scholarly journals Diploid male production correlates with genetic diversity in the parasitoid wasp Venturia canescens: a genetic approach with new microsatellite markers

2016 ◽  
Author(s):  
Marie Collet ◽  
Chloé Vayssade ◽  
Alexandra Auguste ◽  
Laurence Mouton ◽  
Emmanuel Desouhant ◽  
...  
Keyword(s):  
Genetic Diversity ◽  
Sex Determination ◽  
Extinction Risk ◽  
Habitat Type ◽  
Parasitoid Wasp ◽  
Habitat Destruction ◽  
Diploid Male ◽  
Diploid Males ◽  
Venturia Canescens ◽  
Captive Populations

AbstractSex determination is ruled by haplodiploidy in Hymenoptera, with haploid males arising from unfertilized eggs and diploid females from fertilized eggs. However, diploid males with null fitness are produced under Complementary Sex Determination (CSD), whenindividuals are homozygous for this locus. Diploid males are expected to be more frequent in genetically eroded populations (such as islands and captive populations), as genetic diversity at the csd locus should be low. However, only a few studies have focused on the relation between population size, genetic diversity and the proportion of diploid males in the field. Here, we developed new microsatellites markers in order to assess and compare genetic diversity and diploid male proportion in populations from three distinct habitat types (mainland, island or captive), in the parasitoid wasp Venturia canescens. Eroded genetic diversity and higher diploid male proportion were found in island and captive populations, and habitat type had large effect on genetic diversity. Therefore, diploid male proportion reflects the decreasing genetic diversity in small and isolated populations. Thus, Hymenopteran populations can be at high extinction risk due to habitat destruction or fragmentation.

scholarly journals Absence of complementary sex determination in Trichogramma dendrolimi Matsumura (Hymenoptera: Trichogrammatidae)

2019 ◽  
Author(s):  
Quan-quan Liu ◽  
Jin-cheng Zhou ◽  
Chen Zhang ◽  
Qian-jin Dong ◽  
Su-fang Ning ◽  
...  
Keyword(s):  
Sex Ratio ◽  
Sex Determination ◽  
Brood Size ◽  
Indirect Evidence ◽  
Parasitoid Wasp ◽  
Mass Rearing ◽  
Diploid Male ◽  
Diploid Males ◽  
Offspring Sex Ratio ◽  
Complementary Sex Determination

Over 60 species in Hymenoptera have been reported to possess a complementary sex determination (CSD) system. Under CSD, sex is determined by allelic complementation at one or several sex loci. But this mechanism is still uninvestigated in parasitoid wasp Trichogramma dendrolimi, one of the most important biocontrol agents widely used against Lepidopteran pests. We tested CSD in this species by conducting ten consecutive generations of inbreeding, to monitor both direct evidence (diploid male production) and indirect evidence (brood size, sex ratio, mortality). In total 475 males detected from this inbreeding regime, only one was determined as diploidy. The observed proportions of diploid male offspring significantly differed from expected values under CSD model involving up to ten independent loci, allowing us to safely reject CSD in T. dendrolimi. Meanwhile, the possibility of unviable diploid males was excluded by the absence of significant differences in brood size, offspring sex ratio and offspring mortality among different generations. Our study of sex determination in T. dendrolimi provides useful information for the mass rearing conditions in a biofactory and the quality improvement of this biocontrol agent. It also brings necessary background to further study of the sex determination in Trichogramma.

scholarly journals Absence of complementary sex determination in Trichogramma dendrolimi Matsumura (Hymenoptera: Trichogrammatidae)

2019 ◽  
Author(s):  
Quan-quan Liu ◽  
Jin-cheng Zhou ◽  
Chen Zhang ◽  
Qian-jin Dong ◽  
Su-fang Ning ◽  
...  
Keyword(s):  
Sex Ratio ◽  
Sex Determination ◽  
Brood Size ◽  
Indirect Evidence ◽  
Parasitoid Wasp ◽  
Mass Rearing ◽  
Diploid Male ◽  
Diploid Males ◽  
Offspring Sex Ratio ◽  
Complementary Sex Determination

Over 60 species in Hymenoptera have been reported to possess a complementary sex determination (CSD) system. Under CSD, sex is determined by allelic complementation at one or several sex loci. But this mechanism is still uninvestigated in parasitoid wasp Trichogramma dendrolimi, one of the most important biocontrol agents widely used against Lepidopteran pests. We tested CSD in this species by conducting ten consecutive generations of inbreeding, to monitor both direct evidence (diploid male production) and indirect evidence (brood size, sex ratio, mortality). In total 475 males detected from this inbreeding regime, only one was determined as diploidy. The observed proportions of diploid male offspring significantly differed from expected values under CSD model involving up to ten independent loci, allowing us to safely reject CSD in T. dendrolimi. Meanwhile, the possibility of unviable diploid males was excluded by the absence of significant differences in brood size, offspring sex ratio and offspring mortality among different generations. Our study of sex determination in T. dendrolimi provides useful information for the mass rearing conditions in a biofactory and the quality improvement of this biocontrol agent. It also brings necessary background to further study of the sex determination in Trichogramma.

scholarly journals Mapping of multiple complementary sex determination loci in a parasitoid wasp

2019 ◽  
Author(s):  
Cyril Matthey-Doret ◽  
Casper J. van der Kooi ◽  
Daniel L. Jeffries ◽  
Jens Bast ◽  
Alice B. Dennis ◽  
...  
Keyword(s):  
Sex Determination ◽  
Molecular Mechanism ◽  
Molecular Mechanisms ◽  
Parasitoid Wasp ◽  
Diploid Males ◽  
Wasp Species ◽  
Environmental Signals ◽  
Insect Order ◽  
Complementary Sex Determination ◽  
Candidate Regions

AbstractSex determination has evolved in a variety of ways and can depend on environmental and genetic signals. A widespread form of genetic sex determination is haplodiploidy, where unfertilized, haploid eggs develop into males and fertilized diploid eggs into females. One of the molecular mechanisms underlying haplodiploidy in Hymenoptera, a large insect order comprising ants, bees and wasps, is known as complementary sex determination (CSD). In species with CSD, heterozygosity at one or several loci induces female development. Here, we identify the genomic regions putatively underlying multi-locus CSD in the parasitoid wasp Lysiphlebus fabarum using restriction-site associated DNA sequencing. By analysing segregation patterns at polymorphic sites among 331 diploid males and females, we identify four CSD candidate regions, all on different chromosomes. None of the candidate regions feature evidence for homology with the csd gene from the honeybee, the only species in which CSD has been characterized, suggesting that CSD in L. fabarum is regulated via a novel molecular mechanism. Moreover, no homology is shared between the candidate loci, in contrast to the idea that multi-locus CSD should emerge from duplications of an ancestral single-locus system. Taken together, our results suggest that the molecular mechanisms underlying CSD in Hymenoptera are not conserved between species, raising the question as to whether CSD may have evolved multiple times independently in the group.Author summaryThe genetic or environmental signals that govern whether an organism develops into a male or female differ across species, and understanding their evolution is a key aspect of biology. In this paper, we focus on complementary sex determination (CSD), a genetic sex determination system found in many species of bees, ants and wasps where heterozygosity at one or multiple genetic regions determines the sex of the individual. We identify multiple genetic regions in the parasitoid wasp species Lysiphlebus fabarum that are likely underlying CSD. We show that these candidate CSD regions share no similarity with each other and that they differ from the CSD region known in the honey bee, the only species with a well-characterized CSD system. Our results suggest a different molecular mechanism underlying CSD in the wasp and that multiple CSD regions do not necessarily arise from duplications as generally thought.

scholarly journals Quantitative genetics in conservation biology

1999 ◽  
Vol 74 (3) ◽  
pp. 237-244 ◽  
Author(s):  
RICHARD FRANKHAM
Keyword(s):  
Genetic Diversity ◽  
Endangered Species ◽  
Quantitative Genetics ◽  
Conservation Biology ◽  
Extinction Risk ◽  
Outbreeding Depression ◽  
Genetic Adaptation ◽  
Genetic Management ◽  
Captive Populations ◽  
Adaptation To Captivity

Most of the major genetic concerns in conservation biology, including inbreeding depression, loss of evolutionary potential, genetic adaptation to captivity and outbreeding depression, involve quantitative genetics. Small population size leads to inbreeding and loss of genetic diversity and so increases extinction risk. Captive populations of endangered species are managed to maximize the retention of genetic diversity by minimizing kinship, with subsidiary efforts to minimize inbreeding. There is growing evidence that genetic adaptation to captivity is a major issue in the genetic management of captive populations of endangered species as it reduces reproductive fitness when captive populations are reintroduced into the wild. This problem is not currently addressed, but it can be alleviated by deliberately fragmenting captive populations, with occasional exchange of immigrants to avoid excessive inbreeding. The extent and importance of outbreeding depression is a matter of controversy. Currently, an extremely cautious approach is taken to mixing populations. However, this cannot continue if fragmented populations are to be adequately managed to minimize extinctions. Most genetic management recommendations for endangered species arise directly, or indirectly, from quantitative genetic considerations.

scholarly journals Effects of ploidy and sex-locus genotype on gene expression patterns in the fire ant Solenopsis invicta

2014 ◽  
Vol 281 (1797) ◽  
pp. 20141776 ◽  
Author(s):  
Mingkwan Nipitwattanaphon ◽  
John Wang ◽  
Kenneth G. Ross ◽  
Oksana Riba-Grognuz ◽  
Yannick Wurm ◽  
...  
Keyword(s):  
Gene Expression ◽  
Sex Determination ◽  
Ploidy Level ◽  
Solenopsis Invicta ◽  
Expression Profiles ◽  
Expression Patterns ◽  
Early Gene ◽  
Diploid Male ◽  
Diploid Males ◽  
Sex Locus

Males in many animal species differ greatly from females in morphology, physiology and behaviour. Ants, bees and wasps have a haplodiploid mechanism of sex determination whereby unfertilized eggs become males while fertilized eggs become females. However, many species also have a low frequency of diploid males, which are thought to develop from diploid eggs when individuals are homozygous at one or more sex determination loci. Diploid males are morphologically similar to haploids, though often larger and typically sterile. To determine how ploidy level and sex-locus genotype affect gene expression during development, we compared expression patterns between diploid males, haploid males and females (queens) at three developmental timepoints in Solenopsis invicta . In pupae, gene expression profiles of diploid males were very different from those of haploid males but nearly identical to those of queens. An unexpected shift in expression patterns emerged soon after adult eclosion, with diploid male patterns diverging from those of queens to resemble those of haploid males, a pattern retained in older adults. The finding that ploidy level effects on early gene expression override sex effects (including genes implicated in sperm production and pheromone production/perception) may explain diploid male sterility and lack of worker discrimination against them during development.

scholarly journals Mapping of Multiple Complementary Sex Determination Loci in a Parasitoid Wasp

2019 ◽  
Vol 11 (10) ◽  
pp. 2954-2962 ◽  
Author(s):  
Cyril Matthey-Doret ◽  
Casper J van der Kooi ◽  
Daniel L Jeffries ◽  
Jens Bast ◽  
Alice B Dennis ◽  
...  
Keyword(s):  
Sex Determination ◽  
Molecular Mechanisms ◽  
Parasitoid Wasp ◽  
Diploid Males ◽  
Insect Order ◽  
Complementary Sex Determination ◽  
Locus System ◽  
Candidate Regions ◽  
Genomic Regions ◽  
Candidate Loci

Abstract Sex determination has evolved in a variety of ways and can depend on environmental and genetic signals. A widespread form of genetic sex determination is haplodiploidy, where unfertilized, haploid eggs develop into males and fertilized diploid eggs into females. One of the molecular mechanisms underlying haplodiploidy in Hymenoptera, the large insect order comprising ants, bees, and wasps, is complementary sex determination (CSD). In species with CSD, heterozygosity at one or several loci induces female development. Here, we identify the genomic regions putatively underlying multilocus CSD in the parasitoid wasp Lysiphlebus fabarum using restriction-site associated DNA sequencing. By analyzing segregation patterns at polymorphic sites among 331 diploid males and females, we identify up to four CSD candidate regions, all on different chromosomes. None of the candidate regions feature evidence for homology with the csd gene from the honey bee, the only species in which CSD has been characterized, suggesting that CSD in L. fabarum is regulated via a novel molecular mechanism. Moreover, no homology is shared between the candidate loci, in contrast to the idea that multilocus CSD should emerge from duplications of an ancestral single-locus system. Taken together, our results suggest that the molecular mechanisms underlying CSD in Hymenoptera are not conserved between species, raising the question as to whether CSD may have evolved multiple times independently in the group.

scholarly journals Genetic diversity in fishes is influenced by habitat type and life-history variation

2018 ◽  
Vol 8 (23) ◽  
pp. 12022-12031 ◽  
Author(s):  
Alexander S. Martinez ◽  
Janna R. Willoughby ◽  
Mark R. Christie
Keyword(s):  
Genetic Diversity ◽  
Life History ◽  
Habitat Type ◽  
Life History Variation

SEX AND SUPERNUMERARY CHROMOSOMES IN THE DIOECIOUS GRASS SOHNSIA FILIFOLIA

1972 ◽  
Vol 14 (1) ◽  
pp. 175-180 ◽  
Author(s):  
D. N. Singh
Keyword(s):  
Sex Determination ◽  
Y Chromosome ◽  
Supernumerary Chromosome ◽  
The Other ◽  
Male Plant ◽  
Diploid Male ◽  
Male And Female ◽  
Supernumerary Chromosomes ◽  
Determination System ◽  
Sex Determination System

A dioecious grass Sohnsia filifolia (Fourn.) Airy Shaw (Syn. Calamochloa filifolia Fourn.) from Mexico has been found to have 2n = 20 chromosomes in both male and female plants. The staminate plants have one chromosome much longer than the other chromosomes of the complement. One pistillate plant was found to have 30 chromosomes, among which the largest chromosome is quite similar to the largest component of the diploid male plant. The longest chromosome has been designated as the Y chromosome. An XY-mechanism of the Drosophilia type has been suggested for the sex determination system in this species. One small supernumerary chromosome was observed in the microsporocytes of some male plants, but was absent in roots.

scholarly journals Range reduction of the Oblong Rocksnail, Leptoxis compacta, shapes riverscape genetic patterns

2020 ◽  
Author(s):  
Aaliyah D. Wright ◽  
Nicole L. Garrison ◽  
Ashantye’ S. Williams ◽  
Paul D. Johnson ◽  
Nathan V. Whelan
Keyword(s):  
Genetic Diversity ◽  
Gene Flow ◽  
Human Impacts ◽  
Isolation By Distance ◽  
Extinction Risk ◽  
River System ◽  
High Genetic Diversity ◽  
Range Contraction ◽  
Genetic Patterns ◽  
Cahaba River

AbstractMany freshwater gastropod species face extinction, including 79% of species in the family Pleuroceridae. The Oblong Rocksnail, Leptoxis compacta, is a narrow range endemic pleurocerid from the Cahaba River basin in central Alabama that has seen rapid range contraction in the last 100 years. Such a decline is expected to negatively affect genetic diversity in the species. However, precise patterns of genetic variation and gene flow across the restricted range of L. compacta are unknown. This lack of information limits our understanding of human impacts on the Cahaba River system and Pleuroceridae. Here, we show that L. compacta has likely seen a species-wide decline in genetic diversity, but remaining populations have relatively high genetic diversity. We also report a contemporary range extension compared to the last published survey. Leptoxis compacta does not display an isolation by distance pattern, contrasting patterns seen in many riverine taxa. Our findings also indicate that historical range contraction has resulted in the absence of common genetic patterns seen in many riverine taxa like isolation by distance as the small distribution of L. compacta allows for relatively unrestricted gene flow across its remaining range despite limited dispersal abilities. Two collection sites had higher genetic diversity than others, and broodstock sites for future captive propagation and reintroduction efforts should utilize sites identified here as having the highest genetic diversity. Broadly, our results support the hypothesis that range contraction will result in the reduction of species-wide genetic diversity, and common riverscape genetic patterns cannot be assumed to be present in species facing extinction risk.

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