so, in one instance, some of these viruses contain core photosynthesis genes. they're actually able to boost photosynthesis during infection in these particular hosts. narrator: a virus infects its host by injecting its genetic material into the cell causing the cell's biochemistry to switch over to making more virus particles. sometimes dna from the two sources gets mixed up, and the host takes away some of the genetic makeup from the virus. sullivan: so, is the virus just lysing and killing those host cells or are they also perhaps taking genes from the host and moving those genes back into the host after they've changed a little bit in the viral population? narrator: maureen coleman has been studying the genetic composition of several prochlorococcus strains. she was able to identify signatures in their genomes to suggest that viruses are actually important in moving genetic information between host cells. and this transfer of genetic information leads to diversification within the population. even though everything looks similar if you look at it under a mi

carbon dioxide is cycled through the atmosphere through many natural processes such as photosynthesis respiration and decay of vegetation, and sea surface gas exchange. this natural transfer, known as the carbon cycle, is in near balance. the amount being emitted to the atmosphere is close to the amount being absorbed. but the burning of fossil fuels is adding co2 faster than natural systems can respond. pieter tans is taking careful measurements of the atmospheric concentration of carbon dioxide to better understand the carbon cycle. dr. tans: when you study the carbon cycle, what matters is what happens to co2 exchange between the atmosphere and the oceans. what are terrestrial ecosystems doing? are they losing carbon? gaining carbon? why? so we use the atmosphere as a diagnostic to get a handle on these processes to quantify where these processes take place and how large they are. we want to diagnose how the carbon cycle is developing and we want to understand why. now, the first accurate measurements of carbon dioxide in the atmosphere were done in 1956 by david keeling. he was al

now you don't have as much to work with light wise for photosynthesis. if you can adapt to this habitat, you are stuck here, because you have to grow in that habitat, and it doesn't exist anywhere outside mediterranean regions. that's why the mediterranean regions of the world are biodiversity hotspots. so many plants have adapted to grow just in that climate that they are full of endemics, and that shoots up the biodiversity even higher. one feature that a lot of the plants that live in mediterranean climates share in common is - they are beautiful! they have gorgeous flowers and they produce lots of them. so the one that's right in front of me here, this lotus, is a good example. i mean it's covered with yellow flowers, pea-shaped flowers, because this plant is in the pea family. but we also have things like sand verbenas, which are actually an abronia, they're in a different genus. here the beautiful pink abronia umbellata is in full flower even now in late winter. but if you come back in just a few weeks, this place is absolutely covered with poppies

the name of it is phytophotodermatitis, caused by a photosynthesis-including chemical in the lime and other fruits and vegetables. and they don't really know if the marks are going to go away yet. >> oh, my gosh. now, the girls have all been cleared to go to school, but they have been told they have to limit their time in the sun, obviously, to prevent any major scarring. my goodness these poor girls. >> yeah, i know, so sweet. >> it's one of those things that you never really expect is going to happen. you're having a good time in the summer in the sun. >> got my attention. >> yeah. >> the next time the limes come out in the summertime. i'm going to be careful. >>> a guy in australia can truly say he is lucky to be alive this morning after coming within inches of an almost certain death. there he is at a service station counter, paying for a magazine with a credit card. an extra second made the difference. just then -- an suv blasts through the front of the store window. holy mackerel. >> the next thing you know, i see this car come through in the corner of my eye. it was just a big