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Genes and inheritance

By Ranger Steve Mueller

 

Some male and female organisms look nearly identical. It is not easy to recognize a male and female robin apart. Is it a boy or girl cottontail hopping through the yard? Plants like wild strawberries have both sexes in one flower while others like willows are either male or female plants.

Male and female American Goldfinches look very different in summer but by winter look quite similar. It is the outward appearance we notice. What is hidden from view is the genetics. We can observe the results but the secrets for how genes and inheritance help species survive in nature niches is an ongoing discovery process. 

DNA sequencing has become popular for tracing personal family origins and is a tool for solving cold case crimes. As an ecological tool, molecular analysis aids understanding the evolution of species. 

DNA and RNA analysis has provided great advances toward understanding origins of species. It has also revealed new difficulties to decipher. When I first encountered the Northern Blue butterfly in Michigan, I confused it with Karner Blue butterfly. The two are nearly identical twins in appearance. 

Mo Nielsen immediately told me I did not make a Karner Blue discovery in the Upper Peninsula when I reported one. He said there is no wild blue lupine there that the Karner Blue requires. He instructed me to look closely at the wing pattern to see if it was a Northern Blue. I was unfamiliar with the Northern Blue but that is what I found. It was a breeding colony that confirmed the species as a Michigan resident. The Michigan DNR nongame program provided a grant for me to conduct life history research for this new Michigan species. 

I was not involved with the molecular analysis, but it was found the Northern Blue showed a closer relationship with the Karner Blues genetically than with the Northern Blues of western North America. Outwardly, Michigan Northern Blues look more like Karner Blues than they look like western Northern Blues. 

As scientific abilities become more advanced, we find separation between species is more difficult to assess. We like to think species are distinct entities that are clearly separated. They are not. A key feature that helps define species separations is ecological nature niche adaptations. Species adapt to utilize different food plants and micro-habitats that result to speciation. 

Many species are cryptic. Physically they look alike but are ecologically and reproductively separated. They share habitat but have developed isolating survival strategies that are different from the parent species. Specific isolating adaptations create new species but interbreeding during the process complicates analysis. 

Yellow-shafted and Red-shafted Flickers (woodpeckers) were considered separate species. We planted trees across the Great Plains and the two got together. They mate and produce fertile offspring. The two are now lumped as one species called the Northern Flicker. Interestingly where they live together, the yellow and red do not readily interbreed. This has caused some ecologists to think they should be considered separate sibling species. Others think they are one species with two color forms that reduces interbreeding based on appearance. 

We experience the same difficulty among humans where Danes, Germans, French, Hispanics, and other races live together. Our genes are fully compatible. There was a time when people thought each race was a separate species but DNA sequencing indicates our genetic differences are superficial and too minor to separate humans as different species. The differences are primarily cultural. We are one species that developed different physical adaptations that helped us survive in various climatic conditions. Cultural isolation helped define our races.

Science is supported by physical evidence. It often conflicts with what we want or choose to believe. Our cultural background helps define our behavior. Like flickers, some people like Karen (Norwegian) and me (German) intermixed our genes while others choose to limit relationships to their race and cultural history. 

Natural history questions or topic suggestions can be directed to Ranger Steve (Mueller) at odybrook@chartermi.net – Ody Brook Nature Sanctuary, 13010 Northland Dr. Cedar Springs, MI 49319 or call 616-696-1753.

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