Testosterone level, nasal gland volume and Leydig cell morphometry in capybaras (Hydrochoerus hydrochaeris)

Paula, Tarcízio Antônio Rêgo de

doi:10.1590/s0102-09352006000600017

Cited by 19 publications

(20 citation statements)

References 12 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…A final point can be made regarding the correlation found in previous studies between volume of the morrillo and testosterone concentration in blood (Costa & Paula, 2006). This correlation, in conjunction with the findings of this study that males with larger morrillos have larger spleens, i.e., a more competent immune system, is contrary to the so-called "immunocompentence handicap hypothesis" put forward by Folstad and Karter (1992).…”

Section: Discussionsupporting

confidence: 52%

mentioning

confidence: 87%

“…Furthermore, because of its large size and conspicuousness in dominant males, Moreira, Macdonald and Clarke (1997) have suggested that the morrillo may act as a visual sign of dominance. The size of this gland also significantly correlates with testosterone titer in blood (Costa & Paula, 2006).Capybaras carry many species of intestinal helminths and blood parasites (Mones, 1982;Salas & Herrera, 2004). Among the intestinal helminths, the intensities of infestation by Monoecocestus macrobursatum and Viannella hydrochoeri have been found to correlate negatively with the physical condition of the host, as assessed by the residuals of the body weight-body length regression (Salas & Herrera, 2004).…”

mentioning

confidence: 99%

See 2 more Smart Citations

Trypanosoma evansi (Kinetoplastida: Trypanosomatidae) in capybaras (Hydrochoerus hydrochaeris, Rodentia: Hydrochoeridae): prevalence, effect and sexual selection

Herrera¹,

Castro²

2017

RBT

View full text Add to dashboard Cite

Parasites play a crucial role in the ecology of animals. They also appear to be important in mechanisms underlying sexual selection processes. In this article we study the prevalence, effect and potential role in sexual selection of the protozoon Trypanosoma evansi in capybaras, Hydrochoerus hydrochaeris. We collected our samples from the annual capybara cull of a ranch in Venezuela, using the volume of the snout scent gland as an indicator of dominance; the residuals of body weight as indicators of condition; and the residuals of the spleen mass as indicators of immune function. Overall prevalence was 30.9 % (N= 97) with no difference between males and females, and no relation between infection with T. evansi and condition. However, we found that infected animals had larger spleens (residuals), indicating an immunological cost of the infection. Furthermore, males with larger snout scent glands (more dominant) were less likely to be infected than males with smaller glands (less dominant), suggesting that by choosing males with a large glands, females may be using the gland as an indicator of health, which is consistent with the "good genes" view of sexual selection. Rev. Biol. Trop. Parasites are important factors in the dynamics of their host's populations (Pedersen & Greives, 2008) by affecting their survival, reproduction (Albon et al., 2002) and behavior (Berdoy, Webster, & Macdonald, 2000). However, suspected parasites can often be commensals or even mutualistic symbionts (Ewald, 1987). Even when clear phenotypic effects of a parasitic infection are not apparent, an infection can carry a significant immunological cost (Lochmiller & Deerenberg, 2000). Parasites have also been hypothesized as central role players in the process of sexual selection. Thus, Hamilton and Zuk (1982) have argued -and presented evidence-that it is advantageous for a male bird to advertise his lack of parasites by developing and showing off bright coloration in his plumage. Such a display, being costly, would be an honest signal of condition which females could use to choose good quality males (Grafen, 1990;Keyser & Hill, 2000). In mammals, other features such as antlers or manes may play the same role as do colors in birds. In particular, the development of a scent gland and scent marking behavior may be subject to sexual selection (e.g. bats, Voigt et al., 2008; review by Penn & Potts, 1998) and may function as honest signals of health (Zala, Potts, & Penn, 2004).Capybaras, Hydrochoerus hydrochaeris (Linnaeus, 1758), large (50 kg), grazing rodents, are common in the savannahs and wetlands of tropical and subtropical South America (Ojasti, 1973), where they live in stable social groups composed of both males and females, with an average of 3-4 male and 6-7 female adults per group (Herrera & Macdonald, 1987;Herrera, Salas, Congdon, Corriale, & Tang-Martínez, 2011). In these groups, a clear-cut and long-lasting dominance hierarchy is evident among the males: the dominant male is usually able to win all encounters against m...

show abstract

Section: Discussionsupporting

confidence: 52%

mentioning

confidence: 87%

mentioning

confidence: 99%

See 1 more Smart Citation

Trypanosoma evansi (Kinetoplastida: Trypanosomatidae) in capybaras (Hydrochoerus hydrochaeris, Rodentia: Hydrochoeridae): prevalence, effect and sexual selection

Herrera¹,

Castro²

2017

RBT

View full text Add to dashboard Cite

show abstract

“…Immediately after dissecting and weighing the epididymis, one of the testicles from each animal was perfused with Karnovsky solution for fixation (Costa and Paula 2006). Testicular fragments of 2.0 x 5.0 x 5.0 mm were collected and embedded in glycol methacrylate according to Costa et al (2011).…”

Section: Histological Processingmentioning

confidence: 99%

Testicular Histomorphometric Evaluation of Zebu Bull Breeds

Andreussi

Faria

Fernandes

et al. 2014

Braz. arch. biol. technol.

View full text Add to dashboard Cite

show abstract

“…Nas observações, foram registrados o número e a composição de animais em cada grupo. Para isso, foi considerado como capivara macho todo adulto com glândula supra nasal localizada na superfície superior do focinho, assim como descrito por vários autores (MONES; OJASTI, 1986;HERRERA, 1992;TOMAZZONI, 2003;COSTA;PAULA, 2006). Para verificar variações ao longo dos anos a média do número de capivaras, bem como a proporção de adultos e filhotes, foram comparadas pelo teste de Qui-quadrado, a 5% de significância.…”

Section: Methodsunclassified

Dinâmica E Biologia De Uma População De Capivaras Em Ambiente Antrópico, Curitiba-Pr

Almeida

Biondi

Monteiro‐Filho

2014

C & N

View full text Add to dashboard Cite

show abstract

Testosterone level, nasal gland volume and Leydig cell morphometry in capybaras (Hydrochoerus hydrochaeris)

Cited by 19 publications

References 12 publications

Trypanosoma evansi (Kinetoplastida: Trypanosomatidae) in capybaras (Hydrochoerus hydrochaeris, Rodentia: Hydrochoeridae): prevalence, effect and sexual selection

Trypanosoma evansi (Kinetoplastida: Trypanosomatidae) in capybaras (Hydrochoerus hydrochaeris, Rodentia: Hydrochoeridae): prevalence, effect and sexual selection

Testicular Histomorphometric Evaluation of Zebu Bull Breeds

Dinâmica E Biologia De Uma População De Capivaras Em Ambiente Antrópico, Curitiba-Pr

Contact Info

Product

Resources

About