Genome evolution in plethodontid salamanders: molecular and modeling-based analyses of genomic gigantism

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Different animal species have different amounts of DNA (a.k.a. different genome sizes). Although it seems logical that more complex animals would have more DNA, this is not true; in fact, amoebas have more DNA than humans. Within vertebrates, birds have the least DNA and salamanders have the most; salamanders have 25 times as much DNA as humans and 50 times as much as birds. Surprisingly, most species' DNA (including humans and salamanders) is not in genes that underlie development or function of the organism. Rather, it is highly repetitive DNA sequences that multiply and spread throughout an organism's genome, sometimes even harming the organism. Because of this, these repetitive sequences are nicknamed "parasitic" or "selfish" DNA. This project will identify the selfish DNA in salamanders and examine why salamanders have so much more DNA than other vertebrates. These goals will be met by sequencing part of the genome of several salamander species that differ in total DNA content.Understanding the forces that shape genomes, including the human genome, is a major goal of biology. Because salamanders are such outliers in terms of genome size and amount of selfish DNA, comparing their genomes to those of well-studied species, including humans, will clarify why genomes of different animals are so different. The project also includes an outreach component to elementary and high schools in Colorado. Students are always extremely interested to learn that most of their own DNA has a "life of its own" and that its function, if any, is largely unknown.