galápagos marine iguanas (amblyrhynchus cristatus). receptive females spent 78.9+/-23.2 kj of energy on mate ch ... | 2007 | 17593966 |
| steroid hormones and aggression in female galápagos marine iguanas. | we studied steroid hormone patterns and aggression during breeding in female galápagos marine iguanas (amblyrhynchus cristatus). females display vigorously towards courting males after copulating (female-male aggression), as well as fight for and defend nest sites against other females (female-female aggression). to understand the neuroendocrine basis of this aggressive behavior, we examined changes in testosterone (t), estradiol (e2), corticosterone (cort), and progesterone (p4) during the mati ... | 2005 | 15916763 |
| corticosterone suppresses immune activity in territorial galápagos marine iguanas during reproduction. | individuals that display elaborate sexually selected characters often show reduced immune function. according to the immunocompetence handicap hypothesis, testosterone (t) is responsible for this result as it drives the development and maintenance of sexual characters and causes immunosuppression. but glucocorticoids also have strong influences on immune function and may also be elevated in reproductively active males. here, we compared immune activity using the phytohemagglutinin (pha) skin tes ... | 2005 | 15777807 |
| morphological correlates of locomotor performance in hatchling amblyrhynchus cristatus. | previous studies of locomotor performance from a variety of perspectives often assumed that speed and limb length were strongly correlated. despite support of this assumption from biomechanical models, few empirical studies have demonstrated a significant relationship between measures of locomotor capacity, such as maximum velocity, and length of the hindlimb at either the inter- or intra-specific level. we examined whether one measure of locomotor performance, maximum velocity, correlates with ... | 1995 | 28306782 |
| temporal pattern of foraging and microhabitat use by galápagos marine iguanas, amblyrhynchus cristatus. | we observed a colony of marine iguanas (amblyrhynchus cristatus) on isla fernandina, galápagos, ecuador, while measuring local micrometeorological and tidal conditions. we found size-related differences in foraging mode, with smaller iguanas feeding intertidally during daytime low tides and larger iguanas feeding subtidally. despite having greater opportunity, subtidal foragers did not time their foraging bouts or exploit their environment in ways that optimized their period at high body tempera ... | 1993 | 28313754 |
| ontogenetic changes in food intake and digestion rate of the herbivorous marine iguana (amblyrhynchus cristatus, bell). | young reptiles have higher relative energy demands than adults, but the proposed ontogenetic changes in diet to fulfil these demands were not found in the algae-eating galápagos marine iguanas on santa fé. feeding and digestion rates were investigated to analyse how young achieve higher energy intake. daily food intake of free ranging marine iguana hatchlings (6-11 months old) was about one third that of adults, but relative intake (g dry mass · g(-1) wet mass · day(-1)) was four times higher in ... | 1993 | 28313674 |
| metabolic recovery from exhaustive activity by a large lizard. | gas exchange (vo2 and vco2) and blood lactate concentration were measured in the lizard amblyrhynchus cristatus at 25 and 35 degrees c during resting, running, and recovery after exhaustion (less than or equal to 180 min) to analyze the temperature dependency of metabolic recovery in this lizard. amblyrhynchus exhausted twice as fast (4.2 vs. 8.8 min) at 25 degrees c than when running at the same speed at 35 degrees c. at both temperatures, vo2 and vco2 increased rapidly during activity and decl ... | 1980 | 6769884 |
| the effects of temperature on acid-base balance and ventilation of the marine iguana. | marine iguanas, amblyrhynchus cristatus, held for 12-18 h at 16, 24 and 35 degrees c exhibited an arterial ph change of -0.001 delta ph/delta degree c. the arterial ph changed by -0.004 delta ph/delta degree c between 16 and 24 degrees c and by -0.015 delta ph/delta degree c between 24 and 35 degrees c. when the animals were allowed to cool to 16 degrees c and remarm to 35 degrees c after 12-18 h at 35 degrees c, the ph change was -0.015 delta ph/delta degree c. arterial ph measured during warmi ... | 1980 | 6769140 |
| methods of body temperature assessment in conolophus subcristatus, conolophus pallidus (galápagos land iguanas), and amblyrhynchus cristatus x c. subcristatus hybrid. | since cardiovascular, respiratory, and metabolic systems of reptiles are affected by temperature, accurate measurements are of great importance in both captive husbandry and research. ectothermic animals generally have core body temperatures close to ambient temperature but can differ from the immediate environment if they are using sunlight to thermoregulate. many zoological facilities and exotic pet caregivers have begun using infrared temperature guns to assess ambient temperatures of reptile ... | 2019 | 30740271 |
| diversity of compounds in femoral secretions of galápagos iguanas (genera: amblyrhynchus and conolophus), and their potential role in sexual communication in lek-mating marine iguanas (amblyrhynchus cristatus). | chemical signals are widely used in the animal kingdom, enabling communication in various social contexts, including mate selection and the establishment of dominance. femoral glands, which produce and release waxy secretions into the environment, are organs of central importance in lizard chemical communication. the galápagos marine iguana (amblyrhynchus cristatus) is a squamate reptile with a lek-mating system. although the lekking behaviour of marine iguanas has been well-studied, their poten ... | 2017 | 28828277 |
| health assessment of conolophus subcristatus, conolophus pallidus, and c. subcristatus x amblyrhynchus cristatus hybrid (galápagos land iguanas). | the land iguanas, conolophus pallidus and conolophus subcristatu are large and charismatic lizards endemic to the galápagos archipelago, but little information exists on their normal health parameters. the former is restricted to santa fe island, while c. subcristatus inhabits the islands of the central and western region of the archipelago. both species are classified as vulnerable by the iucn red list of threatened species. as part of a population health assessment authorized by the galápagos ... | 2019 | 31618199 |
| uneven frequency of vibrio alginolyticus-group isolates among different populations of galápagos marine iguana (amblyrhynchus cristatus). | the presence of vibrio isolates was investigated in cloacal swabs from the galápagos marine iguana (amblyrhyncus cristatus). such unique iguana is endemic to the galápagos archipelago, it is listed as vulnerable in the iucn red list (2009), and is strictly protected by cites and ecuador laws. our results revealed an uneven isolation frequency of vibrios from animals living in different settings: maximal among the santa fe population, scarce at bahía tortuga but practically absent in the samples ... | 2010 | 23766014 |
| body size and sexual size dimorphism in marine iguanas fluctuate as a result of opposing natural and sexual selection: an island comparison. | body size is often assumed to represent the outcome of conflicting selection pressures of natural and sexual selection. marine iguana (amblyrhynchus cristatus) populations in the galápagos exhibit 10-fold differences in body mass between island populations. there is also strong sexual size dimorphism, with males being about twice as heavy as females. to understand the evolutionary processes shaping body size in marine iguanas, we analyzed the selection differentials on body size in two island po ... | 1997 | 28568579 |
| a reappraisal of the aquatic specializations of the galapagos marine iguana (amblyrhynchus cristatus). | | 1977 | 28563712 |