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Ingo Schlupp - One of the best experts on this subject based on the ideXlab platform.

  • Placing the hybrid origin of the asexual Amazon molly (Poecilia Formosa) based on historical climate data
    Biological Journal of The Linnean Society, 2020
    Co-Authors: Gabriel C. Costa, Ingo Schlupp
    Abstract:

    Abstract Asexual hybrids are important model organisms for addressing questions in evolution and ecology, especially for understanding the role of hybridization in speciation. They are rare in nature and several hypotheses have been suggested to explain this. We use an asexual fish, the Amazon molly (Poecilia Formosa), to establish the area in which it was formed via hybridization 125 000 years ago. Using species distribution models and climate models for the Last Interglacial (LIG) we found that model projections to the LIG show a similar map to the present climate model and parental species potentially overlapped in a relatively small area near Tampico, Mexico. This makes P. Formosa one of a few hybrid species for which we know the parental species, the time of hybridization, and likely the place of hybridization. Based on the small area of overlap, our data is in agreement with the idea that asexual hybrids may be rare not because they are evolutionary dead ends but are formed rarely.

  • the gonadal transcriptome of the unisexual amazon molly Poecilia Formosa in comparison to its sexual ancestors Poecilia mexicana and Poecilia latipinna
    BMC Genomics, 2018
    Co-Authors: Ina Maria Schedina, Ingo Schlupp, Detlef Groth, Ralph Tiedemann
    Abstract:

    The unisexual Amazon molly (Poecilia Formosa) originated from a hybridization between two sexual species, the sailfin molly (Poecilia latipinna) and the Atlantic molly (Poecilia mexicana). The Amazon molly reproduces clonally via sperm-dependent parthenogenesis (gynogenesis), in which the sperm of closely related species triggers embryogenesis of the apomictic oocytes, but typically does not contribute genetic material to the next generation. We compare for the first time the gonadal transcriptome of the Amazon molly to those of both ancestral species, P. mexicana and P. latipinna. We sequenced the gonadal transcriptomes of the P. Formosa and its parental species P. mexicana and P. latipinna using Illumina RNA-sequencing techniques (paired-end, 100 bp). De novo assembly of about 50 million raw read pairs for each species was performed using Trinity, yielding 106,922 transcripts for P. Formosa, 115,175 for P. latipinna, and 133,025 for P. mexicana after eliminating contaminations. On the basis of sequence similarity comparisons to other teleost species and the UniProt databases, functional annotation, and differential expression analysis, we demonstrate the similarity of the transcriptomes among the three species. More than 40% of the transcripts for each species were functionally annotated and about 70% were assigned to orthologous genes of a closely related species. Differential expression analysis between the sexual and unisexual species uncovered 2035 up-regulated and 564 down-regulated genes in P. Formosa. This was exemplary validated for six genes by qRT-PCR. We identified more than 130 genes related to meiosis and reproduction within the apomictically reproducing P. Formosa. Overall expression of these genes seems to be down-regulated in the P. Formosa transcriptome compared to both ancestral species (i.e., 106 genes down-regulated, 29 up-regulated). A further 35 meiosis and reproduction related genes were not found in the P. Formosa transcriptome, but were only expressed in the sexual species. Our data support the hypothesis of general down-regulation of meiosis-related genes in the apomictic Amazon molly. Furthermore, the obtained dataset and identified gene catalog will serve as a resource for future research on the molecular mechanisms behind the reproductive mode of this unisexual species.

  • The gonadal transcriptome of the unisexual Amazon molly Poecilia Formosa in comparison to its sexual ancestors, Poecilia mexicana and Poecilia latipinna
    BMC Genomics, 2018
    Co-Authors: Ina Maria Schedina, Ingo Schlupp, Detlef Groth, Ralph Tiedemann
    Abstract:

    Background The unisexual Amazon molly ( Poecilia Formosa ) originated from a hybridization between two sexual species, the sailfin molly ( Poecilia latipinna ) and the Atlantic molly ( Poecilia mexicana ). The Amazon molly reproduces clonally via sperm-dependent parthenogenesis (gynogenesis), in which the sperm of closely related species triggers embryogenesis of the apomictic oocytes, but typically does not contribute genetic material to the next generation. We compare for the first time the gonadal transcriptome of the Amazon molly to those of both ancestral species, P. mexicana and P. latipinna . Results We sequenced the gonadal transcriptomes of the P. Formosa and its parental species P. mexicana and P. latipinna using Illumina RNA-sequencing techniques (paired-end, 100 bp). De novo assembly of about 50 million raw read pairs for each species was performed using Trinity, yielding 106,922 transcripts for P. Formosa , 115,175 for P. latipinna , and 133,025 for P. mexicana after eliminating contaminations. On the basis of sequence similarity comparisons to other teleost species and the UniProt databases, functional annotation, and differential expression analysis, we demonstrate the similarity of the transcriptomes among the three species. More than 40% of the transcripts for each species were functionally annotated and about 70% were assigned to orthologous genes of a closely related species. Differential expression analysis between the sexual and unisexual species uncovered 2035 up-regulated and 564 down-regulated genes in P. Formosa . This was exemplary validated for six genes by qRT-PCR. Conclusions We identified more than 130 genes related to meiosis and reproduction within the apomictically reproducing P . Formosa . Overall expression of these genes seems to be down-regulated in the P . Formosa  transcriptome compared to both ancestral species (i.e., 106 genes down-regulated, 29 up-regulated). A further 35 meiosis and reproduction related genes were not found in the  P . Formosa transcriptome, but were only expressed in the sexual species. Our data support the hypothesis of general down-regulation of meiosis-related genes in the apomictic Amazon molly. Furthermore, the obtained dataset and identified gene catalog will serve as a resource for future research on the molecular mechanisms behind the reproductive mode of this unisexual species.

  • allele specific expression at the androgen receptor alpha gene in a hybrid unisexual fish the amazon molly Poecilia Formosa
    PLOS ONE, 2017
    Co-Authors: Ingo Schlupp, Ralph Tiedemann
    Abstract:

    : The all-female Amazon molly (Poecilia Formosa) is the result of a hybridization of the Atlantic molly (P. mexicana) and the sailfin molly (P. latipinna) approximately 120,000 years ago. As a gynogenetic species, P. Formosa needs to copulate with heterospecific males including males from one of its bisexual ancestral species. However, the sperm only triggers embryogenesis of the diploid eggs. The genetic information of the sperm donor typically will not contribute to the next generation of P. Formosa. Hence, P. Formosa possesses generally one allele from each of its ancestral species at any genetic locus. This raises the question whether both ancestral alleles are equally expressed in P. Formosa. Allele-specific expression (ASE) has been previously assessed in various organisms, e.g., human and fish, and ASE was found to be important in the context of phenotypic variability and disease. In this study, we utilized Real-Time PCR techniques to estimate ASE of the androgen receptor alpha (arα) gene in several distinct tissues of Amazon mollies. We found an allelic bias favoring the maternal ancestor (P. mexicana) allele in ovarian tissue. This allelic bias was not observed in the gill or the brain tissue. Sequencing of the promoter regions of both alleles revealed an association between an Indel in a known CpG island and differential expression. Future studies may reveal whether our observed cis-regulatory divergence is caused by an ovary-specific trans-regulatory element, preferentially activating the allele of the maternal ancestor.

  • kin recognition in a clonal fish Poecilia Formosa
    PLOS ONE, 2016
    Co-Authors: Amber M Makowicz, Ralph Tiedemann, Rachel N Steele, Ingo Schlupp
    Abstract:

    Relatedness strongly influences social behaviors in a wide variety of species. For most species, the highest typical degree of relatedness is between full siblings with 50% shared genes. However, this is poorly understood in species with unusually high relatedness between individuals: clonal organisms. Although there has been some investigation into clonal invertebrates and yeast, nothing is known about kin selection in clonal vertebrates. We show that a clonal fish, the Amazon molly (Poecilia Formosa), can distinguish between different clonal lineages, associating with genetically identical, sister clones, and use multiple sensory modalities. Also, they scale their aggressive behaviors according to the relatedness to other females: they are more aggressive to non-related clones. Our results demonstrate that even in species with very small genetic differences between individuals, kin recognition can be adaptive. Their discriminatory abilities and regulation of costly behaviors provides a powerful example of natural selection in species with limited genetic diversity.

Manfred Schartl - One of the best experts on this subject based on the ideXlab platform.

  • the occurrence of spermatozoa in the ovary of the gynogenetic viviparous teleost Poecilia Formosa poeciliidae
    Journal of Morphology, 2016
    Co-Authors: Mari Carmen Uribe, Harry J Grier, Gabino De La Rosacruz, Manfred Schartl
    Abstract:

    The reproductive mode of the female viviparous teleost Poecilia Formosa (Poeciliidae) represents the phenomenon known as gynogenesis; that is, parthenogenetic development is initiated by spermatozoa which are needed for physiological activation of the egg and the initiation of gestation, but spermatozoa are prevented from contributing to the genome of the embryo. For the reason that no previous histological analyses of the ovary of this species during the reproductive cycle has been published the present study has been conducted. This study examined the histology of the ovary of P. Formosa during nongestation and gestation phases and identified the presence of spermatozoa inside the ovary. Spermatozoa were observed in folds of the ovarian epithelium of P. Formosa during both the nongestation and gestation phases. Sperm storage as documented in this study is a very important trait for the gynogenetic viviparous fish P. Formosa contributing to the understanding of this species reproduction. J. Morphol. 277:341–350, 2016. © 2015 Wiley Periodicals, Inc.

  • isolation of a cancer associated microchromosome in the sperm dependent parthenogen Poecilia Formosa
    Cytogenetic and Genome Research, 2011
    Co-Authors: Dunja K Lamatsch, V Trifonov, Susanne Schories, Jorg T Epplen, M Schmid, Manfred Schartl
    Abstract:

    In the asexual all-female fish species Poecilia Formosa , the Amazon molly, supernumerary chromosomes have frequently been found in both laboratory-reared and wild-caught individuals

  • monophyletic origin of multiple clonal lineages in an asexual fish Poecilia Formosa
    Molecular Ecology, 2010
    Co-Authors: Matthias Stock, Ingo Schlupp, Kathrin P Lampert, Dirk Moller, Manfred Schartl
    Abstract:

    Despite the advantage of avoiding the costs of sexual reproduction, asexual vertebrates are very rare and often considered evolutionarily disadvantaged when compared to sexual species. Asexual species, however, may have advantages when colonizing (new) habitats or competing with sexual counterparts. They are also evolutionary older than expected, leaving the question whether asexual vertebrates are not only rare because of their ‘inferior’ mode of reproduction but also because of other reasons. A paradigmatic model system is the unisexual Amazon molly, Poecilia Formosa, that arose by hybridization of the Atlantic molly, Poecilia mexicana, as the maternal ancestor, and the sailfin molly, Poecilia latipinna, as the paternal ancestor. Our extensive crossing experiments failed to resynthesize asexually reproducing (gynogenetic) hybrids confirming results of previous studies. However, by producing diploid eggs, female F1-hybrids showed apparent preadaptation to gynogenesis. In a range-wide analysis of mitochondrial sequences, we examined the origin of P. Formosa. Our analyses point to very few or even a single origin(s) of its lineage, which is estimated to be approximately 120 000 years old. A monophyletic origin was supported from nuclear microsatellite data. Furthermore, a considerable degree of genetic variation, apparent by high levels of clonal microsatellite diversity, was found. Our molecular phylogenetic evidence and the failure to resynthesize the gynogenetic P. Formosa together with the old age of the species indicate that some unisexual vertebrates might be rare not because they suffer the long-term consequences of clonal reproduction but because they are only very rarely formed as a result of complex genetic preconditions necessary to produce viable and fertile clonal genomes and phenotypes (‘rare formation hypothesis’).

  • morphology testes development and behaviour of unusual triploid males in microchromosome carrying clones of Poecilia Formosa
    Journal of Fish Biology, 2010
    Co-Authors: Dunja K Lamatsch, Ingo Schlupp, Jakob Parzefall, Matthias Stock, R Fuchs, M Dobler, Robin Wacker, Manfred Schartl
    Abstract:

    : In a microchromosome-carrying laboratory stock of the normally all-female Amazon molly Poecilia Formosa triploid individuals were obtained, all of which spontaneously developed into males. A comparison of morphology of the external and internal insemination apparatus and the gonads, sperm ploidy and behaviour, to laboratory-bred F(1) hybrids revealed that the triploid P. Formosa males, though producing mostly aneuploid sperm, are partly functional males that differ mainly in sperm maturation and sexual motivation from gonochoristic P. Formosa males.

  • Male Mate Choice in Mixed Bisexual/Unisexual Breeding Complexes of Poecilia (Teleostei: Poeciliidae)
    Ethology, 2010
    Co-Authors: Ingo Schlupp, J. Parzefall, Manfred Schartl
    Abstract:

    The livebearing all-female fish Poecilia Formosa reproduces by gynogenesis, a modified form of parthenogenesis. P. Formosa forms at least two breeding complexes: in its northern range it exists sympatrically with Poecilia latipinna and in its southern range with Poecilia mexicana. Differences between these complexes and their possible origin are discussed. Embryogenesis is triggered by sperm of males of these closely related sympatric species. Because inheritance is strictly maternal, from the male point of view energy and time invested are totally lost. In this study we wanted to elucidate whether males are able to distinguish between conspecific and parasitic females. It could be shown that males are able to distinguish females optically, but that this ability was obscured as soon as chemical and/or tactile contact was possible. Furthermore, we found that females in an attractive phase of their sexual cycle are always preferred, regardless of species. This is possibly the mechanism by which parasitic females obtain the matings they need to reproduce.

Ralph Tiedemann - One of the best experts on this subject based on the ideXlab platform.

  • the gonadal transcriptome of the unisexual amazon molly Poecilia Formosa in comparison to its sexual ancestors Poecilia mexicana and Poecilia latipinna
    BMC Genomics, 2018
    Co-Authors: Ina Maria Schedina, Ingo Schlupp, Detlef Groth, Ralph Tiedemann
    Abstract:

    The unisexual Amazon molly (Poecilia Formosa) originated from a hybridization between two sexual species, the sailfin molly (Poecilia latipinna) and the Atlantic molly (Poecilia mexicana). The Amazon molly reproduces clonally via sperm-dependent parthenogenesis (gynogenesis), in which the sperm of closely related species triggers embryogenesis of the apomictic oocytes, but typically does not contribute genetic material to the next generation. We compare for the first time the gonadal transcriptome of the Amazon molly to those of both ancestral species, P. mexicana and P. latipinna. We sequenced the gonadal transcriptomes of the P. Formosa and its parental species P. mexicana and P. latipinna using Illumina RNA-sequencing techniques (paired-end, 100 bp). De novo assembly of about 50 million raw read pairs for each species was performed using Trinity, yielding 106,922 transcripts for P. Formosa, 115,175 for P. latipinna, and 133,025 for P. mexicana after eliminating contaminations. On the basis of sequence similarity comparisons to other teleost species and the UniProt databases, functional annotation, and differential expression analysis, we demonstrate the similarity of the transcriptomes among the three species. More than 40% of the transcripts for each species were functionally annotated and about 70% were assigned to orthologous genes of a closely related species. Differential expression analysis between the sexual and unisexual species uncovered 2035 up-regulated and 564 down-regulated genes in P. Formosa. This was exemplary validated for six genes by qRT-PCR. We identified more than 130 genes related to meiosis and reproduction within the apomictically reproducing P. Formosa. Overall expression of these genes seems to be down-regulated in the P. Formosa transcriptome compared to both ancestral species (i.e., 106 genes down-regulated, 29 up-regulated). A further 35 meiosis and reproduction related genes were not found in the P. Formosa transcriptome, but were only expressed in the sexual species. Our data support the hypothesis of general down-regulation of meiosis-related genes in the apomictic Amazon molly. Furthermore, the obtained dataset and identified gene catalog will serve as a resource for future research on the molecular mechanisms behind the reproductive mode of this unisexual species.

  • The gonadal transcriptome of the unisexual Amazon molly Poecilia Formosa in comparison to its sexual ancestors, Poecilia mexicana and Poecilia latipinna
    BMC Genomics, 2018
    Co-Authors: Ina Maria Schedina, Ingo Schlupp, Detlef Groth, Ralph Tiedemann
    Abstract:

    Background The unisexual Amazon molly ( Poecilia Formosa ) originated from a hybridization between two sexual species, the sailfin molly ( Poecilia latipinna ) and the Atlantic molly ( Poecilia mexicana ). The Amazon molly reproduces clonally via sperm-dependent parthenogenesis (gynogenesis), in which the sperm of closely related species triggers embryogenesis of the apomictic oocytes, but typically does not contribute genetic material to the next generation. We compare for the first time the gonadal transcriptome of the Amazon molly to those of both ancestral species, P. mexicana and P. latipinna . Results We sequenced the gonadal transcriptomes of the P. Formosa and its parental species P. mexicana and P. latipinna using Illumina RNA-sequencing techniques (paired-end, 100 bp). De novo assembly of about 50 million raw read pairs for each species was performed using Trinity, yielding 106,922 transcripts for P. Formosa , 115,175 for P. latipinna , and 133,025 for P. mexicana after eliminating contaminations. On the basis of sequence similarity comparisons to other teleost species and the UniProt databases, functional annotation, and differential expression analysis, we demonstrate the similarity of the transcriptomes among the three species. More than 40% of the transcripts for each species were functionally annotated and about 70% were assigned to orthologous genes of a closely related species. Differential expression analysis between the sexual and unisexual species uncovered 2035 up-regulated and 564 down-regulated genes in P. Formosa . This was exemplary validated for six genes by qRT-PCR. Conclusions We identified more than 130 genes related to meiosis and reproduction within the apomictically reproducing P . Formosa . Overall expression of these genes seems to be down-regulated in the P . Formosa  transcriptome compared to both ancestral species (i.e., 106 genes down-regulated, 29 up-regulated). A further 35 meiosis and reproduction related genes were not found in the  P . Formosa transcriptome, but were only expressed in the sexual species. Our data support the hypothesis of general down-regulation of meiosis-related genes in the apomictic Amazon molly. Furthermore, the obtained dataset and identified gene catalog will serve as a resource for future research on the molecular mechanisms behind the reproductive mode of this unisexual species.

  • allele specific expression at the androgen receptor alpha gene in a hybrid unisexual fish the amazon molly Poecilia Formosa
    PLOS ONE, 2017
    Co-Authors: Ingo Schlupp, Ralph Tiedemann
    Abstract:

    : The all-female Amazon molly (Poecilia Formosa) is the result of a hybridization of the Atlantic molly (P. mexicana) and the sailfin molly (P. latipinna) approximately 120,000 years ago. As a gynogenetic species, P. Formosa needs to copulate with heterospecific males including males from one of its bisexual ancestral species. However, the sperm only triggers embryogenesis of the diploid eggs. The genetic information of the sperm donor typically will not contribute to the next generation of P. Formosa. Hence, P. Formosa possesses generally one allele from each of its ancestral species at any genetic locus. This raises the question whether both ancestral alleles are equally expressed in P. Formosa. Allele-specific expression (ASE) has been previously assessed in various organisms, e.g., human and fish, and ASE was found to be important in the context of phenotypic variability and disease. In this study, we utilized Real-Time PCR techniques to estimate ASE of the androgen receptor alpha (arα) gene in several distinct tissues of Amazon mollies. We found an allelic bias favoring the maternal ancestor (P. mexicana) allele in ovarian tissue. This allelic bias was not observed in the gill or the brain tissue. Sequencing of the promoter regions of both alleles revealed an association between an Indel in a known CpG island and differential expression. Future studies may reveal whether our observed cis-regulatory divergence is caused by an ovary-specific trans-regulatory element, preferentially activating the allele of the maternal ancestor.

  • kin recognition in a clonal fish Poecilia Formosa
    PLOS ONE, 2016
    Co-Authors: Amber M Makowicz, Ralph Tiedemann, Rachel N Steele, Ingo Schlupp
    Abstract:

    Relatedness strongly influences social behaviors in a wide variety of species. For most species, the highest typical degree of relatedness is between full siblings with 50% shared genes. However, this is poorly understood in species with unusually high relatedness between individuals: clonal organisms. Although there has been some investigation into clonal invertebrates and yeast, nothing is known about kin selection in clonal vertebrates. We show that a clonal fish, the Amazon molly (Poecilia Formosa), can distinguish between different clonal lineages, associating with genetically identical, sister clones, and use multiple sensory modalities. Also, they scale their aggressive behaviors according to the relatedness to other females: they are more aggressive to non-related clones. Our results demonstrate that even in species with very small genetic differences between individuals, kin recognition can be adaptive. Their discriminatory abilities and regulation of costly behaviors provides a powerful example of natural selection in species with limited genetic diversity.

  • sequence evolution and expression of the androgen receptor and other pathway related genes in a unisexual fish the amazon molly Poecilia Formosa and its bisexual ancestors
    PLOS ONE, 2016
    Co-Authors: Ingo Schlupp, Ralph Tiedemann
    Abstract:

    The all-female Amazon molly (Poecilia Formosa) originated from a single hybridization of two bisexual ancestors, Atlantic molly (Poecilia mexicana) and sailfin molly (Poecilia latipinna). As a gynogenetic species, the Amazon molly needs to copulate with a heterospecific male, but the genetic information of the sperm-donor does not contribute to the next generation, as the sperm only acts as the trigger for the diploid eggs’ embryogenesis. Here, we study the sequence evolution and gene expression of the duplicated genes coding for androgen receptors (ars) and other pathway-related genes, i.e., the estrogen receptors (ers) and cytochrome P450, family19, subfamily A, aromatase genes (cyp19as), in the Amazon molly, in comparison to its bisexual ancestors. Mollies possess–as most other teleost fish—two copies of the ar, er, and cyp19a genes, i.e., arα/arβ, erα/erβ1, and cyp19a1 (also referred as cyp19a1a)/cyp19a2 (also referred to as cyp19a1b), respectively. Non-synonymous single nucleotide polymorphisms (SNPs) among the ancestral bisexual species were generally predicted not to alter protein function. Some derived substitutions in the P. mexicana and one in P. Formosa are predicted to impact protein function. We also describe the gene expression pattern of the ars and pathway-related genes in various tissues (i.e., brain, gill, and ovary) and provide SNP markers for allele specific expression research. As a general tendency, the levels of gene expression were lowest in gill and highest in ovarian tissues, while expression levels in the brain were intermediate in most cases. Expression levels in P. Formosa were conserved where expression did not differ between the two bisexual ancestors. In those cases where gene expression levels significantly differed between the bisexual species, P. Formosa expression was always comparable to the higher expression level among the two ancestors. Interestingly, erβ1 was expressed neither in brain nor in gill in the analyzed three molly species, which implies a more important role of erα in the estradiol synthesis pathway in these tissues. Furthermore, our data suggest that interactions of steroid-signaling pathway genes differ across tissues, in particular the interactions of ars and cyp19as.

Jakob Parzefall - One of the best experts on this subject based on the ideXlab platform.

  • morphology testes development and behaviour of unusual triploid males in microchromosome carrying clones of Poecilia Formosa
    Journal of Fish Biology, 2010
    Co-Authors: Dunja K Lamatsch, Ingo Schlupp, Jakob Parzefall, Matthias Stock, R Fuchs, M Dobler, Robin Wacker, Manfred Schartl
    Abstract:

    : In a microchromosome-carrying laboratory stock of the normally all-female Amazon molly Poecilia Formosa triploid individuals were obtained, all of which spontaneously developed into males. A comparison of morphology of the external and internal insemination apparatus and the gonads, sperm ploidy and behaviour, to laboratory-bred F(1) hybrids revealed that the triploid P. Formosa males, though producing mostly aneuploid sperm, are partly functional males that differ mainly in sperm maturation and sexual motivation from gonochoristic P. Formosa males.

  • geographic variation in female mate copying in the species complex of a unisexual fish Poecilia Formosa
    Behaviour, 2008
    Co-Authors: Katja U Heubel, Jakob Parzefall, Katja Hornhardt, Tanja Ollmann, Michael J Ryan, Ingo Schlupp
    Abstract:

    Summary The Amazon molly, Poecilia Formosa, is a gynogenetic, all-female fish. Its mating system relies on heterospecific matings with males of closely related sexual species. In mixed populations, males mate with conspecific sexual females and heterospecific asexual females. Such matings are not isolated dyadic interactions but rather elements of a communication network, because multiple females can observe these interactions. This is the only known case of heterospecific mate-copying and, thus, a system in which the potential for mate-copying could be influenced by the presence of another species. Here we show that mate-copying is exhibited by the sexual species P. mexicana and P. latipinna, and the asexual P. Formosa . Both sexual and asexual females copy each other’s mate choice decisions in sympatry, but females from allopatric populations do not show heterospecific mate-copying. Males benefit from heterospecific matings with Amazon mollies because these increase their attractiveness to the conspecific sexual females. In mixed shoals, mate-copying potentially imposes costs as it increases a male’s attractiveness to heterospecific females. We argue that the net-effect of mate-copying is beneficial to males because the relative strength of mate-copying is lower in Amazon mollies. We hypothesize that an added benefit to males lies in the signal value of copulations.

  • male mating behaviour of a molly Poecilia latipunctata a third host for the sperm dependent amazon molly Poecilia Formosa
    Acta Ethologica, 2002
    Co-Authors: Andreas Niemeitz, Manfred Schartl, Jakob Parzefall, Ralf Kreutzfeldt, Ingo Schlupp
    Abstract:

    The Tamesi molly, Poecilia latipunctata, has a very limited biogeographical range in northeast Mexico. This area is nested within the ranges of the Atlantic molly, Poecilia mexicana, and the unisexual Amazon molly, Poecilia Formosa. Based on morphology, especially fin shape, the Tamesi molly has been considered to be a "short-fin" molly. We describe the courtship sequence of P. latipunctata. The courtship clearly places the species into the clade of "long-fin" mollies, a finding that corroborates earlier studies based on nuclear DNA and mitochondrial DNA. All three species live together in certain habitats. This renders P. latipunctata a potential host species for the sperm-dependent, unisexual Amazon molly. Using behavioural tests, we demonstrate that P. latipunctata males actually copulate with Amazon mollies, despite a pronounced preference for conspecific females. In laboratory experiments P. latipunctata males are capable of triggering embryogenesis in P. Formosa females. Field observations support the hypothesis that P. latipunctata is a third host species for P. Formosa, indicating that the Amazon molly effectively exploits all available host species for its gynogenetic mode of reproduction.

  • biogeography of the amazon molly Poecilia Formosa
    Journal of Biogeography, 2002
    Co-Authors: Jakob Parzefall, Ingo Schlupp, Manfred Schartl
    Abstract:

    Aim The unisexual Amazon molly (Poecilia Formosa) is a clonal, all-female fish but depends on sperm of heterospecific males to trigger embryogenesis. Thus, one very important factor shaping its geographical range is the presence of suitable host males. Several species of the genus Poecilia from Central America, Mexico and the USA can provide sperm in the laboratory, but are not utilized as hosts in nature. Consequently the potential geographic range of the Amazon molly is much larger than the actual range. This raises the question of what is responsible for the biogeographical range of the Amazon molly? Location Southern USA, Mexico and Central America. Methods We review the current data available for the distribution of the Amazon molly. We further tested whether salinity might hinder the dispersal of the species. Results Amazon mollies tolerate marine conditions. We review the available data on recent and human influenced introductions of Amazon mollies. Main conclusions We argue that male preferences are not responsible for the current range. We propose that prevailing near-shore marine currents act as an effective barrier against further dispersal. Furthermore, we discuss recent changes in the biogeography of the Amazon molly.

  • A Sexual Preference in the Amazon Molly, Poecilia Formosa
    Environmental Biology of Fishes, 1999
    Co-Authors: Katrin Landmann, Jakob Parzefall, Ingo Schlupp
    Abstract:

    The Amazon molly, Poecilia Formosa, is an all-female species that reproduces by gynogenesis, i.e., it relies on sperm of males of closely related species to trigger embryogenesis. Sperm is supplied by males of P. latipinna and P. mexicana. Amazon mollies live in sympatry with at least one of these species, a few populations live in sympatry with two sperm-donor species. As P. Formosa is sperm dependent, it needs mechanisms for species and mate recognition. To investigate the effect of rearing conditions on sexual preferences of Amazon mollies, we raised Amazon mollies in sympatry with P. latipinna and P. mexicana males. We used simultaneous choice tests to determine the effect of age on female sexual preferences. Immature Amazon mollies do not exhibit a preference if given a choice between a P. latipinna and a P. mexicana male, whereas adult P. Formosa do have a preference for the P. latipinna male. We used two different stimuli in this study, live males and videotapes of males.

Michael Tobler - One of the best experts on this subject based on the ideXlab platform.

  • Differences in resource assimilation between the unisexual Amazon molly, Poecilia Formosa (Poeciliidae) and its sexual host (Poecilia latipinna)
    Environmental Biology of Fishes, 2014
    Co-Authors: Laura Alberici Da Barbiano, Michael Tobler, Reginald J. Robinson, Andrea S. Aspbury, Caitlin R. Gabor
    Abstract:

    Unisexual sperm-dependent species depend on a sexual host for reproduction, and must live in sympatry with their sperm donor. If niche overlap between the species is substantial, the intrinsic faster population growth of the unisexual over sexual species can cause competitive exclusion of the host from resources, causing the demise of the unisexual species. However, theoretical models predict that coexistence is possible, even without niche differentiation, if the unisexual species is a poorer competitor than the sexual host and if the effect of the unisexual species on the exploitative abilities of the sexual species is smaller than the effect that the sexually reproducing individuals have among themselves. We tested these predictions in the unisexual-bisexual mating complex of Poecilia Formosa, and one of its sexual hosts, P. latipinna . Fishes were housed from parturition for 76 days with both conspecific and heterospecific individuals under both limited and ad libitum food regimes. Only one of the predictions of the models was met: the effects of intraspecific competition for P. latipinna were stronger than the effects of interspecific competition. Poecilia latipinna raised with conspecifics with limited food stored fewer fats than both heterospecific P. Formosa , and conspecifics raised in any other treatment.

  • dietary niche overlap in sympatric asexual and sexual livebearing fishes Poecilia spp
    Journal of Fish Biology, 2011
    Co-Authors: Kristin Scharnweber, Martin Plath, Kirk O Winemiller, Michael Tobler
    Abstract:

    The present study investigated the spatiotemporal patterns in trophic resource use in a system of a gynogenetic poeciliid fish, the Amazon molly Poecilia Formosa, and its sexual congeners the sailfin molly Poecilia latipinna and the Atlantic molly Poecilia mexicana using gut contents analysis. No statistically significant differences in trophic resource use were found between sexual and gynogenetic species, but gut contents varied significantly across sites and over time. In addition, variation in trophic morphology (i.e. gut length) was significant across sites but not species, and laboratory experiments indicated that gut length is phenotypically plastic. Overall, trophic differentiation between coexisting asexual and sexual Poecilia appears to be minimal, and it is unlikely that niche differentiation contributes to a stable coexistence of the two reproductive forms.

  • Feeding efficiency and food competition in coexisting sexual and asexual livebearing fishes of the genus Poecilia
    Environmental Biology of Fishes, 2011
    Co-Authors: Kristin Scharnweber, Martin Plath, Michael Tobler
    Abstract:

    Considering its immediate costs of producing dispensable males, the maintenance of sexual reproduction is a major paradox in evolutionary biology. Asexual lineages that do not face such costs theoretically should replace sexuals over time. Nonetheless, several systems are known in which closely related sexual and asexual lineages stably coexist. In the present study, we studied a sexual/asexual mating complex of a sperm-dependent parthenogenetic fish (amazon molly, Poecilia Formosa ) and its sexual congeners, the sailfin molly P. latipinna and the Atlantic molly P. mexicana . We asked whether differences in feeding behavior could contribute to their stable coexistence. We conducted a laboratory experiment to compare feeding efficiencies and also measured the competitive abilities between the two reproductive forms. Additionally, we measured gut fullness of fishes caught in natural habitats. Contrary to our predictions, we could not find P. Formosa to be less efficient in feeding. We argue that food competition in mollies plays a minor role in mediating coexistence between closely related asexual and sexual mollies.

  • Differential susceptibility to food stress in neonates of sexual and asexual mollies (Poecilia, Poeciliidae)
    Evolutionary Ecology, 2010
    Co-Authors: Michael Tobler, Ingo Schlupp
    Abstract:

    The maintenance of sex is still an evolutionary puzzle given its immediate costs. Stably coexisting complexes of asexually and sexually reproducing forms allow to study mechanisms that balance the costs and benefits of both asexual and sexual reproduction. Here, we tested whether coexisting asexual and sexual fish of the genus Poecilia differed in neonate mortality when exposed to environmental stress in the form of fluctuating temperatures and food deprivation. We find that asexual Amazon mollies, Poecilia Formosa , are significantly more sensitive to food stress than their sexual relative Poecilia latipinna , but both are equally unaffected by variable temperatures. Differences in the susceptibility to environmental stress may contribute to diminishing the asexuals’ benefits of a higher intrinsic population growth rate and thus mediate stable coexistence of the two reproductive forms.

  • polymorphic mhc loci in an asexual fish the amazon molly Poecilia Formosa poeciliidae
    Molecular Ecology, 2008
    Co-Authors: Helmut Schaschl, Martin Plath, Michael Tobler, Dustin J Penn, Ingo Schlupp
    Abstract:

    Genes of the major histocompatibility complex (MHC) encode molecules that control immune recognition and are highly polymorphic in most vertebrates. The remarkable polymorphisms at MHC loci may be maintained by selection from parasites, sexual selection, or both. If asexual species show equal (or higher) levels of polymorphisms at MHC loci as sexual ones, this would mean that sexual selection is not necessary to explain the high levels of diversity at MHC loci. In this study, we surveyed the MHC diversity of the asexual amazon molly (Poecilia Formosa) and one of its sexual ancestors, the sailfin molly (P. latipinna), which lives in the same habitat. We found that the asexual molly has polymorphic MHC loci despite its clonal reproduction, yet not as polymorphic as the sexual species. Although the nucleotide diversity was similar between the asexual and sexual species, the sexual species exhibited a greater genotypic diversity compared to the asexual one from the same habitats. Within-genome diversity was similar for MHC class I loci, but for class IIB, the sexual species had higher diversity compared to the asexual — despite the hybrid origins and higher levels of heterozygosity at microsatellite loci in the asexual species. The level of positive selection appears to be similar between the two species, which suggests that these polymorphisms are maintained by selection. Thus, our findings do not allow us to rule out the sexual selection hypothesis for the evolution of MHC diversity, and although the sexual fish has higher levels of MHC-diversity compared to the asexual species, this may be due to differences in demography, parasites, or other factors, rather than sexual selection.