Weitz Group @ Georgia Tech

Theoretical Ecology and Quantitative Biology


Monday, June 4, 2018 - 10:13

A recent New York Times article on 'Trillions Upon Trillions of Viruses Fall From the Sky Each Day' focused on the role of viruses of microorganisms in shaping life on Earth. The article highlighted a recent call for a new initiative in this area, proposed by Prof. Weitz and colleagues - Prof. Steven Wilhelm (UT-Knoxville) and Prof. Matthew Sullivan (Ohio State University):

'Last year, three experts called for a new initiative to better understand viral ecology, especially as the planet changes. “Viruses modulate the function and evolution of all living things,” wrote Matthew B. Sullivan of Ohio State, Joshua Weitz of Georgia Tech, and Steven W. Wilhelm of the University of Tennessee. “But to what extent remains a mystery.”'

The initiative proposed by Weitz, Wilhelm, and Sullivan is termed Unveiling the Viral Ecology of Earth and was released as part of the Science Philanthrophy Alliance's XO Files.


Monday, November 28, 2016 - 20:48

Prof. Weitz has had a number of interviews, blogs, and other events of late. Notices of these will be available moving forward on twitter @joshuasweitz & @weitz_group.

Here are a few:

This page will be updated occasionally, but check out twitter for more up-to-date information.


Thursday, September 18, 2014 - 21:09

In a 2014 PNAS article, Michael Cortez (now faculty at Utah State) led an effort to characterize how coevolutionary dynamics can affect ecological dynamics. In a linked series of theoretical analyses, computational simulations and statistical analysis of time series data, we show how predator peaks can precede prey peaks when both predators and prey possess multiple genotypes within their corresponding populations. Hence, changing genotype frequencies influences the structure of the total dynamics of populations. This article has discussed here:

Friday, February 7, 2014 - 19:21

In November 2012, the Spanish government announced a fast track naturalization policy targeted to non-citizens who are both Jewish and whose ancestors were expelled from Spain during the inquisition-related dislocation of Jews in 1492. The announcement received extensive media coverage in Spain (e.g. El Pais) and globally (e.g., NY Times).

The policy is ostensibly meant to target “Sephardic” Jews, i.e., a minority of the global Jewish population who retain cultural practices associated with ancestral origins in the Iberian Peninsula. However, in a paper appearing in January 2014 in PLoS One, Prof. Weitz proposes and analyzes a variant of standard genealogical models, well-established in other contexts, to show that most Jews, regardless of whether they self-identify as Sephardic or not, are likely to have one, if not many more, ancestors who were expelled from Spain in 1492.

Dr. Weitz's research has been profiled as part of the following news articles and blog entries, including a series by reporter Josh Nathan-Kazis of The Forward


Monday, January 28, 2013 - 23:43

The rise of antibiotic-resistant bacteria has initiated a quest for alternatives to conventional antibiotics. One potential alternative is PlyC, a potent enzyme that kills the bacteria that causes strep throat and streptococcal toxic shock syndrome. PlyC operates by locking onto the surface of a bacteria cell and chewing a hole in the cell wall large enough for the bacteria's inner membrane to protrude from the cell, ultimately causing the cell to burst and die.

Tesearch has shown that alternative antimicrobials such as PlyC can effectively kill bacteria. However, fundamental questions remain about how bacteria respond to the holes that these therapeutics make in their cell wall and what size holes bacteria can withstand before breaking apart. Answering those questions could improve the effectiveness of current antibacterial drugs and initiate the development of new ones.

Researchers at the Georgia Institute of Technology (Gabriel Mitchell, Prof. Kurt Wiesenfeld, and Prof. Joshua Weitz) and the University of Maryland (Prof. Daniel Nelson) recently conducted a study to try to answer those questions. The researchers created a biophysical model of the response of a Gram-positive bacterium to the formation of a hole in its cell wall. Then they used experimental measurements to validate the theory, which predicted that a hole in the bacteria cell wall larger than 15 to 24 nanometers in diameter would cause the cell to lyse, or burst. These small holes are approximately one-hundredth the diameter of a typical bacterial cell.

More information in the article available online at the Journal of the Royal Society Interface


Wednesday, February 1, 2012 - 11:32

Joshua Weitz is a member of a research team led by Michigan State researchers Justin Meyer and Richard Lenski who published an article detailing how viruses evolve key innovations. The original article can be found on the Science homepage. More coverage can be found here:


Thursday, January 13, 2011 - 16:15

The Weitz group has recently published a "Breakthrough Technology" article based on user-assisted software to analyze the structure of leaf venation networks. The program, called Leaf Extraction and Analysis Framework Graphical User Interface (LEAF GUI), enables scientists and breeders to measure the properties of thousands of veins much more quickly than manual image analysis tools.

More details concerning press coverage can be found here:


Tuesday, November 2, 2010 - 21:12

Prof. Weitz and Richard Joh are two of the co-instructors for the first ever Georgia Tech International Genetically Engineered Machine (iGEM) team, along with Prof. Eric Gaucher and Prof. Mark Styczynski. Initiated in January 2003, the iGEM competition is considered the premiere undergraduate synthetic biology competition. Since spring 2010, the team of 13 undergraduates has focused on a project designed to synthetically engineer heat-producing bacterial cells in response to exposure to cold environments.

More info about the team can be found here:

Monday, October 4, 2010 - 13:02

Gabriel Mitchell and Joshua Weitz -- from our group here at the Georgia Institute of Technology -- collaborated with Daniel Nelson, a biochemist specializing in phage lytic enzymes at the University of Maryland, in a collaborative project to develop a novel assay to quantify how a new class of enzybiotics can explode bacterial pathogens. The results are available online on Physical Biology.

Discussion of this work can be found online:


Wednesday, October 1, 2008 - 00:00

For many bacterial viruses, the choice of whether to kill host cells or enter a latent state depends on the multiplicity of coinfection. We recently suggested a nonlinear basis for the finding that deterministic decisions can be reached, e.g., lysis or latency, depending on the cellular multiplicity of infection. The results were published in Biophysical Journal, Collective decision making in bacterial viruses.

Discussion of our findings can be found online: