Postmating, prezygotic phenotypes, especially those that underlie reproductive isolation between closely related species, have been a central focus of evolutionary biologists over the past two ...decades. Such phenotypes are thought to evolve rapidly and be nearly ubiquitous among sexually reproducing eukaryotes where females mate with multiple partners. Because these phenotypes represent interplay between the male ejaculate and female reproductive tract, they are fertile ground for reproductive senescence – as ejaculate composition and female physiology typically change over an individual's life span. Although these phenotypes and their resulting dynamics are important, we have little understanding of the proteins that mediate these phenotypes, particularly for species groups where postmating, prezygotic traits are the primary mechanism of reproductive isolation. Here, we utilize proteomics, RNAi, mating experiments, and the Allonemobius socius complex of crickets, whose members are primarily isolated from one another by postmating, prezygotic phenotypes (including the ability of a male to induce a female to lay eggs), to demonstrate that one of the most abundant ejaculate proteins (a male accessory gland-biased protein similar to a trypsin-like serine protease) decreases in abundance over a male's reproductive lifetime and mediates the induction of egg-laying in females. These findings represent one of the first studies to identify a protein that plays a role in mediating both a postmating, prezygotic isolation pathway and reproductive senescence.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Two of the most well-supported patterns to have emerged over the past two decades of research in evolutionary biology are the occurrence of divergent natural selection acting on many male and female ...reproductive tract proteins and the importance of postmating, prezygotic phenotypes in reproductively isolating closely related species. Although these patterns appear to be common across a wide variety of taxa, the link between them remains poorly documented. Here, we utilize comparative proteomic techniques to determine whether or not there is evidence for natural selection acting on the ejaculate proteomes of two cricket species (Allonemobius fasciatus and A. socius) which are reproductively isolated primarily by postmating, prezygotic phenotypes. In addressing this question, we compare the degree of within-species polymorphism and between-species divergence between the ejaculate and thorax proteomes of these two species. We found that the ejaculate proteomes are both less polymorphic and more divergent than the thorax proteomes. Additionally, we assessed patterns of nucleotide variation for two species-specific ejaculate proteins and found evidence for both reduced levels of variation within species and positive selection driving divergence between species. In contrast, non-species-specific proteins exhibited higher levels of within-species nucleotide variation and no signatures of positive selection. Nucleotide and putative functional data for the two species-specific proteins, along with data for a third protein (ejaculate serine protease), suggest that all three of these genes are candidate speciation genes in need of further study. Overall, these patterns of proteome and nucleotide divergence provide support for the hypothesis that there is a causative link between selection-driven divergence of male ejaculate proteins and the evolution of postmating, prezygotic barriers to gene flow within Allonemobius.
Changes in temperature can result in fundamental changes in plant physiology. This study investigated the impact of different temperatures from 14 to 26°C on the resistance or susceptibility to the ...Hessian fly, Mayetiola destructor (Say), of selected wheat cultivars that are either currently popular in the Great Plains area or soon to be released to this region. We found that many wheat cultivars including ‘Bill Brown,’ ‘Byrd,’ ‘Endurance,’ ‘Fuller,’ ‘GA-031257-10LE34,’ and ‘KS09H19-2-3’ were susceptible to Hessian fly infestation at ≥20°C, but became resistant at a certain lower temperature, depending on different cultivars. These cultivars were classified as Hessian fly susceptible according to the traditional standards, and their impact on Hessian fly management needs to be reevaluated. However, many wheat cultivars that were resistant at ≤20°C became destabilized at a certain higher temperature. Phenotypic variations among the resistant cultivars at different temperatures were also observed, suggesting potential different resistance mechanisms. Studies on the genetic and molecular mechanisms associated with resistance at different temperatures are needed, which may lead to improved wheat cultivars with more durable resistance to Hessian fly infestation.
Changes in temperature can result in fundamental changes in plant physiology. This study investigated the impact of different temperatures from 14 to 26 degree C on the resistance or susceptibility ...to the Hessian fly, Mayetiola destructor (Say), of selected wheat cultivars that are either currently popular in the Great Plains area or soon to be released to this region. We found that many wheat cultivars including 'Bill Brown,' 'Byrd,' 'Endurance,' 'Fuller,' 'GA-031257-10LE34,' and 'KS09H19-2-3' were susceptible to Hessian fly infestation at greater than or equal to 20 degree C, but became resistant at a certain lower temperature, depending on different cultivars. These cultivars were classified as Hessian fly susceptible according to the traditional standards, and their impact on Hessian fly management needs to be reevaluated. However, many wheat cultivars that were resistant at less than or equal to 20 degree C became destabilized at a certain higher temperature. Phenotypic variations among the resistant cultivars at different temperatures were also observed, suggesting potential different resistance mechanisms. Studies on the genetic and molecular mechanisms associated with resistance at different temperatures are needed, which may lead to improved wheat cultivars with more durable resistance to Hessian fly infestation.
Pheromone traps have been widely used to monitor insect population activity. However, sticky pheromone traps for the Hessian fly (Mayetiola destructor), one of the most destructive pests of wheat, ...have been used only in recent years. Hessian fly male adults are small and fragile, and preserving specimens during sorting of sticky pheromone traps is a challenge when intact specimens are often required to visually distinguish them from related insects such as fungus gnats. In this study, we have established a quick and reliable method based on polymerase chain reaction markers to correctly distinguish Hessian fly males from other closely related insects. Two Hessian fly-specific markers were established, one based on the trypsin gene MDP-10 and the other based on a gene encoding the salivary gland protein SSGP31-5. Both markers provided >98% identification success of 110 Hessian fly samples prepared from single insects. The method should provide a useful tool to allow for identification of Hessian fly individuals on sticky pheromone traps or in other situations when Hessian fly eggs, larvae, pupae, and adults are difficult to distinguish from other insects.
Pheromone traps have been widely used to monitor insect population activity. However, sticky pheromone traps for the Hessian fly (Mayetiola destructor), one of the most destructive pests of wheat, ...have been used only in recent years. Hessian fly male adults are small and fragile, and preserving specimens during sorting of sticky pheromone traps is a challenge when intact specimens are often required to visually distinguish them from related insects such as fungus gnats. In this study, we have established a quick and reliable method based on polymerase chain reaction markers to correctly distinguish Hessian fly males from other closely related insects. Two Hessian fly-specific markers were established, one based on the trypsin gene MDP-10 and the other based on a gene encoding the salivary gland protein SSGP31-5. Both markers provided >98% identification success of 110 Hessian fly samples prepared from single insects. The method should provide a useful tool to allow for identification of Hessian fly individuals on sticky pheromone traps or in other situations when Hessian fly eggs, larvae, pupae, and adults are difficult to distinguish from other insects.
PDF
