RESUMO
Variations in hematological profile in reptiles can be caused by multiple factors, including parasites presence. Our goals were to identify and morphologically describe blood cells of Liolaemus pacha and analyze their relationship with sex, body condition, individual reproductive/post-reproductive period and mite infestation. Blood smear analyses do not indicate the presence of hemoparasites, suggesting that the mites Neopterygosoma do not serve as vectors for these organisms, as has been proposed for other genera of ectoparasitic mites. In post-reproductive period, there was a reduction in specimens' body condition and a higher leukocyte count in uninfected lizards. This could be a consequence of the testosterone effects, in higher concentration during the reproductive season, which can increase the metabolic rate, decreasing feeding rate. Infested and non-infested lizards showed no differences in body condition, as well as in leukocyte count, hence the host's immune system could be developing infestation tolerance. Infested specimens had a higher count of monocytes, thrombocytes, heterophils and lymphocytes. Based on cells function, mites' effect could be associated with inflammatory processes, allergic reactions or infectious diseases. These results suggested a complex interaction between lizards' hematological parameters and factors associated to ectoparasites or body conditions. We consider this work as a diagnostic tool for genus Liolaemus, to evaluate health quality, with relevance to the conservation or management of this lizard's genus.
Assuntos
Infestações por Ácaros , Reprodução , Animais , Infestações por Ácaros/veterinária , Infestações por Ácaros/parasitologia , Masculino , Feminino , Reprodução/fisiologia , Estações do Ano , Iguanas/fisiologia , Iguanas/parasitologia , Iguanas/sangue , Ácaros/fisiologia , Ácaros/classificação , Lagartos/parasitologia , Lagartos/sangue , Lagartos/fisiologiaRESUMO
Carnivorous reptiles exhibit an intense metabolic increment during digestion, which is accompanied by several cardiovascular adjustments responsible for meeting the physiological demands of the gastrointestinal system. Postprandial tachycardia, a well-documented phenomenon in these animals, is mediated by the withdrawal of vagal tone associated with the chronotropic effects of non-adrenergic and non-cholinergic (NANC) factors. However, herbivorous reptiles exhibit a modest metabolic increment during digestion and there is no information about postprandial cardiovascular adjustments. Considering the significant impact of feeding characteristics on physiological responses, we investigated cardiovascular and metabolic responses, as well as the neurohumoral mechanisms of cardiac control, in the herbivorous lizard Iguana iguana during digestion. We measured oxygen consumption rate (O2), heart rate (fH), mean arterial blood pressure (MAP), myocardial activity, cardiac autonomic tone, fH/MAP variability and baroreflex efficiency in both fasting and digesting animals before and after parasympathetic blockade with atropine followed by double autonomic blockade with atropine and propranolol. Our results revealed that the peak of O2 in iguanas was reached 24â h after feeding, accompanied by an increase in myocardial activity and a subtle tachycardia mediated exclusively by a reduction in cardiac parasympathetic activity. This represents the first reported case of postprandial tachycardia in digesting reptiles without the involvement of NANC factors. Furthermore, this withdrawal of vagal stimulation during digestion may reduce the regulatory range for short-term fH adjustments, subsequently intensifying the blood pressure variability as a consequence of limiting baroreflex efficiency.
Assuntos
Iguanas , Lagartos , Animais , Atropina/farmacologia , Pressão Sanguínea , Digestão/fisiologia , Frequência Cardíaca/fisiologia , Iguanas/fisiologia , Lagartos/fisiologia , Miocárdio , TaquicardiaRESUMO
Large body mass (Mb) in vertebrates is associated with longer pulse intervals between heartbeats (PI) and thicker arterial walls. Longer PI increases the time for diastolic pressure decay, possibly resulting in loss of cardiac energy as "oscillatory power," whereas thicker arterial walls may affect the transmission of impulses and sensing of pressure fluctuations thus impairing baroreflex function. We aimed to investigate the effect of growth on the relative cardiac energy loss and baroreflex function. We predicted that 1) the relative use of cardiac energy should be preserved with increased time constant for pressure decay (τ = vascular resistance × compliance) and 2) if arterial circumferential distensibility does not change, baroreflex function should be unaltered with Mb. To test these hypotheses, we used green iguanas (Iguana iguana) weighing from 0.03 to 1.34 kg (43-fold increment in Mb). PI (P = 0.037) and τ (P = 0.035) increased with Mb, whereas the oscillatory power fraction (P = 0.245) was unrelated to it. Thus, the concomitant alterations of τ and PI allowed the conservation of cardiac energy in larger lizards. Larger animals had thicker arterial walls (P = 0.0007) and greater relative collagen content (P = 0.022). Area compliance scaled positively to Mb (P = 0.045), though circumferential distensibility (P = 0.155) and elastic modulus (P = 0.762) were unaltered. In addition, baroreflex sensitivity, measured by both the pharmacological (P = 0.152) and sequence methods (P = 0.088), and the baroreflex effectiveness index (P = 0.306) were also unrelated to Mb. Therefore, changes in arterial morphology did not affect circumferential distensibility and presumably sensing of pressure fluctuation, and the cardiovagal baroreflex is preserved across different Mb.
Assuntos
Barorreflexo , Iguanas , Animais , Barorreflexo/fisiologia , Iguanas/anatomia & histologia , Iguanas/fisiologia , Frequência Cardíaca , Pressão Sanguínea/fisiologia , CoraçãoRESUMO
The pink land iguana, Conolophus marthae, is one of four species of iguanas (three terrestrial and one marine) in the Galápagos Islands, and the only one listed as critically endangered by the IUCN. The species can only be found on the north-west slopes of the highest volcano on Isabela Island and was first described to science in 2009. As part of a population telemetry study, a health assessment was authorized by the Galápagos National Park. Wild adult iguanas were captured on Wolf Volcano in September 2019 and April 2021 to record morphological and physiological parameters including body temperature, heart rate, intraocular pressures, tear formation, and infrared iris images. Blood samples were also collected and analyzed. An i-STAT portable blood analyzer was used to obtain values for base excess in the extracellular fluid compartment (BEecf), glucose (Glu), hematocrit (HctPCV), hemoglobin (Hb), ionized calcium (iCa), partial pressure of carbon dioxide (pCO2), partial pressure of oxygen (pO2), percent oxygen saturation (sO2%), pH, potassium (K), and sodium (Na). When possible, data were compared to previously published and available data for the other Galápagos iguanas. The results reported here provide baseline values that will be useful in detecting changes in health status among pink land iguanas affected by climate change, invasive species, anthropogenic threats, or natural disturbances. The collected data also provide an invaluable resource for conservation scientists planning to implement conservation strategies, like translocations, that may temporarily alter these baseline values.
Assuntos
Iguanas , Animais , Equador , Iguanas/fisiologiaRESUMO
Lizard species have diverse behavioral and physiological responses to thermo-environmental conditions, which allow them to inhabit a broad range of latitudes and elevations. Because the availability of suitable thermal resources is limited and more variable at high-elevation environments than at lower elevations, we expect high-elevation lizards to be constrained in their thermoregulation relative to lizards at lower elevations by the fewer available thermal resources to reach optimal temperatures (colder environment). We studied the thermal biology of an endemic and Critically Endangered lizard, Liolaemus aparicioi, to assess its thermal responses along a 1000 m elevational gradient in La Paz Valley from May to August of 2015 (dry season). We took field body and microhabitat temperatures at capture sites (substrate and air above ground), and body size (snout-vent length and mass) of individuals at Taypichullo (3000 m asl), Gran Jardín de la Revolución Municipal Park (3500 m asl), and Taucachi (4000 m asl) localities. Operative temperatures were taken from calibrated models deployed in different available microhabitats. Preferred temperatures and thermal tolerance limits were determined in laboratory settings for lizards from each locality. Field body, microhabitat, and operative temperatures decreased with increasing elevation and differed between sexes. Lizards at the high elevation locality had the lowest thermoregulatory efficiency as compared with the mid and lower elevation localities. In laboratory measurements, while the preferred temperatures varied between sexes, pooled preferred temperatures and thermal tolerances were similar in all localities. Although thermal resources at high elevation can limit thermoregulatory possibilities in L. aparicioi, behavioral microhabitat use, time allocated to thermoregulation, and physiological adjustments seem to be possible strategies to counteract thermal costs along elevational gradients.
Assuntos
Altitude , Regulação da Temperatura Corporal , Iguanas/fisiologia , Termotolerância , Animais , Bolívia , Feminino , MasculinoRESUMO
Light/dark cycle affects the physiology of vertebrates and hypothalamic orexin neurons (ORX) are involved in this function. The breathing pattern of the green iguana changes from continuous to episodic across the light/dark phases. Since the stimulatory actions of ORX on breathing are most important during arousal, we hypothesized that ORX regulates changes of breathing pattern in iguanas. Thus, we: (1) Localized ORX neurons with immunohistochemistry; (2) Quantified cyclic changes in plasma orexin-A levels by ELISA; (3) Compared breathing pattern at rest and during hypoxia and hypercarbia; (4) Evaluated the participation of the ORX receptors in ventilation with intracerebroventricular microinjections of ORX antagonists during light and dark phases. We show that the ORX neurons of I. iguana are located in the periventricular hypothalamic nucleus. Orexin-A peaks during the light/active phase and breathing parallels these cyclic changes: ventilation is higher during the light phase than during the dark phase. However, inactivation of ORX-receptors does not affect the breathing pattern. Iguanas increase ventilation during hypoxia only during the light phase. Conversely, CO2 promotes post-hypercarbic hyperpnea during both phases. We conclude that ORXs potentiate the post-hypercarbic (but not the hypoxic)-drive to breathe and are not involved in light/dark changes in the breathing pattern.
Assuntos
Iguanas/fisiologia , Orexinas/genética , Fotoperíodo , Respiração/genética , Animais , Iguanas/sangue , Iguanas/genética , Neurônios/metabolismo , Neurônios/fisiologia , Neuropeptídeos/sangue , Receptores de Orexina , Orexinas/sangueRESUMO
Background: The Green iguana (Iguana iguana) is a reptile belonging to the Iguanidae family. It is an ectothermic animalwith arboreal habits and a daytime activity pattern. Leaves, fruits, and eggs are part of their diet. These animals can be foundin the South, North and Central America. Free-living Green iguanas may suffer stress during environmental changes, whichcan lead to a homeostatic imbalance. There is a correlation between stress and anorexia which results in an increase in theoccurrence of fractures. Reptile fractures are generally treated by providing rigid stabilization and alignment maintenance.The present study reports the use of locking-plate osteosynthesis in one iguana.Case: One female green iguana, weighing 1.690 kg, was assisted at the Hospital Veterinário (Hovet) - Federal da Universidade Federal de Mato Grosso (UFMT). During anamnesis, it was observed that this iguana was a non-captive animal,which had fallen from a tree. The animal was unable to perform physical movements with the forearm displaying bonecrepitation. It was also observed apathy and dehydration. The iguana was subjected to a range of supplementary examinations and on the x-ray image, it was detected that there was a complete right humerus fracture. Following examination,the animal underwent surgery for fracture stabilization. Humerus osteosynthesis was performed with compression in a 1.5mm 6-hole locking-plate. During the osteosynthesis procedure a morphogenetic graft was inserted. Immediate post-surgeryradiographic evaluation was performed, and that confirmed fracture reduction and bone alignment. The animal displayedclinical improvement after the second post-operative day once it returned to regular ingestion of diet. On the 30th postoperative day, the radiographic evaluation showed evidence of bone consolidation. On the 40th post-operative day, theanimal displayed satisfactory gait and voluntary ingestion of food, thus enabling its return to...(AU)
Assuntos
Animais , Feminino , Iguanas/fisiologia , Fixação Interna de Fraturas/veterinária , Fraturas do Úmero/cirurgia , Fraturas do Úmero/veterinária , Placas Ósseas/veterinária , Proteína Morfogenética Óssea 1RESUMO
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 National Park, wild adult iguanas from three islands (North Seymour, South Plazas, and Santa Fe) were captured in July 2018. Data from a single C. subcristatus X Amblyrhynchus cristatus hybrid captured on South Plazas is also included. We analyzed blood samples drawn from 52 healthy wild adult land iguanas captured on three islands. An iSTAT portable blood analyzer was used to obtain values for pH, lactate, pO2, pCO2, HCO3-, sO2%, hematocrit, packed cell volume (PCV), hemoglobin Na, K, iCa, and glucose. Standard laboratory hematology techniques were employed for PCV determination; resulting values were also compared to the hematocrit values generated by the iSTAT. Body temperature, heart rate, respiratory rate, and body measurements were also recorded and compared to previously published data for the marine iguana (Amblyrhynchus cristatus), which shares a common ancestor with the land iguana. The data reported here provide preliminary baseline values that may be useful in comparisons between captive and wild populations, between wild populations, and in detecting changes in health status among Galápagos land iguanas affected by anthropogenic threats, climate change, or natural disturbances.
Assuntos
Iguanas/fisiologia , Animais , Temperatura Corporal/fisiologia , Pesos e Medidas Corporais , Equador , Feminino , Frequência Cardíaca/fisiologia , Masculino , Taxa Respiratória/fisiologiaRESUMO
The sequence method is an alternative to the traditional pharmacological approach (i.e., the Oxford technique) used to calculate baroreflex gain (G) in mammals. Although the sequence method assesses baroreflex by measuring spontaneous events of blood pressure regulation, the pharmacological method relies on the injection of vasoactive drugs that impact the baroreflex mechanism itself. The sequence method might be relevant for dynamic measurement of baroreflex modulation but it was never validated for vertebrates with low heart rate. Hence, we tested the sequence method in three species of reptiles and compared the results with those provided by the classic pharmacological method. G was similar between both methods and values correlated when parameters for the sequence method were set at delay 0 or 1 (i.e., the baroreflex system responds immediately to blood pressure changes or after 1 heartbeat). Calculation of the baroreflex effectiveness index was adequate at a minimum of 300 cycles and a delay of 1 for the three species. Therefore, the sequence method has been validated to investigate baroreflex regulation in reptiles, enabling studies during dynamic alterations in homeostasis.
Assuntos
Barorreflexo/fisiologia , Pressão Sanguínea/fisiologia , Frequência Cardíaca/fisiologia , Animais , Pressão Sanguínea/efeitos dos fármacos , Crotalus/fisiologia , Iguanas/fisiologia , Lagartos/fisiologia , Nitroprussiato/farmacologia , Fenilefrina/farmacologia , Reprodutibilidade dos Testes , Vasoconstritores/farmacologia , Vasodilatadores/farmacologiaRESUMO
Background: The Green iguana (Iguana iguana) is a reptile belonging to the Iguanidae family. It is an ectothermic animalwith arboreal habits and a daytime activity pattern. Leaves, fruits, and eggs are part of their diet. These animals can be foundin the South, North and Central America. Free-living Green iguanas may suffer stress during environmental changes, whichcan lead to a homeostatic imbalance. There is a correlation between stress and anorexia which results in an increase in theoccurrence of fractures. Reptile fractures are generally treated by providing rigid stabilization and alignment maintenance.The present study reports the use of locking-plate osteosynthesis in one iguana.Case: One female green iguana, weighing 1.690 kg, was assisted at the Hospital Veterinário (Hovet) - Federal da Universidade Federal de Mato Grosso (UFMT). During anamnesis, it was observed that this iguana was a non-captive animal,which had fallen from a tree. The animal was unable to perform physical movements with the forearm displaying bonecrepitation. It was also observed apathy and dehydration. The iguana was subjected to a range of supplementary examinations and on the x-ray image, it was detected that there was a complete right humerus fracture. Following examination,the animal underwent surgery for fracture stabilization. Humerus osteosynthesis was performed with compression in a 1.5mm 6-hole locking-plate. During the osteosynthesis procedure a morphogenetic graft was inserted. Immediate post-surgeryradiographic evaluation was performed, and that confirmed fracture reduction and bone alignment. The animal displayedclinical improvement after the second post-operative day once it returned to regular ingestion of diet. On the 30th postoperative day, the radiographic evaluation showed evidence of bone consolidation. On the 40th post-operative day, theanimal displayed satisfactory gait and voluntary ingestion of food, thus enabling its return to...
Assuntos
Feminino , Animais , Fixação Interna de Fraturas/veterinária , Fraturas do Úmero/cirurgia , Fraturas do Úmero/veterinária , Iguanas/fisiologia , Placas Ósseas/veterinária , Proteína Morfogenética Óssea 1Assuntos
Hemoglobinas/química , Hemoglobinas/metabolismo , Iguanas/fisiologia , Difosfato de Adenosina/metabolismo , Regulação Alostérica , Animais , Concentração de Íons de Hidrogênio , Iguanas/metabolismo , Modelos Moleculares , Oxigênio/metabolismo , Estrutura Secundária de Proteína , TemperaturaRESUMO
The extent to which evolution is deterministic (predictable), or random, is a fundamental question in evolution. This case study attempts to determine the extent to which interspecific divergence can be predicted from intraspecific trends related species. The mountainous Lesser Antilles are occupied by one or two anole species with very substantial intraspecific differences in the quantitative traits between xeric and rainforest habitats. These ecologically determined differences tend to be in parallel in each island species. A related species (Anolis bonairensis) lives on the far more xeric island of Bonaire, and this study tests the extent to which its interspecific divergence in hue and pattern traits can be predicted from the parallel intraspecific variation exhibited in Lesser Antillean anoles. Regression against a multivariate climate variable suggests that the hue and pattern of the Bonaire anole are consistently predicted from the ecologically determined intraspecific variation of its Lesser Antillean relatives. However, this predictability may be less consistent with other character systems, for example, scalation.
Assuntos
Evolução Biológica , Ambientes Extremos , Iguanas/genética , Animais , Clima , Iguanas/anatomia & histologia , Iguanas/fisiologia , Ilhas , Modelos Genéticos , Análise Multivariada , Filogenia , Análise de Regressão , Pigmentação da Pele/genética , Especificidade da EspécieRESUMO
The role of the most common land iguana (Conolophus subcristatus) in the Galápagos Islands as an effective seed disperser is explored in this study. A total of 5705 seeds of 32 plant species were identified from 160 scats, 4545 of which (80%) appeared visually undamaged. Germination trials of 849 seeds from 29 species revealed that at least 10 species remained viable after passing through the iguana's gut, although only a small proportion of those seeds (4%) germinated. In any case, we argue that C. subcristatus exerts an important role on the 7 Galapagos islands where it occurs because of its abundance and capacity to ingest and disperse seeds at long distances. Our results strongly suggest that the Galápagos C. subcristatus plays an important role as a seed disperser of not only of native species but also some introduced plants in the Galápagos Islands.
Assuntos
Germinação , Iguanas/fisiologia , Dispersão de Sementes , Sementes/fisiologia , Animais , Equador , FezesRESUMO
The autonomic control of heart rate was studied throughout development in embryos of the green iguana, Iguana iguana by applying receptor agonists and antagonists of the parasympathetic and sympathetic systems. Acetylcholine (Ach) slowed or stopped the heart and atropine antagonized the response to Ach indicating the presence of muscarinic cholinoceptors on the heart of early embryos. However, atropine injections had no impact on heart rate until immediately before hatching, when it increased heart rate by 15%. This cholinergic tonus increased to 34% in hatchlings and dropped to 24% in adult iguanas. Although epinephrine was without effect, injection of propranolol slowed the heart throughout development, indicating the presence of ß-adrenergic receptors on the heart of early embryos, possibly stimulated by high levels of circulating catecholamines. The calculated excitatory tonus varied between 33% and 68% until immediately before hatching when it fell to 25% and 29%, a level retained in hatchlings and adults. Hypoxia caused a bradycardia in early embryos that was unaffected by injection of atropine indicating that hypoxia has a direct effect upon the heart. In later embryos and hatchlings hypoxia caused a tachycardia that was unaffected by injection of atropine. Subsequent injection of propranolol reduced heart rate both uncovering a hypoxic bradycardia in late embryos and abolishing tachycardia in hatchlings. Hypercapnia was without effect on heart rate in late stage embryos and in hatchlings.
Assuntos
Embrião não Mamífero/fisiologia , Frequência Cardíaca/fisiologia , Coração/fisiologia , Iguanas/fisiologia , Acetilcolina/farmacologia , Adrenérgicos/farmacologia , Agonistas Adrenérgicos beta/farmacologia , Antagonistas Adrenérgicos beta/farmacologia , Animais , Atropina/farmacologia , Sistema Nervoso Autônomo/efeitos dos fármacos , Sistema Nervoso Autônomo/embriologia , Sistema Nervoso Autônomo/fisiologia , Colinérgicos/farmacologia , Agonistas Colinérgicos/farmacologia , Eletrocardiografia , Embrião não Mamífero/efeitos dos fármacos , Embrião não Mamífero/embriologia , Epinefrina/farmacologia , Coração/efeitos dos fármacos , Coração/embriologia , Frequência Cardíaca/efeitos dos fármacos , Iguanas/embriologia , Antagonistas Muscarínicos/farmacologia , Miocárdio/metabolismo , Propranolol/farmacologia , Receptores Adrenérgicos beta/metabolismo , Receptores Colinérgicos/metabolismoRESUMO
The persistence of reptile populations in a specific location is influenced by individuals' capacity to regulate their body temperatures, among other factors. Anthropogenic climate change may pose a risk to the survival of ectothermic animals due to their dependence on external heat sources to thermoregulate. In this study, we calculated indices of thermal habitat quality, thermoregulatory precision, and thermoregulatory effectiveness for the endemic spiny-tailed iguana Ctenosaura oaxacana. We evaluated these indices and the thermoregulatory behavior of the iguanas in the four types of vegetation that provide the most favorable conditions for thermoregulation. We also performed our experiments during both the wet and dry seasons to capture the full range of thermal conditions available to C. oaxacana over the course of a year. Finally, we evaluated the potential niche for the iguana in the years 2020, 2050, and 2080. Thermoregulation depends on both seasonal and environmental factors in this species. We found that thermoregulation effectiveness in both wet and dry seasons depends not only on the thermal conditions of the immediate environment, but also on the cover vegetation and habitat structure available across the range of habitats the species uses. Thus, heterogeneous habitats with dispersed vegetation may be most suitable for this species' thermoregulatory strategy. Likewise, niche modeling results suggested that suitable habitat for our study species may continue to be available for the next few decades, despite global warming tendencies, as long as cover vegetation remains unaltered. Our results suggest that thermoregulation is a complex process that cannot be generalized for all ectothermic species inhabiting a given region. We also found that temperature changes are not the only factor one must consider when estimating the risk of species loss. To understand the necessary thermal conditions and extinction risk for any ectothermic species, it is necessary to focus studies on the species' general ecology.
Assuntos
Comportamento Animal , Regulação da Temperatura Corporal/fisiologia , Aquecimento Global , Iguanas/fisiologia , Animais , Temperatura Corporal , Ecossistema , Feminino , Masculino , México , Modelos Teóricos , Plantas , Estações do Ano , TemperaturaRESUMO
We describe a new species of Stenocercus from the interandean valley of Río Chotano on the Amazonian slope of the northern portion of the Cordillera Occidental of Peru (Cajamarca Region), at elevations of between 1997 and 2318 m. Stenocercus arndti sp. nov. differs from other Stenocercus, except from S. bolivarensis, S. carrioni, S. chlorostictus, S. crassicaudatus, S. empetrus, S. eunetopsis, S. simonsii, and S. torquatus, in having granular scales on the posterior surface of the thighs, two caudal whorls per autotomic segment, mucronate caudal scales, and distinct longitudinal row of enlarged vertebral scales. However, Stenocercus arndti sp. nov. is easily distinguished from these species in having a bold black transversal band at midbody that extends ventrolaterally in adult males.
Assuntos
Iguanas/anatomia & histologia , Iguanas/classificação , Distribuição Animal , Animais , Feminino , Iguanas/fisiologia , Masculino , PeruRESUMO
Ecomorphological studies of lizards have explored the role of various morphological traits and how these may be associated with, among other things, habitat use. We present an analysis of selected traits of internal morphology of the hind limbs of Neotropical iguanian lizards and their relationship to habitat use. Considering that one of the most widely-held hypotheses relating to the origin of grasping is associated with the exploitation of the narrow-branch arboreal habitat, we include subdivisions of this designation as two of our ecologically defined categories of habitat exploitation for analysis, and compare lizards assigned to these categories to the features displayed by terrestrial lizards. The influence of phylogeny in shaping the morphology of lizards was assessed by using the comparative method. K values were significant for several osteological traits. Most of the K values for the variables based upon muscle and tendon morphometric characters (13 out 21), by contrast, had values <1, suggesting that their variation cannot be explained by phylogeny alone. Results of our phylogenetic and conventional ANCOVA analyses reveal that the characters highlighted through the application of the comparative method are not absolutely related to habitat in terms of the categories considered here. It appears that the bauplan of the lizard pes incorporates a morphological configuration that is sufficiently versatile to enable exploitation of almost all of the available habitats. As unexpected as conservation of internal gross morphology appears, it represents a means of accommodating to environmental challenges by apparently permitting adequacy for all situations examined.
Assuntos
Comportamento Animal , Hábitos , Membro Posterior/anatomia & histologia , Iguanas/anatomia & histologia , Atividade Motora , Adaptação Fisiológica , Análise de Variância , Animais , Evolução Biológica , Fenômenos Biomecânicos , Feminino , Membro Posterior/fisiologia , Iguanas/fisiologia , Masculino , Músculo Esquelético/anatomia & histologia , Músculo Esquelético/fisiologia , Filogenia , Tendões/anatomia & histologia , Tendões/fisiologiaRESUMO
Adaptations of lizards inhabiting hot arid environments should include mechanisms of behavioural thermoregulation. In contrast, in environments with lower temperatures lizards tend to behave as thermoconformers. Herein we aim to infer thermoregulatory behaviours exhibited by Liolaemus lutzae (a lizard species endemic to restingas in the coast of the state of Rio de Janeiro, Brazil) in two different seasonal thermal environments. In the dry season, the body temperatures (Tb) of the lizards were higher than air temperature (Ta) and similar to substrate temperature (Ts), suggesting thermoconformer thermoregulatory behaviour using Ts. During the rainy season, the higher percentage of negative values of ΔTs (=Tb-Ts) and ΔTa (=Tb-Ta) and the tendency for lower Tb compared to Ts suggest a more active behavioural thermoregulation in that season. The ΔTs was higher for juveniles in the rainy season, suggesting that youngest lizards tended to thermoregulate more actively regarding to Ts than adults. L. lutzae probably survives under high Ts due to the behaviour of the individuals sheltering inside burrows or under detritus and burying themselves into the sand. This behavioural flexibility may potentially reduce variations in Tb of active lizards in changing thermal environments both during the daily cycle and between seasons.
Assuntos
Adaptação Fisiológica/fisiologia , Comportamento Animal/fisiologia , Regulação da Temperatura Corporal/fisiologia , Iguanas/fisiologia , Estações do Ano , Animais , BrasilRESUMO
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. First, we summarize the behavior of the predator-naive marine iguanas (Amblyrhynchus cristatus) on the Galápagos Islands, which are threatened by feral dogs and cats imported by humans. We also describe the unique life cycle of the spiny-tailed iguana (Ctenosaura bakeri) from the island of Utila (Honduras), a rare species whose populations are declining because of habitat destructions. In contrast to these threatened, endemic island species, the Green iguana (Iguana iguana) is still widely distributed, although, as a result of de-forestation, in some areas of South America local populations have disappeared. We conclude that Wallace was correct in his prediction that, because of human activities, numerous species of animals and plants will be driven to extinction, notably on islands.
Assuntos
Evolução Biológica , Biologia/história , Ecossistema , Iguanas/fisiologia , Animais , Equador , Extinção Biológica , Feminino , História do Século XIX , Honduras , Atividades Humanas , Humanos , Espécies Introduzidas , Ilhas , Masculino , Comportamento PredatórioRESUMO
We describe a new species of Stenocercus from an interandean valley of the upper Río Huallaga on the Amazonian slope of central Peru (Región Huánuco), at an elevation of 1700-1900 m. The new species differs from other Stenocercus, except S. boettgeri, S. haenschi, S. humeralis, and S. varius, by the combination of the following characters: presence of granular scales on the posterior surface of the thighs, enlarged vertebrals, three caudal whorls per autotomic segment, a medially complete antegular fold, non-spinose caudals, and by males lacking a black transverse band on the ventral surface of the neck. However, the new Stenocercus differs from these, with the exception of S. humeralis, by having more scales around the midbody (104-107, =105.66) than S. boettgeri (79-104, Mean= 88.61), S. haenschi (57-64, Mean=60.50), and S. varius (74-88, Mean=82.35); and from S. humeralis by having the scales in the frontonasal region nearly equal in size to the scales in the occipitoparietal region, while in S. humeralis the scales on the frontonasal region are twice or three times longer than the scales on the occipitoparietal region.