Homogeneity of intrinsic properties of sexually dimorphic vocal motoneurons in male and female zebra finches

Ablation of hypothalamic AgRP (Agouti-related protein) neurons is known to lead to fatal anorexia, whereas their activation stimulates voracious feeding and suppresses other motivational states including fear and anxiety. Despite the critical role of AgRP neurons in bidirectionally controlling feeding, there are currently no therapeutics available specifically targeting this circuitry. The melanocortin-3 receptor (MC3R) is expressed in multiple brain regions and exhibits sexual dimorphism of expression in some of those regions in both mice and humans. MC3R deletion produced multiple forms of sexually dimorphic anorexia that resembled aspects of human anorexia nervosa. However, there was no sexual dimorphism in the expression of MC3R in AgRP neurons, 97% of which expressed MC3R. Chemogenetic manipulation of arcuate MC3R neurons and pharmacologic manipulation of MC3R each exerted potent bidirectional regulation over feeding behavior in male and female mice, whereas global ablation of MC3R-expressing cells produced fatal anorexia. Pharmacological effects of MC3R compounds on feeding were dependent on intact AgRP circuitry in the mice. Thus, the dominant effect of MC3R appears to be the regulation of the AgRP circuitry in both male and female mice, with sexually dimorphic sites playing specialized and subordinate roles in feeding behavior. Therefore, MC3R is a potential therapeutic target for disorders characterized by anorexia, as well as a potential target for weight loss therapeutics.

Download Full-text

Gynandromorphs and intersexes: potential to understand the mechanism of sex determination in arthropods

Terrestrial Arthropod Reviews ◽

10.1163/187498310x496190 ◽

2010 ◽

Vol 3 (1) ◽

pp. 63-96 ◽

Cited By ~ 37

Author(s):

Rodrigo Pereira ◽

Satoko Narita ◽

Daisuke Kageyama ◽

Finn Kjellberg

Keyword(s):

Sex Chromosome ◽

Morphological Characters ◽

The Other ◽

Sexually Dimorphic ◽

Double Fertilization ◽

Low Frequencies ◽

Causal Factors ◽

Male And Female ◽

Sexual Phenotype ◽

Laboratory Populations

AbstractArthropods are sexually dimorphic. An arthropod individual usually differentiates into a male or a female. With very low frequencies, however, individuals with both male and female morphological characters have repeatedly been found in natural and laboratory populations of arthropods. Gynandromorphs (i.e., sexual mosaics) are genetically chimeric individuals consisting of male and female tissues. On the other hand, intersexes are genetically uniform (i.e., complete male, complete female or intermediate in every tissue) but all or some parts of their tissues have either a sexual phenotype opposite to their genetic sex or an intermediate sexual phenotype. Possible developmental processes (e.g., double fertilization of a binucleate egg, loss of a sex chromosome or upregulation/downregulation of sex-determining genes) and causal factors (e.g., mutations, genetic incompatibilities, temperatures or endosymbionts) for the generation of gynandromorphs and intersexes are reviewed and discussed.

Download Full-text

Heightened condition dependent expression of structural colouration in the faces, but not wings, of male and female flies

Current Zoology ◽

10.1093/cz/zoab087 ◽

2021 ◽

Author(s):

Thomas E White ◽

Amy Locke ◽

Tanya Latty

Keyword(s):

Mate Choice ◽

Condition Dependence ◽

Sexually Dimorphic ◽

Male And Female ◽

Honest Signals ◽

Mutual Mate Choice ◽

Close Range ◽

Males And Females ◽

Structural Colouration

Abstract Structurally coloured sexual signals are a conspicuous and widespread class of ornament used in mate choice, though the extent to which they encode information on the quality of their bearers is not fully resolved. Theory predicts that signalling traits under strong sexual selection as honest indicators should evolve to be more developmentally integrated and exaggerated than nonsexual traits, thereby leading to heightened condition dependence. Here we test this prediction through examination of the sexually dimorphic faces and wings of the cursorial fly Lispe cana. Males and females possess structural UV-white and golden faces, respectively, and males present their faces and wings to females during close-range, ground-based courtship displays, thereby creating the opportunity for mutual inspection. Across a field-collected sample of individuals, we found that the appearance of the faces of both sexes scaled positively with individual condition, though along separate axes. Males in better condition expressed brighter faces as modelled according to conspecific flies, whereas condition scaled with facial saturation in females. We found no such relationships for their wing interference pattern nor abdomens, with the latter included as a nonsexual control. Our results suggest that the structurally coloured faces, but not the iridescent wings, of male and female Lispe cana are reliable guides to individual quality and support the broader potential for structural colours as honest signals. They also highlight the potential for mutual mate choice in this system, while arguing for one of several alternate signalling roles for wing interferences patterns among the myriad taxa which bear them.

Download Full-text

Performance, but not size, of hindleg weaponry is sexually dimorphic in the giant mesquite bug (Thasus neocalifornicus)

10.1101/2020.08.03.234385 ◽

2020 ◽

Cited By ~ 1

Author(s):

Zackary A. Graham ◽

Nicole Kaiser ◽

Alexandre V. Palaoro

Keyword(s):

Sexual Dimorphism ◽

Muscle Mass ◽

Sexually Dimorphic ◽

Aggressive Interaction ◽

Body Parts ◽

Single Measure ◽

Male And Female ◽

Aggressive Interactions ◽

Sexual Dimorphisms

ABSTRACTIn many species, males possess specialized weaponry that have evolved to confer a benefit during aggressive interactions. Because male weaponry is typically an exaggerated or extreme version of pre-existing body parts, females often possess reduced or weaponry. Although much research has investigated sexual dimorphism in the sizes of such weapons, other weapon components, such as weapon performance or alternative weapon forms can also explain the evolution of weapon sexual dimorphisms. Here, we investigated the allometry and variation of multiple weapon components of hindleg weaponry in the male and female giant mesquite bugs, Thasus necalifornicus. Despite theory predicating greater allocation in male weaponry, we found that females allocated more into the lengths of their hindlegs compared to males. Despite this allocation, males possess relatively wider hindlegs, which likely increase area of muscle mass. Indeed, the squeezing performance of male hindlegs was much greater than that of female hindlegs. Lastly, we also described the allometry and variation in a male weapon component, prominent tibial spines, which likely are used to damage competitors during aggressive interaction. Overall, our findings highlight the intricacies of weapon sexual dimorphism and demonstrate the importance of measuring multiple weapon components and not a single measure.

Download Full-text

Sex differences in the development and expression of a preference for familiar vocal signals in songbirds

PLoS ONE ◽

10.1371/journal.pone.0243811 ◽

2021 ◽

Vol 16 (1) ◽

pp. e0243811

Author(s):

Tomoko G. Fujii ◽

Maki Ikebuchi ◽

Kazuo Okanoya

Keyword(s):

Vocal Response ◽

Multiple Time ◽

Sexually Dimorphic ◽

Male And Female ◽

Young Males ◽

Courtship Signal ◽

Selective Approach ◽

Multiple Time Points ◽

Early Developmental ◽

Higher Sensitivity

Production and perception of birdsong critically depends on early developmental experience. In species where singing is a sexually dimorphic trait, early life song experience may affect later behavior differently between sexes. It is known that both male and female songbirds acquire a life-long memory of early song experience, though its function remains unclear. In this study, we hypothesized that male and female birds express a preference for their fathers’ song, but do so differently depending on the developmental stage. We measured preference for their father’s song over an unfamiliar one in both male and female Bengalese finches at multiple time points across ontogeny, using phonotaxis and vocal response as indices of preference. We found that in males, selective approach to their father’s song decreased as they developed while in females, it remained stable regardless of age. This may correspond to a higher sensitivity to tutor song in young males while they are learning and a retained sensitivity in females because song is a courtship signal that is used throughout life. In addition, throughout development, males vocalized less frequently during presentation of their father’s song compared to unfamiliar song, whereas females emitted more calls to their father’s song. These findings contribute to a deeper understanding of why songbirds acquire and maintain such a robust song memory.

Download Full-text

Sexually dimorphic SCAMP1 expression in the forebrain motor pathway for song production of juvenile zebra finches

Developmental Neurobiology ◽

10.1002/dneu.20354 ◽

2007 ◽

Vol 67 (4) ◽

pp. 474-482 ◽

Cited By ~ 14

Author(s):

Yu Ping Tang ◽

Camilla Peabody ◽

Michelle L. Tomaszycki ◽

Juli Wade

Keyword(s):

Sexually Dimorphic ◽

Zebra Finches ◽

Motor Pathway ◽

Song Production

Download Full-text

Cross-sexual Transfer

Developmental Plasticity and Evolution ◽

10.1093/oso/9780195122343.003.0021 ◽

2003 ◽

Author(s):

Mary Jane West-Eberhard

Keyword(s):

Sex Determination ◽

Sexually Dimorphic ◽

Male And Female ◽

Alternative Phenotypes ◽

Opposite Sex ◽

Critical Age ◽

Sexual Traits ◽

Discrete Traits ◽

Dimorphic Species ◽

Determination Mechanism

Distinctive male and female traits are perhaps the most familiar of all divergent specializations within species. In cross-sexual transfer, discrete traits that are expressed exclusively in one sex in an ancestral species appear in the opposite sex of descendants. An example is the expression of brood care by males in a lineage where ancestral females are the exclusive caretakers of the young, as in some voles (Thomas and Birney, 1979). Despite the prominence of sexual dimorphism and sex reversals in nature, and an early explicit treatment by Darwin, discussed in the next section, cross-sexual transfer is not often recognized as a major factor in the evolution of novelty (but see, on animals, Mayr, 1963, pp. 435-439; Mayr, 1970, p. 254; on plants, Iltis, 1983). When more widely investigated, cross-sexual transfer may prove to rival heterochrony and duplication as an important source of novelties in sexually dimorphic lineages. For this reason, I devote more attention here to cross-sexual transfer than to these other, well-established general patterns of change. The male and female of a sexually dimorphic species may be so different that it is easy to forget that each individual carries most or all of the genes necessary to produce the phenotype of the opposite sex. Sex determination, like caste determination and other switches between alternative phenotypes, depends on only a few genetic loci or, in many species, environmental factors (Bull, 1983). There is considerable flexibility in sex determination and facultative reversal in some taxa. Among fish, for example, there is even a species wherein sex is determined by juvenile size at a critical age (Francis and Barlow, 1993). The sex determination mechanism, whatever its nature, leads to a series of sex-limited responses, often coordinated by hormones and not necessarily all occurring at once. A distinguishing aspect of sexually dimorphic traits in adults is that there is often a close homology between the secondary sexual traits that are differently modified in the two sexes.

Download Full-text