A Sex-Linked Allele, Autosomal Modifiers and Temperature-Dependence Appear to Regulate Melanism in Male Mosquitofish (Gambusia holbrooki)

About 1% of male mosquitofish (Gambusia holbrooki) express melanic (mottled-black) body coloration, which differs dramatically from the wild-type, silvery-gray coloration. Here, I report on the genetic inheritance pattern of melanic coloration, which indicates Y-linkage, and at least one autosomal modifier. Phenotypic expression of melanism is also affected by temperature. Expression is constitutive ( temperature insensitive) in some populations, inducible ( temperature sensitive) in others. Constitutive and inducible expression occur among geographically proximal populations. However, males from any single population demonstrate the same constitutive or inducible expression pattern as one another. The F1 males from inter-population crosses demonstrate temperature-related expression patterns like their sires\u27. As well, the sex ratio of melanic males\u27 progeny differs among populations. Here, inter-population crosses demonstrate a sex-ratio bias in the same direction as intra-population crosses of the sire population. About 20% of the male progeny of melanic sires express the wild-type phenotype. These silver F1 males sire only silver offspring, suggestive of loss of the melanin gene in F1 males from crossover between sex chromosomes, or control by additional modifiers, or involvement of additional factors. In nature, melanic males persist at very low frequencies. The data collected here on heritability indicate that genetic factors contribute to the rarity of melanic male mosquitofish

A Genetically Distinct Hybrid Zone Occurs for Two Globally Invasive Mosquito Fish Species with Striking Phenotypic Resemblance

Hybrid zones allow for the investigation of incipient speciation and related evolutionary processes of selection, gene flow, and migration. Interspecific dynamics, like competition, can impact the size, shape, and directional movement of species in hybrid zones. Hybrid zones contribute to a paradox for the biological species concept because interbreeding between species occurs while parental forms remain distinct. A long‐standing zone of intergradation or introgression exists for eastern and western mosquito fish (Gambusia holbrooki and G. affinis) around Mobile Bay, AL. The region has been studied episodically, over decades, making it perfect for addressing temporal dynamics and for providing a deeper understanding of the genetics of these periodically reclassified fishes (as species or subspecies). We used six microsatellite markers to assess the current population structure and gene flow patterns across 19 populations of mosquito fish and then compared our results with historical data. Genetic evidence demonstrates that the current hybrid zone is located in a similar geographic region as the historical one, even after three decades. Hybrid fish, however, demonstrate relatively low heterozygosity and are genetically distinct from western and eastern mosquito fish populations. Fin ray counts, sometimes used to distinguish the two species from one another, demonstrate more eastern (G. holbrooki) phenotype fish within the molecular genetic hybrid zone today. Mosquito fish are globally invasive, often found on the leading edge of flooded waters that they colonize, so the impact of hurricanes in the wake of climate change was also evaluated. An increase in the frequency and intensity of hurricanes in the hybrid region has occurred, and this point warrants further attention since hurricanes are known to move these aggressive, invasive species into novel territory. This work contributes to our classical understanding of hybrid zone temporal dynamics, refines our understanding of mosquito fish genetics in their native range, evaluates important genotype–phenotype relationships, and identifies a potential new impact of climate change

Heritable Melanism and Parasitic Infection Both Result in Black-Spotted Mosquitofish

Male Gambusia holbrooki (Eastern Mosquitofish) express a heritable pigmentation polymorphism: ≈99% of males are silver, and only ≈1% have a melanic, black-spotted pattern. Sex-linkage, an autosomal modifier, and temperature control the expression of this heritable melanism. In many teleosts, melanin also accumulates around the site of parasitic invasion. We have identified black-spot disease in wild mosquitofish from their native habitat. Here, we demonstrate convergence upon the black-pigmented phenotype through two means: 1) heritable melanism, and 2) melanic spotting on the silver genotype that results from infection with immature encysted trematodes. Females are silver and express greater avoidance ofmelanic males during mating attempts. The resemblance of the black-spotted pattern of the melanic genotype to that of silver genotype infected with trematodes may affect the fitness ofmelanic males if females perceive them as diseased. Alternatively, females may shun parasitized silverfish because they resemble the melanic genotype, which is larger and has a larger mating orga

Advancing Our Understanding of the Inheritance and Transmission of Pectus Excavatum

Pectus excavatum is the most common congenital chest wall abnormality expressed in children, yet its inheritance is poorly understood. Here we present the first comprehensive assessment of the inheritance of this disorder. After evaluating 48 pedigrees and 56 clinical traits of probands and family members, we find strong evidence of autosomal recessive, genetic control for this disorder. Additionally there is likely more than one pectus disease-associated allele, as well as a relatively large number of disease allele carriers in the human population. Some clinical traits appear important and may serve as reliable indicators for predicting the likelihood of pectus excavatum in children before severe symptoms present. Quantifying sex-ratio bias in probands demonstrates a highly significant male bias associated with pectus excavatum. When combined with pedigree data, sex-bias is indicative of sex-linked, sex-limited, and/or epigenetic control such as X-inactivation, reiterating a point made with pedigrees alone, which is that more than one mutation is likely responsible for this disorder

Sensory genes and mate choice: Evidence that duplications, mutations, and adaptive evolution alter variation in mating cue genes and their receptors

AbstractFascinating new data, revealed through gene sequencing, comparative genomics, and genetic engineering, precisely establish which genes are involved in mate choice and mating activity—behaviors that are surprisingly understudied from a genetic perspective. Discussed here are some of the recently identified visual and chemosensory genes that are involved in mate choice and mating behavior. These genes’ products are involved in the production, transmission, and receipt of crucial sensory mate-choice cues that affect fitness. This review exposes newfound evidence that alternative splicing, gene-expression pattern changes, and molecular genetic variation in sensory genes are crucial for both intra- and interspecific mate choice and mating success. Many sensory genes have arisen through gene duplications, and data amassed from studies conducted at scales ranging from individual genes to genomic comparisons show that strong, positive Darwinian selection acts on several mating-related genes and that these genes evolve rapidly

JAEData.NestHomeParasitization

This file addresses the number of holes in mason bee homes that were colonized by mason bees (eggs laid) but then damaged by parasitizing predatory species like wasps

JAEData.NestHomeColonization

This file contains data on mason bee nest home colonization on berry farm

JAEData.StrawberryData

This file contains measurements of berries on nine farm plots where half of each plot is a treatment (mason bee addition) and half is a control (no bee addition

Data from: Supplementing small farms with native mason bees increases strawberry size and growth rate

Pollination services, especially those of bees, play a vital role in agriculture. Declining honeybee populations require us to find alternative solutions for sustainable agriculture. Native bees are proving to be efficient pollinators. Mason bees (Osmia lignaria) provide valuable pollinator services for some woody orchard species, but their value as pollinators for herbaceous crops is largely untested. We assessed the effectiveness of O. lignaria supplementation on nine strawberry farms over two growing seasons. We specifically selected mason bees for this work because they emerge from cocoons in the springtime, when few other bees are available for pollination. Cocoons are easily deployed on farms and emerged bees have a small flight radius, so they remain localized. We placed cocoons on one side of each berry farm plot (our mason bee addition treatment) but not on the opposite side (our control). We tagged and monitored berries on nine farms throughout the growing season. We performed statistical comparisons of berries from the treatment and control for differences in berry growth rate and size. In addition, we supplemented farms with native bee homes constructed from three materials (bamboo, Phragmites and wood). This allowed us to determine whether adult mason bees would produce a subsequent generation of bees on farms and whether the bees had a preference for nest material type. Our work demonstrates that mason bees can be used successfully to pollinate herbaceous berry crops. We found that berry growth rate was significantly higher and berry volume was significantly larger for berries from the treatment relative to the control. We also found that adult bees successfully utilized the bee homes for laying the next generation of offspring and that bees colonized bamboo homes more than other home types. Synthesis and applications. Our results are the first to show that native mason bees (Osmia lignaria) can be used successfully to provide pollination services on strawberry farms. Their use results in the production of bigger berries and faster berry growth rates than managed honeybees alone. Mason bees overwinter (and can be purchased) in cocoons, offering great potential for efficient and effective pollination services, for a variety of agricultural applications across different geographical regions. The availability of suitable nesting sites and protection of subsequent generations of cocoons from wasp parasitization warrant future consideration

Wild bees preferentially visit Rudbeckia flower heads with exaggerated ultraviolet absorbing floral guides

Here, we report on the results of an experimental study that assessed the visitation frequency of wild bees to conspecific flowers with different sized floral guides. UV absorbent floral guides are ubiquitous in Angiosperms, yet surprisingly little is known about conspecific variation in these guides and very few studies have evaluated pollinator response to UV guide manipulation. This is true despite our rich understanding about learning and color preferences in bees. Historical dogma indicates that flower color serves as an important long-range visual signal allowing pollinators to detect the flowers, while floral guides function as close-range signals that direct pollinators to a reward. We initiated the work presented here by first assessing the population level variation in UV absorbent floral guides for conspecific flowers. We assessed two species, Rudbeckia hirta and R. fulgida. We then used several petal cut-and-paste experiments to test whether UV floral guides can also function to attract visitors. We manipulated floral guide size and evaluated visitation frequency. In all experiments, pollinator visitation rates were clearly associated with floral guide size. Diminished floral guides recruited relatively few insect visitors. Exaggerated floral guides recruited more visitors than smaller or average sized guides. Thus, UV floral guides play an important role in pollinator recruitment and in determining the relative attractiveness of conspecific flower heads. Consideration of floral guides is therefore important when evaluating the overall conspicuousness of flower heads relative to background coloration. This work raises the issue of whether floral guides serve as honest indicators of reward, since guide size varies in nature for conspecific flowers at the same developmental stage and since preferences for larger guides were found. To our knowledge, these are the first cut-and-paste experiments conducted to examine whether UV absorbent floral guides affect visitation rates and pollinator preference