Diving behaviour of male and female western grebes

1988 ◽  
Vol 66 (12) ◽  
pp. 2695-2698 ◽  
Author(s):  
L. Scott Forbes ◽  
Spencer G. Sealy
Keyword(s):  
British Columbia ◽  
Body Size ◽  
Water Depth ◽  
Wave Action ◽  
Diving Behaviour ◽  
Sexually Dimorphic ◽  
Habitat Conditions ◽  
Male And Female ◽  
Males And Females

We studied diving in western grebes (Aechmophorus occidentalis), which are sexually dimorphic, at Duck and Kootenay lakes in southeastern British Columbia to determine if differences in sex, and hence body size, resulted in differences in behaviour. Springing dives were used more frequently in deeper water and when wave action was higher, but there were no clear differences between males and females. As well, the dive–pause regressions for males and females did not differ. We conclude that differences in body size are not important determinants of diving behaviour in western grebes, but that habitat conditions (e.g., water depth, wave action) are.

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

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.

Fishery and Reproductive Cycle of the Red Sea Urchin, Strongylocentrotus franciscanus, in British Columbia

1977 ◽  
Vol 34 (5) ◽  
pp. 604-610 ◽  
Author(s):  
F. R. Bernard
Keyword(s):  
British Columbia ◽  
Body Size ◽  
Sex Ratio ◽  
Local Conditions ◽  
Strongylocentrotus Franciscanus ◽  
Male And Female ◽  
Glycogen Accumulation ◽  
Fishing Season ◽  
Gonadal Index ◽  
Red Sea Urchin

Gametogenesis and gonadal index undergo an annual cycle with minima in September and maxima in May for a population of red urchins, Strongylocentrotus franciscanus, from southwestern Vancouver Island. Postspawning recovery is rapid and there are no significant differences between male and female gonadal indices, but a small gonad to body-size correlation is evident. Gonadal index is not the product of gametogenesis, but is correlated to glycogen accumulation which may reach 13% gonad total weight. The fishing season for roe in southern British Columbia extends from October to April with several weeks variability depending on local conditions and weather. Yields constitute up to 25% total drained weight. Key words: urchins, fishery, gametogenesis, glycogen, hermaphroditism, sex ratio

Intersexual differences in chemosensory responses to selected lipids reveal different messages conveyed by femoral secretions of male Iberian rock lizards

2008 ◽  
Vol 29 (4) ◽  
pp. 572-578 ◽  
Author(s):  
Pilar López ◽  
José Martín
Keyword(s):  
Body Size ◽  
Social Behavior ◽  
Mate Choice ◽  
Tongue Flick ◽  
Secondary Sexual Traits ◽  
Male And Female ◽  
Males And Females ◽  
Sexual Traits ◽  
Chemical Traits ◽  
Femoral Secretions

AbstractThe effects of intrasexual selection (i.e., male-male competition) and intersexual selection (i.e., mate choice) may result on the evolution of different secondary sexual traits. We tested whether chemosensory responses of male and female Iberolacerta cyreni lizards to femoral secretion of conspecific males (a chemical sexual trait used in social behavior) were eliciting by different chemical traits. Tongue-flick essays showed that males and females had similar chemosensory responses to the femoral secretions of males, but males and females differed in the magnitude of their chemosensory responses to the different chemicals found in secretions. Moreover, responses to chemicals related to body size depended on the own body size of the responding male, but did not in females. These results might support that femoral secretions of males convey different messages for male or female I. cyreni lizards.

scholarly journals The status of Asthenopus Curtus (Hagen) (Ephemeroptera: Polymitarcyidae) ()

1978 ◽  
Vol 8 (1) ◽  
pp. 103-105 ◽  
Author(s):  
Lewis Berner
Keyword(s):  
Adult Male ◽  
Single Species ◽  
Sexually Dimorphic ◽  
Male And Female ◽  
The Status ◽  
Males And Females

Abstract Study of a series of reared adult male and female mayflies in the genus Asthenopus from the Amazon demonstrated that males had been described by Hagen as A. curtus and females as A. amazonicus. As only a single species is represented by the strongly sexually dimorphic males and females, all should be designated as A. curtus (Hagen) and A. amazonicus (Hagen) is, therefore, a synonym.

scholarly journals Correlates of reproductive success in a population of nine-banded armadillos

1998 ◽  
Vol 76 (10) ◽  
pp. 1815-1821 ◽  
Author(s):  
W J Loughry ◽  
Paulo A Prodöhl ◽  
Colleen M McDonough ◽  
W S Nelson ◽  
John C Avise
Keyword(s):  
Body Size ◽  
Reproductive Success ◽  
The Body ◽  
Birth Date ◽  
Dasypus Novemcinctus ◽  
Male And Female ◽  
Significant Relationships ◽  
Microsatellite Dna Markers ◽  
Body Sizes ◽  
Males And Females

We used microsatellite DNA markers to identify the putative parents of 69 litters of nine-banded armadillos (Dasypus novemcinctus) over 4 years. Male and female parents did not differ in any measure of body size in comparisons with nonparents. However, males observed paired with a female were significantly larger than unpaired males, although paired females were the same size as unpaired females. Females categorized as possibly lactating were significantly larger than females that were either definitely lactating or definitely not lactating. There was no evidence of assortative mating: body-size measurements of mothers were not significantly correlated with those of fathers. Nine-banded armadillos give birth to litters of genetically identical quadruplets. Mothers (but not fathers) of female litters were significantly larger than mothers of male litters, and maternal (but not paternal) body size was positively correlated with the number of surviving young within years, but not cumulatively. There were no differences in dates of birth between male and female litters, nor were there any significant relationships between birth date and maternal body size. Body size of either parent was not correlated with the body sizes of their offspring. Cumulative and yearly reproductive success did not differ between reproductively successful males and females. Average reproductive success (which included apparently unsuccessful individuals) also did not differ between males and females. The majority of adults in the population apparently failed to produce any surviving offspring, and even those that did usually did so in only 1 of the 4 years. This low reproductive success is unexpected, given the rapid and successful range extension of this species throughout the southeastern United States in this century.

Sexual dichromatism in the marbled salamander, Ambystoma opacum

2007 ◽  
Vol 85 (9) ◽  
pp. 1008-1013 ◽  
Author(s):  
Brian D. Todd ◽  
Andrew K. Davis
Keyword(s):  
Body Size ◽  
Surface Area ◽  
Relative Proportion ◽  
Dorsal Surface ◽  
Sexual Dichromatism ◽  
Sexually Dimorphic ◽  
Ambystoma Opacum ◽  
Males And Females ◽  
Marbled Salamander ◽  
Image Analysis Techniques

Reports of sexual dichromatism in salamanders are rare and have been generally restricted to a few species in the families Hynobiidae and Salamandridae. We used image analysis techniques to examine sexual dichromatism in the marbled salamander, Ambystoma opacum (Gravenhorst, 1807). We measured the average hue of white saddles on male and female marbled salamanders (n = 118), as well as the proportion of white dorsal surface area relative to the black dorsal surface area, to determine the extent of sexual dichromatism in this species. We also tested whether patterning and coloration were correlated with body size or relative body mass. Males had significantly whiter saddles and higher relative proportions of white coloration on their dorsal surfaces than did females. Furthermore, the relative proportion of white areas on the dorsum was positively correlated to body condition in both males and females. Body size was not correlated with hue or proportion of white area on the dorsum. To our knowledge, we report the first confirmation of sexually dimorphic coloration in the ambystomatid salamander family, extending the known distribution of sexual dichromatism in the order Caudata.

The link between sexual dimorphism, activity budgets, and group cohesion: the case of the plains zebra (Equus burchelli)

2002 ◽  
Vol 80 (8) ◽  
pp. 1437-1441 ◽  
Author(s):  
P Neuhaus ◽  
K E Ruckstuhl
Keyword(s):  
Body Size ◽  
Reproductive Status ◽  
Sexually Dimorphic ◽  
Time Budgets ◽  
Activity Budgets ◽  
Equus Burchelli ◽  
Lactating Females ◽  
Males And Females ◽  
Reproductive Females ◽  
Dimorphic Species

Animals that differ in reproductive status and body size have different needs in terms of foraging and resting. In most social ungulates this leads to sexual segregation, probably because of incompatibilities between the activity budgets of males and females. Since most studies on behavioural differences between the sexes have been done on sexually dimorphic species, we decided to look at a system in which males and females are similar in body size. We studied time budgets, synchrony of behaviour, and bite rates of plains zebras (Equus burchelli) to evaluate the factors that enable these extremely social ungulates to stay in stable mixed-sex family groups throughout the year. As we predicted, time budgets were similar among males, lactating females, pregnant females, and non-reproductive females. Furthermore, we observed close synchronization of behaviours between females that differed in reproductive status and males. Lactating females, however, did take more bites per minute when foraging than either pregnant or non-reproducing females or males. We assume that the higher bite rates of lactating females were due to the extra costs of producing milk for their foal. We concluded that the special harem mating system, and for females the year-round possibility of conceiving, force the animals to synchronize their time budgets, which might be a major reason for the lack of difference in body size between males and females.

Critical Swimming Speed of Fraser and Thompson River Pink Salmon (Oncorhynchus gorbuscha)

1987 ◽  
Vol 44 (2) ◽  
pp. 348-356 ◽  
Author(s):  
I. V. Williams ◽  
J. R. Brett
Keyword(s):  
British Columbia ◽  
Swimming Speed ◽  
Pink Salmon ◽  
Oncorhynchus Gorbuscha ◽  
Fraser River ◽  
Critical Swimming Speed ◽  
Pink Salmon Oncorhynchus Gorbuscha ◽  
Male And Female ◽  
Males And Females ◽  
River Fish

Critical swimming speeds were determined for male and female pink salmon (Oncorhynchus gorbuscha) captured from the Fraser and Thompson rivers and Seton Creek, British Columbia. The fish were categorized into two basic groups. Lower river fish were captured from the Fraser River at Fort Langley and Yale, and up-river fish were captured from the Thompson River at the Canyon and at Ashcroft and from Seton Creek near Lillooet, British Columbia. The critical swimming speeds of males and females in various stages of maturation were compared. In general, the up-river fish were stronger swimmers than the lower river fish. Gravid fish were stronger swimmers than spawning fish, which in turn were stronger swimmers than fish which were spawned out. Standardized critical swimming speeds ranged from a mean of 1.73 ± 0.35 (SE) body lengths/s for spawned females up to 3.39 ± 0.48 lengths/s for up-river gravid males.

scholarly journals Differences in Pelvic Fin Length Represent Sexual Dimorphism in Utah Chub (Gila atraria)

2014 ◽  
Vol 7 (1) ◽  
pp. 42-45 ◽  
Author(s):  
Mark C. Belk ◽  
Scott Bird ◽  
Mehmet Cemal Oguz ◽  
Jerald B. Johnson
Keyword(s):  
Body Size ◽  
Sexual Dimorphism ◽  
Cyprinid Fish ◽  
Sexually Dimorphic ◽  
Adaptive Function ◽  
Males And Females ◽  
The Difference ◽  
Sexually Mature ◽  
Fin Length ◽  
Pelvic Fin

The cyprinid fish Gila atraria Girard (Utah chub) is generally considered a sexually monomorphic species. However, prior observations revealed variation in pelvic fin length within populations that appears sexually dimorphic. We measured the relative pelvic fin length of 419 sexually mature Utah chub from 8 different locations to determine the magnitude and generality of this apparent dimorphism. Pelvic fin length in G. atraria differs between sexes by about 10% on average; males have longer pelvic fins than females. The dimorphism is general across all locations, but it is not related to body size. Magnitude of the dimorphism varies by predation environment – the difference between males and females is slightly greater in low predation environments. We find no evidence for an adaptive function for this dimorphism; however, it does provide an efficient mechanism for determining sex without dissection.

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

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

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.

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