scholarly journals Experience and relatedness influence mating interactions in a simultaneously hermaphroditic snail, Physa gyrina

2019 ◽  
Author(s):  
Thomas M. McCarthy
Keyword(s):  
Chemical Cues ◽  
Simultaneous Hermaphrodite ◽  
Male Role ◽  
Female Role ◽  
Behavioral Dynamics ◽  
Physa Gyrina ◽  
Current Partner ◽  
Mating Interaction ◽  
Resistance Rates ◽  
Simultaneous Hermaphrodites

AbstractThe means by which animals assess potential mates is an important issue in studies of reproductive systems. I tested whether an individual’s previous experiences and the relatedness of mates affected mating behavior in a simultaneous hermaphrodite snail, Physa gyrina. Previous work with this species showed reduced reproductive success resulting from both strong outbreeding and inbreeding. Thus, I predicted that individuals should prefer partners of intermediate relatedness. During activity trials, snails moved longer distances when exposed to chemical cues from conspecifics of lesser relatedness. Furthermore, during mating interactions, behavioral responses to relatedness varied with gender-role: male-role behaviors did not vary across relatedness treatments, while snails paired with either closely related or highly dissimilar partners increased their female-role resistance behaviors as interactions escalated. Experiences with their current partner also affected behavioral dynamics. Familiar pairs had fewer matings and longer latency times until a mating occurred than unfamiliar pairs. Snails acting in the female role also exhibited higher resistance rates in familiar pairs than in unfamiliar pairs. Previous, brief exposure to chemical cues in a non-mating context also influenced behavior during a subsequent mating interaction. Snails that were previously exposed to chemical cues from unfamiliar individuals tended to be more likely to occupy the male role following an encounter, and had significantly lower copulation frequencies and higher female-role resistance rates (i.e. were choosier) than those previously exposed to cues from familiar individuals. Overall, the results show that: 1) relatedness, past exposure to conspecific chemical cues, and experience with a current partner all influence mating behaviors in these snails; and 2) in these simultaneous hermaphrodites, an individual’s responses depend on whether it is occupying the male or female role.

scholarly journals Disposable penis and its replenishment in a simultaneous hermaphrodite

2013 ◽  
Vol 9 (2) ◽  
pp. 20121150 ◽  
Author(s):  
Ayami Sekizawa ◽  
Satoko Seki ◽  
Masakazu Tokuzato ◽  
Sakiko Shiga ◽  
Yasuhiro Nakashima
Keyword(s):  
Sexual Selection ◽  
Outer Surface ◽  
Mating Behaviour ◽  
Sperm Storage ◽  
Simultaneous Hermaphrodite ◽  
Storage Organ ◽  
Simultaneous Hermaphrodites

Although it is often thought that sexual selection is weaker in simultaneous hermaphrodites than in gonochorists, some simultaneous hermaphrodites exhibit bizarre mating behaviour. In the simultaneously hermaphroditic nudibranch Chromodoris reticulata , we found a peculiar mating behaviour, wherein the nudibranch autotomized its penis after each copulation and was able to copulate again within 24 h. To have sufficient length to be replenished for three copulations, the penis is compressed and spiralled internally. No other animal is known to repeatedly copulate using such ‘disposable penes’. Entangled sperm masses were observed on the outer surface of the autotomized penis, which is equipped with many backward-pointed spines. There is a possibility that the nudibranch removes sperm already stored in a mating partner's sperm storage organ(s).

Courtship behavior as a war of attrition in a simultaneous hermaphrodite

2019 ◽  
Vol 69 (1) ◽  
pp. 47-62 ◽  
Author(s):  
Maria Cristina Lorenzi ◽  
Alice Araguas ◽  
Céline Bocquet ◽  
Laura Picchi ◽  
Claire Ricci-Bonot
Keyword(s):  
Courtship Behavior ◽  
Copulatory Behavior ◽  
The Other ◽  
Simultaneous Hermaphrodite ◽  
Sexual Role ◽  
War Of Attrition ◽  
Behavioral Traits ◽  
Behavioral Cue ◽  
Mating Interaction ◽  
First Time

Abstract In outcrossing hermaphrodites with unilateral mating, where for each mating interaction one individual assumes the female role and the other the male role, each individual must take a sexual role opposite to that of its partner. In the polychaete worm Ophryotrocha diadema, the decision on sexual role is likely at stake during the day-long courtship. Here we describe, for the first time, courtship and pseudocopulation in this species, quantify their pre-copulatory behavior, and search for behavioral traits predicting the prospective sexual role (i.e., behavioral sexual dimorphism), by analyzing the courtship behavior of pairs of worms during the day preceding a mating event. We did not find any behavioral cue predicting the sexual role worms were to play; partners’ pre-copulatory behaviors were qualitatively and quantitatively symmetrical. We interpret this as the outcome of a war of attrition where partners share the preference for the same sexual role, and both hide their ‘willingness’ to play the less preferred one, until one individual reaches its cost threshold and accepts the less preferred sexual role.

No effect of group size on sex allocation in a protandric-simultaneous hermaphroditic shrimp

2007 ◽  
Vol 87 (5) ◽  
pp. 1169-1174 ◽  
Author(s):  
J. Antonio Baeza
Keyword(s):  
Sperm Competition ◽  
Group Size ◽  
Sex Allocation ◽  
Male Gender ◽  
Male Mating ◽  
Gender Preferences ◽  
Female Role ◽  
First Clutch ◽  
Lysmata Wurdemanni ◽  
Simultaneous Hermaphrodites

Lysmata wurdemanni is a protandric-simultaneous hermaphroditic shrimp. Individuals reproduce as males first and late in life as simultaneous hermaphrodites. I examined whether sex allocation (resources devoted to ova vs sperm) varies with group size in shrimps that have just matured as hermaphrodites. Focal males were reared with different numbers of hermaphrodites (1, 2, 5 or 10). Sperm stored in the ejaculatory ducts and eggs brooded underneath the abdomen were retrieved and weighted immediately after focal shrimps matured as hermaphrodites. Hermaphrodites should invest more into sperm with increasing group size to cope with more intense sperm competition. The proportion of focal shrimps that lost their first clutch of eggs after maturing as hermaphrodites increased with group size. This suggests male gender preferences by hermaphrodites experiencing large group sizes. No differences in sex allocation among group sizes were recorded for shrimps that did not lose their first clutch of eggs. Thus, group size does not affect sex allocation in terms of ova and sperm mass. This lack of phenotypic plasticity might be explained if sperm competition is not important in L. wurdemanni. It should not pay in terms of fitness for shrimps to produce and inseminate female-role hermaphrodites with large amounts of sperm when full paternity is assured in the absence of multi-male mating. In agreement with this idea, a second experiment demonstrated that female-role hermaphrodites invariably mated only once with a single other shrimp.

scholarly journals Sex allocation predicts mating rate in a simultaneous hermaphrodite

2009 ◽  
Vol 276 (1676) ◽  
pp. 4247-4253 ◽  
Author(s):  
Tim Janicke ◽  
Lukas Schärer
Keyword(s):  
Sex Allocation ◽  
Mating Behaviour ◽  
Reproductive Investment ◽  
Mating Strategy ◽  
Species Variation ◽  
Simultaneous Hermaphrodite ◽  
Female Function ◽  
Sexual Selection Theory ◽  
The Relationship ◽  
Simultaneous Hermaphrodites

Sexual selection theory for separate-sexed animals predicts that the sexes differ in the benefit they can obtain from multiple mating. Conventional sex roles assume that the relationship between the number of mates and the fitness of an individual is steeper in males compared with females. Under these conditions, males are expected to be more eager to mate, whereas females are expected to be choosier. Here we hypothesize that the sex allocation, i.e. the reproductive investment devoted to the male versus female function, can be an important predictor of the mating strategy in simultaneous hermaphrodites. We argue that within-species variation in sex allocation can cause differences in the proportional fitness gain derived through each sex function. Individuals should therefore adjust their mating strategy in a way that is more beneficial to the sex function that is relatively more pronounced. To test this, we experimentally manipulated the sex allocation in a simultaneously hermaphroditic flatworm and investigated whether this affects the mating behaviour. The results demonstrate that individuals with a more male-biased sex allocation (i.e. relatively large testes and small ovaries) are more eager to mate compared with individuals with a more female-biased sex allocation (i.e. relatively small testes and large ovaries). We argue that this pattern is comparable to conventional gender roles in separate-sexed organisms.

Do Female and Male Role Models Who Embody STEM Stereotypes Hinder Women’s Anticipated Success in STEM?

2011 ◽  
Vol 2 (6) ◽  
pp. 656-664 ◽  
Author(s):  
Sapna Cheryan ◽  
John Oliver Siy ◽  
Marissa Vichayapai ◽  
Benjamin J. Drury ◽  
Saenam Kim
Keyword(s):  
Computer Science ◽  
Role Models ◽  
Role Model ◽  
Current Work ◽  
Stem Fields ◽  
Male Role ◽  
Female Role ◽  
Science Technology ◽  
And Mathematics

Women who have not yet entered science, technology, engineering, and mathematics (STEM) fields underestimate how well they will perform in those fields (e.g., Correll, 2001 ; Meece, Parsons, Kaczala, & Goff, 1982). It is commonly assumed that female role models improve women’s beliefs that they can be successful in STEM. The current work tests this assumption. Two experiments varied role model gender and whether role models embody computer science stereotypes. Role model gender had no effect on success beliefs. However, women who interacted with nonstereotypical role models believed they would be more successful in computer science than those who interacted with stereotypical role models. Differences in women’s success beliefs were mediated by their perceived dissimilarity from stereotypical role models. When attempting to convey to women that they can be successful in STEM fields, role model gender may be less important than the extent to which role models embody current STEM stereotypes.

Reduced egg laying caused by a male accessory gland product opens the possibility for sexual conflict in a simultaneous hermaphrodite

2009 ◽  
Vol 59 (4) ◽  
pp. 435-448 ◽  
Author(s):  
Joris Koene ◽  
Jeroen Hoffer ◽  
Annelies Brouwer
Keyword(s):  
Sexual Conflict ◽  
Lymnaea Stagnalis ◽  
Seminal Fluid ◽  
Accessory Gland ◽  
Egg Laying ◽  
Simultaneous Hermaphrodite ◽  
Internal Fertilization ◽  
Sperm Donors ◽  
Underlying Mechanisms ◽  
Simultaneous Hermaphrodites

AbstractPromiscuity, sperm storage and internal fertilization enhance sperm competition, which leads to sexual conflict whenever an advantageous trait for sperm donors is harmful to recipients. In separate-sex species, such conflicts can severely impact the evolution of reproductive characteristics, physiology and behaviours. For simultaneous hermaphrodites, the generality of this impact remains unclear and underlying mechanisms remain largely unexplored. In the hermaphrodite Lymnaea stagnalis several previous studies showed that investment in eggs differs depending on semen receipt, but these were inconsistent about the direction of change. We investigated whether the change in egg laying is caused by a seminal fluid component. By intravaginally injecting animals, we here reveal that a component of the seminal fluid inhibits egg laying, thus providing the first direct evidence for involvement of such components in competition for fertilization in hermaphrodites. We discuss the broad implications that this finding has on a number of previous studies performed in the same species.

scholarly journals The evolution of egg trading in simultaneous hermaphrodites

2018 ◽  
Author(s):  
Jorge Peña ◽  
Georg Nöldeke ◽  
Oscar Puebla
Keyword(s):  
Mating System ◽  
Analytical Model ◽  
Egg Production ◽  
High Probability ◽  
Rare Occurrence ◽  
Male Role ◽  
Encounter Rates ◽  
Simultaneous Hermaphrodites

AbstractEgg trading, whereby simultaneous hermaphrodites exchange each other’s eggs for fertilization, constitutes one of the few rigorously documented and most widely cited examples of direct reciprocity among unrelated individuals. Yet how egg trading may initially invade a population of non-trading simultaneous hermaphrodites is still unresolved. Here, we address this question with an analytical model that considers mate encounter rates and costs of egg production in a population that may include traders (who provide eggs for fertilization only if their partners also have eggs to reciprocate), providers (who provide eggs regardless of whether their partners have eggs to reciprocate), and withholders (“cheaters” who only mate in the male role and just use their eggs to elicit egg release from traders). Our results indicate that a combination of inter-mediate mate encounter rates, sufficiently high costs of egg production, and a sufficiently high probability that traders detect withholders (in which case eggs are not provided) is conducive to the evolution of egg trading. Under these conditions traders can invade—and resist invasion from—providers and withholders alike. The prediction that egg trading evolves only under these specific conditions is consistent with the rare occurrence of this mating system among simultaneous hermaphrodites.

Courtship, copulation, and sperm trading in the sea slug, Navanax inermis (Opisthobranchia: Cephalaspidea)

1985 ◽  
Vol 63 (12) ◽  
pp. 2719-2729 ◽  
Author(s):  
Janet L. Leonard ◽  
Ken Lukowiak
Keyword(s):  
Mating System ◽  
Temporal Relationship ◽  
Trading System ◽  
Male Role ◽  
Sexual Role ◽  
Sea Slug ◽  
Sexual Roles ◽  
And Function ◽  
Simultaneous Hermaphrodites ◽  
Over Time

Navanax inermis are internally fertilizing, simultaneous hermaphrodites that normally mate in pairs. Copulations usually occur in bouts with active alternation of sexual roles and function. Over the study, individuals copulated equally often and for equal periods of time as each sex. The sequence of behaviors involved in courtship, copulation, and role switching is described. While the sequence of behaviors associated with each sexual role is quite stereotyped, the temporal relationship between the behaviors of the two partners is variable. A mating bout is initiated when one individual assumes the male role, finding and following a conspecific mucous trail, and then courts and copulates as a male. Each individual initiated approximately one-half of the copulatory bouts in which it was involved; size played no role in determining which individual initiated the bout. Our observations suggest that in N. inermis, individuals are always willing to be female, while willingness to be male varies over time. The mating system of N. inermis is based on sperm trading. Individuals apparently act as males, donating sperm, to obtain sperm, and are more willing to be fertilized than to fertilize, in violation of Bateman's principle. In N. inermis, females control fertilization and therefore copulation involves greater risks for males than females. The sperm-trading system is "enforced" by the maintenance of intromission until the partner shows courtship behaviour.

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