Official websites use .gov
A
.gov website belongs to an official
government organization in the United States.
Secure .gov websites use HTTPS
A lock (
) or https:// means you've safely
connected to the .gov website. Share sensitive
information only on official, secure websites.
Relative fraction of “trunk” branches (red), other interior branches (green), or exterior branches to isolates (blue) that are characterized by a negative, neutral, or positive change in human adaptedness, following the shift from avian-to-human host prior to 1918. Error bars represent standard error based on the number of observations. All genes show a similar distribution.
