Format

Send to

Choose Destination
Proc Natl Acad Sci U S A. 2018 Apr 17;115(16):4006-4014. doi: 10.1073/pnas.1722232115. Epub 2018 Mar 26.

Processes and patterns of interaction as units of selection: An introduction to ITSNTS thinking.

Author information

1
Department of Biochemistry and Molecular Biology, Dalhousie University, Halifax, NS B3H 4R2, Canada; ford@dal.ca.
2
Department of Biochemistry and Molecular Biology, Dalhousie University, Halifax, NS B3H 4R2, Canada.
3
Department of Philosophy, Dalhousie University, Halifax, NS B3H 4R2, Canada.

Abstract

Many practicing biologists accept that nothing in their discipline makes sense except in the light of evolution, and that natural selection is evolution's principal sense-maker. But what natural selection actually is (a force or a statistical outcome, for example) and the levels of the biological hierarchy (genes, organisms, species, or even ecosystems) at which it operates directly are still actively disputed among philosophers and theoretical biologists. Most formulations of evolution by natural selection emphasize the differential reproduction of entities at one or the other of these levels. Some also recognize differential persistence, but in either case the focus is on lineages of material things: even species can be thought of as spatiotemporally restricted, if dispersed, physical beings. Few consider-as "units of selection" in their own right-the processes implemented by genes, cells, species, or communities. "It's the song not the singer" (ITSNTS) theory does that, also claiming that evolution by natural selection of processes is more easily understood and explained as differential persistence than as differential reproduction. ITSNTS was formulated as a response to the observation that the collective functions of microbial communities (the songs) are more stably conserved and ecologically relevant than are the taxa that implement them (the singers). It aims to serve as a useful corrective to claims that "holobionts" (microbes and their animal or plant hosts) are aggregate "units of selection," claims that often conflate meanings of that latter term. But ITSNS also seems broadly applicable, for example, to the evolution of global biogeochemical cycles and the definition of ecosystem function.

KEYWORDS:

evolution; microbiome; natural selection; persistence; process

PMID:
29581311
PMCID:
PMC5910863
DOI:
10.1073/pnas.1722232115
[Indexed for MEDLINE]
Free PMC Article

Supplemental Content

Full text links

Icon for HighWire Icon for PubMed Central
Loading ...
Support Center