The authors explained that this newly described concept holobiont biology underpins a multidisciplinary and holistic understanding of how life’s forms and functions from human disease to agricultural output depend upon the relationships between microorganisms and their hosts. Penn State News spoke with Bordenstein about the paper and the emerging field of holobiont biology.

Q: In simple terms what is evolution? Why do organisms vary in traits?

Bordenstein: The longstanding definition of evolution is the process by which living things change over time by gradually mutating and adapting to their environments. This happens often through a process known as natural selection where traits that help an organism survive and reproduce are passed on to future generations while less useful traits gradually disappear.a

Q: What can this new paper tell us about what has been overlooked in the study of life?

Bordenstein: Traditionally biologists have studied visible and invisible life in silos which has caused our concepts of life to separate. Many scientists were settled in their ways of thinking of microbes as background noise or transient contaminants without major impact on host life. Yet microbial cells in and on the human body can actually outnumber human cells.

Q: Historically the field of biology tends to categorize living things into taxa the filing system for species genus family order etc. How does holobiont biology fit into or challenge that framework?

Bordenstein: We envision that microbes are fundamental to how biologists explain variation in host life forms for example animals and plants. So in the case of classification of species we’re making the case that organisms are not autonomous. They exist by definition always in association and in contact with microbes.

Q: How do you bring about this new paradigm shift in the life sciences?

Bordenstein: It starts with how we define and teach biology. That means rethinking how we describe animals and plants we're not calling them animals and plants anymore. We’re thinking of animals and plants as a consortium of host and microbial cells that influence anatomy and physiology because that is the reality of nature. We cannot think about animal or plant genomes in a way that's separate from microbial genomes when we know that both genomic compartments are all part of the functional unit.

Source: https://www.psu.edu/news/research/story/qa-how-do-microbiomes-influence-study-life