Australopithecus feed on seeds and soft fruits ~4.4 Mya (million years ago) until ~2.5 Mya ~2 Mya and persisted for ~1 Myr. Pleistocene Homo erectus Bulbs and roots H. sapiens meat “you are what you eat”-diet and human evolution Pictures adapted from google images

Diet not only affect human structure, but also genes:  Human have roughly three times of Amylase gene than chimpanzee: intensive starch diet  Genetically regulated lactose tolerance is in association with cattle milk consumption

Object: 16s rRNA gene sequence of gut microorganism from human, non-human primates, other mammal species, non-vertebrate and free living microorganisms. Two approaches applied:  1. UniFrac distance  2. Operational taxonomy unit(OTU) based analysis: single level of phylogenetic resolution

Measures the evolutionary distance between microbial communities Information adapted from dparks.wdfiles.com/local-- files/exploringmicrobial.../UniFrac.ppt

Operational taxonomic Unit (OTU): definition of a taxonomic unit based on sequence divergence  “species” 97% sequence homology  “genus” 90% sequence homology  “family” 80% sequence homology

1. UniFrac distances between samples from same species were significantly smaller than distances between samples from different species 2. samples from same species share more genus- level OTUs than samples from other species

 Herbivore : animals which only eat plant material, foregut fermenter vs hindgut fermenter  Ominivore: animals which eat both plants and meat  Carnivore: animals which eat meat, have simple gut Image adapted from

BC A B4 C36 D433 ABC PC1 PC2

schematic key of network analysis1

1. Principal coordinate analysis(PCoA) and network diagram clearly separates bacterial communities obtained from the vertebrate gut from freeliving communities 2. Obvious dichotomy is observed across bacterial tree and within phyla

 Random immigration, birth events and death events (Neutral model) : tree holes, human lungs and lakes  Adaptive immune system, selection pressure on the host, nutrient-redox potential dichotomy :vertebrate gut

dev.nsta.org/evwebs/1887/present_technolo gy_4.htm

Healthy Not Healthy darmano.typepad.com/.../07/human_hierarchy. html

 Stable Temperature  Nutrient rich  Anaerobic  Oxidized environment

 Mammalian gut microbiota is related to diet and gut morphology : mammalian gut bacterial community type can be roughly categorized into herbivore, omniviore and carnivore  Overal, gut microbiota among vertebrates are closer related to each other than to other communities, as demonstrated by PCoA and network analysis  Selection pressure on vertebrate gut microbiota: Adaptive immune system, selection pressure on the host, nutrient-redox potential dichotomy