Sexual dimorphism in size and plumage of the polyandrous Dotterel (Charadrius morinellus): sex roles and constraints on sexual selection

1988 ◽  
Vol 66 (6) ◽  
pp. 1334-1341
Author(s):  
John Atle Kålås
Keyword(s):  
Sexual Dimorphism ◽  
Wing Length ◽  
Pair Formation ◽  
Egg Laying ◽  
Published Data ◽  
Museum Specimens ◽  
Time Activity ◽  
Monogamous Species ◽  
First Clutch ◽  
Behaviour Data

Data on live birds and previously published data reveal that female Dotterel (Charadrius morinellus) were on average larger than males for all measurements. However, sexual dimorphism on the basis of size appears weaker than expected when Dotterel are compared with closely related monogamous species. Female museum specimens have less disrupted (brighter) plumage colours than males, and dimorphism in plumage is more pronounced than it is in size. A discriminant analysis based on plumage characters did not separate the sexes totally, however. Females moult earlier in the spring than males, but summer plumage is still not fully developed for all females by the first period of pair formation, suggesting that female plumage is most important in reproduction only after the first clutch is complete. No significant differences were evident in wing length and plumage colour between 1882–1917 and 1957–1982. Time–activity studies on the polyandrous Dotterel during the arrival, prelaying, and egg-laying periods showed small differences between the sexes in the amount of time devoted to agonistic and courtship behaviour. Data from prelaying periods showed no difference between the sexes as to who initiates bouts of courtship and agonistic behaviour. The behaviour of paired birds was highly synchronized. Three hypotheses on the slight sexual dimorphism in size and plumage of this polyandrous species are presented and discussed.

Relative testis size and mating systems in anurans: large testis in multiple-male mating in foam-nesting frogs

2011 ◽  
Vol 61 (2) ◽  
pp. 225-238 ◽  
Author(s):  
Wen Bo Liao ◽  
Zhi Ping Mi ◽  
Cai Quan Zhou ◽  
Ling Jin ◽  
Xian Han ◽  
...  
Keyword(s):  
Sperm Competition ◽  
Published Data ◽  
Male Mating ◽  
Data Sets ◽  
Testis Size ◽  
Data Set ◽  
Monogamous Species ◽  
Large Testis ◽  
Testes Size ◽  
Testis Mass

AbstractComparative studies of the relative testes size in animals show that promiscuous species have relatively larger testes than monogamous species. Sperm competition favours the evolution of larger ejaculates in many animals – they give bigger testes. In the view, we presented data on relative testis mass for 17 Chinese species including 3 polyandrous species. We analyzed relative testis mass within the Chinese data set and combining those data with published data sets on Japanese and African frogs. We found that polyandrous foam nesting species have relatively large testes, suggesting that sperm competition was an important factor affecting the evolution of relative testes size. For 4 polyandrous species testes mass is positively correlated with intensity (males/mating) but not with risk (frequency of polyandrous matings) of sperm competition.

scholarly journals Reproductive biology of Sympterygia bonapartii (Chondrichthyes: Rajiformes: Arhynchobatidae) in San Matías Gulf, Patagonia, Argentina

2017 ◽  
Vol 15 (1) ◽  
Author(s):  
María L. Estalles ◽  
María R. Perier ◽  
Edgardo E. Di Giácomo
Keyword(s):  
Sexual Dimorphism ◽  
Reproductive Biology ◽  
Early Spring ◽  
Egg Laying ◽  
Reproductive Pattern ◽  
Reproductive Parameters ◽  
Egg Capsules ◽  
Northern Patagonia ◽  
Total Length

ABSTRACT This study estimates and analyses the reproductive parameters and cycle of Sympterygia bonapartii in San Matías Gulf, northern Patagonia, Argentina. A total of 827 males and 1,299 females were analysed. Males ranged from 185 to 687 mm of total length (TL) and females from 180 to 742 mm TL. Sexual dimorphism was detected; females were larger, heavier, exhibited heavier livers, wider discs and matured at lager sizes than males. Immature females ranged from 180 to 625 mm TL, maturing females from 408 to 720 mm TL, mature ones from 514 to 742 mm TL and females with egg capsules from 580 to 730 mm TL. Immature males ranged from 185 to 545 mm TL, maturing ones from 410 to 620 mm TL and mature males from 505 to 687 mm TL. Size at which 50% of the skates reached maturity was estimated to be 545 mm TL for males and 594 mm TL for females. According to the reproductive indexes analysed, S. bonapartii exhibited a seasonal reproductive pattern. Mating may occur during winter-early spring and the egg-laying season, during spring and summer.

Breeding Cycle and Behavior of the Semipalmated Sandpiper at Barrow, Alaska

The Auk ◽  
1979 ◽  
Vol 96 (1) ◽  
pp. 56-67 ◽  
Author(s):  
Shoshana Ashkenazie ◽  
Uriel N. Safriel
Keyword(s):  
Home Range ◽  
Pair Formation ◽  
Egg Laying ◽  
Breeding Cycle ◽  
Male And Female ◽  
Semipalmated Sandpiper ◽  
The Family ◽  
Polygonal Area ◽  
Calidris Pusilla ◽  
And Behavior

Abstract Pair formation of Calidris pusilla near Barrow, Alaska occurs 3-6 days after the territory is established. The pair is then engaged in nest scraping displays during 2-3 days, in which 10-12 scrapes are made by the male and examined by the female. Eventually 2-3 scrapes are lined by the female, and in one of these the first egg is laid 4-6 days after pairing. During the egg-laying period further lining is performed by the female and partial incubation takes place by both sexes. Continuous incubation commences 8 h prior to laying of the 4th egg. Male and female alternate in incubation: in the first 2 days a turn lasts 3-5 h, and the duration gradually increases up to 13-14 h during the 2nd week. Long incubation turns reduce the number of approaches to the nest and may therefore reduce the chances of it being discovered by predators. The incubating bird is intermittently engaged in egg-rolling and in camouflaging the nest by bending adjacent grass blades over its back, and is constantly alert. The off-duty bird may feed 2-3 km away from the nest. The eggs hatch after 20 days of incubation, all within 1 day. Females desert the family 2-8 days after hatching: they desert late if hatching is early, and early if hatching is late in the season. After female departure the family moves from the nesting territory, typically in a high-centered polygonal area, to establish a home range as far as 2-3 km away, often in a low-centered polygonal area. During the first 6-8 days after hatching, the male prepares each evening a scrape for night brooding. After fledging, the male and young join wandering flocks.

Benefits of Courtship-Feeding for Rifleman (Acanthisitta Chloris) Parents

Behaviour ◽  
1989 ◽  
Vol 109 (3-4) ◽  
pp. 303-318 ◽  
Author(s):  
Greg Sherley
Keyword(s):  
Egg Laying ◽  
Early Season ◽  
Food Items ◽  
Total Food Intake ◽  
Energy Demands ◽  
Pair Bonds ◽  
Courtship Feeding ◽  
Total Food ◽  
First Clutch ◽  
Maintenance Requirements

Abstract1. Courtship-feeding was studied in riflemen (Acanthisitta chloris) in a population at Kaikoura, South Island, New Zealand between 1982 and 1984. The proportion of the food males collected which was donated to his mate was calculated and what proportion of the female's diet this represented. This information revealed that males made a significant early season contribution to parental care. 2. Allied information collected during the pre-lay and egg-laying periods included the time to form eggs, laying interval and clutch size. 3. Courtship-feeding in riflemen involved no ceremony. 4. Copulation attempts did not correspond with bouts courtship-feeding or the peak of courtship-feeding. 5. Pairs spent 91.2% of daylight hours in each other's company, which facilitated coursthip-feeding. 6. Food items delivered in courtship-feeding were significantly larger than those eaten by males or females while foraging for themselves, and larger food items were consistently offered throughout the pre-laying and egg-laying periods. 7. The peak in the volume of food delivered to the female occurred about 3.5 days after the first egg was laid. 8. Overall the male contributed 42% of the food he gathered to the female and this comprised 35% of her total food intake. 9. Females fed themselves enough food to meet maintenance requirements and the extra required for oogenesis was received from the male through courtship-feeding and any reserves stored by the female. 10. Riflemen laid eggs every 48 hours which probably reduced peak energy demands during oogenesis. 11. Courtship-feeding was not associated with second clutches which were significantly smaller than the first clutch laid and reared in a season. 12. Incubation occurred after the last egg was laid but was sometimes delayed. During the delay courtship-feeding continued until incubation started. 13. Courtship-feeding represents a significant early season investment by male riflemen in their offspring which probably allows time to rear two broods thereby improving both parents' productivity. Such early season investment might influence sexual selection towards stable, monogamous pair bonds.

Sexual dimorphism of the major chela and sex ratio as indicators of the mating system in the estuarine snapping shrimp Alpheus colombiensis Wicksten, 1988 (Decapoda: Caridea: Alpheidae)

2020 ◽  
Vol 40 (6) ◽  
pp. 649-656
Author(s):  
Juan C Azofeifa-Solano ◽  
Jeffrey A Sibaja-Cordero ◽  
Ingo S Wehrtmann
Keyword(s):  
Sexual Selection ◽  
Sexual Dimorphism ◽  
Sex Ratio ◽  
Mating System ◽  
Mate Guarding ◽  
Female Size ◽  
Monogamous Species ◽  
Low Degree ◽  
Adult Sex Ratio ◽  
Snapping Shrimps

Abstract The sexual selection over traits that favor access to mating partners could promote the emergence of sexual dimorphism when the pressure is different between sexes. Monogamous species are considered to have a low degree of sexual dimorphism. The highly diverse snapping shrimps are usually regarded as monogamous, but the mating system has been studied only in few species. We aimed to provide insights into the mating system and sexual dimorphism of Alpheus colombiensisWicksten, 1988. The adult sex ratio was female biased, and solitary ovigerous females were found, suggesting a temporary mate guarding type of mating system. Our results also revealed sexual dimorphism on the snapping claw, which is larger in males than in females. The male’s snapping claw is probably under sexual selection, which can be mediated by male-male competition or female choice. We also estimated the A. colombiensis female size at maturity at 5.2 ± 0.76 mm. Our results contradict the common idea that snapping shrimps are monogamous species, and support that A. colombiensis probably have a temporary mate guarding (e.g., males can sexually interact with more than one female, in opposition to sexual monogamy). This study also sustains the growing evidence that alpheid shrimps display snapping claw sexual dimorphism.

scholarly journals Sexual Selection and Tail-Length Dimorphism in Scissor-Tailed Flycatchers

The Auk ◽  
2001 ◽  
Vol 118 (1) ◽  
pp. 167-175 ◽  
Author(s):  
Jonathan V. Regosin ◽  
Stephen Pruett-Jones
Keyword(s):  
Sexual Dimorphism ◽  
Tail Length ◽  
Female Tail ◽  
Monogamous Species ◽  
Female Quality ◽  
Early Arrival ◽  
Socially Monogamous ◽  
Breeding Grounds ◽  
Clutch Initiation ◽  
Beak Length

Abstract Scissor-tailed Flycatchers (Tyrannus forficatus) exhibit elongated tails in both sexes, and sexual dimorphism in tail length. At Fort Sill, Oklahoma, during 1991 and 1992, Scissor-tailed Flycatchers exhibited sexual dimorphism (male–female) in tail length (1.48), with more moderate sexual dimorphism in wing length (1.09) and beak length (1.04). Based on an analysis of museum specimens, immature birds (<1 year of age) of both sexes in their first calendar year exhibited significantly shorter tails than adults (measured in the field). Furthermore, tail length was highly variable among both sexes relative to other morphological traits. Male tail length was correlated with early clutch initiation by the male's mate and, in 1991, with larger clutch size. Similarly, female tail length was correlated with early clutch initiation, and, in one year, larger clutches. Longer-tailed females also tended to arrive earlier on the breeding grounds in 1992, the only year for which such data were available. Assortative mating by tail length was observed. Those findings support the hypothesis that tail length is a sexually selected trait in this socially monogamous species, and that female tail length may be correlated with measures of female quality (e.g. early arrival and breeding, large clutches). However, confounding effects of age on tail length make it difficult to distinguish among various hypotheses for evolution of elongated tails in this species.

Intraspecific Variation in Courtship and Copulation Frequency: an Effect of Mismatch in Partner Attractiveness?

Behaviour ◽  
1993 ◽  
Vol 127 (3-4) ◽  
pp. 265-277 ◽  
Author(s):  
Marion Petrie ◽  
Fiona M. Hunter
Keyword(s):  
Theoretical Model ◽  
High Frequency ◽  
Mating Behaviour ◽  
Poor Quality ◽  
Pair Formation ◽  
The Poor ◽  
Monogamous Species ◽  
Socially Monogamous ◽  
Copulation Behaviour

AbstractThe aim of this paper is to present a verbal theoretical model that could account for the among pair variability in courtship and copulation behaviour that occurs both during and after pair formation in socially monogamous species. We assume that copulation acts to prevent mate loss, by reducing the availability of an individual to other potential partners. Variation in copulation and courtship frequency then arises as a result of variation in the risk of mate loss. Because of the constraints on free or ideal choice, pairs will form in which it may be possible for one individual to improve upon the quality of its partner. In a mismatched pair it will pay the poorer quality mate to guard the higher quality individual and prevent it from leaving to pair with a better quality mate. The poor quality individual will therefore solicit copulations at a high frequency while it's partner may not always respond. We predict that high levels of courtship and solicitation will relate to a high risk of mate loss and that a lack of response by a partner will relate to the potential opportunities it has to improve on partner quality. Our thesis is that variation in mating behaviour arises as a result of any deviations from assortative mating that may exist in a population.

Breeding of the toad Bufo verrucosissimus: sexual dimorphism and shifting spawning sites

1994 ◽  
Vol 15 (2) ◽  
pp. 191-198 ◽  
Author(s):  
David N. Tarkhnishvili
Keyword(s):  
Body Size ◽  
Sexual Dimorphism ◽  
Site Fidelity ◽  
Inverse Correlation ◽  
Pair Formation ◽  
Mountain Forests ◽  
Reproductive Tactics ◽  
Breeding Sites ◽  
Toad Bufo ◽  
Spawning Sites

AbstractThe Colchic toad (Bufo verrucosissimus) inhabits wet mountain forests of Caucasia and breeds in small and unstable slow streams and seepage pools. Pair formation usually takes place on land. Amplexing couples search for new breeding sites every year; there is little site fidelity. Active searching for breeding sites is facilititated by the small size of males; the species is highly dimorphic, males having a mean body length of 70-85 mm, females a length of 100-130 mm. If a larger, more permanent water body appears in a region, reproductive tactics change and males wait for females around the pond. These generalizations are supported by data collected from 1989-1993. There was an inverse correlation between body size of females and males in amplexing pairs.

Female polymorphism in Chilothrips strobilus (Thysanoptera: Thripidae), with the first description of the male

Zootaxa ◽  
2017 ◽  
Vol 4358 (1) ◽  
pp. 193 ◽  
Author(s):  
YANZE CUI ◽  
JINGHUI XI ◽  
JUN WANG
Keyword(s):  
Body Size ◽  
Sexual Dimorphism ◽  
Intraspecific Variation ◽  
Abdominal Segment ◽  
Wing Length ◽  
Northeastern China ◽  
Liaoning Province ◽  
Female Polymorphism ◽  
Small Genus ◽  
Different Parts

Polymorphism and sexual dimorphism are common in insects. Thrips have been reported to exhibit intraspecific variation in body size, color and wing length (Mound 2005), also sexual dimorphism in abdominal pore plates, antennal sensoria and fore leg armature (Tyagi et al. 2008). Chilothrips Hood is a small genus that currently comprises seven species (ThripsWiki 2017), three from USA, one from Japan, and three from China. No male has been reported in the three species from China, C. strobilus, C. jiuxiensis and C. hangzhouensis (Hu & Feng 2015), and C. strobilus was described on three female specimens from cones of Pinus in Liaoning Province, northeastern China (Tong & Zhang, 1994). Recently, we have surveyed different parts of northeastern China and collected many male individuals of C. strobilus. We have observed that this species shows sexual dimorphism in mouth cone length, and remarkable variation in form of abdominal segment X among females. 

Mixed roosts in the Montagu’s harrier Circus pygargus during courtship

Biologia ◽  
2010 ◽  
Vol 65 (2) ◽  
Author(s):  
Jaroslaw Wiącek
Keyword(s):  
Formation Process ◽  
Pair Formation ◽  
Egg Laying ◽  
Predator Detection ◽  
Circus Pygargus ◽  
Montagu’S Harrier ◽  
Communal Roosting ◽  
First Time ◽  
Predator Behaviour ◽  
Montagu's Harrier

AbstractMixed communal roosting of Montagu’s harrier Circus pygargus in the pre-laying period was observed on Calcareous Marshes in Eastern Poland from 1992 to 1995. To my knowledge, this behaviour was described in literature for the first time. The communal roosting in Montagu’s harrier during courtship can help in estimation of mate attraction and finally in mate choice. Harriers from communal roosts start egg laying earlier when compared to the outside roosts. Communal roosting as anti-predator behaviour can help with predator detection and provides benefits to all members of the group. The pair formation process has led to disintegration of communal roosting. Males were more common in the roosting places than females. The time of roosting was correlated with the photoperiod. The weather and predators impact delayed the formation of mixed roosting places.

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