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).

Differential survival of allosperm by location within the female storage organ of the snail Cornu aspersum

2008 ◽  
Vol 86 (11) ◽  
pp. 1244-1251 ◽  
Author(s):  
Ronald Chase ◽  
Emily Darbyson
Keyword(s):  
Sexual Selection ◽  
Sperm Competition ◽  
Female Choice ◽  
Complex Structure ◽  
Sperm Storage ◽  
Storage Organ ◽  
Differential Survival ◽  
Cornu Aspersum ◽  
The Mean ◽  
Epithelial Wall

The sperm storage organ of terrestrial gastropod molluscs is implicated in sexual selection because it has a complex structure and it functions in a context of intense sperm competition. Received sperm are stored in spermathecal tubules. In our sample using the brown garden snail ( Cornu aspersum (Müller, 1774)) (n = 58), the mean number of tubules per animal was 16, with lengths ranging from ≤40 to 2480 μm. A hereditary influence on tubule number was indicated by clutch-dependent variations. From histological sections, we counted the spermatozoa that were present in the tubules of ex-virgin snails 1, 2, 4, and 8 weeks after mating (n = 40). Sperm were distributed, on average, across 75% of the tubules in individual snails, thus contradicting one proposed mechanism for cryptic female choice. The total number of sperm declined 66% over 8 weeks, with the largest losses incurred by sperm in the lumens of the tubules and sperm gathered in clusters. By contrast, in the same period, the numbers of sperm that were in contact with the walls of the tubules remained relatively stable. These data imply that sperm survive best when attached to the epithelial wall, either because they derive nutrition from the epithelium or because they use the epithelium as an anchor.

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.

The Effects of the sphragis on male and female genitalia in Acraea (Nymphalidae) butterflies

2020 ◽  
Vol 22 ◽  
Author(s):  
Shannon L Summers ◽  
Akito Y Kawahara ◽  
Ana P. S. Carvalho
Keyword(s):  
Interspecific Variation ◽  
Sperm Storage ◽  
Male Mating ◽  
Museum Collections ◽  
Storage Organ ◽  
Mating Plug ◽  
Males And Females ◽  
Comparison And Analysis ◽  
Imagej Software ◽  
Sexually Antagonistic Coevolution

Male mating plugs have been used in many species to prevent female re-mating and sperm competition. One of the most extreme examples of a mating plug is the sphragis, which is a large, complex and externalized plug found only in butterflies. This structure is found in many species in the genus Acraea (Nymphalidae) and provides an opportunity for investigation of the effects of the sphragis on the morphology of the genitalia, which is poorly understood. This study aims to understand morphological interspecific variation in the genitalia of Acraea butterflies. Using specimens from museum collections, abdomen dissections were conducted on 19 species of Acraea: 9 sphragis bearing and 10 non-sphragis bearing species. Genitalia imaging was performed for easier comparison and analysis and measurements of genitalia structures was done using ImageJ software. Some distinguishing morphological features in the females were found. The most obvious difference is the larger and more externalized copulatory opening in sphragis bearing species, with varying degrees of external projections. Females of the sphragis bearing species also tend to have a shorter ductus (the structure that connects the copulatory opening with the sperm storage organ) than those without the sphragis. These differences may be due to a sexually antagonistic coevolution between the males and females, where the females evolve larger and more difficult to plug copulatory openings and the males attempt to prevent re-mating with the sphragis.

Behavioural and genetic analyses of mate choice and reproductive success in two Chinook salmon populations

2013 ◽  
Vol 70 (2) ◽  
pp. 263-270 ◽  
Author(s):  
Melissa L. Evans ◽  
Bryan D. Neff ◽  
Daniel D. Heath
Keyword(s):  
Sexual Selection ◽  
Natural Selection ◽  
Reproductive Success ◽  
Mate Choice ◽  
Mhc Class Ii ◽  
Chinook Salmon ◽  
Oncorhynchus Tshawytscha ◽  
Mating Behaviour ◽  
Selection Pressures ◽  
Evolutionary Force

Sexual selection is recognized as an important evolutionary force in salmon. However, relatively little is known about variation in sexual selection pressures across salmon populations or the potential role of natural selection as a driver of adaptive mating patterns. Here, we examine mating behaviour and correlates of reproductive success in Chinook salmon (Oncorhynchus tshawytscha) from the Quinsam and Little Qualicum rivers in British Columbia, Canada — two populations for which we have previously found evidence of natural selection operating on major histocompatibility complex (MHC) genes. In both populations, males courted females and exhibited dominance behaviour towards other males, and the frequency of each behaviour was positively associated with reproductive success. Males were more aggressive towards females with whom they would produce offspring of low or high MHC class II diversity, and the offspring of males from the Quinsam River exhibited higher diversity at the MHC class I than expected. We discuss our results in relation to local natural selection pressures on the MHC and the potential for MHC-dependent mate choice.

A mating plug in a squid? Sneaker spermatophores can block the female sperm-storage organ in Doryteuthis plei

Zoology ◽  
2018 ◽  
Vol 130 ◽  
pp. 47-56 ◽  
Author(s):  
Luiza O. Saad ◽  
Thomas Schwaha ◽  
Stephan Handschuh ◽  
Andreas Wanninger ◽  
José E.A.R. Marian
Keyword(s):  
Sperm Storage ◽  
Storage Organ ◽  
Mating Plug

Size‐selective harvesting fosters adaptations in mating behaviour and reproductive allocation, affecting sexual selection in fish

2019 ◽  
Vol 88 (9) ◽  
pp. 1343-1354 ◽  
Author(s):  
Valerio Sbragaglia ◽  
Catalina Gliese ◽  
David Bierbach ◽  
Andrew E. Honsey ◽  
Silva Uusi‐Heikkilä ◽  
...  
Keyword(s):  
Sexual Selection ◽  
Mating Behaviour ◽  
Reproductive Allocation ◽  
Selective Harvesting

scholarly journals Sperm numbers vary between inter- and intra-population matings of the grasshopper Chorthippus parallelus

2006 ◽  
Vol 2 (2) ◽  
pp. 239-241 ◽  
Author(s):  
Klaus Reinhardt
Keyword(s):  
Sexual Selection ◽  
Reproductive Isolation ◽  
Reproductive Output ◽  
Mating Effort ◽  
Sperm Number ◽  
Storage Organ ◽  
Genetic Incompatibility ◽  
Chorthippus Parallelus ◽  
Mating Signals ◽  
Crucial Assumption

Comparing the reproductive output of intra- and inter-population matings is the most common way to assess whether post-mating reproductive isolation is caused by genetic incompatibilities. Such genetic incompatibility can however, only assume that the quantity of the post-mating signals involved does not differ between intra- and inter-population matings. This assumption may not be true because sexual selection predicts reduced mating effort towards low-quality mates and in many circumstances, allopatric partners are low-quality mates. Post-mating efforts may, therefore, be reduced in inter- compared to intra-population matings. Here, I test this crucial assumption by studying variation in one post-mating trait, sperm number, in crosses of two parapatric grasshopper populations. In both populations, males transferred fewer sperm to allopatric than sympatric females. If such plasticity with respect to population is common in other post-mating traits, differences between inter- and intra-population crosses may be more frequently caused by differences in sperm number rather than gamete incompatibility. Additionally, I found that sperm numbers declined less rapidly in the female storage organ of allopatric than sympatric females but its rate differed markedly between populations. This is discussed with respect to female adaptations to male traits.

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