scholarly journals Sexual Dimorphism and Foraging Trips of the Laysan Albatross (Phoebastria immutabilis) on Guadalupe Island

Animals ◽  
2019 ◽  
Vol 9 (6) ◽  
pp. 364
Author(s):  
Julio César Hernández Montoya ◽  
Maricela Juárez-Rodríguez ◽  
Federico Méndez-Sánchez ◽  
Alfonso Aguirre-Muñoz ◽  
Evaristo Rojas-Mayoral ◽  
...  
Keyword(s):  
Sexual Dimorphism ◽  
Wing Length ◽  
Predictor Variables ◽  
Seabird Species ◽  
Phoebastria Immutabilis ◽  
Invasive Method ◽  
Student’S T ◽  
Guadalupe Island ◽  
Breeding Seasons ◽  
Laysan Albatross

Sexual dimorphism in the Laysan albatross (Phoebastria immutabilis) on Guadalupe Island was evaluated during the breeding seasons of 2015–2018 by measuring and comparing 10 morphological attributes: cranial length, bill length, nostril length, cranial width, bill height, bill width, tarsus length, closed wing length, opened wing length, and wingspan length in reproductive adults (n = 135). Males were larger than females across all traits (Student’s t-test, p < 0.05, p < 0.05). We created a logistic model using stepwise regression to predict sex based on morphological variables. This model indicated four significant morphological predictor variables (z < 0.05) and was able to successfully predict the sex of P. immutabilis individuals in more than 90% of the cases. Based on these predictor variables, a web app was developed to determine the sex of the Laysan albatross in the field, providing a non-invasive method for rapid data collection that reduces costs and handling times while improving conservation efforts. We tracked Laysan albatross (n = 36) during breeding seasons and found no significant differences between females and males for either trip length (GLMM, F = 0.017, DF = 1, 1, p = 0.917 > 0.05) or maximum trip distance (GLMM, F = 0.374, DF = 1, 1, p = 0.651 > 0.05). Our results suggest that both sexes show a strong preference to travel to highly productive coastal waters northeast of the breeding colony that are influenced by the California Current. The present research will serve to establish a baseline to protect this species on Guadalupe Island and highlights the importance of understanding sexual dimorphism in at-risk seabird species.

First record of Laysan Albatross (Phoebastria immutabilis) in Korea

2018 ◽  
Vol 25 (1) ◽  
pp. 19-22
Author(s):  
Jin-Won Yang ◽  
Seung-Gu Kang ◽  
Won-Ho Lee ◽  
Meong-Kyu Jeong
Keyword(s):  
First Record ◽  
Phoebastria Immutabilis ◽  
Laysan Albatross

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.

scholarly journals Photographic Facial Soft Tissue Analysis by Means of Linear and Angular Measurements in an Adolescent Persian Population

2015 ◽  
Vol 9 (1) ◽  
pp. 346-356 ◽  
Author(s):  
Vahid Moshkelgosha ◽  
Sheida Fathinejad ◽  
Zeinab Pakizeh ◽  
Mohammad Shamsa ◽  
Ali Golkari
Keyword(s):  
High School Students ◽  
Sexual Dimorphism ◽  
Soft Tissue ◽  
Computer Software ◽  
Facial Soft Tissue ◽  
School Students ◽  
Angular Measurements ◽  
Mouth Width ◽  
Student’S T ◽  
Student’S T Test

Objective : To obtain objective average measurements of the profile and frontal facial soft tissue to be used as a guide for aesthetic treatment goals. Methods and Materials : This observational study included 110 females and 130 males high school students aged 16-18 years. None of the subjects had any facial deformities. All of them and their parents gave consent to take part in this study. In each case, two standard photographs of profile and frontal views were taken 27 landmarks were digitized on photographs. The mean, standard deviation, and range for a total of 43 facial indices were calculated digitally by computer software. The Student’s t-test was used to compare males and females. Results : The ratio between the lower and middle facial thirds was one to one, but the height of the upper facial third was proportionally smaller than the other two-thirds in both sexes. Boys had greater nasal length, depth, and prominence than girls with statistically significant differences. Both upper and lower lips were more prominent in girls than in boys. All measurements of the chin showed sexual dimorphism characterized by greater chin height and prominence and deeper mentolabial sulcus. Boys had greater facial dimensions than girls. Mouth width, nasal base width, and intercanthal distance were significantly greater in boys. Conclusion : The labial, nasal, and chin areas showed sexual dimorphism in most of the parameters used in this study. Boys had larger faces, greater facial heights, longer nasal, labial, and chin lengths, and greater nasal, labial, and chin prominence.

scholarly journals Sexual dimorphism of sharks from the amazonian equatorial coast

2015 ◽  
Vol 20 (3) ◽  
pp. 297 ◽  
Author(s):  
Jorge Luiz Silva Nunes ◽  
Ana Paula Barbosa Martins ◽  
Ednaldo Da Silva Filho ◽  
Leonardo Manir Feitosa ◽  
Luiz Phelipe Nunes e Silva ◽  
...  
Keyword(s):  
Sexual Dimorphism ◽  
Discriminant Analysis ◽  
Mating Behavior ◽  
T Test ◽  
Internal Fertilization ◽  
Morphometric Characters ◽  
Morphological Differences ◽  
Student’S T ◽  
Different Levels ◽  
Student’S T Test

Sexual dimorphism is a widespread feature in several groups of vertebrates. Chondrichthyans differ sexually due to the presence of the clasper, a structure for internal fertilization, and other sexual differences in secondary characteristics. Nevertheless, studies assessing these variations are fairly rare. The main goal of this study is to identify differences in sexual dimorphism in three species of sharks from the Carcharhinidae family (<em>Rhizoprionodon porosus</em>, <em>Carcharhinus porosus</em> and <em>Isogomphodon oxyrhynchus</em>) using morphometric tools. A total of 213 specimens were captured in the Amazonian Equatorial Coast and analyzed using 65 morphometric characters. Discriminant analysis and The Student's t-test were used to demonstrate the morphological differences among sexes. Sexual dimorphism was reported at different levels for the three species. This study suggests that the most likely explanation for the presence of these variations is related to their reproductive characteristics and mating behavior.

scholarly journals GPS tracking reveals highly consistent use of restricted foraging areas by European Storm-petrels Hydrobates pelagicus breeding at the largest UK colony: implications for conservation management

2020 ◽  
pp. 1-18
Author(s):  
MARK BOLTON
Keyword(s):  
High Precision ◽  
Survival Rates ◽  
Gps Tracking ◽  
Conservation Action ◽  
Seabird Species ◽  
Adult Body Mass ◽  
Statutory Protection ◽  
Precision Tracking ◽  
High Concentrations ◽  
Breeding Seasons

Summary Seabirds face a diverse array of threats and are considered to comprise one of the most threatened avian groups globally. Development of appropriate conservation action requires a knowledge of the marine distribution of seabirds, furnished either by tracking the movements of individuals, or from at-sea surveys. Obtaining information on the distribution of the smallest seabird species, the storm-petrels Hydrobatidae, is challenging, but the recent development of <1 g GPS tracking tags now enables high-precision tracking and this study reports the first multi-year high-precision tracking of European Storm-petrels Hydrobates pelagicus from their largest UK breeding colony. A total of 42 successful tag deployments were made over four breeding seasons during incubation, brooding and post-brood phases, and there was no evidence of adverse impacts on adult body mass or nest survival rates. Foraging trips lasted between one and three days and ranged up to 397 km from the colony (median = 159 km). Foraging range and total distance covered were positively correlated with trip duration but did not differ across breeding stages. Storm-petrels did not feed to the west of the colony at the edge of the continental shelf where high concentrations have been reported in previous decades from boat surveys, but rather, foraging was restricted to shallow waters south of the colony, consistent across individuals, breeding stages and years. Two areas were identified that exceed the threshold criteria for marine Important Bird Area status and should be considered for statutory protection. The home range estimated across all three breeding stages overlapped with 206 active hydrocarbon wells and 14 operating platforms which represent potential threats as sources of surface pollution or through attraction of birds to gas flares. Improved understanding of the foraging distribution of storm-petrels from this protected colony greatly assists the identification of potential threats and informs appropriate marine spatial planning.

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. 

scholarly journals Dental Sexual Dimorphism

2015 ◽  
Vol 03 (03) ◽  
pp. 135-139
Author(s):  
Manisha Sharma ◽  
Sameer Gupta ◽  
Avdesh Sharma ◽  
Vandana Bhardwaj ◽  
Pooja Sharma ◽  
...  
Keyword(s):  
Sexual Dimorphism ◽  
Forensic Odontology ◽  
Mean Value ◽  
Criminal Proceedings ◽  
Index Method ◽  
Mean Values ◽  
Arch Width ◽  
Significant Difference ◽  
Law And Justice ◽  
Student’S T

Abstract Objective : Forensic odontology is a lineage that deals in relation to jaws and teeth as evidence to law and justice. Tooth serves as a prime importance in the context of sex identification. (1) To investigate whether there exists any correlation between odontometric measures and sexual dimorphism. (2) To compare the inter-canine arch width of mandible. (3) To evaluate the mean value of standard mandibular canine index. Method: This study is an odontometric analysis performed intra-orally with a sample of 150 teeth (75male:75 female) on students of Kanti Devi Dental college, Mathura. Mesiodistal dimensions of mandibular right and left canine with a caliper device and statistical analysis for significance of sexual dimorphism was done with student’s t test. Result: The result showed that sexual dimorphism is significant in relation to mesiodistal diameter of canine. Furthermore, there was statistical significant difference in tooth crown dimension between males and females where the males showed higher mean values. Conclusion: The study show definite statistically significant sexual dimorphism hence they can play significant role in providing expertise in civil & criminal proceedings to ensure that forensic dentistry will remain viable component of forensic medicine.

Laysan Albatross (Phoebastria immutabilis)

2009 ◽  
Author(s):  
Jill A. Awkerman ◽  
David J. Anderson ◽  
G. Causey Whittow
Keyword(s):  
Phoebastria Immutabilis ◽  
Laysan Albatross
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