I’ve been asked a few times the difference between genetics and genomics, so I thought I’d take the time to explain how I see each differently, specifically in a conservation context. Genetics, in a classic sense, deals with genes. Genetics may tackle topics such as what gene underlies a trait of interest; how does overexpression, underexpression, or knocking-out a gene effect growth and development; where does a gene fit into a regulatory or metabolic pathway; or what are the functional differences between alleles? Genetics also deals with inheritance, including understanding that alleles can be dominant or recessive; the frequency of lethal alleles of a genetic disease in a population; X-inactivation in cells for dosage compensation; or fitness coefficients for phenotypic traits.
Genomics differs in that it considers the whole genome, so genes + non-coding sequence + tagging of genes (via phosphorylation or methylation) for expression + local inversions or rearrangements of chromosomes. Genomes interact with the environment where a stress on the organism may turn on or off (or change the level of expression of) different gene products; thereby producing variation in response to the environment. While we continue to learn more about inheritance at the genomic level (eg- inheritance of the epigenome), a lot of research, especially in humans, focuses on how traits are associated with these genome-by-environment interactions.
I think part of the lack of understanding between genetics and genomics in a conservation context is that conservation genetics uses a multi locus approach. When genetics is defined in a single locus = single gene context, it can be easy to think of the 10-20 microsatellites or hundreds of amplified fragment length polymorphisms (AFLPs) as being genome studies. Sure, multiple evenly spaced markers will give more information about parameters of interest to conservation genetics (including population genetic diversity, inbreeding level, individual heterozygosity, and/or gene flow), but it’s not genetics in the classic sense as the markers are at neutral loci not genes. But that’s okay because conservation geneticists know they are doing population genetics not classical genetics. That said, when the conversation turns to conservation genomics, it seems like an issue of increasing the number of loci and estimating those same parameters with more markers representative of a larger proportion of the genome. But it’s not, because genomics does not just offer a finer scale of measurement but different measurements. If studies are only using genomics to refine traditional population genetic parameters, we should question whether the study is truly conservation genomics or simply conservation genetics with a lot of markers (and potentially higher power).
This always leads me to think (and feel free to disagree) that conservation genomics is not a real sub-discipline. I have yet to see a study that took a genomics approach to answer a conservation question. I think genomics provides the tools for detailed evolutionary studies which some researchers frame as conservation studies. No doubt the development of next-generation sequencing and non-reference genome based analyses has allowed for expanded evolutionary studies of species of conservation concern; but evolutionary genomics of species of conservation concern does not equal conservation genomics. Moving forward, is conservation genomics simply a buzz phrase or will it develop into a meaningful sub-discipline for the conservation of biodiversity?