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.

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).

scholarly journals Evolution of sex allocation plasticity and its predictors in a flatworm genus

2020 ◽  
Author(s):  
Pragya Singh ◽  
Lukas Schärer
Keyword(s):  
Intraspecific Variation ◽  
Sex Allocation ◽  
Interspecific Variation ◽  
Mating Strategy ◽  
Effect Sizes ◽  
Standardized Effect Sizes ◽  
Self Fertilization ◽  
Species Being ◽  
Simultaneous Hermaphrodites ◽  
Reciprocal Mating

AbstractLocal sperm competition (LSC), which occurs when related sperm compete for access to a given set of eggs, can influence sex allocation (SA) in simultaneous hermaphrodites. Different factors that have been predicted to affect LSC—and hence, optimal SA—include the mating strategy (such as reciprocal mating vs. hypodermic insemination) and the ability to self-fertilize. Moreover, the level of LSC experienced could vary temporally and/or spatially, favouring the evolution of SA plasticity. However, it is unknown how the mating strategy and ability to self-fertilize can influence SA and SA plasticity. Here, we explored this by collecting estimates of SA and SA plasticity for seven species of the flatworm genus, Macrostomum, and performing analyses while controlling for phylogeny. While we found substantial interspecific variation in SA, neither the mating strategy nor the ability to self-fertilize had a significant effect on SA. Next, we estimated standardized effect sizes for SA plasticity in response to i) the presence of mating partners and ii) the strength of LSC for each species, and tested if the mating strategy or ability to self-fertilize predicted these effect sizes. We found considerable interspecific variation in SA plasticity, with some species being highly plastic and others showing no significant plasticity. Moreover, self-fertilization predicted SA plasticity with respect to the presence of mating partners, with SA plasticity being lower for self-fertilizing species. Finally, we showed that interspecific variation in SA is nearly three times higher than intraspecific variation, suggesting that SA estimates in field-collected specimens can, at least to some degree, be interpreted as representing interspecific rather than intraspecific variation. Our study suggests that both SA and SA plasticity can evolve rapidly, with self-fertilization being an important predictor for the latter in Macrostomum.

scholarly journals Hermaphrodites and parasitism: size-specific female reproduction drives infection by an ephemeral parasitic castrator

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Caitlin R. Fong ◽  
Armand M. Kuris ◽  
Ryan F. Hechinger
Keyword(s):  
Reproductive Effort ◽  
Reproductive Function ◽  
Simultaneous Hermaphrodite ◽  
Female Reproduction ◽  
Female Function ◽  
Males And Females ◽  
Selection For ◽  
Parasitic Castrator ◽  
Male Reproductive Effort ◽  
The Relationship

AbstractSex can influence patterns of parasitism because males and females can differ in encounter with, and susceptibility to, parasites. We investigate an isopod parasite (Hemioniscus balani) that consumes ovarian fluid, blocking female function of its barnacle host, a simultaneous hermaphrodite. As a hermaphrodite, sex is fluid, and individuals may allocate energy differentially to male versus female reproduction. We predicted the relationship between barnacle size and female reproductive function influences the distribution of parasites within barnacle populations. We surveyed 12 populations spanning ~400 km of coastline of southern California and found intermediate-sized barnacles where most likely to be actively functioning as females. While it is unclear why larger individuals are less likely to be actively reproducing as females, we suggest this reduced likelihood is driven by increased investment in male reproductive effort at larger sizes. The female function-size relationship was mirrored by the relationship between size and parasitism. We suggest parasitism by Hemioniscus balani imposes a cost to female function, reinforcing the lack of investment in female function by the largest individuals. Within the subset of suitable (=female) hosts, infection probability increased with size. Hence, the distribution of female function, combined with selection for larger hosts, primarily dictated patterns of infection.

scholarly journals HUBUNGAN ANTARA KOMPOSISI IKAN TARGET DAN PRESENTASE TUTUPAN KARANG HIDUP DI KEPULAUAN KEI KECIL, MALUKU

2020 ◽  
Vol 26 (3) ◽  
pp. 147
Author(s):  
Ana Faricha ◽  
Isa Nagib Edrus ◽  
Rizkie Satriya Utama ◽  
Ahmad R. Dzumalex ◽  
Abdullah Salatalohi ◽  
...  
Keyword(s):  
Coral Reef ◽  
Reef Fishes ◽  
Average Density ◽  
Species Variation ◽  
Live Coral ◽  
Visual Census ◽  
Underwater Visual Census ◽  
Ecological Values ◽  
Average Biomass ◽  
The Relationship

Ikan terumbu karang memiliki peranan penting baik secara ekonomi maupun ekologi, namun kondisi terumbu karang termasuk di perairan Indonesia yang menjadi habitat utama ikan karang mengalami degradasi. Penelitian ikan karang sudah banyak dilakukan, namun di Indonesia kondisi habitat ikan karang memiliki karakter yang berbeda-beda. Tujuan penelitian ini adalah untuk mengetahui hubungan antara komposisi ikan karang target dan tutupan karang hidup. Penelitian ini dilakukan pada bulan Oktober 2019 di Kepulauan Kei Kecil, Maluku. Metode yang digunakan adalah UVC (Underwater Visual Census) untuk data ikan karang dan UPT (Underwater Photo Transect) untuk mengkaji tutupan karang hidup. Hasil pengamatan menunjukkan bahwa terdapat 130 spesies ikan karang target yang mewakili 19 famili, dengan variasi jenis ikan target antar lokasi pengamatan berkisar antara 25-66 spesies. Kepadatan rata-rata ikan karang target sebesar 8.811 ± 4.107 Ind/ha, dan biomassa rata-rata 1.335 ± 899 Kg/ha. Komposisi ikan karang target yang memiliki kedekatan dengan tutupan karang hidup yaitu famili Siganidae, Serranidae, Lutjanidae, Holocentridae, dan Pomacentridae. Akan tetapi hubungan tersebut rendah, dan kemungkinan besar ada faktor lain yang mempengaruhi. Reef fishes have an important economic and ecological values. However, the coral reef of the globe including in the most of the Indonesian waters which is the vital habitat for reef fishes is degraded. Study on the reef fishes is an abundance, while the habitat characteristic of reef fishes in Indonesian waters has a differences. The aim of this study is to determine the relationship between the target reef fishes compositions and the percentage live coral covers. This study was carried out in October 2019 at the Kei Kecil islands, Maluku. The method used in this study is UVC (Underwater Visual Census) for collecting the reef fishes data, and the UPT (Underwater Photo Transect) for assessing the live coral coverage. The result shows that there are about 130 fishes, which representing 19 families, with species variation ranges from 25 to 66 species among the observation sites. The average density of target fishes was about 8.811 ± 4.107 Ind/ha, whereas the average biomass of target fishes was 1,335 ± 899 Kg/ha. The target reef fishes compositions that has relation with live coral covers is family Siganidae, Serranidae, Lutjanidae, Holocentridae, and Pomacentridae. However, this relationship is weak, and may influenced by other factors.

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 Cephalo-traumatic secretion transfer in a hermaphrodite sea slug

2014 ◽  
Vol 281 (1774) ◽  
pp. 20132424 ◽  
Author(s):  
Rolanda Lange ◽  
Johanna Werminghausen ◽  
Nils Anthes
Keyword(s):  
Central Nervous System ◽  
Nervous System ◽  
Mating Behaviour ◽  
Species Variation ◽  
Animal Kingdom ◽  
Sea Slug ◽  
The Central Nervous System

Mating rituals in the animal kingdom are often quite extraordinary, in particular when mating is traumatic. We here describe the exceptional traumatic mating behaviour of the currently undescribed sea slug, Siphopteron sp. 1. Similar to four congeners, Siphopteron sp. 1 routinely exhibits traumatic secretion transfer through a stylet-like penis appendage. Contrary to previous descriptions, however, prostate secretions are injected centrally into the partner's forehead, representing, to our knowledge, the first-known instance of ‘cephalo-traumatic secretion transfer’. We further provide a comparative quantification of within- and between-species variation in injection sites and derive a potential neurophysiological function of prostate secretions that are injected close to, or into, the central nervous system.

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 Sexual selection and hermaphroditic organisms: Testing theory

2013 ◽  
Vol 59 (4) ◽  
pp. 579-588 ◽  
Author(s):  
Janet L. Leonard
Keyword(s):  
Sexual Selection ◽  
Reproductive Success ◽  
Multiple Mating ◽  
The Other ◽  
Operational Sex Ratio ◽  
Sexual Role ◽  
Sexual Roles ◽  
Sexual Selection Theory ◽  
Variance In Reproductive Success ◽  
Simultaneous Hermaphrodites

Abstract Sexual selection is widespread if not ubiquitous in hermaphroditic organisms. Although many phenomena that have been described as sexual selection in gonochores, (e.g. harem polygamy, multiple mating, elaborate courtship, even secondary sexual characters) can be found in some hermaphrodites, what is more interesting is the ways in which sexual selection in hermaphrodites may differ from dioecious taxa. In hermaphrodites, an individual’s mating success includes its success from both sexual roles. Secondly, in many simultaneously hermaphroditic taxa there is strong evidence of sexual selection and yet the operational sex ratio is 1:1, by definition. Many simultaneous hermaphrodites have elaborate courtship and genital anatomy, suggesting sexual selection plays an important role in reproductive success. Sperm competition and cryptic female choice mean that the number of mates acquired is not necessarily a predictor of reproductive success. Even in simultaneous hermaphrodites with reciprocal mating, variance in reproductive success through the male role and through the female role may differ in a population. Moreover hermaphrodites may choose to emphasize one sexual role over the other. Data suggest that the preferred role varies in hermaphrodites, which creates an opportunity to test fundamental predictions and assumptions of sexual selection theory. Hermaphrodites may vary their emphasis on one sexual role over the other either developmentally or behaviorally in response to environmental or social parameters. How they use this capability in acquiring more or higher quality mates still requires study.

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