2 1 3 4 Diversification of mammals
Millions of years
Origin of mammal-associated Bartonella between 89.5-119 million years ago
Problem
Most human infections likely came from animals When did these transitions from animals to humans occur?
Timing the diversification of a
mammal parasite, Bartonella
Clif McKee
Biology/GDPE
@clifmckee
clifton.mckee@gmail.com
Background
Bartonella bacteria cause several human diseases
Related animals have related Bartonella strains
Bartonella infects blood cells and is carried by insects
Goal
Estimate when Bartonella evolved Time the origin of human infections
Methods
Assemble genetic data
Known Bartonella species New strains from bats
Calibrate molecular clock
Genetic material changes at some rate Rate is flexible over time Average rate set from host-specific bacteria ‘Tune’ clock using origins of animal hosts
0 0.02 0.04 0.06 0.08 0.1 0.12 0.14 0.16 0 100 200 300 Evolutionary distance
Millions of years ago
Results/Conclusions
Bartonella is much older than we knew! Bartonella started as gut bacteria in insects Bartonella diversified with mammals starting ~100 million years ago
Monkey and human B. quintana (cause of trench fever) split 2 million years ago
Cretaceous-Paleogene extinction of dinosaurs
B. apis found in bees