scholarly journals Different effects of mating group size as male and as female on sex allocation in a simultaneous hermaphrodite

2020 ◽  
Vol 10 (5) ◽  
pp. 2492-2498
Author(s):  
Masami M. Tamechika ◽  
Kohei Matsuno ◽  
Satoshi Wada ◽  
Yoichi Yusa
Keyword(s):  
Group Size ◽  
Sex Allocation ◽  
Simultaneous Hermaphrodite ◽  
Mating Group

scholarly journals SEX ALLOCATION ADJUSTMENT TO MATING GROUP SIZE IN A SIMULTANEOUS HERMAPHRODITE

Evolution ◽  
2013 ◽  
Vol 67 (11) ◽  
pp. 3233-3242 ◽  
Author(s):  
Tim Janicke ◽  
Lucas Marie-Orleach ◽  
Katrien De Mulder ◽  
Eugene Berezikov ◽  
Peter Ladurner ◽  
...  
Keyword(s):  
Group Size ◽  
Sex Allocation ◽  
Simultaneous Hermaphrodite ◽  
Mating Group

Evidence that Mating Group Size Affects Allocation of Reproductive Resources in a Simultaneous Hermaphrodite

1991 ◽  
Vol 138 (5) ◽  
pp. 1206-1217 ◽  
Author(s):  
Peter T. Raimondi ◽  
Janine E. Martin
Keyword(s):  
Group Size ◽  
Simultaneous Hermaphrodite ◽  
Mating Group

scholarly journals Early social conditions affect female fecundity in hermaphrodites

2015 ◽  
Vol 61 (6) ◽  
pp. 983-990 ◽  
Author(s):  
Elio Cannarsa ◽  
Maria Cristina Lorenzi ◽  
Gabriella Sella
Keyword(s):  
Group Size ◽  
Social Stress ◽  
Sexual Maturity ◽  
Reproductive Investment ◽  
Egg Laying ◽  
Social Conditions ◽  
Male Reproduction ◽  
Female Fecundity ◽  
Female Function ◽  
Mating Group

Abstract Social conditions experienced prior to sexual maturity influence reproduction later in life in many animals. In simultaneous hermaphrodites, variation in mating group size influences reproductive investment. As the mating group size increases, reproductive resources devoted to the female function decrease in favor of the male function. Prior to sexual maturity, many hermaphrodites have a protandrous phase during which they produce sperm and can fertilize hermaphrodites’ eggs. In the simultaneously hermaphroditic polychaete worm Ophryotrocha diadema, the cost of male reproduction during adolescence is spread over the whole energy budget of worms as shown by a reduced growth rate, a delayed age at sexual maturity and the shortening of life span compared to protandrous males that do not reproduce. Little is known on whether social conditions experienced during development affect reproductive investment of immature individuals. We investigated whether social conditions affected the length of the protandrous phase, body size and also the subsequent female fecundity of same-age protandrous individuals of O. diadema, which did not had to face competition for egg fertilization. Results show that in large group sizes protandrous males lengthened their protandrous phase, slowed down body growth and decreased their individual investment at the first egg laying compared to protandrous males that were reared in isolation. In the successive egg layings worms adjusted their egg output to the current social conditions. We interpreted these results as an indication that early social conditions represent a social stress resulting in a reduction of the overall reproductive resources up to the first egg laying.

scholarly journals Copulation rate declines with mating group size in dusky dolphins (Lagenorhynchus obscurus)

2015 ◽  
Vol 93 (6) ◽  
pp. 503-507 ◽  
Author(s):  
D.N. Orbach ◽  
G.G. Rosenthal ◽  
B. Würsig
Keyword(s):  
New Zealand ◽  
Group Size ◽  
Energy Costs ◽  
Indirect Benefits ◽  
Lagenorhynchus Obscurus ◽  
Mating Group ◽  
Copulation Rate ◽  
Mating Opportunities ◽  
Dusky Dolphins ◽  
Time And Energy

Males in polygamous species often engage in intrasexual competition for mates. If females actively evade mating attempts, it may benefit males to cooperate to restrict female movement, as has been found in some mammals. We tested if male dusky dolphins (Lagenorhynchus obscurus (Gray, 1828)) cooperate or compete during group mating chases. If they cooperate, then the per-male probability of copulating should increase with group size; if they compete, then the probability should decrease. We followed mating groups by boat during the breeding season (October 2013 – January 2014) off Kaikoura, New Zealand. The copulation rate per male decreased with increasing group size and with the number of noncopulating males in proximity to a copulating female. Male dusky dolphins have multiple mates and appear to use sperm and exploitative scramble competition. Males may remain in mating groups despite competition because there are alliances within the groups, they are unable to exclude rivals from joining a group, the time and energy costs of searching for unescorted females exceed the costs of reduced mating opportunities in a group, they receive other direct or indirect benefits that offset the costs of reduced mating opportunities, or they are in the group largely for social learning rather than procreation.

Adaptive Sex Allocation in a Simultaneous Hermaphrodite

Evolution ◽  
1999 ◽  
Vol 53 (5) ◽  
pp. 1599 ◽  
Author(s):  
Sandrine Trouve ◽  
Joseph Jourdane ◽  
Francois Renaud ◽  
Patrick Durand ◽  
Serge Morand
Keyword(s):  
Sex Allocation ◽  
Simultaneous Hermaphrodite

An Evolutionary Ecological Approach to Sex Allocation and Sex Determination in Crustaceans

2020 ◽  
pp. 177-196
Author(s):  
Kota Sawada ◽  
Sachi Yamaguchi
Keyword(s):  
Sex Determination ◽  
Sex Allocation ◽  
Evolutionary Ecology ◽  
Empirical Studies ◽  
Ecological Approach ◽  
Sexual Strategies ◽  
Sexual Systems ◽  
Mating Group ◽  
Simultaneous Hermaphrodites ◽  
Allocation Strategies

This chapter reviews sex determination and sex allocation strategies among crustaceans with different sexual systems (gonochorism, sequential and simultaneous hermaphroditism, and androdioecy), from the perspective of evolutionary ecology. The discussion includes genetic, environmental, and cytoplasmic sex determination in free-living and parasitic crustaceans, timing and frequency of sex change especially in partial protandry, the effects of mating group size on resource allocation by simultaneous hermaphrodites, and sex ratio and determination in androdioecious crustaceans. The fascinating diversity of crustacean reproduction stimulated theoretical biologists to construct models to explain them, and empirical biologists attempted to test hypotheses derived from those models. This review clearly shows that the interaction between theoretical and empirical studies has facilitated understanding of the evolutionary conditions of diverse sexual strategies among crustaceans. Since sexual strategies often interact with other aspects of adaptive strategies such as life history, integrating different aspects into both theoretical and empirical studies will provide further understandings into crustacean sexual systems. In addition, the authors point out the potential of phylogenetic comparative analyses using natural history data as a tool to understand the tempo and mode of evolution of sex allocation strategies.

scholarly journals ADAPTIVE SEX ALLOCATION IN A SIMULTANEOUS HERMAPHRODITE

Evolution ◽  
1999 ◽  
Vol 53 (5) ◽  
pp. 1599-1604 ◽  
Author(s):  
Sandrine Trouvé ◽  
Joseph Jourdane ◽  
François Renaud ◽  
Patrick Durand ◽  
Serge Morand
Keyword(s):  
Sex Allocation ◽  
Simultaneous Hermaphrodite

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.

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