Static allometry suggests female ornaments in the long-tailed dance fly (Rhamphomyia longicauda) are not deceptive

2021 ◽  
Author(s):  
Jessica H Browne ◽  
Darryl T. Gwynne
Keyword(s):  
Body Size ◽  
Prey Capture ◽  
Hind Femur ◽  
Positive Allometry ◽  
Female Ornamentation ◽  
Female Ornaments ◽  
Ornamental Traits ◽  
Steep Slopes ◽  
Dance Fly ◽  
Static Allometry

Abstract Despite their prevalence in nature, the evolution of sex-specific female ornaments is still not well understood. Although in some cases (often carotenoid-based ornaments) they appear to honestly signal quality, such as fecundity, it has been suggested that some female ornaments have evolved to deceptively to obtain matings. We address these two hypotheses in the long-tailed dance fly ( Rhamphomyia longicauda ), where females possess two sex-specific ornaments: pinnate scales on the hind femur and tibia and abdominal sacs that are inflated in female-biased display swarms. Although several studies have suggested that female ornaments in this species are deceptive, evidence is mixed and requires further investigation. Here, we use static allometry (with body size as a proxy for condition) of both ornamental and non-ornamental traits in females (and homologous non-ornamental traits in males) in order to determine whether they are honest or deceptive signals of quality. Most male traits scaled isometrically with body size, however male leg hairs showed positive static allometry, probably because they are involved in nuptial-prey capture or in grasping mates. Ornamental traits in females (abdomen area and tibia scale length) showed significant positive allometry and had steep slopes relative to non-ornamental traits. As larger females invest more in ornamentation relative to smaller females, this suggests that these traits are likely honest, condition-dependent signals of quality. We note that honesty and deception are not mutually exclusive hypotheses. Individuals may vary in their signalling strategy, resulting in, for example, deception from some low condition individuals but honesty overall. Although our finding of positive allometry makes it unlikely this occurs in long tailed dance flies, simultaneous honesty and deception should be considered in future studies of female ornamentation.

scholarly journals Why the Static Allometry of Sexually-Selected Traits Is So Variable: The Importance of Function

2019 ◽  
Vol 59 (5) ◽  
pp. 1290-1302 ◽  
Author(s):  
Rafael Lucas Rodríguez ◽  
William G Eberhard
Keyword(s):  
Body Size ◽  
Body Part ◽  
Positive Allometry ◽  
Large Structures ◽  
Sexually Selected Traits ◽  
Body Sizes ◽  
Selected Traits ◽  
Courtship Signals ◽  
Aggressive Signals ◽  
Static Allometry

AbstractSexually-selected traits often show positive static allometry, with large individuals bearing disproportionately large structures. But many other sexually-selected traits show isometry or even negative allometry, with trait size varying relatively little with body size. We recently proposed that the functions of these traits (as aggressive signals, weapons, courtship signals, and contact courtship devices) determine their allometries. Positive allometry is generally favored for aggressive signals because aggressive signals are selected to emphasize body size (and thus fighting prowess). In contrast, the biomechanics of force application in weapons only sometimes select for positive allometry; the content of courtship signals is even less often related to body size; and contact courtship devices are selected to be relatively invariant across body sizes. Here we summarize the arguments in favor of this “functional allometry” hypothesis and expand a comparative test of its predictions. Our results indicate that sexual traits have the allometric slopes predicted by our hypothesis, regardless of which body part bears the structure.

scholarly journals Female ornamentation and the fecundity trade-off in a sex-role reversed pipefish

2018 ◽  
Author(s):  
Kenyon B. Mobley ◽  
John R. Morrongiello ◽  
Matthew Warr ◽  
Diane Bray ◽  
Bob B. M. Wong
Keyword(s):  
Body Size ◽  
Egg Size ◽  
Sex Role ◽  
Relative Fitness ◽  
Reproductive Value ◽  
Female Fecundity ◽  
Body Width ◽  
Trade Off ◽  
Female Ornamentation ◽  
Female Ornaments

AbstractFemale ornaments are a rare occurrence in nature. One explanation for this is that female ornaments are costly to produce and maintain and, therefore, females must trade-off resources related to reproduction to promote ornament expression. Here, we investigate the potential trade-off between female ornamentation and fecundity in the sex-role reversed, wide-bodied pipefish, Stigmatopora nigra. We measured two components of the female ornament, body width and stripe thickness, and tested the relationship between these ornaments and female fecundity and the mean egg size. Both body width and stripe thickness were strongly and positively related to female body size. After controlling for the influence of body size, we found no evidence of a cost of belly width or stripe thickness on female fecundity. Rather, females that have larger ornaments have higher fecundity and thus a greater relative fitness advantage. However, larger females suffered a slight decrease in egg size, consistent with a potential trade-off between egg size and body size, although no relationship between egg size and ornaments was observed. Our results suggest that larger S. nigra females accurately advertise their reproductive value to males, and underscore the importance of investigating the potential mechanisms that promote and maintain honesty of female ornaments.

Allometry of secondary, primary, and nonsexual traits in the beautiful demoiselle (Calopteryx virgo meridionalis)

2012 ◽  
Vol 90 (9) ◽  
pp. 1094-1101 ◽  
Author(s):  
D. Outomuro ◽  
A. Cordero-Rivera
Keyword(s):  
Body Size ◽  
Functional Significance ◽  
Spot Size ◽  
The Body ◽  
Shaft Length ◽  
Positive Allometry ◽  
Selective Pressures ◽  
Functional Knowledge ◽  
Significant Regression ◽  
Static Allometry

The static allometry between the size of a trait and the body size results from the net selection forces acting on the evolution of both the trait and the body size. An increased knowledge of the functional significance of traits is necessary to understand observed allometric patterns. We studied several traits of males of the beautiful demoiselle ( Calopteryx virgo meridionalis Sélys, 1873), for which there is a good functional knowledge of the genitalic traits and ornaments. We found positive allometry for the wing spot size (considered a secondary sexual trait) and for the distal width (but not length) of the anal appendages, which are used for grasping the female prior to copulation. Regarding the male secondary genitalia, the length but not the width of the big horns of the aedeagus showed an isometric pattern. The aedeagus shaft length showed a negative allometric pattern, while its distal width did not show a significant regression. The slopes of the regressions were higher when using wing length than when using body length as estimators of body size, with the exception of wing spot length. Results are discussed based on the functional significance of the study traits, as well as the pre- and post-copulatory selective pressures acting on them.

Allometry and Paleoecology of Medial Miocene Dwarf Rhinoceroses from the Texas Gulf Coastal Plain

Paleobiology ◽  
1982 ◽  
Vol 8 (1) ◽  
pp. 16-30 ◽  
Author(s):  
Donald R. Prothero ◽  
Paul C. Sereno
Keyword(s):  
Body Size ◽  
Coastal Plain ◽  
Sympatric Species ◽  
High Plains ◽  
Gulf Coastal Plain ◽  
Canine Tooth ◽  
Positive Allometry ◽  
Mammalian Faunas ◽  
The Common ◽  
Limb Proportions

Barstovian (medial Miocene) mammalian faunas from the Texas Gulf Coastal Plain contained four apparently sympatric species of rhinoceroses: the common forms Aphelops megalodus and Teleoceras medicornutus, a dwarf Teleoceras, and a dwarf Peraceras. Previous work has suggested positive allometry in tooth area with respect to body size in several groups of mammals, i.e., larger mammals have relatively more tooth area. However, dwarfing lineages were shown to have relatively more tooth area for their body size. Our data show no significant allometry in post-canine tooth area of either artiodactyls or ceratomorphs. Similarly, dwarf rhinoceroses and hippopotami show no more tooth area than would be predicted for their size. Limbs are proportionately longer and more robust in larger living ceratomorphs (rhinos and tapirs) than predicted by previous authors. Limb proportions of both dwarf rhinoceroses and dwarf hippopotami are even more robust than in their living relatives.The high rhinoceros diversity reflects the overall high diversity of Barstovian faunas from the Texas Gulf Coastal Plain. The first appearance of several High Plains mammals in these faunas indicates “ecotone”-like conditions as faunal composition changed. Study of living continental dwarfs shows that there is commonly an ecological separation between browsing forest dwarfs and their larger forebears, which are frequently savannah grazers. This suggests that the dwarf rhinoceroses might have been forest browsers which were sympatric with the larger grazing rhinos of the High Plains during the Barstovian invasion. The continental dwarf model also suggests that insular dwarfism may be explained by the browsing food resources that predominate on islands.

scholarly journals Estimating maximum bite performance in Tyrannosaurus rex using multi-body dynamics

2012 ◽  
Vol 8 (4) ◽  
pp. 660-664 ◽  
Author(s):  
K. T. Bates ◽  
P. L. Falkingham
Keyword(s):  
Body Size ◽  
Feeding Behaviour ◽  
Ontogenetic Change ◽  
Positive Allometry ◽  
Musculoskeletal Models ◽  
Terrestrial Animal ◽  
Body Dynamics ◽  
Mode Of Life ◽  
Scaling Analyses ◽  
Multi Body

Bite mechanics and feeding behaviour in Tyrannosaurus rex are controversial. Some contend that a modest bite mechanically limited T. rex to scavenging, while others argue that high bite forces facilitated a predatory mode of life. We use dynamic musculoskeletal models to simulate maximal biting in T. rex . Models predict that adult T. rex generated sustained bite forces of 35 000–57 000 N at a single posterior tooth, by far the highest bite forces estimated for any terrestrial animal. Scaling analyses suggest that adult T. rex had a strong bite for its body size, and that bite performance increased allometrically during ontogeny. Positive allometry in bite performance during growth may have facilitated an ontogenetic change in feeding behaviour in T. rex , associated with an expansion of prey range in adults to include the largest contemporaneous animals.

scholarly journals Scaling the feeding mechanism of the largemouth bass (Micropterus salmoides): motor pattern

1995 ◽  
Vol 198 (5) ◽  
pp. 1161-1171 ◽  
Author(s):  
P Wainwright ◽  
B Richard
Keyword(s):  
Body Size ◽  
Largemouth Bass ◽  
Standard Length ◽  
Prey Capture ◽  
Micropterus Salmoides ◽  
Motor Pattern ◽  
Onset Time ◽  
Small Fish ◽  
Scaling Effects ◽  
Emg Signal

We present the first analysis of scaling effects on the motor pattern of a feeding vertebrate. Data are presented for the effects of body size on the pattern of activity in four head muscles during prey capture in the largemouth bass, Micropterus salmoides. Electromyographic (EMG) recordings were made from three expansive-phase muscles (the epaxialis, the sternohyoideus and the levator arcus palatini) and one compressive-phase muscle (the adductor mandibulae), during the capture of small fish prey. Recordings were made of 181 prey-capture events from 19 bass that ranged in size from 83 to 289 mm standard length. We measured seven variables from the myogram of each capture to quantify the temporal pattern of muscle activation, including the duration of activity in each muscle and the onset time of each muscle, relative to the onset of the sternohyoideus muscle. Regressions of the mean value of each variable for the 19 individuals on standard length revealed that only the onset time of the adductor mandibulae changed with fish body size. The increase in onset time of the adductor muscle appears to reflect the longer time taken to open the mouth fully in larger fish. Other research shows that the kinematics of the strike in this species slows significantly with increasing body size. The combined results indicate that the duration of the EMG signal is not directly correlated with the duration of force production in muscles when compared between fish of different sizes. The lack of scaling of burst duration variables suggests that the reduced speeds of prey-capture motion are explained not by changes in the envelope of muscle activity, but rather by the effects of scale on muscle contractile kinetics. These scaling effects may include changes in the relative resistance of the jaw and head structures to movement through water and changes in the intrinsic contractile properties of the muscles of the feeding apparatus.

Cranial morphology and ontogeny of the Permo-Carboniferous temnospondyl Archegosaurus decheni Goldfuss, 1847 from the Saar–Nahe Basin, Germany

2005 ◽  
Vol 96 (2) ◽  
pp. 131-162 ◽  
Author(s):  
Florian Witzmann
Keyword(s):  
Prey Capture ◽  
Three Dimensional ◽  
Nasolacrimal Duct ◽  
Larval Period ◽  
Cranial Morphology ◽  
Growth Stages ◽  
Ontogenetic Changes ◽  
Positive Allometry ◽  
Lateral Process ◽  
Different Growth Stages

ABSTRACTMorphology and ontogenetic changes in the skull and hyobranchium of the Permo-Carboniferous temnospondyl Archegosaurus decheni from the Saar–Nahe Basin (SW Germany) are described in detail, based on 181 skulls ranging from 18 to 279 mm in length. Three-dimensional skull reconstructions including the palate of different growth stages are provided. The extremely elongate choanae and up to four median symphyseal teeth are unique to A. decheni. Among neurocranial elements, the exoccipital is well ossified and forms the paroccipital process as in stereospondyls. The shaft of the stapes which projects into the squamosal embayment grows with positive allometry and possesses a distinct lateral process. The basibranchial is well ossified in adults and exhibits a complex, spoon-like morphology. Small larvae were euryphagous and used non-directed suction and jaw prehension during prey capture. Larger larvae and adults were mainly ichthyophagous, as is indicated by the increasingly elongated snout, differentiation of marginal teeth, and nutrition remains. After a prolonged larval period, juvenile and adult A. decheni remained in the aquatic habitat, as suggested by the presence of lateral line sulci, the ‘aquatic type’ of septomaxilla and choana, and the absence of a nasolacrimal duct.

scholarly journals Mother-Offspring Relations: Prey Quality and Maternal Size Affect Egg Size of an Acariphagous Lady Beetle in Culture

2012 ◽  
Vol 2012 ◽  
pp. 1-7
Author(s):  
Eric W. Riddick ◽  
Zhixin Wu
Keyword(s):  
Body Size ◽  
Egg Size ◽  
Lima Bean ◽  
Hind Femur ◽  
Spider Mites ◽  
Lady Beetle ◽  
High Rate ◽  
Phaseolus Lunatus ◽  
Maternal Size ◽  
Prey Quality

We investigated mother-offspring relations in a lady beetleStethorus punctillumWeise that utilizes spider mites as prey. Our objectives were to determine if (1) prey quality affects egg size, (2) maternal size correlates with egg size, and (3) egg size affects hatching success. We fed predators spider mitesTetranychus urticaeKoch from lima beanPhaseolus lunatusL. foliage in the laboratory. Mothers of unknown body size offered high rather than low quality spider mites since birth produced larger eggs. Mothers of known body size offered only high quality spider mites, produced eggs of variable size, but mean egg size correlated positively with hind femur length. Mothers laid their eggs singly, rather than in batches, and eggs were large relative to femur size. Egg size did not affect hatch success; mean hatch rate exceeded 95% regardless of egg size. In conclusion, the quality of prey consumed byS. punctillummothers while in the larval stage can affect their size as adults and, consequently, the size of their eggs. The behavior of laying eggs singly, the positive relationship between maternal size and mean egg size, and the high rate of egg hatch suggest thatS. punctillummothers invest heavily in offspring.

scholarly journals Experimental evidence that female ornamentation increases the acquisition of sperm and signals fecundity

2006 ◽  
Vol 274 (1609) ◽  
pp. 583-590 ◽  
Author(s):  
Charlie K Cornwallis ◽  
Tim R Birkhead
Keyword(s):  
Sexual Selection ◽  
Mate Choice ◽  
Sexual Partners ◽  
Male Mating ◽  
Female Ornamentation ◽  
Female Ornament ◽  
Female Ornaments ◽  
Sexual Ornamentation ◽  
Gain Access

Mate choice can lead to the evolution of sexual ornamentation. This idea rests on the assumption that individuals with more elaborate ornaments than competitors have higher reproductive success due to gaining greater control over mating decisions and resources provided by partners. Nevertheless, how the resources and quality of sexual partners that individuals gain access to are influenced by the ornamentation of rival individuals remains unclear. By experimentally concealing and subsequently revealing female ornaments to males, we confirm in the fowl, Gallus gallus , that female ornamentation influences male mating decisions. We further show, by manipulating the relative ornament size of females, that when females had larger ornaments than competitors they were more often preferred by males and obtained more sperm, especially from higher quality males, as measured by social status. Males may benefit by investing more sperm in females with larger ornaments as they were in better condition and produced heavier eggs. Female ornament size also decreased during incubation, providing a cue for males to avoid sexually unreceptive females. This study reveals how inter-sexual selection can lead to the evolution of female ornaments and highlights how the reproductive benefits gained from mate choice and bearing ornaments can be dependent upon social context.

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