Burrow use and sexual dimorphism as indicators of the mating system in the symbiotic pea crab Austinixa patagoniensis (Rathbun 1918) (Decapoda, Brachyura, Pinnotheridae)

2021 ◽  
Author(s):  
Marcio C. A. João ◽  
Patricio Hernáez
BMC Biology ◽  
2021 ◽  
Vol 19 (1) ◽  
Author(s):  
Basabi Bagchi ◽  
Quentin Corbel ◽  
Imroze Khan ◽  
Ellen Payne ◽  
Devshuvam Banerji ◽  
...  

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.


2020 ◽  
Vol 40 (6) ◽  
pp. 649-656
Author(s):  
Juan C Azofeifa-Solano ◽  
Jeffrey A Sibaja-Cordero ◽  
Ingo S Wehrtmann

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.


Author(s):  
Douglas F. Peiró ◽  
J. Antonio Baeza ◽  
Fernando L. Mantelatto

Austinixa aidaeinhabits burrows of the ghost shrimpCallichirus majorat Perequê-açu beach, Ubatuba, Brazil. We described the host-use pattern and sexual dimorphism ofA. aidaeto test for monogamy given the generality of this mating system in the subfamily Pinnothereliinae (family Pinnotheridae) to whichA. aidaebelongs. Against expectations,A. aidaelives as solitary individuals within burrows more frequently than expected by chance alone. Additional observations suggested thatA. aidaeexhibits a polygynandrous mating system with males moving among burrows in search of receptive females. First, only 21% of the burrows harboured heterosexual pairs of crabs and the body size of paired crabs was poorly correlated. This suggests pair instability and frequent shifts among burrows by male and/or female crabs, as reported before for other symbiotic crustaceans in which the body size of paired crabs is poorly correlated. Second, males paired with females that were sexually receptive (without embryos) or that have been receptive recently (carrying early embryos) were found more frequently than expected by chance alone. The above agrees with that reported for species in which sexual pairing does not last long. Third, sexual dimorphism in terms of claw size and coloration was evident. Claws were larger in males than in females, a condition that argues in favour of male–male competition inA. aidae. In addition, the body coloration of males was more similar to the sand grains of the beach than that of females. This sex-specific coloration suggests that males are ‘better adapted' than females to roam on the surface of the beach in search of burrows because their coloration should diminish the risk of detection by predators. Experiments are needed to reveal the details of the polygynandrous mating system herein inferred forA. aidaeand to understand those conditions favouring particular reproductive strategies in symbiotic decapod crustaceans.


Zoosymposia ◽  
2012 ◽  
Vol 7 (1) ◽  
pp. 177-184 ◽  
Author(s):  
GUILLAUME CAULIER ◽  
ERIC PARMENTIER ◽  
GILLES LEPOINT ◽  
FLEUR VAN NEDERVELDE ◽  
IGOR EECKHAUT

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.


2020 ◽  
Vol 181 ◽  
pp. 104263
Author(s):  
Romain P. Boisseau ◽  
Mark M. Ero ◽  
Simon Makai ◽  
Luc J.G. Bonneau ◽  
Douglas J. Emlen

Zootaxa ◽  
2016 ◽  
Vol 4196 (1) ◽  
pp. 120 ◽  
Author(s):  
DANIELA ELIANA SGANGA ◽  
LUCAS RAUL FERNANDEZ PIANA ◽  
LAURA SUSANA LÓPEZ GRECO

Neocaridina davidi is a caridean shrimp that has gained popularity in recent years as an ornamental species. Using geometric morphometrics, we investigated sexual dimorphism in carapace and second abdominal segment shape of N. davidi. Adult females displayed a more elongated carapace and a longer rostrum than males. However, male carapace shape was similar to that of juvenile females. The second abdominal pleura was more elongated and wider in adult females than in males. Significant differences were found in centroid size for the carapace and the second abdominal segment between sexes, which is consistent with sexual size dimorphism. These results support the hypothesis of a “pure search” mating system in N. davidi, where small males search actively for receptive females, and after insemination they continue searching. 


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