Ovarian Hormones Influence Territorial Aggression in Free-Living Female Mountain Spiny Lizards

1999 ◽  
Vol 35 (3) ◽  
pp. 205-214 ◽  
Author(s):  
Sarah K. Woodley ◽  
Michael C. Moore
Keyword(s):  
Ovarian Hormones ◽  
Free Living ◽  
Territorial Aggression

scholarly journals Progesterone modulates aggression in sex-role reversed female African black coucals

2008 ◽  
Vol 275 (1638) ◽  
pp. 1053-1060 ◽  
Author(s):  
Wolfgang Goymann ◽  
Andrea Wittenzellner ◽  
Ingrid Schwabl ◽  
Musa Makomba
Keyword(s):  
Aggressive Behaviour ◽  
Sex Role ◽  
Bird Species ◽  
General Mechanism ◽  
Hormonal Changes ◽  
Free Living ◽  
Experimental Conditions ◽  
Resource Defence ◽  
Territorial Aggression ◽  
African Black

Testosterone is assumed to be the key hormone related to resource-defence aggression. While this role has been confirmed mostly in the context of reproduction in male vertebrates, the effect of testosterone on the expression of resource-defence aggression in female vertebrates is not so well established. Furthermore, laboratory work suggests that progesterone inhibits aggressive behaviour in females. In this study, we investigated the hormonal changes underlying territorial aggression in free-living female African black coucals, Centropus grillii (Aves; Cuculidae). Females of this sex-role reversed polyandrous bird species should be particularly prone to be affected by testosterone because they aggressively defend territories similar to males of other species. We show, however, that territorial aggression in female black coucals is modulated by progesterone. After aggressive territorial challenges female black coucals expressed lower levels of progesterone than unchallenged territorial females and females without territories, suggesting that progesterone may suppress territorial aggression and is downregulated during aggressive encounters. Indeed, females treated with physiological concentrations of progesterone were less aggressive than females with placebo implants. This is one of the first demonstrations of a corresponding hormone–behaviour interaction under challenged and experimental conditions in free-living females. We anticipate that our observation in a sex-role reversed species may provide a more general mechanism, by which progesterone—in interaction with testosterone—may regulate resource-defence aggression in female vertebrates.

scholarly journals Testosterone induces plumage ornamentation followed by enhanced territoriality in a female songbird

2020 ◽  
Vol 31 (5) ◽  
pp. 1233-1241 ◽  
Author(s):  
Jordan Boersma ◽  
Erik D Enbody ◽  
John Anthony Jones ◽  
Doka Nason ◽  
Elisa Lopez-Contreras ◽  
...  
Keyword(s):  
Territorial Behavior ◽  
Free Living ◽  
Territory Defense ◽  
Testosterone Treatment ◽  
Territorial Aggression ◽  
Proximate Mechanisms ◽  
Active Life ◽  
Pretreatment Period ◽  
Territorial Behaviors ◽  
Partial Acquisition

Abstract We know little of the proximate mechanisms underlying the expression of signaling traits in female vertebrates. Across males, the expression of sexual and competitive traits, including ornamentation and aggressive behavior, is often mediated by testosterone. In the white-shouldered fairywren (Malurus alboscapulatus) of New Guinea, females of different subspecies differ in the presence or absence of white shoulder patches and melanic plumage, whereas males are uniformly ornamented. Previous work has shown that ornamented females circulate more testosterone and exhibit more territorial aggression than do unornamented females. We investigated the degree to which testosterone regulates the expression of ornamental plumage and territorial behavior by implanting free-living unornamented females with testosterone. Every testosterone-treated female produced a male-like cloacal protuberance, and 15 of 20 replaced experimentally plucked brown with white shoulder patch feathers but did not typically produce melanic plumage characteristic of ornamented females. Testosterone treatment did not elevate territorial behavior prior to the production of the plumage ornament or during the active life of the implant. However, females with experimentally induced ornamentation, but exhausted implants, increased the vocal components of territory defense relative to the pretreatment period and also to testosterone-implanted females that did not produce ornamentation. Our results suggest that testosterone induces partial acquisition of the ornamental female plumage phenotype and that ornament expression, rather than testosterone alone, results in elevations of some territorial behaviors.

Androgens and Mating Systems: Testosterone-induced Polygyny in Normally Monogamous Birds

The Auk ◽  
1984 ◽  
Vol 101 (4) ◽  
pp. 665-671 ◽  
Author(s):  
John C. Wingfield
Keyword(s):  
Reproductive Cycle ◽  
Plasma Levels ◽  
Mating Systems ◽  
Courtship Behavior ◽  
Hormone Secretion ◽  
Free Living ◽  
Hormonal Profile ◽  
Territorial Aggression ◽  
Monogamous Species ◽  
Circulating Levels

Abstract Recent investigations of the plasma profiles of testosterone (T) in free-living birds suggest that circulating levels of T during the reproductive cycle remain elevated longer in males of polygynous species than in males of monogamous species. When the hormonal profile of polygynous males is mimicked by the administration of subcutaneous implants of T to males of monogamous species, thus maintaining plasma levels of this androgen at high vernal levels, frequencies of territorial aggression and courtship behavior remain elevated, resulting in a marked increase in the size of the territory. A substantial number of T-implanted males also become polygynous, attracting two and sometimes three females to settle on their enlarged territories. These data suggest strongly that the nature of avian mating systems is regulated proximately by temporal patterns of hormone secretion.

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.

scholarly journals Testosterone induces a female ornament followed by enhanced territoriality in a tropical songbird

2020 ◽  
Author(s):  
Jordan Boersma ◽  
Erik D. Enbody ◽  
John Anthony Jones ◽  
Doka Nason ◽  
Elisa Lopez-Contreras ◽  
...  
Keyword(s):  
Territorial Behavior ◽  
Similar Function ◽  
Free Living ◽  
Territory Defense ◽  
Territorial Aggression ◽  
Proximate Mechanisms ◽  
Naturally Occurring ◽  
Female Ornament ◽  
Empirical Tests ◽  
Partial Acquisition

ABSTRACTWe know little of the proximate mechanisms underlying expression of signaling traits in female vertebrates. Across males the expression of sexual and competitive traits, including ornamentation and aggressive behavior, is often mediated by testosterone. In the White-shouldered Fairywren (Malurus alboscapulatus) of New Guinea, females of different subspecies differ in presence or absence of white shoulder patches and melanic plumage, while males are uniformly ornamented. Previous work has shown that ornamented females circulate more testosterone and exhibit more territorial aggression than do unornamented females. We investigated the degree to which testosterone regulates expression of ornamental plumage and territorial behavior by implanting free-living unornamented females with testosterone. Every testosterone-treated female produced a male-like cloacal protuberance, and 15 of 20 replaced plucked brown feathers with white shoulder patch feathers, but did not produce melanic plumage characteristic of ornamented females. Testosterone treatment did not elevate territorial behavior prior to production of the plumage ornament and exhaustion of the implant. However, females with experimentally induced ornamentation, but exhausted implants, increased the vocal components of territory defense relative to fully unornamented control and also to testosterone-implanted females. Our results suggest that testosterone induces partial acquisition of the ornamental plumage phenotype, and that ornament expression, rather than testosterone alone, results in elevated territorial behavior.Lay SummaryTestosterone regulates expression of a suite of competitive traits in male organisms and could have similar function in females. Empirical tests are needed to determine the extent to which testosterone promotes production of ornamentation and competitive behaviors in female animals. We supplemented testosterone in unornamented females of a species where naturally occurring ornamented females circulate higher testosterone and are more territorially aggressive. Implanted females produced partial ornamentation, which was followed by increased territoriality that was apparently unrelated to testosterone circulation itself.

Ultrastructure of neuromuscular relationships in the canine heartworm (dirofilaria immitis)

1986 ◽  
Vol 44 ◽  
pp. 278-279
Author(s):  
W. L. Steffens ◽  
Nancy B. Roberts ◽  
J. M. Bowen
Keyword(s):  
Dirofilaria Immitis ◽  
Domestic Dogs ◽  
Structural Description ◽  
Pharmacological Effects ◽  
Free Living ◽  
Canine Heartworm ◽  
The World ◽  
Synaptic Region ◽  
Muscle Innervation ◽  
Insight Into

The canine heartworm is a common and serious nematode parasite of domestic dogs in many parts of the world. Although nematode neuroanatomy is fairly well documented, the emphasis has been on sensory anatomy and primarily in free-living soil species and ascarids. Lee and Miller reported on the muscular anatomy in the heartworm, but provided little insight into the peripheral nervous system or myoneural relationships. The classical fine-structural description of nematode muscle innervation is Rosenbluth's earlier work in Ascaris. Since the pharmacological effects of some nematacides currently being developed are neuromuscular in nature, a better understanding of heartworm myoneural anatomy, particularly in reference to the synaptic region is warranted.

Sign in / Sign up

Export Citation Format

Share Document