کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
5587567 | 1568855 | 2017 | 44 صفحه PDF | دانلود رایگان |
عنوان انگلیسی مقاله ISI
When the ball is in the female's court: How the scramble-competition mating system of the North American red squirrel has shaped male physiology and testosterone dynamics
ترجمه فارسی عنوان
هنگامی که توپ در دادگاه زن است: چگونه سیستم جفت گیری رقابت سنجاب قرمز آمریکای شمالی به شکل فیزیولوژی مردانه و پویایی تستوسترون
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کلمات کلیدی
موضوعات مرتبط
علوم زیستی و بیوفناوری
بیوشیمی، ژنتیک و زیست شناسی مولکولی
علوم غدد
چکیده انگلیسی
Male reproductive success in most mammals is determined by their success in direct inter-male competition through aggression and conflict, resulting in female-defense mating systems being predominant. This is linked to male testosterone levels and its dynamics. However, in certain environments, a scramble-competition mating system has evolved, where female reproductive behavior takes precedence and male testosterone dynamics are unlikely to be related to inter-male competition. We studied the North American red squirrel (Tamiasciurus hudsonicus), a species with a well-established scramble-competition system. Using an ACTH hormonal challenge protocol as a proxy for competitive interactions, we compared the testosterone dynamics in breeding males in late winter with that in nonbreeding males in late spring in the Yukon. To gain an integrated picture of their physiological state, we also assessed changes in their stress response, body mass, energy mobilization, and indices of immune function. Testosterone levels at the base bleed were high in breeding males (2.72Â ng/mL) and virtually absent in non-breeding males (0.04Â ng/mL). Breeding males were in better condition (heavier body mass, higher hematocrit, and higher erythrocytes), had higher indices of immune function (neutrophil:lymphocyte ratio), but a similar ability to mobilize energy (glucose) compared with non-breeding males. Though total cortisol was higher in non-breeding males, free cortisol was twice as high in breeding males as their corticosteroid binding globulin levels were half as high. In response to the ACTH challenge, testosterone levels in breeding males declined 49% over the first hour and increased 36% over the next hour; in non-breeding males levels showed no change. Free cortisol increased only modestly (26% in breeding males; 23% in non-breeding males). Glucose levels changed similarly in breeding and nonbreeding males, declining for the first 30Â min and then increasing for the next 60Â min. Thus, testosterone and components of the stress axis function in a profoundly different manner in male red squirrels than in males of mammals with female-defense mating systems. There are four probable interrelated reasons for these adaptations in male red squirrels: the marginal benefits of each mating, the constraints of mate searching away from their own resource-based territories, energy mobilization in a harsh environment, and a long life span.
ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: General and Comparative Endocrinology - Volume 252, 1 October 2017, Pages 162-172
Journal: General and Comparative Endocrinology - Volume 252, 1 October 2017, Pages 162-172
نویسندگان
Rudy Boonstra, Adam Dušek, Jeffrey E. Lane, Stan Boutin,