Genetic Architecture of Hybrid Male Sterility in Drosophila: Analysis of Intraspecies Variation for Interspecies Isolation

Background: The genetic basis of postzygotic isolation is a central puzzle in evolutionary biology. Evolutionary forces causing hybrid sterility or inviability act on the responsible genes while they still are polymorphic, thus we have to study these traits as they arise, before isolation is complete. Methodology/Principal Findings: Isofemale strains of D. mojavensis vary significantly in their production of sterile F 1 sons when females are crossed to D. arizonae males. We took advantage of the intraspecific polymorphism, in a novel design, to perform quantitative trait locus (QTL) mapping analyses directly on F1 hybrid male sterility itself. We found that the genetic architecture of the polymorphism for hybrid male sterility (HMS) in the F1 is complex, involving multiple QTL, epistasis, and cytoplasmic effects. Conclusions/Significance: The role of extensive intraspecific polymorphism, multiple QTL, and epistatic interactions in HMS in this young species pair shows that HMS is arising as a complex trait in this system. Directional selection alone would be unlikely to maintain polymorphism at multiple loci, thus we hypothesize that directional selection is unlikely to be the only evolutionary force influencing postzygotic isolation

Worlds Further Apart: The Widening Gap in Life Expectancy among Communities of the Indianapolis Metropolitan Area

Indianapolis metro area residents are a diverse group of people. What we have in common is that many of our best and worst days have been lived within this larger community. We may recall warm summer hours in our favorite park, a day spent at “the track,” or taking the kids to the Children’s Museum. We may also remember days spent at the bedside of a sick family member in an area hospital or places of tragic loss. Year after year, we build our lives within the Indianapolis metro area. In this way, our lives are linked by a shared community. However, in the neighborhoods we each call home, our daily lives are often vastly different. For some, getting groceries means lugging plastic sacks onto the IndyGo bus after waiting on a patch of worn grass. For others, grocery shopping is a quick drive to one of three favorite options, and the farmer’s market is a weekend routine for fresh produce. Some kids go to school with laptops and fresh smelling pages of new textbooks, while others have worn books and no internet access. Playing outside with friends in one neighborhood builds fitness and friendships, while in another playing outside triggers an asthma attack because of all the car exhaust along the busy roadway. Place differences add up over the days of our lives to affect our health and length of life. The children of one neighborhood have the same biological capacity for a long and healthy life as do the children of any other neighborhood, but where they live and grow and learn often unfairly cuts short their opportunities and their life. In our updated analysis of 104 ZIP Codes in the metro area (2014-2018), we identified the northern suburb of Fishers as our longest living community and just 17 miles away, within the Indianapolis city limits, is the shortest living community within the metro area. Though only 17 miles of distance separate them, their life expectancy is worlds apart. As the White River winds its way through the metro area, flowing northeast to southwest, it connects us as a larger community across time and space. The history of central Indiana is rooted in access to this shared life-supporting resource, where tribes, then towns and cities grew along its banks. Following the winding path of the White River, we see a pattern in life expectancy that also plays out throughout the metro area (See Life Expectancy Mapped Along the White River, 2014-2018, on next page). Life expectancy is lowest in places within the urban core of Indianapolis and also on the outer periphery of the metro area (red), while highest life expectancy is found in the suburban transitions from the city (green). Similar to our earlier findings residents of the longest-living community are living years longer than the U.S. average with a life expectancy comparable to the top high-income countries of the world.1 Residents of the shortest living community are living only as long as U.S. residents lived on average more than six decades ago, and the gap has widened. There is no genetic reason for this inequity. These data compel us to put equity at the forefront in addressing the economic and social policies and structures driving this unfairness. Inequity, in life and health, “saps the strength of the whole society.”

Worlds Further Apart: The Widening Gap in Life Expectancy among Communities of the Indianapolis Metropolitan Area

Indianapolis metro area residents are a diverse group of people. What we have in common is that many of our best and worst days have been lived within this larger community. We may recall warm summer hours in our favorite park, a day spent at “the track,” or taking the kids to the Children’s Museum. We may also remember days spent at the bedside of a sick family member in an area hospital or places of tragic loss. Year after year, we build our lives within the Indianapolis metro area. In this way, our lives are linked by a shared community. However, in the neighborhoods we each call home, our daily lives are often vastly different. For some, getting groceries means lugging plastic sacks onto the IndyGo bus after waiting on a patch of worn grass. For others, grocery shopping is a quick drive to one of three favorite options, and the farmer’s market is a weekend routine for fresh produce. Some kids go to school with laptops and fresh smelling pages of new textbooks, while others have worn books and no internet access. Playing outside with friends in one neighborhood builds fitness and friendships, while in another playing outside triggers an asthma attack because of all the car exhaust along the busy roadway. Place differences add up over the days of our lives to affect our health and length of life. The children of one neighborhood have the same biological capacity for a long and healthy life as do the children of any other neighborhood, but where they live and grow and learn often unfairly cuts short their opportunities and their life. In our updated analysis of 104 ZIP Codes in the metro area (2014-2018), we identified the northern suburb of Fishers as our longest living community and just 17 miles away, within the Indianapolis city limits, is the shortest living community within the metro area. Though only 17 miles of distance separate them, their life expectancy is worlds apart. As the White River winds its way through the metro area, flowing northeast to southwest, it connects us as a larger community across time and space. The history of central Indiana is rooted in access to this shared life-supporting resource, where tribes, then towns and cities grew along its banks. Following the winding path of the White River, we see a pattern in life expectancy that also plays out throughout the metro area (See Life Expectancy Mapped Along the White River, 2014-2018, on next page). Life expectancy is lowest in places within the urban core of Indianapolis and also on the outer periphery of the metro area (red), while highest life expectancy is found in the suburban transitions from the city (green). Similar to our earlier findings residents of the longest-living community are living years longer than the U.S. average with a life expectancy comparable to the top high-income countries of the world.1 Residents of the shortest living community are living only as long as U.S. residents lived on average more than six decades ago, and the gap has widened. There is no genetic reason for this inequity. These data compel us to put equity at the forefront in addressing the economic and social policies and structures driving this unfairness. Inequity, in life and health, “saps the strength of the whole society.”