scholarly journals Free-Living Male Mountain White-Crowned Sparrows Exhibit Territorial Aggression Without Modulating Total or Free Plasma Testosterone

The Condor ◽  
2007 ◽  
Vol 109 (1) ◽  
pp. 173-180 ◽  
Author(s):  
Sharon E. Lynn ◽  
Thomas P. Hahn ◽  
Creagh W. Breuner
Keyword(s):  
Aggressive Behavior ◽  
Free Testosterone ◽  
Plasma Testosterone ◽  
Zonotrichia Leucophrys ◽  
Territorial Aggression ◽  
Testosterone Secretion ◽  
Corticosteroid Binding Globulin ◽  
Simulated Territorial Intrusion ◽  
Territorial Intrusion ◽  
Free Plasma

Abstract Abstract In some species, expression of territorial aggression is accompanied by a rise in testosterone secretion, but in others aggressive behavior is expressed while testosterone levels remain unchanged. Corticosteroid binding globulin (CBG) binds both corticosterone and testosterone in avian plasma. Thus, increasing corticosterone may result in fluctuations in unbound (“free”) testosterone; this could result in greater biological activity of testosterone without an increase in testosterone secretion. We investigated whether such plasma interactions of testosterone, corticosterone, and CBG might result in alterations of free testosterone in male Mountain White-crowned Sparrows (Zonotrichia leucophrys oriantha). We conducted simulated territorial intrusions during incubation and compared total and free testosterone of males captured immediately following a simulated territorial intrusion with that of males captured passively. All experimental males showed aggressive behavior, but apparently did not modulate total or free testosterone relative to controls.

Opposite Changes in Plasma Testosterone and Corticosterone Levels Following a Simulated Territorial Challenge in Male Great Tits

Behaviour ◽  
2004 ◽  
Vol 141 (4) ◽  
pp. 451-467 ◽  
Author(s):  
Rianne Pinxten ◽  
Lutgarde Arckens ◽  
Els van Duyse ◽  
Marcel Eens ◽  
Veerle Darras
Keyword(s):  
Parus Major ◽  
Time Of Day ◽  
Behavioural Response ◽  
Egg Laying ◽  
Plasma Testosterone ◽  
Breeding Cycle ◽  
Territorial Defence ◽  
Breeding Stage ◽  
Simulated Territorial Intrusion ◽  
Territorial Intrusion

AbstractThe apparent ability of plasma testosterone (T) and corticosterone (B) levels to fluctuate rapidly in response to agonistic interactions, suggests that these hormones may play an important role in an animal's acute behavioural response during such interactions. In the present study, free-living male great tits, Parus major, were subjected to a simulated territorial intrusion (STI) during the egg laying, incubation and nestling stage of first broods. Plasma T and B levels of challenged males were compared to those of control males matched for breeding stage, day in breeding stage, and time of day. Plasma B levels were significantly higher in challenged males compared to control males during the egg laying and incubation stage but not during the nestling stage. On the other hand, challenged males had significantly lower plasma T levels than control males throughout the breeding cycle. While having low plasma T and elevated plasma B levels, challenged males showed a vigorous and unrelenting territorial response to the STI. Plasma T and B levels of challenged males did not correlate with the intensity of the behavioural response to the STI. These findings do not agree with the predictions of the 'challenge hypothesis' that males exposed to a territorial challenge while having breeding baseline T levels will respond with an increase in T or that T correlates with the intensity of aggression during a challenge. Together, our findings suggest a role for B rather than T in the regulation of territorial defence in male great tits.

scholarly journals Male White-shouldered Fairywrens (Malurus alboscapulatus) elevate testosterone when courting females but not during territorial challenges

2021 ◽  
Author(s):  
Jordan Boersma ◽  
John Anothny Jones ◽  
Erik D Enbody ◽  
Joseph F Welklin ◽  
Serena Ketaloya ◽  
...  
Keyword(s):  
Bird Species ◽  
Plasma Testosterone ◽  
Network Approach ◽  
Challenge Hypothesis ◽  
Agonistic Interactions ◽  
Causal Factors ◽  
Behavioral Traits ◽  
Social Network Approach ◽  
Simulated Territorial Intrusion ◽  
Territorial Intrusion

Testosterone mediates suites of physical and behavioral traits across vertebrates, and circulation varies considerably across and within taxa. However, an understanding of the causal factors of variation in circulating testosterone has proven difficult despite decades of research. According to the challenge hypothesis, agonistic interactions between males immediately prior to the breeding season produce the highest levels of testosterone measured during this period. While many studies have provided support for this hypothesis, most species do not respond to male-male competition by elevating testosterone. As a result, a recent revision of the hypothesis (challenge hypothesis 2.0) places male-female interactions as the primary cause of rapid elevations in testosterone circulation in male vertebrates. Here, we offer a test of both iterations of the challenge hypothesis in a tropical bird species. We first illustrate that male White-shouldered Fairywrens (Malurus alboscapulatus) differ by subspecies in plasma testosterone concentrations. Then we use a social network approach to find that males of the subspecies with higher testosterone are characterized by greater social interaction scores, including more time aggregating to perform sexual displays. Next, we use a controlled experiment to test whether males respond to simulated territorial intrusion or courtship interaction contexts by elevating testosterone. Males sampled during courtship had greater plasma testosterone both relative to flushed controls and males sampled during simulated intrusion. Ultimately, our results are consistent with challenge hypothesis 2.0, as males rapidly elevated testosterone following interactions with females, but not during territorial challenges.

scholarly journals Testosterone Does not Increase in Response to Conspecific Challenges in the White-Bellied Antbird (Myrmeciza Longipes), A Resident Tropical Passerine

The Auk ◽  
2006 ◽  
Vol 123 (1) ◽  
pp. 61-66
Author(s):  
Bradley C. Fedy ◽  
Bridget J. M. Stutchbury
Keyword(s):  
Breeding Season ◽  
Temperate Zone ◽  
Plasma Testosterone ◽  
Tropical Species ◽  
Zone Model ◽  
Territorial Aggression ◽  
Social Instability ◽  
Testosterone Levels ◽  
Testosterone Secretion ◽  
Removal Experiments

Abstract Resident tropical passerines that exhibit year-round territorial aggression do not fit well into the temperate-zone model, because testosterone does not increase substantially during the breeding season. We studied patterns of testosterone secretion in the White-bellied Antbird (Myrmeciza longipes), a resident tropical species in Panama that maintains territories year-round and is capable of aggression throughout the year, regardless of its stage of reproduction. Levels of plasma testosterone were low (mean = 0.30 ng mL−1) throughout the breeding and nonbreeding seasons and did not differ between them. Testosterone also did not increase in response to simulated conspecific intrusions. When we used temporary removal experiments to induce natural, extended conflict between males, testosterone levels did not increase in response to the extended social instability that resulted. White-bellied Antbirds demonstrate an apparent uncoupling of testosterone and territorial aggression throughout the year. La Testosterona no Aumenta como Respuesta a Desafíos de Individuos Coespecíficos en Myrmeciza longipes, un Paserino Residente de la Zona Tropical

scholarly journals Ignoring the challenge? Male black redstarts ( Phoenicurus ochruros ) do not increase testosterone levels during territorial conflicts but they do so in response to gonadotropin-releasing hormone

2011 ◽  
Vol 278 (1722) ◽  
pp. 3233-3242 ◽  
Author(s):  
Beate Apfelbeck ◽  
Wolfgang Goymann
Keyword(s):  
Breeding Season ◽  
Gonadotropin Releasing Hormone ◽  
Plasma Testosterone ◽  
Releasing Hormone ◽  
Social Challenges ◽  
Testosterone Levels ◽  
Territorial Conflicts ◽  
Territory Defence ◽  
Simulated Territorial Intrusion ◽  
Territorial Intrusion

Competition elevates plasma testosterone in a wide variety of vertebrates, including humans. The ‘challenge hypothesis’ proposes that seasonal peaks in testosterone during breeding are caused by social challenges from other males. However, during experimentally induced male–male conflicts, testosterone increases only in a minority of songbird species tested so far. Why is this so? Comparative evidence suggests that species with a short breeding season may not elevate testosterone levels during territory defence. These species may even be limited in their physiological capability to increase testosterone levels, which can be tested by injecting birds with gonadotropin-releasing hormone (GnRH). We studied two populations of black redstarts that differ in breeding altitude, morphology and the length of their breeding season. Unexpectedly, males of neither population increased testosterone in response to a simulated territorial intrusion, but injections with GnRH resulted in a major elevation of testosterone. Thus, black redstarts would have been capable of mounting a testosterone response during the male–male challenge. Our data show, for the first time, that the absence of an androgen response to male–male challenges is not owing to physiological limitations to increase testosterone. Furthermore, in contrast to comparative evidence between species, populations of black redstarts with a long breeding season do not show the expected elevation in testosterone during male–male challenges.

scholarly journals Not one hormone or another: Aggression differentially affects progesterone and testosterone in a South American ovenbird

2018 ◽  
Author(s):  
Nicolas M. Adreani ◽  
Wolfgang Goymann ◽  
Lucia Mentesana
Keyword(s):  
Parental Care ◽  
Social Interactions ◽  
Breeding Cycle ◽  
South American ◽  
Male Behavior ◽  
Free Living ◽  
Mating Period ◽  
Territorial Aggression ◽  
Simulated Territorial Intrusion ◽  
Territorial Intrusion

AbstractBehaviors such as territorial interactions among individuals can modulate vertebrate physiology and vice versa. Testosterone has been pointed out as a key hormone that can be rapidly affected by aggressive interactions. However, experimental evidence for such a link is mixed. In addition, behaviors can elicit changes in multiple hormones, which in turn have the potential to synergistically feedback to behavior. For example testosterone and progesterone can act interdependently in modulating male behavior. However, if aggression can affect progesterone levels in males remain unknown and – to the best of our knowledge – no one has yet tackled if and how aggressive behavior simultaneously affects testosterone and progesterone in free-living animals. We addressed these questions by performing simulated territorial intrusion experiments measuring both hormones and their ratio in male rufous horneros (Aves, Furnarius rufus) during the mating and parental care periods. Aggression affected testosterone and progesterone differentially depending on the period of testing: challenged birds had higher levels of progesterone during the mating period and lower levels of testosterone during parental care compared to controls. Challenged individuals had similar progesterone to testosterone ratios during both periods and these ratios were higher than those of control birds. In summary, territorial aggression triggered hormonal pathways differentially depending on the stage of the breeding cycle, but equally altered their ratio independent of it. Our results indicate that multiple related hormones could be playing a role rather than each hormone alone in response to social interactions.

The development of a testosterone stimulation test in the Virginia opossum (Didelphis virginiana) and its use in evaluating deslorelin contraception

2008 ◽  
Vol 20 (5) ◽  
pp. 563 ◽  
Author(s):  
S. D. Johnston ◽  
F. C. Camacho ◽  
L. Carrillo ◽  
N. Guy ◽  
J. Govea ◽  
...  
Keyword(s):  
Cell Types ◽  
Didelphis Virginiana ◽  
Stimulation Test ◽  
Plasma Testosterone ◽  
Sperm Production ◽  
Testosterone Secretion ◽  
Gonadotrophin Releasing Hormone ◽  
Testicular Histology ◽  
Virginia Opossum ◽  
And Control

The aims of the present study were to examine the variability of testosterone secretion in the Virginia Opossum over a 24 h period and to develop a testosterone stimulation test that would provide an index of the prevailing testosterone biosynthetic capacity of the testes; the latter was used to clinically evaluate the efficacy of a gonadotrophin-releasing hormone agonist contraceptive. Sexually-mature captive opossums (n = 12) located in Africam Safari (Mexico) sampled every 12 h over 24 h consistently showed basal (<0.21 ng mL–1) blood testosterone concentrations. Intra-muscular injection of buserelin (2 μg mL–1) and human chorionic gonadotrophin (hCG; 1000 IU) resulted in an increase (P < 0.05) of plasma testosterone concentrations with maximal concentrations (3.9 ng mL–1 and 5.8 ng mL–1 respectively) occurring 120 min after injection. Plasma testosterone declined relatively rapidly to basal concentrations after 240 min with hCG but remained elevated after the same period of time with buserelin. Male opossums treated with (n = 6) and without (n = 6) a controlled-release deslorelin implant (Suprelorin; 4.7 mg deslorelin) were evaluated over a 10-week period for changes in testosterone secretion (hCG stimulation test) and sperm production (spermatorrhea). At the end of this period, the animals were hemi-castrated and their relative testicular quantitative histology compared. Testosterone concentration decreased over the course of the study in both treated and control animals (P < 0.0001) but there was no apparent effect of deslorelin on testosterone secretion, testicular histology (relative proportions of testicular cell types and seminiferous tubule diameter), or sperm production (presence of sperm in the cauda epididymis or urine)

Effects of cadmium chloride administration on the testicular growth and plasma testosterone secretion of Chios ram-lambs

2003 ◽  
Vol 49 (1) ◽  
pp. 51-60 ◽  
Author(s):  
A.G. Lymberopoulos ◽  
V.-P. Kotsaki-Kovatsi ◽  
N. Papaioannou ◽  
A. Taylor ◽  
P. Brikas ◽  
...  
Keyword(s):  
Cadmium Chloride ◽  
Plasma Testosterone ◽  
Testosterone Secretion ◽  
Testicular Growth ◽  
Ram Lambs
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