Yacare Research Articles

First Report of Trypanosoma sp. in Spectacled Caiman (Caiman crocodilus): Morphological and Phylogenetic Relationships.

In Crocodylidae family three trypanosomes species were described, T. grayi in African crocodilian and T. cecili and Trypanosoma sp. in Caimans species from Brazil. T. grayi was transmitted by tsetse flies and the vector of Brazilian caimans trypanosomes is unknown. We characterized first Brazilian trypanosome isolated in spectacled caiman (Caiman crocodilus) from Mato Grosso State in Brazil. Morphological findings in epimastigotes forms from axenic culture showed high similarity with Trypanosoma sp. described in Caiman yacare from Brazilian Pantanal. Phylogenetic studies performed with SSU rDNA and gGAPDH (glyceraldehydes-3-phosphato dehydrogenase glycosomal) clustering in T. grayi Clade and together to genotype Cay 01 from Trypanosoma unnamed species isolated in C. yacare. This is the first isolate of Trypanosoma sp. from C. crocodilus and the phylogenetic position with isolates in C. yacare from Pantanal region and demonstrates the low host specificity of cayman trypanosomes in Brazil.

Yacare caiman (Caiman yacare ) trim hamburger and sausage subjected to different smoking techniques

Caiman, as well as having skin that, after tanning, produces leather of high added value, exceptional quality and good market value, also possesses a meat with a remarkably smooth taste and appearance. This study aimed to characterize hamburger and sausages made from Yacare caiman (Caiman yacare) meat trim. Hot smoked products contained less moisture than the unsmoked products. Protein and ash were higher, respectively, for hot smoked hamburger and sausage. Lipids had greater presence in hot smoked sausage (9.72%), whereas in the burgers they were higher in the liquid smoked burgers (6.71%). The hot smoked products had lower water activity. Hot smoked products displayed less luminance, but the a* and b* chroma were higher in smoked hamburgers. Taste, texture and general acceptability were significant for the hamburger, whereas for the sausage there was a significant effect for texture, salt and purchase intent. For all the products, the hot smoking resulted in the lowest acceptability.

Hambúrgueres de aparas de jacaré-do-pantanal (Caiman yacare) submetidos a diferentes técnicas de defumação

Avaliaram-se hambúrgueres de aparas de jacaré-do-pantanal (Caiman yacare) quanto à composição centesimal, cor e análise sensorial. O delineamento foi inteiramente ao acaso, em três tratamentos: T1= sem defumação; T2= defumação a quente e T3= defumação líquida, e nove repetições. As aparas foram moídas e condimentadas para o hambúrguer. Os hambúrgueres para defumação a quente foram colocados no defumador 60 min a 60ºC com gerador de fumaça por fricção. Foi pulverizada fumaça líquida, sobre os produtos (T3), e estes foram colocados em desidratador por 60 min a 60ºC. Houve diferença significativa quanto à composição centesimal entre os hambúrgueres defumados, T2 = 43,1% e T3 = 60,9%, e verificou-se menor teor de umidade em relação aos sem defumação, 73,3%. A proteína, 39,9%, e as cinzas, 6,1%, foram mais altas nos defumados a quente. Os hambúrgueres defumados a quente apresentaram menor luminosidade, 42,05, e maiores valores do croma a*, 14,65, e b*, 28,57, em relação aos demais tratamentos. As variáveis sensoriais foram significativas para sabor, textura e aceitação geral. Os produtos defumados a quente apresentaram a pior aceitação. Concluiu-se que a defumação a quente proporciona produtos com menor teor de umidade, com pigmentação mais intensa, porém menos aceitos pelos provadores.

Mortadella sausage manufactured with Caiman yacare (Caiman crocodilus yacare) meat, pork backfat, and soybean oil

Mortadellas manufactured using Caiman yacare meat (70%) and pork fat (30%) were reformulated by substituting pork fat with increasing amounts of soybean oil (25%, 50%, and 100%) and evaluated 7, 30, and 60days post-manufacture. The substitutions resulted in an increase in fat content and in the percentage of polyunsaturated fatty acids (total PUFA; 18:2 n−6 and 18:3 n−3), and a reduction in saturated fatty acids (total SFA; 14:0 and 16:0). These alterations reduced (P<0.01) the indices of atherogenicity and thrombogenicity by 4- to 5-fold in the formulation with 100% soybean oil compared to the original formulation. The levels of TBARS obtained at day 7 were positively correlated (P<0.01) with 18:2 n−6 and 18:3 n−3 (r=0.83 and 0.84, respectively) and negatively correlated with 17:0 and 17:1 (r=−0.91 and −0.89, respectively). All formulations received favourable overall acceptability by the sensory panel.

Do individual crocodilians adjust their signaling to habitat structure?

All crocodilians use long-distance signals, composed of infrasound, vocal sounds and/or slaps. These components differ in their ability to carry information about the animal's location and status through air and water. It has been previously shown that signal composition differs between species and allopatric conspecific populations; species and populations living in fragmented aquatic habitats use more vocal signals and/or fewer slaps than species and populations living in continuous aquatic habitats, thus adjusting their signaling to habitat structure. There are two possible mechanisms for such adjustment: behavioral plasticity and evolved differences between species and populations. In the present study, it is shown (a) that individual yacare caimans (Caiman yacare) do not change the composition of their signals in response to changes in aquatic habitat continuity, and (b) that in areas where both continuous and fragmented aquatic habitats are available, American alligators (Alligator mississippiensis) and Nile crocodiles (Crocodylus niloticus) living in small bodies of water do not differ in signal composition from those living in large bodies of water. Therefore the previously found differences in signaling between species and between allopatric conspecific populations are evolved adaptations rather than behavioral responses by individual animals.

Respuesta bioquímica y morfométrica a la incorporación de pescado, pollo y carne vacuna en la dieta de Caiman yacare en cautiverio

&lt;p&gt;Los indicadores bioquímicos nutricionales, el peso y las dimensiones corporales, permiten evaluar el impacto de distintas dietas sobre el crecimiento de &lt;em&gt;Caiman yacare&lt;/em&gt;, así como optimizar su cría comercial. En un establecimiento del nordeste argentino se evaluaron tres dietas utilizando 60 ejemplares sub-adultos de dicha especie (peso: 1,46 ± 0,06 kg y longitud hocico-cloaca: 37,29 ± 0,28 cm), divididos en tres lotes de 20 animales cada uno (50% de cada sexo). Todos recibieron una dieta base (70%) de alimento balanceado (MS 88%, PB 30%, EE 11%, cenizas 4,5%) y un suplemento (30%) que varió según el grupo (carne vacuna, pollo o pescado). Al inicio y al final de la experiencia (170 días) se realizaron pesajes y mediciones corporales de los reptiles. Además, se efectuaron análisis sanguíneos (perfil nutricional) a 10 animales de cada lote (50% de cada sexo).&lt;/p&gt;&lt;p&gt;A través de un diseño completamente aleatorizado se realizó el análisis de la covarianza (ANCOVA). Las variables longitud y ancho de cabeza, así como los valores de proteínas totales, albúmina, relación albúmina-globulina, hematocrito, hemoglobina, glucosa y potasio no revelaron diferencias significativas entre dietas. Los caimanes que recibieron la ración suplementada con pollo, mostraron mayores incrementos de peso vivo, longitud total, longitud hocico-cloaca y perímetro torácico, así como niveles superiores de globulinas totales, globulina beta, colesterol total, C-LDL, sodio y fósforo inorgánico (p&amp;lt;0,05). Los animales que consumieron pescado exhibieron niveles sanguíneos significativamente mayores de alfa y gamma globulinas, creatinina, C-HDL, fructosamina y calcio. Los reptiles suplementados con carne vacuna presentaron mayores niveles de urea, triglicéridos y magnesio (p&amp;lt;0,05). En ningún caso se registraron cuadros compatibles con deficiencias nutricionales. Por el contrario, los resultados indican que los tres suplementos utilizados revelaron ser útiles para la alimentación de &lt;em&gt;C. yacare&lt;/em&gt;, especialmente el de origen aviar por su significativa repercusión sobre los aumentos de peso y dimensiones corporales de los caimanes. &lt;/p&gt;

Glutathione status and antioxidant enzymes in a crocodilian species from the swamps of the Brazilian Pantanal

In a previous study oxidative damage markers – lipid peroxidation and protein oxidation – were determined in organs of wild Caiman yacare captured in winter-2001 and summer-2002 at various developmental stages. An increase in oxidative damage occurred in the hatchling-juvenile transition (but not in the juvenile-adult transition) and winter–summer transition (in juveniles), suggesting that oxidative stress is associated with development and season. Herein the effect of development and season on glutathione (GSH) metabolism and the effect of development on the activity of antioxidant enzymes (catalase, glutathione peroxidase, glutathione reductase and glutathione S-transferase) and glucose 6-phosphate dehydrogenase were analyzed. The ratio GSSG:GSH-eq increased in lung, liver, kidney and brain by 1.8- to 4-fold in the embryo/hatchling to juvenile transition. No changes occurred in juvenile–adult transition. GSSG:GSH-eq across seasons was significantly elevated in summer. Total-glutathione content was mostly stable in various organs; in liver it increased in the embryo–juvenile transition. Enzyme activities were only determined in summer-animals (embryos, hatchlings and juveniles). For most antioxidant enzymes, activities increased from embryo/hatchling to juvenile in liver and Kidney. In lung, there was an inverse trend for enzyme activities and total glutathione content. Thus, increased metabolic rates during early caiman growth – in embryo–juvenile transition – appears to be related to redox imbalance as suggested by increased GSSG:GSH-eq and activation of antioxidant defenses. Differences in oxidative stress across seasons were related with summer–winter nocturnal temperatures. These results, as a whole, were interpreted in the context of ecological biochemistry.

Histologia, histoquímica e histometria do intestino de jacaré-do-Pantanal criado em cativeiro

A criação de jacaré-do-Pantanal tem se consolidado no estado de Mato Grosso como atividade alternativa e legal para as propriedades rurais na área de ocorrência natural da espécie, coibindo a caça predatória e colaborando na preservação da espécie. A racionalização do processo produtivo na criação de jacaré é uma ação relativamente nova, que permite obter pele de melhor qualidade e de utilização integral, diferentemente daquelas oriundas de animais da natureza. Considerando a importância dos intestinos como sede dos principais eventos relacionados à obtenção de nutrientes para o metabolismo corpóreo, este trabalho teve por objetivo caracterizar qualitativa e quantitativamente a mucosa dos intestinos delgado e grosso de jacaré-do-Pantanal jovens. Para a caracterização ao microscópio óptico da estrutura da parede intestinal e da histometria da mucosa foram coletadas amostras intestinais de 16 animais, sendo três deles também destinados ao estudo histoquímico. As amostras foram obtidas de cinco regiões, sendo quatro do intestino delgado e uma do intestino grosso. Elas foram fixadas em solução de Bouin, processadas de acordo com técnicas preconizadas para inclusão em parafina. Cortes histológicos semi-seriados (quatro micrômetros) foram obtidos e o material foi desparafinizado, hidratado e corado pela hematoxilina-eosina para a descrição geral e estudo histométrico, que consistiu da mensuração da freqüência das vilosidades intestinais; dos comprimentos do epitélio e da lâmina própria da mucosa e da espessura da mucosa. Na análise estatística foi empregada a análise de variância e Teste de Tukey. Para o estudo histoquímico foram utilizadas a reação ao ácido periódico de Schiff, alcian blue pH 1,0 contrastado com hematoxilina e alcian blue pH 2,5 conjugado ao ácido periódico de Schiff. Para a descrição das estruturas histológicas foi empregada a terminologia disponível na Nomina Histologia. A estrutura da parede do intestino delgado e grosso do jacaré-do-Pantanal era constituída pelas túnicas mucosa, muscular e serosa. A mucosa era formada por epitélio de revestimento do tipo cilíndrico simples constituído por epiteliócitos colunares e por exocrinócitos caliciformes; lâmina própria de tecido conjuntivo frouxo e muscular da mucosa única. A túnica muscular era constituída por dois estrados, o circular e o longitudinal, sendo o estrato circular o mais desenvolvido. A serosa era típica. As especializações da mucosa observadas no intestino delgado e grosso, respectivamente, foram vilosidades e pregas intestinais, e ao longo das regiões dos intestinos, apresentaram diminuição de sua complexidade. O estudo histométrico da mucosa demonstrou diferença estatisticamente significante entre o intestino delgado e grosso. Embora a estrutura da parede intestinal de C. yacare seja semelhante à de outros crocodilianos, a da tartaruga verde e avestruz, ainda se faz necessário estudos sobre a histofisiologia para que o manejo nutricional da espécie em cativeiro seja incrementado.

Misconceptions about the taxonomy and distribution of Caiman crocodilus chiapasius and C. crocodilus fuscus (Reptilia: Crocodylia: Alligatoridae)

Four subspecies are currently recognized for the Spectacled Caiman, Caiman crocodilus (Linnaeus 1758): Caiman crocodilus fuscus (Cope 1868: Perosuchus fuscus), described from a single specimen from the Magdalena River, Colombia; C. c. chiapasius (Bocourt 1876: Alligator chiapasius), described from the Tonalá Valley, Chiapas, México; C. c. apaporiensis (Medem 1955) from the upper Apaporis River, Colombia; and, C. c. crocodilus (Linnaeus 1758: Lacerta crocodilus), named for the species originally described (Smith &amp; Smith 1977; Busack &amp; Pandya 2001). Caiman yacare was previously considered to be a fifth subspecies (i.e., C. c. yacare), but it is now generally accepted that it is a full species (King &amp; Burke 1989), and is no longer treated as a subspecies (Velasco &amp; Ayarzagüena 2010). There is some confusion about the current distributions of C. c. chiapasius and C. c. fuscus, and although some works have attempted to clarify this situation (Busack &amp; Pandya 2001), the confusion still remains (i.e., Rueda-Almonacid et al. 2007; Velasco &amp; Ayarzagüena 2010). Here, we present a brief review of the taxonomic status of caiman subspecies, and its implications for their distributions.

Sequência de ossificação do sincrânio e hioide em embriões de Caiman yacare (Crocodylia, Alligatoridae)

O crânio representa uma estrutura única e complexa dos vertebrados, sendo foco relevante objeto de estudos morfológicos e sistemáticos. Embora os crocodilianos constituam um importante grupo representante dos Archosauria, nossos conhecimentos acerca de seu desenvolvimento e homologias ainda são escassos. Aqui descrevemos uma sequência detalhada de ossificação dos ossos do crânio de Caiman yacare (Daudin, 1802), objetivando contribuir com informações de foco anatômico. Coletaram-se ao acaso embriões em intervalos regulares durante todo o período de incubação, sendo estes posteriormente submetidos a protocolo de diafanização e coloração de ossos. O padrão de ossificação em C. yacare segue parâmetros gerais em répteis e outros tetrápodes. Os primeiros centros de ossificação correspondem aos ossos dérmicos, envolvidos com funções primárias como a alimentação e respiração (e.g. maxila, dentário, esplenial, angular, pterigoide, ectopterigoide e jugal, incluindo ainda os dentes). Os ossos da porção dorsal do neurocrânio se ossificam posteriormente, evidenciando uma fontanela cranial que permanece até o momento da eclosão. Os ossos parietal, frontal e opstótico possuem mais de um centro de ossificação que se fundem durante a ontogenia. O centro de ossificação do parisfenoide está ausente, e apenas um centro de ossificação está presente para o basisfenoide. A porção posterior do crânio é formada por centros de substituição do condrocrânio que se ossificam em estágios posteriores.

Anurans as paratenic hosts in the transmission of Hepatozoon caimani to caimans Caiman yacare and Caiman latirostris

Prevalence of Hepatozoon caimani has been reported in 76% of caimans Caiman yacare from the Pantanal region. Culex (Melanoconion) spp. mosquitoes were recently identified as natural vectors of this parasite. However, culicids are not typically eaten by crocodilians, suggesting that the main transmission route is through ingestion of insectivorous vertebrates, such as anurans. The susceptibility of wild frogs Leptodactylus chaquensis, Leptodactylus podicipinus and Scinax nasicus to infection by H. caimani was verified. Wild-caught anurans were force fed with sporulated oocysts from laboratory-bred Culex (Melanoconion) mosquitoes. Frogs were killed 30 days postinfection, and their internal organs were fed to caimans C. yacare and Caiman latirostris. Cystozoites were identified in fresh liver impression smears of L. chaquensis. C. yacare fed on anuran organ presented gametocytes in peripheral blood circulation between 74 and 80 days postinoculation (dpi). Gametocytes were also verified in C. latirostris fed on the internal organs of L. podicipinus and S. nasicus between 60-70 and 69-75 dpi, respectively. Since frogs used in experiment are sympatric with C. yacare and C. latirostris and may occur in the diet of these caimans, the results suggest these amphibians are paratenic hosts in the natural transmission cycle of H. caimani in Pantanal.

ISOLATION OF SALMONELLA SPP. FROM YACARE CAIMAN (CAIMAN YACARE) AND BROAD-SNOUTED CAIMAN (CAIMAN LATIROSTRIS) FROM THE ARGENTINE CHACO

Presence of Salmonella spp. was evaluated in yacare caiman (Caiman yacare) and broad-snouted caiman (Caiman latirostris) from a ranching facility in the Argentine Chaco. Crocodilian ranching programs are based on captive breeding of wild-harvested eggs and release of excess hatchlings into the wild. Samples for bacterial isolation were collected from 102 captive (35 C. yacare and 67 C. latirostris) and seven free-ranging caiman (four C. yacare and three C. latirositris) between 2001 and 2005 and from three artificially incubated C. yacare wild eggs. Two Salmonella spp. of known zoonotic potential, S. infantis and S. nottingham, were isolated from captive caiman in 2001 and 2002, respectively. This is the first report for S. nottingham in reptiles and of S. infantis in caiman. Salmonella spp. prevalence varied significantly between years, with a 77% prevalence peak in 2002. Although the cause of this increase was not confirmed, we found no correlation with the type of enclosure, caiman species, or body weight. Deteriorated physical condition of caiman hatchlings due to dietary changes in 2002 could have influenced Salmonella spp. shedding. However, external sources such as food, water, or enclosures could not be ruled out. Pathogenic Salmonella spp. present a risk for human infection. Inadvertent introduction of Salmonella spp. or other bacteria into the environment when caiman are released could pose a threat to wild caiman populations. Prophylactic measures to detect and decrease Salmonella spp. presence in caiman ranching facilities are recommended to reduce risk to humans and make caiman-ranching a sound conservation strategy for crocodilian species.

Comparison of plasma dipeptidyl peptidase IV activity in two caiman species: Caiman latirostris and Caiman yacare (Crocodylia, Alligatoridae)

Abstract Dipeptidyl peptidase IV (DPPIV) is a well-characterized protease with broad substrate specificity, functionally-related to the activity of many bioactive peptides. It plays an important role as physiological regulator of a number of peptides that serve as biochemical messengers within the immune system. Plasma DPPIV activity was characterized with respect to temperature, kinetics and concentration dependence in two species of caiman, the broad-snouted caiman (Caiman latirostris) and the black yacare (Caiman yacare). DPPIV activity showed a significant positive correlation from titrations carried out in the presence of different plasma concentrations. DPPIV activity was lower in C. yacare than in C. latirostris at all temperatures tested. C. yacare DPPIV activity showed a significant increase only at higher temperatures whilst C. latirostris plasma demonstrated a strong positive correlation starting at the lowest temperature, probably due to an adaptation for the tolerance of lower temperatures. Exposure of C. latirostris and C. yacare plasma at different time points showed that plasma DPPIV activities were time-dependent, and that the titer-dependent curves were different for the two species. These results revealed that plasma DPPIV activities were different between these two crocodilian species, which could contribute to the differences in susceptibility to infection between them.

Caiman-Biting Mosquitoes and the Natural Vectors of Hepatozoon caimani in Brazil

Abstract Mosquitoes that feed on crocodilians are poorly known, despite the potential role of these exothermic animals as reservoirs of arboviruses. In this article, we assessed the frequency, abundance, and temporal variation of caiman-biting mosquitoes as well as searched for the natural vectors of the blood parasite of caimans, Hepatozoon caimani, in the Pantanal area of central-western Brazil from captures conducted bimonthly from September 2006 to September 2007 and in February 2008. A total of 5,272 mosquitoes belonging to 10 species of five genera was caught on caimans. The most abundant species were Culex (Melanoconion) theobaldi, Mansonia (Mansonia) titillans, Mansonia (Man.) humeralis, and Mansonia (Man.) amazonensis, which together accounted for 80% of all sampled individuals. Other blood-feeding Melanoconion species were also found quite frequently on caimans, including Culex clarki, Culex idottus, and Culex bastagarius. Oocysts of H. caimani were exclusively detected in Culex species, mainly in individuals of the subgenus Melanoconion, and we accomplished experimental transmission from naturally infected mosquitoes to uninfected Caiman yacare. The highest infection rates were observed in Cx. theobaldi (0.55%), which is therefore indicated as the primary vector of H. caimani. In addition, because the above mentioned Melanoconion and Mansonia species are abundant, widespread, and have a broad set of hosts, including crocodilians, they may be suggested as potential vectors of arboviruses, such as West Nile virus, in the Southern Cone in South America.

Caiman-Biting Mosquitoes and the Natural Vectors of &lt;I&gt;Hepatozoon caimani&lt;/I&gt; in Brazil

Mosquitoes that feed on crocodilians are poorly known, despite the potential role of these exothermic animals as reservoirs of arboviruses. In this article, we assessed the frequency, abundance, and temporal variation of caiman-biting mosquitoes as well as searched for the natural vectors of the blood parasite of caimans, Hepatozoon caimani, in the Pantanal area of central-western Brazil from captures conducted bimonthly from September 2006 to September 2007 and in February 2008. A total of 5,272 mosquitoes belonging to 10 species of five genera was caught on caimans. The most abundant species were Culex (Melanoconion) theobaldi, Mansonia (Mansonia) titillans, Mansonia (Man.) humeralis, and Mansonia (Man.) amazonensis, which together accounted for 80% of all sampled individuals. Other blood-feeding Melanoconion species were also found quite frequently on caimans, including Culex clarki, Culex idottus, and Culex bastagarius. Oocysts of H. caimani were exclusively detected in Culex species, mainly in individuals of the subgenus Melanoconion, and we accomplished experimental transmission from naturally infected mosquitoes to uninfected Caiman yacare. The highest infection rates were observed in Cx. theobaldi (0.55%), which is therefore indicated as the primary vector of H. caimani. In addition, because the above mentioned Melanoconion and Mansonia species are abundant, widespread, and have a broad set of hosts, including crocodilians, they may be suggested as potential vectors of arboviruses, such as West Nile virus, in the Southern Cone in South America.

Fatty acid profiles in meat from Caiman yacare (Caiman crocodilus yacare) raised in the wild or in captivity

Chemical composition and fatty acid profiles were determined in Caiman yacare meat originating from the neck and tail cuts of animals raised in the wild (n=6) or in captivity (n=6), slaughtered at a live weight of approximately 6 kg. All experimental methods were approved by the appropriate environmental protection agencies. Most chemical components were affected by the origin-cut interaction, with the tail cut of wild animals having the highest amount of intramuscular fat (19.2% of DM) and the lowest of moisture (71.8%) and protein (77.0% of DM). Yacare meat had low amounts of SFA (35.1%), which were similar (P>0.05) in the cuts and origins studied. The total amount of PUFA was higher (P<0.05) in wild (31.0%) than in captive animals (23.6%), and n-3 fatty acids had means of about 5% and 2% for the same groups, respectively (P<0.05). In general, the FA profile of intramuscular fat in yacare meat had a desirable PUFA/SFA ratio above 0.4.

Hepatozoon caimani (Apicomplexa: Hepatozoidae) in Wild Caiman, Caiman yacare, from the Pantanal Region, Brazil

The prevalence and parasitemia of Hepatozoon caimani in the natural population of the caiman, Caiman yacare, from the Pantanal area, state of Mato Grosso do Sul, central Brazil, were evaluated according to gender and month of capture from July 2006 to February 2008. Blood samples were obtained bimonthly from a total of 229 caimans, and 76% were positive. Prevalence varied significantly according to sampling month and animal size. Almost all adults (100%) and young-adults (97%) were positive, while 63% of juvenile caimans were positive and all of the youngest individuals were negative. These results indicate that caimans are infected for the first time as juveniles. The mean parasitemia in blood was 13.5 +/- 13.0 (n = 174; 1-96 parasites) and did not significantly vary with respect to gender, month of sampling, size, or weight of the caiman. The frequency distribution of parasites in the caiman population was aggregated. Differences in feeding habits and exposure to vectors between the youngest caimans and juveniles are hypothesized as the main risk factors for caimans to acquire H. caimani in central Brazil.

Food habits of the Broad‐snouted Caiman (Caiman latirostris: Crocodylia, Alligatoridae) in northwestern Uruguay

The food habits of the Broad‐snouted Caiman (Caiman latirostris) were studied in northwestern Uruguay. The most common prey were insects, the shrimp Pseudopalaemon bouvieri, the snail Pomacea canaliculata, fish and birds. Spiders, crabs, amphibians, snakes, turtles and mammals were consumed less frequently. Arthropods were the most frequent prey for juvenile caiman. Fish and snails were consumed by all size classes. The proportion of stomach contents with invertebrates decreased with increasing caiman size, and that with vertebrates was greater in the diet of larger caiman. Diet composition and ontogenetic shift are similar to that of other crocodilians considered as opportunistic generalist predators. Se estudiaron los hábitos alimenticios del Yacaré (Caiman latirostris) en el noroeste de Uruguay. Las presas más comunes fueron insectos, el camarón Pseudopalaemon bouvieri, el caracol Pomacea canaliculata, peces y aves. Arañas, cangrejos, anfibios, serpientes, tortugas y mamíferos fueron consumidos menos frecuentemente. Los artrópodos fueron las presas más frecuentes de juveniles. Peces y aves fueron consumidos por todos los tamaños. La proporción de contenidos estomacales con invertebrados disminuyó al aumentar el tamaño de los caimanes, y la de vertebrados fue mayor en los individuos de mayor tamaño. La composición y cambio ontogenético en la dieta resultan similares a los de crocodilianos considerados predadores generalistas oportunistas.

Evolutionary history of trypanosomes from South American caiman (Caiman yacare) and African crocodiles inferred by phylogenetic analyses using SSU rDNA and gGAPDH genes

In this study, using a combined data set of SSU rDNA and gGAPDH gene sequences, we provide phylogenetic evidence that supports clustering of crocodilian trypanosomes from the Brazilian Caiman yacare (Alligatoridae) and Trypanosoma grayi, a species that circulates between African crocodiles (Crocodilydae) and tsetse flies. In a survey of trypanosomes in Caiman yacare from the Brazilian Pantanal, the prevalence of trypanosome infection was 35% as determined by microhaematocrit and haemoculture, and 9 cultures were obtained. The morphology of trypomastigotes from caiman blood and tissue imprints was compared with those described for other crocodilian trypanosomes. Differences in morphology and growth behaviour of caiman trypanosomes were corroborated by molecular polymorphism that revealed 2 genotypes. Eight isolates were ascribed to genotype Cay01 and 1 to genotype Cay02. Phylogenetic inferences based on concatenated SSU rDNA and gGAPDH sequences showed that caiman isolates are closely related to T. grayi, constituting a well-supported monophyletic assemblage (clade T. grayi). Divergence time estimates based on clade composition, and biogeographical and geological events were used to discuss the relationships between the evolutionary histories of crocodilian trypanosomes and their hosts.

Cross-species amplification of microsatellites in crocodilians: assessment and applications for the future

Microsatellite DNA loci have emerged as the dominant genetic tool for addressing questions associated with genetic diversity in many wildlife species, including crocodilians. Despite their usefulness, their isolation and development can be costly, as well as labour intensive, limiting their wider use in many crocodilian species. In this study, we investigate the cross-species amplification success of 82 existing microsatellites previously isolated for the saltwater crocodile (Crocodylus porosus) in 18 non-target crocodilian species; Alligator sinensis, Caiman crocodylus, Caiman latirostris, Caiman yacare, Melanosuchus niger, Paleosuchus palpebrosus, Crocodylus acutus, Mecistops cataphractus, Crocodylus intermedius, Crocodylus johnstoni, Crocodylus mindorensis, Crocodylus moreletii, Crocodylus niloticus, Crocodylus novaeguineae, Crocodylus palustis, Crocodylus rhombifer, Crocodylus siamensis, and Osteolaemus tetraspis. Our results show a high level of microsatellites cross-amplification making available polymorphic markers for a range of crocodilian species previously lacking informative genetic markers.