1
|
Nishimura T, Tanaka M. Generation of Self-Fertilizing Hermaphroditic Fish from Gonochoristic Fish, Medaka (Oryzias latipes). Sex Dev 2023; 16:283-288. [PMID: 36450233 DOI: 10.1159/000526073] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2022] [Accepted: 07/08/2022] [Indexed: 12/02/2022] Open
Abstract
INTRODUCTION Hermaphroditism is a mode of reproduction involving an individual animal that possesses both a testis and an ovary either sequentially or simultaneously. The mechanism creating hermaphrodites remains unknown. Previously, we identified foxl3 as the germline sex determination gene in a gonochoristic fish, medaka (Oryzias latipes). foxl3 loss-of-function (foxl3-/-) females produce functional sperm as well as eggs in the ovary. However, these two gametes are not self-fertilizing because of the histological separation of each gamete production. In this study, we attempted to generate self-fertilizing medaka from female medaka by modifying germline sex using foxl3-/- mutants and by using exogenous androgen to induce partial sex reversal of somatic cells. METHODS foxl3-/- XX females were treated with 11-ketotestosterone (11-KT), a potent teleost fish androgen, at the sexually mature stage for 30 days (90-120 dph). Then, the fish were kept under normal conditions until they were either being dissected or crossed with infertile males. RESULTS AND DISCUSSION We showed that the foxl3-/- XX female medaka can be transformed into a self-fertilizing hermaphrodite by inducing the formation of a male-like structure with exogenous 11-KT. Self-fertilization occurs in either the ovarian cavity, the oviduct, or both where sperm is released from a tubule-like structure which is likely derived from germinal epithelium, suggesting that timely modification of 2 independent mechanisms, regulation of germline sex and partial sex reversal of somatic cells, are critical to change the reproduction mode. Our results will provide insights in developmental and evolutional occurrence of hermaphrodite vertebrates, facilitate an innovative technique to improve the efficient selection of fish with desirable traits, and contribute to the rescue of endangered species.
Collapse
Affiliation(s)
- Toshiya Nishimura
- Graduate School of Biological Science, Nagoya University, Nagoya, Japan.,Faculty and Graduate School of Fisheries Sciences, Hokkaido University, Hakodate, Japan
| | - Minoru Tanaka
- Graduate School of Biological Science, Nagoya University, Nagoya, Japan
| |
Collapse
|
2
|
Berbel-Filho WM, Pacheco G, Tatarenkov A, Lira MG, Garcia de Leaniz C, Rodríguez López CM, Lima SMQ, Consuegra S. Phylogenomics reveals extensive introgression and a case of mito-nuclear discordance in the killifish genus Kryptolebias. Mol Phylogenet Evol 2022; 177:107617. [PMID: 36038055 DOI: 10.1016/j.ympev.2022.107617] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2022] [Revised: 08/03/2022] [Accepted: 08/17/2022] [Indexed: 10/15/2022]
Abstract
Introgression is a widespread evolutionary process leading to phylogenetic inconsistencies among distinct parts of the genomes, particularly between mitochondrial and nuclear-based phylogenetic reconstructions (e.g., mito-nuclear discordances). Here, we used mtDNA and genome-wide nuclear sites to provide the first phylogenomic-based hypothesis on the evolutionary relationships within the killifish genus Kryptolebias. In addition, we tested for evidence of past introgression in the genus given the multiple reports of undergoing hybridization between its members. Our mtDNA phylogeny generally agreed with the relationships previously proposed for the genus. However, our reconstruction based on nuclear DNA revealed an unknown lineage - Kryptolebias sp. 'ESP' - as the sister group of the self-fertilizing mangrove killifishes, K. marmoratus and K. hermaphroditus. All individuals sequenced of Kryptolebias sp. 'ESP' had the same mtDNA haplotype commonly observed in K. hermaphroditus, demonstrating a clear case of mito-nuclear discordance. Our analysis further confirmed extensive history of introgression between Kryptolebias sp. 'ESP' and K. hermaphroditus. Population genomics analyses indicate no current gene flow between the two lineages, despite their current sympatry and history of introgression. We also confirmed introgression between other species pairs in the genus that have been recently reported to form hybrid zones. Overall, our study provides a phylogenomic reconstruction covering most of the Kryptolebias species, reveals a new lineage hidden in a case of mito-nuclear discordance, and provides evidence of multiple events of ancestral introgression in the genus. These findings underscore the importance of investigating different genomic information in a phylogenetic framework, particularly in taxa where introgression is common as in the sexually diverse mangrove killifishes.
Collapse
Affiliation(s)
- Waldir M Berbel-Filho
- Department of Biology, University of Oklahoma, Norman, OK, USA(1); Department of Biosciences, College of Science, Swansea University, Swansea, UK.
| | - George Pacheco
- Section for Marine Living Resources, National Institute of Aquatic Resources, Technical University of Denmark, Vejlsøvej 39, 8600 Silkeborg, Denmark
| | - Andrey Tatarenkov
- Department of Ecology and Evolutionary Biology, University of California, Irvine, USA
| | - Mateus G Lira
- Laboratório de Ictiologia Sistemática e Evolutiva, Departamento de Botânica e Zoologia, Universidade Federal do Rio Grande, Natal, Brazil
| | | | - Carlos M Rodríguez López
- Environmental Epigenetics and Genetics Group, Department of Horticulture, College of Agriculture, Food and Environment, University of Kentucky, Lexington, KY, USA
| | - Sergio M Q Lima
- Laboratório de Ictiologia Sistemática e Evolutiva, Departamento de Botânica e Zoologia, Universidade Federal do Rio Grande, Natal, Brazil
| | - Sofia Consuegra
- Department of Biosciences, College of Science, Swansea University, Swansea, UK
| |
Collapse
|
3
|
Alda P, Lounnas M, Vázquez AA, Ayaqui R, Calvopiña M, Celi-Erazo M, Dillon RT Jr, González Ramírez LC, Loker ES, Muzzio-Aroca J, Nárvaez AO, Noya O, Pereira AE, Robles LM, Rodríguez-Hidalgo R, Uribe N, David P, Jarne P, Pointier JP, Hurtrez-Boussès S. Systematics and geographical distribution of Galba species, a group of cryptic and worldwide freshwater snails. Mol Phylogenet Evol 2021; 157:107035. [PMID: 33285288 DOI: 10.1016/j.ympev.2020.107035] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2020] [Revised: 09/18/2020] [Accepted: 11/30/2020] [Indexed: 01/06/2023]
Abstract
Cryptic species can present a significant challenge to the application of systematic and biogeographic principles, especially if they are invasive or transmit parasites or pathogens. Detecting cryptic species requires a pluralistic approach in which molecular markers facilitate the detection of coherent taxonomic units that can then be analyzed using various traits (e.g., internal morphology) and crosses. In asexual or self-fertilizing species, the latter criteria are of limited use. We studied a group of cryptic freshwater snails (genus Galba) from the family Lymnaeidae that have invaded almost all continents, reproducing mainly by self-fertilization and transmitting liver flukes to humans and livestock. We aim to clarify the systematics, distribution, and phylogeny of these species with an integrative approach that includes morphology, molecular markers, wide-scale sampling across America, and data retrieved from GenBank (to include Old World samples). Our phylogenetic analysis suggests that the genus Galba originated ca. 22 Myr ago and today comprises six species or species complexes. Four of them show an elongated-shell cryptic phenotype and exhibit wide variation in their genetic diversity, geographic distribution, and invasiveness. The remaining two species have more geographically restricted distributions and exhibit a globose-shell cryptic phenotype, most likely phylogenetically derived from the elongated one. We emphasize that no Galba species should be identified without molecular markers. We also discuss several hypotheses that can explain the origin of cryptic species in Galba, such as convergence and morphological stasis.
Collapse
|
4
|
Abstract
Many plants harbor complex mechanisms that promote outcrossing and efficient pollen transfer. These include floral adaptations as well as genetic mechanisms, such as molecular self-incompatibility (SI) systems. The maintenance of such systems over long evolutionary timescales suggests that outcrossing is favorable over a broad range of conditions. Conversely, SI has repeatedly been lost, often in association with transitions to self-fertilization (selfing). This transition is favored when the short-term advantages of selfing outweigh the costs, primarily inbreeding depression. The transition to selfing is expected to have major effects on population genetic variation and adaptive potential, as well as on genome evolution. In the Brassicaceae, many studies on the population genetic, gene regulatory, and genomic effects of selfing have centered on the model plant Arabidopsis thaliana and the crucifer genus Capsella. The accumulation of population genomics datasets have allowed detailed investigation of where, when and how the transition to selfing occurred. Future studies will take advantage of the development of population genetics theory on the impact of selfing, especially regarding positive selection. Furthermore, investigation of systems including recent transitions to selfing, mixed mating populations and/or multiple independent replicates of the same transition will facilitate dissecting the effects of mating system variation from processes driven by demography.
Collapse
Affiliation(s)
- Tiina M Mattila
- Department of Ecology and Genetics, University of Oulu, Oulu, Finland
| | - Benjamin Laenen
- Department of Ecology, Environment, and Plant Sciences, Science for Life Laboratory, Stockholm University, Stockholm, Sweden
| | - Tanja Slotte
- Department of Ecology, Environment, and Plant Sciences, Science for Life Laboratory, Stockholm University, Stockholm, Sweden.
| |
Collapse
|
5
|
Yi-An W, You-Sheng L, Guo-Li Q, Feng S, Yun-Tian X, Jian-Rong D. [Study on biological characteristics: reproduction and viability of Biomphalaria glabrata as an intermediate host of Schistosoma mansoni]. Zhongguo Xue Xi Chong Bing Fang Zhi Za Zhi 2019; 31:362-367. [PMID: 31612669 DOI: 10.16250/j.32.1374.2018277] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
OBJECTIVE To compare the difference of fertility of Biomphalaria glabrata snails between self-fertilization and cross-fertilization and to observe the circadian rhythm of laying eggs, the effect of light on laying eggs and the tolerance of the snail to water and food deficiency, so as to provide the evidence for control and elimination of B. glabrata snails in the field. METHODS Under laboratory conditions, a single B. glabrata egg for self-fertilization was separated and hatched individually, and young snails were raised in different plastic boxes individually. The eggs for cross-fertilization were hatched and the young snails were fed in the same plastic box. The ability of spawn, the development of the eggs, and the number of snails growing from young to adult snails were compared between the self-fertilization and cross-fertilization. The snails were in the water under four environments, all day illumination, all day without illumination, daytime lighting and night without illumination, and daytime without illumination but night lighting. The eggs were collected and counted daily. The circadian rhythm of spawn and the effect of illumination on spawn were observed. The adult snails were divided into 6 groups and exposed to the environments with relative humidity of 0, 65%, 87% and 100%, respectively. The survival rates of the adult snails exposed to the different environments after different time were observed. The adult snails were placed at 25 °C in the oven to remove water content from the soft body of snails. When the dehydration rates of the soft bodies achieved 10%, 20%, 30%, 40%, 50%, 52%, 55%, 57%, 60%, and 70% respectively, the survival rates of the adult snails exposed to the oven were observed. RESULTS In the 25 °C water, the average laying egg number for 15 days per snail was (8.77 ± 16.92) eggs/snail in the self-fertilization snail. The average laying egg number for 15 days per snail was (149.71 ± 142.28) eggs/snail in the cross-fertilization snails. There was a significant difference between the self-fertilization snail and cross-fertilization snail (t = 0.999 999, P < 0.01). The hatching rate and reproductive maturation rate of the self-fertilization snails and cross-fertilization snails were 50.1% and 78.9%, and 19.3% and 3.8%, respectively, There was a significant difference (the hatching rate: χ2 = 18.18, P < 0.01, the reproductive maturation rate: χ2 = 11.83, P < 0.01) . In the natural environment of daytime with illumination and nighttime with darkness, the amount of laying 20 eggs of B. glabrata snail was (944.07 ± 392.53) eggs/day during a whole day, among them the amount of laying eggs during daytime account for 10.1% and the amount of laying eggs during nighttime account for 89.9%, and the laying egg was given priority to with the night. The above results suggested that the dark environment was conducive to B. glabrata snails to lay eggs. The above results suggested that light can promote the increase of spawning of B. glabrata. When B. glabrata was exposed to the environments with the relative humidity of 0, 65%, 87% and 100% at 25 °C, respectively, and the longest survival times of snails were 7, 70, 150 d and 100 d, respectively. In the 25 °C water, the snails could survive for 50 days without food. The adult snails were placed at 25 °C in the oven to remove water content from the soft body of snails. When the dehydration rates of the soft bodies achieved 10%, 20%, 30%, 40%, 50%, 52%, 55%, 57%, 60%, and 70% respectively, the survival rates of the adult snails exposed to the oven were 100%, 100%, 100%, 100%, 70%, 30%, 0, 0, 0 and 0, respectively. CONCLUSIONS B. glabrata can achieve the reproductive process by cross-fertilization or self-fertilization. There is a significant difference in reproductive ability between the cross-fertilization snail and self-fertilization snail, cross-fertilization is stronger than self-fertilization, but the rate of reproduction in the self-fertilization is higher than that in the cross-fertilization. It is indicated that B. glabrata that survive after the dry season plays an important role in the maintenance of local snail populations and transmission of schistosomiasis mansoni.
Collapse
Affiliation(s)
- Wang Yi-An
- Jiangsu Institute of Parasitic Diseases, Key Laboratory of National Health and Family Planning Commission on Parasitic Disease Control and Prevention, Jiangsu Provincial Key Laboratory on Parasites and Vector Control Technology, Wuxi 214064, China.,Zhenjiang Health Inspection Bureau, Jiangsu Province, China
| | - Liang You-Sheng
- Jiangsu Institute of Parasitic Diseases, Key Laboratory of National Health and Family Planning Commission on Parasitic Disease Control and Prevention, Jiangsu Provincial Key Laboratory on Parasites and Vector Control Technology, Wuxi 214064, China
| | - Qu Guo-Li
- Jiangsu Institute of Parasitic Diseases, Key Laboratory of National Health and Family Planning Commission on Parasitic Disease Control and Prevention, Jiangsu Provincial Key Laboratory on Parasites and Vector Control Technology, Wuxi 214064, China
| | - Shi Feng
- Jiangsu Institute of Parasitic Diseases, Key Laboratory of National Health and Family Planning Commission on Parasitic Disease Control and Prevention, Jiangsu Provincial Key Laboratory on Parasites and Vector Control Technology, Wuxi 214064, China
| | - Xing Yun-Tian
- Jiangsu Institute of Parasitic Diseases, Key Laboratory of National Health and Family Planning Commission on Parasitic Disease Control and Prevention, Jiangsu Provincial Key Laboratory on Parasites and Vector Control Technology, Wuxi 214064, China
| | - Dai Jian-Rong
- Jiangsu Institute of Parasitic Diseases, Key Laboratory of National Health and Family Planning Commission on Parasitic Disease Control and Prevention, Jiangsu Provincial Key Laboratory on Parasites and Vector Control Technology, Wuxi 214064, China
| |
Collapse
|
6
|
Chelo IM, Afonso B, Carvalho S, Theologidis I, Goy C, Pino-Querido A, Proulx SR, Teotónio H. Partial Selfing Can Reduce Genetic Loads While Maintaining Diversity During Experimental Evolution. G3 (Bethesda) 2019; 9:2811-2821. [PMID: 31278175 PMCID: PMC6723137 DOI: 10.1534/g3.119.400239] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/03/2019] [Accepted: 06/17/2019] [Indexed: 12/30/2022]
Abstract
Partial selfing, whereby self- and cross- fertilization occur in populations at intermediate frequencies, is generally thought to be evolutionarily unstable. Yet, it is found in natural populations. This could be explained if populations with partial selfing are able to reduce genetic loads and the possibility for inbreeding depression while keeping genetic diversity that may be important for future adaptation. To address this hypothesis, we compare the experimental evolution of Caenorhabditis elegans populations under partial selfing, exclusive selfing or predominant outcrossing, while they adapt to osmotically challenging conditions. We find that the ancestral genetic load, as measured by the risk of extinction upon inbreeding by selfing, is maintained as long as outcrossing is the main reproductive mode, but becomes reduced otherwise. Analysis of genome-wide single-nucleotide polymorphisms (SNPs) during experimental evolution and among the inbred lines that survived enforced inbreeding indicates that populations with predominant outcrossing or partial selfing maintained more genetic diversity than expected with neutrality or purifying selection. We discuss the conditions under which this could be explained by the presence of recessive deleterious alleles and/or overdominant loci. Taken together, our observations suggest that populations evolving under partial selfing can gain some of the benefits of eliminating unlinked deleterious recessive alleles and also the benefits of maintaining genetic diversity at partially dominant or overdominant loci that become associated due to variance of inbreeding levels.
Collapse
Affiliation(s)
- Ivo M Chelo
- Instituto Gulbenkian de Ciência, Apartado 14, P-2781-901 Oeiras, Portugal
- cE3c - Center for Ecology, Evolution and Environmental Changes, Faculdade de Ciências, Universidade de Lisboa, Lisboa, Portugal
| | - Bruno Afonso
- Instituto Gulbenkian de Ciência, Apartado 14, P-2781-901 Oeiras, Portugal
- Institut de Biologie de l'École Normale Supérieure (IBENS), Inserm U1024, CNRS UMR 8197, F-75005 Paris, France
| | - Sara Carvalho
- Instituto Gulbenkian de Ciência, Apartado 14, P-2781-901 Oeiras, Portugal
| | - Ioannis Theologidis
- Institute of Molecular Biology and Biotechnology, Foundation for Research and Technology-Hellas, 73100 Heraklion, Greece
| | - Christine Goy
- Leibniz Research Institute for Environmental Medicine, 40225 Düsseldorf, Germany, and
| | - Ania Pino-Querido
- Instituto Gulbenkian de Ciência, Apartado 14, P-2781-901 Oeiras, Portugal
| | - Stephen R Proulx
- Department of Ecology, Evolution, and Marine Biology, University of California Santa Barbara, CA 93106
| | - Henrique Teotónio
- Institut de Biologie de l'École Normale Supérieure (IBENS), Inserm U1024, CNRS UMR 8197, F-75005 Paris, France
| |
Collapse
|
7
|
Jahnke MR, Etterson JR. Autonomous self-fertilization in Linum sulcatum, a native annual with a previously unknown mating system. J Plant Res 2019; 132:57-67. [PMID: 30554369 DOI: 10.1007/s10265-018-1076-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/12/2018] [Accepted: 11/30/2018] [Indexed: 06/09/2023]
Abstract
The mating systems of wild plant populations have profound effects on their genetic structure and evolution, yet remain unknown or incompletely described for many species. One such species, the herbaceous native annual Linum sulcatum Riddell (Linaceae), is thought to be self-compatible, but there has been no experimental evidence to date to support this claim. To assess the breeding system of this species, seeds were collected from wild populations and reared in a controlled environment. Floral manipulations and controlled pollinations were conducted to determine the degree of self-compatibility of this species and to distinguish between autonomous and facilitated modes of selfing. Additional controlled within- and between-population crosses were conducted to determine the relative degree to which this species can outcross. This study showed that self-fertilization was highly successful and can occur autonomously. In contrast, outcrossing success, both within and between populations, was very limited, suggesting this species may exhibit an extreme degree of cross-incompatibility. A pollen tube growth experiment showed that self-pollination resulted in the formation of more pollen tubes relative to cross-pollination and that complete pollen tube growth can occur less than 2 h following self-pollination. This information is relevant to the future persistence of this species, as much of its remaining habitat is distributed among small, highly fragmented patches subjected to current and future environmental stressors.
Collapse
Affiliation(s)
- Matthew R Jahnke
- Department of Biology, University of Minnesota Duluth, 207A Swenson Science Building, Duluth, MN, 55812, USA.
| | - Julie R Etterson
- Department of Biology, University of Minnesota Duluth, 207A Swenson Science Building, Duluth, MN, 55812, USA
| |
Collapse
|
8
|
Sasson DA, Jacquez AA, Ryan JF. The ctenophore Mnemiopsis leidyi regulates egg production via conspecific communication. BMC Ecol 2018; 18:12. [PMID: 29576018 PMCID: PMC5868061 DOI: 10.1186/s12898-018-0169-9] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2017] [Accepted: 03/15/2018] [Indexed: 11/10/2022] Open
Abstract
Background Communication between individuals of the same species is an important aspect of mating and reproduction in most animals. In simultaneously hermaphroditic species with the ability to self-fertilize, communication with conspecifics can be essential to avoid inbreeding depression. One such behavioral adaptation observed in some simultaneous hermaphrodites is gamete trading. This behavior involves individual hermaphrodites in pairs alternating between reproducing as the male and female, and, as such, necessarily requires communication and coordination between mates. Little is known about communication in ctenophores and conspecific communication has not been described in this group; however, our previous work suggested that the ctenophore Mnemiopsis leidyi might engage in gamete trading. We tested for this possibility by constructing divided arenas (both sealed and permeable) that allowed us to measure individual egg output for paired M. leidyi. Results We found that, when not allowed to interact, size-matched individuals produced similar numbers of eggs on each side of the arena. However, if allowed to interact and exchange water, size-matched pairs produce significantly different numbers of eggs on each side of the arena, suggesting that these pairs use chemical communication to modulate reproduction in the presence of conspecifics as would be expected in gamete trading. Conclusion This finding presents exciting new possibilities for future investigations into the nature of signaling in M. leidyi. Furthermore, this first evidence of conspecific communication in Ctenophora, a group that branched off from the rest of animals more than 600 million years ago, has significant implications for the signaling ability of the last common ancestor of all animals. Electronic supplementary material The online version of this article (10.1186/s12898-018-0169-9) contains supplementary material, which is available to authorized users.
Collapse
Affiliation(s)
- Daniel A Sasson
- Whitney Laboratory for Marine Bioscience, University of Florida, St. Augustine, FL, USA.,Department of Biology, Saint Louis University, Saint Louis, MO, USA
| | - Anya A Jacquez
- Whitney Laboratory for Marine Bioscience, University of Florida, St. Augustine, FL, USA.,Department of Biology, Lewis & Clark College, Portland, OR, USA
| | - Joseph F Ryan
- Whitney Laboratory for Marine Bioscience, University of Florida, St. Augustine, FL, USA. .,Department of Biology, University of Florida, Gainesville, FL, USA.
| |
Collapse
|
9
|
Lomax JL, Carlson RE, Wells JW, Crawford PM, Earley RL. Factors affecting egg production in the selfing mangrove rivulus (Kryptolebias marmoratus). ZOOLOGY 2017; 122:38-45. [PMID: 28268048 DOI: 10.1016/j.zool.2017.02.004] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2016] [Revised: 02/13/2017] [Accepted: 02/15/2017] [Indexed: 02/03/2023]
Abstract
The mangrove rivulus, Kryptolebias marmoratus, is one of two known vertebrate species with preferentially self-fertilizing hermaphrodites. Males also exist, and can outcross with hermaphrodites. Outcrossing events vary across wild populations and occur infrequently in laboratory settings. This study sought to add dimension to our understanding of mangrove rivulus reproductive habits by probing the effects of male presence on hermaphroditic unfertilized egg production. Specifically, we quantified egg production of solitary hermaphrodites compared to hermaphrodites exposed to males and exposed to other hermaphrodites. Hermaphrodites tended to produce more fertilized eggs in the presence of males but unfertilized eggs were produced relatively rarely and did not vary significantly among treatments. The probability that hermaphrodites would produce eggs changed as a function of genetic dissimilarity with their partner and in a season-dependent manner. In the fall, the probability of laying eggs decreased as a function of increased genetic dissimilarity, regardless of the sex of the partner. In the winter/spring, however, the probability of laying eggs increased markedly with increased genetic dissimilarity, regardless of the sex of the partner. Our findings indicate that reproductive decisions are modulated by factors beyond male presence, and we discuss a number of alternative hypotheses that should be tested in future studies.
Collapse
Affiliation(s)
- Justin L Lomax
- Department of Biological Sciences, University of Alabama, 300 Hackberry Lane, Box 870344, Tuscaloosa, AL 35487, USA
| | - Rachel E Carlson
- Department of Biological Sciences, University of Alabama, 300 Hackberry Lane, Box 870344, Tuscaloosa, AL 35487, USA
| | - Judson W Wells
- Department of Biological Sciences, University of Alabama, 300 Hackberry Lane, Box 870344, Tuscaloosa, AL 35487, USA
| | - Patrice M Crawford
- Department of Biological Sciences, University of Alabama, 300 Hackberry Lane, Box 870344, Tuscaloosa, AL 35487, USA
| | - Ryan L Earley
- Department of Biological Sciences, University of Alabama, 300 Hackberry Lane, Box 870344, Tuscaloosa, AL 35487, USA.
| |
Collapse
|
10
|
Giannakara A, Ramm SA. Self-fertilization, sex allocation and spermatogenesis kinetics in the hypodermically inseminating flatworm Macrostomum pusillum. ACTA ACUST UNITED AC 2017; 220:1568-1577. [PMID: 28183866 DOI: 10.1242/jeb.149682] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2016] [Accepted: 02/03/2017] [Indexed: 01/15/2023]
Abstract
The free-living flatworm genus Macrostomum is an emerging model system for studying the links between sex allocation, sexual selection and mating system evolution, as well as the underlying developmental and physiological mechanisms responsible for wide intra- and inter-specific variability in reproductive phenotypes. Despite compelling comparative morphological evidence of sexual diversity, detailed experimental work on reproductive behaviour and physiology in Macrostomum has so far been largely limited to just two species, M. lignano and M. hystrix, an obligate and a preferential outcrosser, respectively. In this study, we establish that a third species, M. pusillum, exhibits a combination of reproductive traits strikingly different from both of its congeners. Unlike M. lignano, we demonstrate that M. pusillum does not adjust sex allocation or the speed of spermatogenesis to the prevailing social group size. Macrostomumpusillum's relatively simple sperm morphology likely explains the short spermatogenesis duration we report, and is linked to a hypodermically inseminating mode of fertilization, which we show also means that these worms are capable of self-fertilization. Surprisingly, and unlike M. hystrix, selfing in isolated worms commences after only a short (if any) delay compared with the onset of reproduction in grouped individuals, with little evidence of differential inbreeding depression in 'isolated' progeny. These combined results suggest that, in nature, M. pusillum may be regularly selfing, in contrast to the congeners studied to date. Our findings highlight the rapid and correlated evolution of reproductive traits, and reinforce the utility of the genus Macrostomum for understanding the evolutionary and developmental mechanisms responsible for this diversity.
Collapse
Affiliation(s)
- Athina Giannakara
- Evolutionary Biology, Bielefeld University, Morgenbreede 45, Bielefeld 33615, Germany
| | - Steven A Ramm
- Evolutionary Biology, Bielefeld University, Morgenbreede 45, Bielefeld 33615, Germany
| |
Collapse
|
11
|
Abstract
BACKGROUND Biparental inbreeding, mating between two relatives, occurs at a low frequency in many natural plant populations, which also often have substantial rates of self-fertilization. Although biparental inbreeding is likely to influence the dynamics of inbreeding depression and the evolution of selfing rates, it has received limited theoretical attention in comparison to selfing. The only previous model suggested that biparental inbreeding can favour the maintenance of stable intermediate selfing rates, but made unrealistic assumptions about the genetic basis of inbreeding depression. Here we extend a genetic model of inbreeding depression, describing nearly recessive lethal mutations at a very large number of loci, to incorporate sib-mating. We also include a constant component of inbreeding depression modelling the effects of mildly deleterious, nearly additive alleles. We analyze how observed rates of sib-mating influence the mean number of heterozygous lethals alleles and inbreeding depression in a population reproducing by a mixture of self-fertilization, sib-mating and outcrossing. We finally use the ensuing relationship between equilibrium inbreeding depression and population selfing rate to infer the evolutionarily stable selfing rates expected under such a mixed mating system. RESULTS We show that for a given rate of inbreeding, sib-mating is more efficient at purging inbreeding depression than selfing, because homozygosity of lethals increases more gradually through sib-mating than through selfing. Because sib-mating promotes the purging of inbreeding depression and the evolution of selfing, our genetic model of inbreeding depression also predicts that sib-mating is unlikely to maintain stable intermediate selfing rates. CONCLUSIONS Our results imply that even low rates of sib-mating affect plant mating system evolution, by facilitating the evolution of selfing via more efficient purging of inbreeding depression. Alternative mechanisms, such as pollination ecology, are necessary to explain stable mixed selfing and outcrossing.
Collapse
Affiliation(s)
- Emmanuelle Porcher
- Centre d'Ecologie et des Sciences de la Conservation (UMR7204), Sorbonne Universités, MNHN, CNRS, UPMC, 57 rue Cuvier, Paris, 75005, France.
| | - Russell Lande
- Department of Life Sciences, Imperial College London, Ascot, Berkshire, UK
| |
Collapse
|
12
|
Sasson DA, Ryan JF. The sex lives of ctenophores: the influence of light, body size, and self-fertilization on the reproductive output of the sea walnut, Mnemiopsis leidyi. PeerJ 2016; 4:e1846. [PMID: 27042395 PMCID: PMC4811168 DOI: 10.7717/peerj.1846] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2015] [Accepted: 03/03/2016] [Indexed: 12/31/2022] Open
Abstract
Ctenophores (comb jellies) are emerging as important animals for investigating fundamental questions across numerous branches of biology (e.g., evodevo, neuroscience and biogeography). A few ctenophore species including, most notably, Mnemiopsis leidyi, are considered as invasive species, adding to the significance of studying ctenophore ecology. Despite the growing interest in ctenophore biology, relatively little is known about their reproduction. Like most ctenophores, M. leidyi is a simultaneous hermaphrodite capable of self-fertilization. In this study, we assess the influence of light on spawning, the effect of body size on spawning likelihood and reproductive output, and the cost of self-fertilization on egg viability in M. leidyi. Our results suggest that M. leidyi spawning is more strongly influenced by circadian rhythms than specific light cues and that body size significantly impacts spawning and reproductive output. Mnemiopsis leidyi adults that spawned alone produced a lower percentage of viable embryos versus those that spawned in pairs, suggesting that self-fertilization may be costly in this species. These results provide insight into the reproductive ecology of M. leidyi and provide a fundamental resource for researchers working with them in the laboratory.
Collapse
Affiliation(s)
- Daniel A Sasson
- Whitney Laboratory for Marine Bioscience, University of Florida, St. Augustine, Florida, United States of America; Department of Biology, University of Florida, Gainesville, Florida, United States of America
| | - Joseph F Ryan
- Whitney Laboratory for Marine Bioscience, University of Florida, St. Augustine, Florida, United States of America; Department of Biology, University of Florida, Gainesville, Florida, United States of America
| |
Collapse
|
13
|
Price MR, Sischo D, Pascua MA, Hadfield MG. Demographic and genetic factors in the recovery or demise of ex situ populations following a severe bottleneck in fifteen species of Hawaiian tree snails. PeerJ 2015; 3:e1406. [PMID: 26587358 PMCID: PMC4647602 DOI: 10.7717/peerj.1406] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2015] [Accepted: 10/26/2015] [Indexed: 01/13/2023] Open
Abstract
Wild populations of endangered Hawaiian tree snails have declined precipitously over the last century due to introduced predators and other human impacts. Life history traits, such as very low fecundity (<5 offspring per year across taxa) and maturity at approximately four years of age have made recovery difficult. Conservation efforts such as in situ predator-free enclosures may increase survival to maturity by protecting offspring from predation, but no long-term data existed prior to this study demonstrating the demographic and genetic parameters necessary to maintain populations within those enclosures. We evaluated over 20 years of evidence for the dynamics of survival and extinction in captive ex situ populations of Hawaiian tree snails established from wild-collected individuals. From 1991 to 2006, small numbers of snails (<15) from fifteen species were collected from the wild to initiate captive-reared populations as a hedge against extinction. This small number of founders resulted in a severe bottleneck in each of the captive-reared populations. We identified key demographic parameters that predicted population recovery from this bottleneck. Species with captive populations that produced between two and four offspring per adult per year and had 20–50% of those offspring survive to maturity recovered to numbers above 100 individuals, and maintained viable populations following a decline that occurred between 2009 and 2014. Those populations that had less than two offspring per adult per year and less than 20% survival to maturity did not reach 100 individuals in captivity, and many of these populations died out during the recent decline. We suggest that small reductions in fitness may contribute to extirpation in taxa with inherently low fecundity, by keeping populations below a threshold number essential to long-term recovery. Future ex situ populations should be founded with no less than 15 adults, and maintained in conditions closely approximating the temperature and humidity of source locations to optimize fitness. Permanent translocations of wild populations for conservation purposes will be more likely to succeed with greater than 100 adults, and should be limited to locations with a similar climate to source locations.
Collapse
Affiliation(s)
- Melissa R Price
- Kewalo Marine Laboratory, Pacific Biosciences Research Center, University of Hawai'i at Mānoa , Honolulu, HI , USA ; Department of Natural Resources and Environmental Management, University of Hawai'i at Mānoa , Honolulu, HI , USA
| | - David Sischo
- Division of Forestry and Wildlife, Department of Land and Natural Resources , Honolulu, HI , USA
| | | | - Michael G Hadfield
- Kewalo Marine Laboratory, Pacific Biosciences Research Center, University of Hawai'i at Mānoa , Honolulu, HI , USA
| |
Collapse
|