Characterization of a population of the Harlequin crab, Lissocarcinus orbicularis Dana, 1852, an obligate symbiont of holothuroids, in Toliara bay (Madagascar)*

Zoosymposia ◽  
2012 ◽  
Vol 7 (1) ◽  
pp. 177-184 ◽  
Author(s):  
GUILLAUME CAULIER ◽  
ERIC PARMENTIER ◽  
GILLES LEPOINT ◽  
FLEUR VAN NEDERVELDE ◽  
IGOR EECKHAUT
Keyword(s):  
Sexual Dimorphism ◽  
Mating System ◽  
Carapace Length ◽  
Barrier Reef ◽  
South West ◽  
Obligate Symbiont ◽  
Adult Crab ◽  
Gravid Females

Harlequin crabs, Lissocarcinus orbicularis, are commensals found on the integument and in the buccal/cloacal cavity of several species of holothuroids. The population of these crabs was investigated on holothuroids of the barrier reef of Toliara (South-West of Madagascar) from 2002 to 2008. Seventeen holothuroid species were observed and eight were crab hosts. There is generally one adult crab or a heterosexual pair per infested holothuroid but up to ten juveniles were recorded on a Thelenota ananas. Carapace length of the observed L. orbicularis was from 0.3 to 1.4 cm from the tip of the rostrum to the end of the cephalothorax, with a mean length of 0.85 cm. L. orbicularis is characterized by a weak sexual dimorphism (females are bigger than males) and the presence of pereiopods morphologically adapted to fixation on the host integument. Gravid females were observed at each month of the survey indicating that the crab reproduces all the year. Considering our results and personal observations, we also discuss the monogamy mating system of the Harlequin crab.

scholarly journals Sexual conflict drives micro- and macroevolution of sexual dimorphism in immunity

BMC Biology ◽  
2021 ◽  
Vol 19 (1) ◽  
Author(s):  
Basabi Bagchi ◽  
Quentin Corbel ◽  
Imroze Khan ◽  
Ellen Payne ◽  
Devshuvam Banerji ◽  
...  
Keyword(s):  
Sex Differences ◽  
Sexual Dimorphism ◽  
Mating System ◽  
Sexual Conflict ◽  
Experimental Evolution ◽  
Parasitic Infections ◽  
Pathogen Dynamics ◽  
Trade Offs ◽  
Host Pathogen ◽  
Seed Beetles

Abstract Background Sexual dimorphism in immunity is believed to reflect sex differences in reproductive strategies and trade-offs between competing life history demands. Sexual selection can have major effects on mating rates and sex-specific costs of mating and may thereby influence sex differences in immunity as well as associated host–pathogen dynamics. Yet, experimental evidence linking the mating system to evolved sexual dimorphism in immunity are scarce and the direct effects of mating rate on immunity are not well established. Here, we use transcriptomic analyses, experimental evolution and phylogenetic comparative methods to study the association between the mating system and sexual dimorphism in immunity in seed beetles, where mating causes internal injuries in females. Results We demonstrate that female phenoloxidase (PO) activity, involved in wound healing and defence against parasitic infections, is elevated relative to males. This difference is accompanied by concomitant sex differences in the expression of genes in the prophenoloxidase activating cascade. We document substantial phenotypic plasticity in female PO activity in response to mating and show that experimental evolution under enforced monogamy (resulting in low remating rates and reduced sexual conflict relative to natural polygamy) rapidly decreases female (but not male) PO activity. Moreover, monogamous females had evolved increased tolerance to bacterial infection unrelated to mating, implying that female responses to costly mating may trade off with other aspects of immune defence, an hypothesis which broadly accords with the documented sex differences in gene expression. Finally, female (but not male) PO activity shows correlated evolution with the perceived harmfulness of male genitalia across 12 species of seed beetles, suggesting that sexual conflict has a significant influence on sexual dimorphisms in immunity in this group of insects. Conclusions Our study provides insights into the links between sexual conflict and sexual dimorphism in immunity and suggests that selection pressures moulded by mating interactions can lead to a sex-specific mosaic of immune responses with important implications for host–pathogen dynamics in sexually reproducing organisms.

scholarly journals Extreme secondary sexual dimorphism in the genus Florarctus (Heterotardigrada: Halechiniscidae)

2021 ◽  
Vol 51 (3) ◽  
Author(s):  
Piotr Gąsiorek ◽  
David Møbjerg Kristensen ◽  
Reinhardt Møbjerg Kristensen
Keyword(s):  
Sexual Dimorphism ◽  
Pacific Ocean ◽  
Barrier Reef ◽  
Queensland Museum ◽  
The Pacific ◽  
Secondary Sexual Dimorphism ◽  
The Pacific Ocean ◽  
A New Species ◽  
Lines Of Evidence ◽  
Secondary Sexual

AbstractSecondary sexual dimorphism in florarctin tardigrades is a well-known phenomenon. Males are usually smaller than females, and primary clavae are relatively longer in the former. A new species Florarctus bellahelenae, collected from subtidal coralline sand just behind the reef fringe of Long Island, Chesterfield Reefs (Pacific Ocean), exhibits extreme secondary dimorphism. Males have developed primary clavae that are much thicker and three times longer than those present in females. Furthermore, the male primary clavae have an accordion-like outer structure, whereas primary clavae are smooth in females. Other species of Florarctus Delamare-Deboutteville & Renaud-Mornant, 1965 inhabiting the Pacific Ocean were investigated. Males are typically smaller than females, but males of Florarctus heimi Delamare-Deboutteville & Renaud-Mornant, 1965 and females of Florarctus cervinus Renaud-Mornant, 1987 have never been recorded. The Renaud-Mornant collection was re-examined, and type series were analysed. Florarctus heimi and F. cervinus were always found together in the coralline sand of Heron Island (Great Barrier Reef). The animals were kept alive and surveyed in the laboratory of the Queensland Museum. All studied individuals of the larger F. heimi (up to ca. 400 μm) were females, and all adults of the smaller F. cervinus (about 170 μm) were males. Males of F. cervinus were observed mating with females of F. heimi. Following those morphological and behavioural lines of evidence, we propose that F. cervinus is a junior synonym of F. heimi. Based on the discovery of dimorphism in F. bellahelenae sp. nov. and the strong sex-related morphological disparities in F. heimi, we suggest that extreme secondary dimorphism may be present in other florarctin arthrotardigrades.

scholarly journals Characterization of the Particle Emission from Ships Operating at Sea Using Unmanned Aerial Vehicles

2017 ◽  
Author(s):  
Tommaso F. Villa ◽  
Reece Brown ◽  
E. Rohan Jayaratne ◽  
L. Felipe Gonzalez ◽  
Lidia Morawska ◽  
...  
Keyword(s):  
Great Barrier Reef ◽  
Co2 Concentration ◽  
Emission Factors ◽  
Barrier Reef ◽  
Ship Emissions ◽  
Optimal Position ◽  
Exhaust Plume ◽  
Aerial Vehicle ◽  
First Time

Abstract. This research demonstrates the use of an unmanned aerial vehicle (UAV) to characterize the gaseous (CO2) and particle (10–500 nm) emissions of a ship at sea. The field study was part of the research voyage The Great Barrier Reef as a significant source of climatically relevant aerosol particles on-board the RV Investigator around the Australian Great Barrier Reef. Measurements of the RV Investigator exhaust plume were carried out while the ship was operating at sea, at a steady engine load of 30 %. The UAV system was flown autonomously using several different programmed paths. These incorporated different altitudes and distances behind the ship in order to investigate the optimal position to capture the ship plume. Five flights were performed, providing a total of 27 horizontal transects perpendicular to the ship exhaust plume. Results show that the most appropriate altitude and distance to effectively capture the plume was 25 m above sea level and 20 m downwind. Particle number (PN) emission factors (EF) were calculated in terms of number of particles emitted (#) per weight of fuel consumed (Kg fuel). Fuel consumption was calculated using the simultaneous measurements of plume CO2 concentration. Calculated EFPN were between 9.19 × 1014 and 5.15 × 1015 #∙(Kg fuel)−1. These values are in line with those reported in the literature for ship emissions ranging from 0.2 6.2 × 1016 #∙(Kg fuel)−1 to 6.2 × 1016 #∙(Kg fuel)−1. This UAV system successfully assessed ship emissions to derive emission factors (EFs) under real world conditions. This is significant as, for the first time, it provides a reliable, inexpensive and accessible way to assess and potentially regulate ship emissions.

Sexual dimorphism and intersexuality in Upogebia stellata (Crustacea: Decapoda: Thalassinidea)

2001 ◽  
Vol 81 (6) ◽  
pp. 1061-1062 ◽  
Author(s):  
Eunice H. Pinn ◽  
R. James A. Atkinson ◽  
Andrew Rogerson
Keyword(s):  
Sexual Dimorphism ◽  
Carapace Length ◽  
Single Specimen ◽  
Male And Female ◽  
Total Length ◽  
Mud Shrimp ◽  
External Characteristics

Evidence of sexual dimorphism in the mud-shrimp Upogebia stellata was observed in the abdomen length, total length, and also in the chelae. For the same carapace length, males had a shorter abdomen and, therefore, total length, whilst their chelae were larger and more robust than the females. Of the 91 U. stellata individuals examined, a single specimen was found to be of an intersex type, i.e. it exhibited both male and female external characteristics. Sexual dimorphism and intersexuality are discussed.

Functional significance and characterization of sexual dimorphism in holothuroids

2018 ◽  
Vol 62 (4) ◽  
pp. 191-201 ◽  
Author(s):  
E. M. Montgomery ◽  
J. M. Ferguson-Roberts ◽  
B. L. Gianasi ◽  
J.-F. Hamel ◽  
A. Kremenetskaia ◽  
...  
Keyword(s):  
Sexual Dimorphism ◽  
Functional Significance

Phenotypical characterization of Kababich breed in peri-urban zone of N’Djamena-Chad

2021 ◽  
Vol 2 (2) ◽  
pp. 041-049
Author(s):  
Djalal Ardjoun Khalil ◽  
Mahamat Ibrahim Souleymane ◽  
Issa Youssouf ◽  
Madjina Tellah ◽  
Mopate Logtene Youssouf ◽  
...  
Keyword(s):  
Sexual Dimorphism ◽  
Genetic Improvement ◽  
The Body ◽  
Phenotypic Characterization ◽  
Phenotypic Traits ◽  
Phenotypic Characteristics ◽  
Young Males ◽  
Urban Zone ◽  
One Year

This work was carried out on the phenotypic characteristics of the Kababich sheep exploited in the peri-urban zone of N'Djamena (Chad). This phenotypic characterization of Kababich sheep should be continued on local breeds for genetic improvement and objective optimization of productivity. The objective of this study is the characterization of phenotypically Kababich sheep exploited in the peri-urban area of ​​N'Djamena-Chad. It was conducted in 39 farms and involved 1035 sheep aged less than one year old. Phenotypic traits were measured according to the guideline defined by FAO. A total of 12 variables were measured including five qualitative and seven quantitative. The results obtained show a positively significant correlation (p> 0.001) between the age of the sheep estimated by the breeder and the dentition (0.83). The ears are drooping and measure 17.90 ± 2.77 cm. The color of the brown dress (fawn) and the smooth and short coat are dominant. The females are matte and the rams of brown dress have horns in the forms of the vestiges. The Kababich is large with a height at the withers of 81.50 ± 9.40 cm, a rump height of 83.24 ± 9.42 cm and a chest circumference of 88.29 ± 9.22 cm. The body is 72.82 ± 9.63 cm long, has a basin width of 19.89 ± 2.53 cm and a chest depth of 40.68 ± 5.16 cm. These measurements show that Kababich is a meat breed by excellence. In addition, the sexual dimorphism very accentuated in this race orients towards a valorization of the young males in the fattening workshops.

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