Allometric models for sex ratio determination in all stages of ontogeny of Chelonia mydas from Bahía de los Ángeles, México

2020 ◽  
Vol 100 (5) ◽  
pp. 825-830
Author(s):  
Elena Solana-Arellano ◽  
David Ramírez-Delgado ◽  
Erika Santacruz-López
Keyword(s):  
Los Angeles ◽  
Gulf Of California ◽  
Carapace Length ◽  
Principal Component ◽  
Tail Length ◽  
Chelonia Mydas ◽  
Background Information ◽  
Adult Males ◽  
Allometric Models ◽  
Adult Females

AbstractIn order to determine the sex of Chelonia mydas individuals found within one of the principal foraging areas of the Gulf of California during any given stage of ontogeny, 529 individuals were sampled in Bahía de los Ángeles from 1995–2012, and their morphometric data were collected. A principal component analysis (PCA) was performed for the morphometric variables, and two principal components were obtained that unambiguously separated sexes and ontogenetic stages. The first component was defined by straight carapace length (SCL), curve carapace length (CCL), plastron length (PL) and carapace depth (CD), while the second factor was represented by total tail length (TTL). Allometric models were fitted with the most important variables determined by the PCA. The model PL = αSCLβ was able to distinguish between adults and immature individuals. For adult organisms, the model that best separated males from females was TTL = αSCLβ. Adult females had SCL values of 66–96.7 cm and TTL values of 16.3–25 cm, while adult males had SCL values of 66.4–12.5 cm and TTL values > 25 cm. As the organisms were considered immature only if SCL < 77.3, we were able to determine the TTL values for immature individuals by using elemental mathematics and solving for SCL in the equation TTL = αSCLβ for each group (i.e. adult females, adult males and immatures). So, considering the mathematical approach and acknowledging the lack of background information, immature individuals may be considered potential females if the TTL value is between 7.04–17.8 cm and potential males if the TTL value > 17.8 cm.

The green turtle, Chelonia mydas, in Queensland: breeding males in the southern Great Barrier Reef

1993 ◽  
Vol 20 (4) ◽  
pp. 513 ◽  
Author(s):  
CJ Limpus
Keyword(s):  
Great Barrier Reef ◽  
Green Turtle ◽  
Carapace Length ◽  
Chelonia Mydas ◽  
Barrier Reef ◽  
Adult Males ◽  
Green Turtles ◽  
Adult Females ◽  
Breeding Seasons ◽  
Slow Growing

Breeding male green turtles, Chelonia mydas, at any one courtship area in the southern Great Barrier Reef mate with females that will nest on rookeries spread throughout the region. In comparison with the breeding females from the same breeding unit, the males are smaller in curved carapace length, and a higher proportion of males remigrate for additional breeding seasons at 1-2-year intervals. Like the adult females, adult males are slow-growing, averaging 0.046 cm year-1. Each male appears to display a fidelity to a particular courtship area, to which it returns in successive breeding migrations. At the conclusion of the courtship period, the males disperse to widely scattered feeding areas.

scholarly journals The Diet and Sexual Differences of the Caspian Bent-Toed Gecko,Tenuidactylus caspius(Squamata: Gekkonidae), in Northern Iran

2014 ◽  
Vol 2014 ◽  
pp. 1-4 ◽  
Author(s):  
Vida Hojati ◽  
Reza Babaei Savasari
Keyword(s):  
Sexual Dimorphism ◽  
Culex Pipiens ◽  
Tail Length ◽  
Adult Males ◽  
Northern Iran ◽  
Widespread Distribution ◽  
Adult Females ◽  
Significant Difference ◽  
Males And Females ◽  
Prey Items

The Caspian bent-toed gecko,Tenuidactylus caspius, is one of the most common nocturnal lizards of Iran with widespread distribution especially in the northern provinces. This research was done in order to study the diet and sexual dimorphism of this species in Sari County from 5 May to 20 October. During this research, 40 specimens of them including 20 males and 20 females were studied for diet and 140 specimens including 70 adult males and 70 adult females were studied for sexual dimorphism. Prey items identified were insects that belong to 15 species of 8 families and 6 orders. The most common prey items wereCulex pipiensandMusca domestica. There is no significant difference between diets of males and females. Results show that the adult males in addition of having the apparent femoral and preanal pores are heavier than females and have larger body, head, and tail length.

Monitoring green turtles (Chelonia mydas) at a coastal foraging area in Baja California, Mexico: multiple indices to describe population status

2003 ◽  
Vol 83 (6) ◽  
pp. 1355-1362 ◽  
Author(s):  
Jeffrey A. Seminoff ◽  
T. Todd Jones ◽  
Antonio Resendiz ◽  
Wallace J. Nichols ◽  
Milani Y. Chaloupka
Keyword(s):  
Los Angeles ◽  
Gulf Of California ◽  
Human Impacts ◽  
Chelonia Mydas ◽  
Sea Turtle ◽  
Catch Per Unit Effort ◽  
Recovery Model ◽  
Size Frequency Distribution ◽  
Green Turtles ◽  
Foraging Area

From June 1995 to August 2002 we assessed green turtle (Chelonia mydas) population structure and survival, and identified human impacts at Bahía de los Angeles, a large bay that was once the site of the greatest sea turtle harvest rates in the Gulf of California, Mexico. Turtles were captured live with entanglement nets and mortality was quantified through stranding surveys and flipper tag recoveries. A total of 14,820 netting hours (617·5 d) resulted in 255 captures of 200 green turtles. Straight-carapace length and mass ranged from 46·0–100·0 cm (mean=74·3±0·7 cm) and 14·5–145·0 kg (mean=61·5±1·7 kg), respectively. The size–frequency distribution remained stable during all years and among all capture locations. Anthropogenic-derived injuries ranging from missing flippers to boat propeller scars were present in 4% of captured turtles. Remains of 18 turtles were found at dumpsites, nine stranded turtles were encountered in the study area, and flipper tags from seven turtles were recovered. Survival was estimated at 0·58 for juveniles and 0·97 for adults using a joint live-recapture and dead-recovery model (Burnham model). Low survival among juveniles, declining annual catch per unit effort, and the presence of butchered carcasses indicated human activities continue to impact green turtles at this foraging area.

scholarly journals Sexual Dimorphism in Red-Eared Sliders (Trachemys scripta elegans) from the Wild Animal Triage Center of the Tiete Ecological Park, São Paulo, Brazil

2017 ◽  
Vol 45 (1) ◽  
pp. 10 ◽  
Author(s):  
Adriana Gradela ◽  
Thamyris Oliveira Carneiro Santiago ◽  
Isabelle Caroline Pires ◽  
Alequisandra De Castro Souza Silva ◽  
Leniker Cordeiro de Souza ◽  
...  
Keyword(s):  
Sexual Dimorphism ◽  
Sex Ratio ◽  
Sexual Maturity ◽  
Carapace Length ◽  
Principal Component ◽  
Tail Length ◽  
Trachemys Scripta ◽  
Sex Characteristics ◽  
Trachemys Scripta Elegans ◽  
Secondary Sex Characteristics

Background: Trachemys scripta elegans is an aquatic turtle native to North America and distributed geographically from the eastern United States to northeastern Mexico. In Brazil, it is an exotic and invasive species and the most illegally traded pet animal. When these turtles grow and they cease to be attractive as pets, they are released clandestinely in lakes, ponds, rivers, and other bodies of water, where they threaten biodiversity and native populations. The present study aimed to characterize specimens of T. s. elegans from the Centro de Triagem de Animais Silvestres do Parque Ecológico do Tiete by analyzing body biometrics, sexual dimorphism, and structure of specimens for sex ratio and size classes.Materials, Methods & Results: Trachemys scripta elegans turtles (39 females and 30 males) were anesthetized, euthanized and frozen. After being thawed, the turtles were sexed according to measurements on secondary sex characters such as claw length (CWL) of the third finger of the right forearm and length of the tail from the tip to the beginning of the cloacal opening (postcloacal tail length, PTL); subsequently, sex was confirmed through dissection. Subsequently, body mass (BM, g) and maximum carapace length (MCL, cm), maximum carapace width (MCW, cm), maximum plastron length (MPL, cm), maximum plastron width (MPW) and shell height (HGT, cm, measured laterally until obtaining the greatest value) were evaluated and the sexual dimorphism index (SDI) was also calculated. All analyses were performed using SAS v. 9.4 software. The results indicate a sex ratio of 1.3 females per male. The identification of males by secondary sex characteristics was performed using only claw length (CWL), which was related to sex and not to maximum carapace length (MCL). The most discriminatory variables were CWL in males and body mass (BM) in females. With the exception of CWL, the sexual dimorphism index (SDI) values all favored females and varied from 1.21 to 2.49, with the greatest value for BM and the lowest value for postcloacal tail length (PTL). Males exhibited a unimodal tendency at a classification interval of 15.0 cm MCL, and females exhibited a bimodal tendency at 21.0- and 22.0 cm MCL. Sexual maturity was identified at 12.0 cm MCL in males and at 12.5 cm MCL in females. The rate of CWL growth in males was higher at the beginning of sexual maturity and subsequently decreased, whereas in females, the rate of CWL escalated after 19.0 cm MCL. In both sexes, principal component 1 (PC1) was composed of the variables related to size and BM, and principal component 2 (PC2) and principal component 3 (PC3) were composed of variables related to secondary sex characteristics (CWL and PTL).Discussion: In members of the genus Trachemys, several secondary sex characteristics can be used to differentiate between the sexes, however, in the present study, recognition of males was performed only by claw length, as it was confirmed by the discriminate analysis and the principal components analysis (PCA) which showed that CWL was the variable that was most discriminatory in males (approximately 76.0%), followed by BM (approximately 50%) in females. The results reinforcing the claim that the degree of development of secondary sex characteristics varies between species as well as between distinct populations of the same species and establish that even under unnatural habitat, sexual dimorphism of size in favor of females is maintained for variables related to mass and size.

Morphological variation in deer mice in relation to sex and habitat

1987 ◽  
Vol 65 (3) ◽  
pp. 527-533 ◽  
Author(s):  
Xuhua Xia ◽  
John S. Millar
Keyword(s):  
Body Length ◽  
Tail Length ◽  
Deer Mice ◽  
Body Measurements ◽  
Adult Males ◽  
Adult Females ◽  
Foot Length ◽  
Hind Foot ◽  
Similar Body ◽  
Juvenile Males

Peromyscus maniculatus borealis were collected in two habitats with contrasting physiognomic features in the Kananaskis Valley, Alberta, in the summer of 1983. We tested for differences between sexes and habitats using 4 body measurements (body length, tail length, hind foot length, and ear length) and 10 cranial (including mandibular) measurements of 222 and 192 adult P. m. borealis, respectively. Body measurements of 132 juveniles and five cranial (including mandibular) measurements from 124 juvenile skulls were analysed similarly. When differences in body length were controlled, adult males had significantly longer hind feet than adult females. The mandible was also significantly longer in adult males than in adult females. We interpreted the longer hind foot length in adult males as an adaptation to provide greater mobility, and the differences in mandibular morphology as a consequence of differential habitat use between the two sexes. No significant differences were found between juvenile males and females. Sexual dimorphism appeared to be age dependent rather than size dependent when adults and juveniles of similar body size were analysed.

scholarly journals Morphological variation of Philodryas patagoniensis (Girard, 1858) (Serpentes, Dipsadidae) from Brazil, based on the study of pholidosis, coloration and morphometric features

2017 ◽  
Vol 17 (1) ◽  
Author(s):  
Rafaella Vallim Gouveia ◽  
Iara Alves Novelli ◽  
Fabiano Matos Vieira ◽  
Bernadete Maria de Sousa
Keyword(s):  
Sexual Dimorphism ◽  
Analysis Of Variance ◽  
Morphological Variation ◽  
Tail Length ◽  
Head Length ◽  
Adult Males ◽  
Adult Females ◽  
Morphometric Features ◽  
The Relationship

Abstract The current study aimed to verify the relationship between the patterns of coloration, the morphometrical features and pholidosis of specimens of Philodryas patagoniensis from Brazil, with the sexual dimorphism of this species. We studied specimens of P. patagoniensis deposited in several herpetological collections from Brazil. A total of 355 specimens were analyzed, of these 145 were males (87 adults and 58 juveniles) and 210 were females (134 adults and 76 juveniles). Adult specimens exhibit sexual dimorphism in snout-vent length, tail length, head length, number of ventral shields, and number of subcaudal shields. The analysis of variance showed that the adult females are significantly longer than adult males, both at snout-vent length and tail length. Females have a greater number of ventral shields (138-210) than males (151-200). The specimens studied also exhibit two distinct patterns of coloration unrelated to geographical or sexual variations.

scholarly journals NATURAL HISTORY OF DEKAY’S BROWNSNAKE, STORERIA DEKAYI (HOLBROOK, 1836), AT A SITE IN NORTHWESTERN PENNSYLVANIA

2014 ◽  
pp. 28-39
Author(s):  
Brian S. Gray
Keyword(s):  
Population Structure ◽  
Site Fidelity ◽  
Additional Data ◽  
Tail Length ◽  
Adult Males ◽  
Morphometric Data ◽  
Erie County ◽  
Adult Females ◽  
History Of ◽  
A Site

A population of Dekay’s Brownsnake, Storeria dekayi was studied using mark-recapture techniques in Erie County, Pennsylvania, USA during the spring, summer and autumn of 2012. Morphometric data were similar to that reported for the species, with adult females averaging larger and more massive than adult males. However, sexual dimorphism in snout-vent length (SVL) and total length (TL) was not significantly different (P>0.05) in juveniles, although relative tail length (tl/TL) was dimorphic. Relative tail length in both juveniles and adults was greater in males (tl/TL = 0.22-0.27) than females (tl/TL = 0.18-0.23). Storeria dekayi were active from 21 March through 22 October, and displayed a bimodal activity pattern, with peaks in April and August. Using the Schnabel and the Schumacher-Eschmeyer methods, population size was estimated to be 122 ± 19 and 130 ± 35 individuals, respectively. Density was estimated to be 244 and 260 snakes/ha, and biomass 1.60 and 1.71 kg/ha. Additional data regarding population structure, mortality, diet, reproduction, body temperature, movements and site fidelity are also presented.

Two new species and taxonomic notes on the Neotropical spiny orb-weaving spi-ders Micrathena and Chaetacis (Araneae: Araneidae), with remarks on the development of Micrathena excavata IVAN L. F. MAGALHÃES & ADALBERTO J. SANTOS (Brazil)

Zootaxa ◽  
2011 ◽  
Vol 2983 (1) ◽  
pp. 39 ◽  
Author(s):  
IVAN L. F. MAGALHÃES ◽  
ADALBERTO J. SANTOS
Keyword(s):  
New Species ◽  
Junior Synonym ◽  
Adult Males ◽  
Development Stages ◽  
Brazilian Amazonia ◽  
Central Brazil ◽  
Adult Females ◽  
Two New Species ◽  
Senior Synonym ◽  
First Time

In this paper, M. yanomami n. sp., from Brazilian Amazonia, Chaetacis bandeirante n. sp., from Central Brazil, and the males of M. gaujoni Simon, 1897 and M. ruschii (Mello-Leitão, 1945) n. comb. , respectively from Ecuador and Brazil, are described and illustrated for the first time. An ontogenetic series of the last development stages of both sexes of Micrathena excavata (C. L. Koch, 1836) is illustrated and briefly described. Adult females are larger and have longer legs and larger abdomens than adult males. Probably females undergo at least one additional moult before adulthood, compared to males. Micrathena ornata Mello-Leitão, 1932 is considered a junior synonym of M. plana (C. L. Koch, 1836), and M. mastonota Mello-Leitão 1940 is synonymized with M. horrida (Taczanowski, 1873). Acrosoma ruschii Mello-Leitão, 1945 is revalidated, transferred to Micrathena and considered a senior synonym of M. cicuta Gonzaga & Santos, 2004. Chaetacis necopinata (Chickering, 1960) is recorded for Brazil for the first time. Chaetacis incisa (Walckenaer, 1841) is considered a nomen dubium.

Spacing, movements, and habitat selection of the river otter in boreal Alberta

1994 ◽  
Vol 72 (7) ◽  
pp. 1314-1324 ◽  
Author(s):  
D. G. Reid ◽  
T. E. Code ◽  
A. C. H. Reid ◽  
S. M. Herrero
Keyword(s):  
Lontra Canadensis ◽  
Home Ranges ◽  
Adult Males ◽  
Movement Rates ◽  
River Otters ◽  
Aquatic Mammal ◽  
Adult Females ◽  
Two Factors ◽  
Bog Lakes ◽  
Selection Of

Seasonal spacing patterns, home ranges, and movements of river otters (Lontra canadensis) were studied in boreal Alberta by means of radiotelemetry. Adult males occupied significantly larger annual home ranges than adult females. Males' ranges overlapped those of females and also each other's. In winter, home ranges of males shrank and showed less overlap. Otters often associated in groups, the core members typically being adult females with young, or adult males. Otters tended to be more solitary in winter. In winter, movement rates of all sex and age classes were similar, and much reduced for males compared with those in other seasons. These data indicated a strong limiting effect of winter ice on behaviour and dispersion. We tested the hypothesis that otters select water bodies in winter on the basis of the suitability of shoreline substrate and morphology for dens with access both to air and to water under ice. Intensity of selection was greatest in winter, with avoidance of gradually sloping shorelines of sand or gravel. Adults selected bog lakes with banked shores containing semi-aquatic mammal burrows, and lakes with beaver lodges. Subadults selected beaver-impounded streams. Apart from human harvest, winter habitats and food availability in such habitats are likely the two factors most strongly limiting otter density in boreal Alberta.

Time-Budgets of Camargue Horses Ii. Time-Budgets of Adult Horses and Weaned Sub-Adults

Behaviour ◽  
1980 ◽  
Vol 72 (1-2) ◽  
pp. 26-48 ◽  
Author(s):  
Patrick Duncan
Keyword(s):  
Social Structure ◽  
Social System ◽  
General Trend ◽  
Small Population ◽  
Time Budgets ◽  
Adult Males ◽  
Adult Females ◽  
Young Horses

AbstractTime-budgets of adult and weaned sub-adult horses were studied in a small population of Camargue horses living in semi-liberty. The categories of activities used were: Standing resting, Lying flat, Lying up, Standing alert, Walking, Trotting, Galloping, Rolling and Foraging. The main differences in time-budgets were related to age and to sex : young horses spent more time lying (sleeping), males spent more time standing alert and in rapid movements (trot, gallop), while usually foraging less than did the adult females. During the three years of the study the population increased from 20 to 54 horses and there were considerable changes in social structure as the number of adult males increased. Associated with these developments there were some changes between years in the time-budgets: the most striking of which was a general trend for all horses to spend less time lying. Nonetheless the time-budgets showed a considerable constancy across years and age/sex-classes, especially with regard to time spent foraging. This conclusion may provide a clue as to why horses have an unusual social system based on long term relationships between a male and the females of his harem.

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