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[Music]

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Thank You Candace so Pedro makes the

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transition to organizers so how why the

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more complex life has evolved over time

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back in 1995 - made and thought Mary

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proposes this can be can be achieved

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through a serious major evolutionary

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transitions including the origins of

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cells genomes genetic code eukaryotes

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sex

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multicellularity social groups such as

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social insects

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among those transitions the origin of

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motifs errantly and allows opportunities

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for further complexity to evolve and led

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to more complex life we see today like

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animals and plants across the Tree of

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Life our earth multicellularity has

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originated independently a number of

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times the thing we want to know is that

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what our minimum necessary steps that

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are required at first usually people do

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this by comparing those Modi's thermal

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images with their unicellular relatives

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but the problem is that those things

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happened long time ago and many changes

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have occurred in the extant species and

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which makes a typical to infer infirmity

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happens in the beginning so one of those

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multicellular lineages it's green algae

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which includes bobasa

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LG this group of algae contains species

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with different levels of complexity from

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unicellular Chlamydomonas to fully

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differentiated

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Volvox so with this unicellular algae

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and how we can replay lights - like tape

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to see how mori celerity

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originates

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in the first place the model species of

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the unicellular algae is law

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chemita Moniz Ryan hardy I it's a model

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system for photosynthesis and motility

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their vegetative cells or asexual cells

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are haploid and their genome has been

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sequenced and annotated which make them

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a great system to do evolution

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experiment experiment ways so that we

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can see how they are phenotypes and

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genotypes change in real time among the

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possible selective pressures and might

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generate multicellularity predation has

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long been her has hypothesized as a

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major cause for motor celerity because

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it favors bigger sites such as groups of

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cells over single cells so here's a

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picture of

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Silius and algae those feed her feelings

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ciliates

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they are also unitl they can feed on

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those single-celled algae however if we

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continuously exposing those algae to

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ciliates and that will generate the

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selective pressure to make them become

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so a few years ago my advisor matt and

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jacob a graduate student in our lab

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disease evolution experiments to say

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select four multicellularity using

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predators so the experiment was started

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with out cross population by making two

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different algae strands so we have

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genetic diversity in the beginning the

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starting population was split into five

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experimental probation that were

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cultured with predators and three

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control populations that were cultured

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without predators those cultures were

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transferred into fresh media every week

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over a year

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at the end of the experiment we two of

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the experimental populations P 2 and P

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five population they involve those multi

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cellular structures not observed in any

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of the control populations so here's a

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time-lapse video over 72 hours of a

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unicellular algae strip strength so you

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can see that when cells go through cell

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division there are some little clumsy

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but soon after that the total cells will

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separate and console division here's one

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of our evolved more tea seller strengths

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and you can see that the cells stayed

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together for a while and then they start

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to pop out those smaller multicellular

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puppeteers here's another multicellular

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strands from the other extreme to

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population p5 they also stay together

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for a while and then they start to pop

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out single motile cells and then they

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start to form those multi solar coasters

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again so there are these two the

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medicinal strands from those two

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populations differ in their life cycles

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but they both from those structures by

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the failure of daughter cells to

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separate among cell division and most

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importantly they from those structures

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in even when their predators are not

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around anymore

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meaning that there's a genetic basis

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so to find out what kind of mutations

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happened in those evolved LG LG strands

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with it Illumina whole genome sequencing

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so for the 2x raindrop operation one

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control population we pick up multiple

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colonies to do whole genome sequencing

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we also sequence the

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- ancestral strength to know what

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genetic gration existed in the beginning

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so that we can know what actually

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happened in those evolved algae so what

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we found out is that appear that is two

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different genetic basis underlying two

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origins of multicellularity in your

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experiment so here are the mutations

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occurring each strand each Royces is an

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evolved isolate the first four are from

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the beetle permission that about

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medicinal properties the next four are

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from the be pipe operation that part

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about single cell properties and the

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last four are come from control

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population that are Romanian insulin and

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each prize mutation happened in their

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genomes and you can see that for the

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multicellular isolate in the b2 and b5

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populations they shared certain set of

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mutation all together suggesting that

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those are or any thousand are important

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for those medicinal phenotypes so how do

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we know that which which mutations are

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actually responsible for those most

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logical changes with it so these

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analyzers code park second analyzes the

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idea is that say let free meat mutations

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in all evolve isolate and we want to

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know whether it's a PC or a BP CAC or

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ABC together that are you responsible

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for the phenotype you can make it with

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the wild-type strength to generate a

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group of cells with different

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combinations of those mutations and then

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we can select full of phenotype we are

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interested in put summary cell phenotype

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and then those

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you know hats associate associated with

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phenotype huapi imaged this way so to

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actually do this with LG we made it our

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evolved multi server phenotypes with the

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unicellular strand to generate an actual

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population with different combination of

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the mutations so some details are multi

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seller and something on unit cell and

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then we select the multi cellular

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phenotype by centrifugation briefly so

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that's the bigger one should sink to the

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bottom more quickly and then so that the

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bottom ones go to the multi seller pool

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and the cells aren't have go to the

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single cell pool by repeating this for

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multiple times we can enrich the multi

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seller genotypes and unison what is the

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genotypes and then we sequence is two of

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pools of cells to see the allele

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frequency differences across their whole

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genomes and it turns out there are

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multiple regions in those LG's genome

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responsible for the motor severity

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evolved in your lab so it's a result

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from the multicellular isolates from the

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p2 population the y-axis means that

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given the overall allele frequency in

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both unicellular and multicellular pool

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these allele the transit alia appear in

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the MOTC report and the higher the dots

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are the laurel urchins are and the more

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likely they are associated with the

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multi cellular phenotypes so you can see

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several peaks here and three of them

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also match to the mutations we

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identified through whole genome

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sequencing approach and then there also

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other pics they're suggesting certain

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genetic background is important for

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those mute new mutations to arise here's

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the results from the b5 isolate and the

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other population that you bought

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multicellularity and we also see a

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similar trend so while the pigs match to

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one of the mutations we identified well

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there are several other pics that

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suggesting its ancestral genetic

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background plot the mute mutations

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responsible for those phenotypes both

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these mutations and the why I showed in

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the last slide now then they are either

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in introns or intergenic regions or none

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of them change amino acid sequences so I

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still working on what they actually do

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to change those phenotypes to summarize

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we evolved multicellularity black with

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predators we have identified mutations

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that ever happened in those evolved

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algae appear that is two different

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genetic bases undesigned those two

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different origins of multicellularity we

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are working on the functional relevance

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of those mutations at the moment for

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future directions now that we have

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evolved those simple modular structures

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we want to know how cellular

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differentiation would evolve and another

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postdoc in your lab is working on this

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project right now she's pretending a

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poster today if you haven't talked to

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her you should so what I presented today

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is multiple people's work especially

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Matt who oversees this whole project and

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we also like to paint our funding

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sources

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[Applause]

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we have time for some questions

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[Laughter]

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[Music]

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great talk thank you much I know you're

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working on hallucinating the genetic

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basis for the drive towards

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multicellularity under these

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circumstances but do you have any sort

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of predictions or hypotheses about what

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the phenotypic you know results of these

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genetic mutations are what would drive

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the con

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you know the collective nature can be

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something evolving cell lung cell cycle

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that one day what usually when cell goes

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through division there will from those

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two four or eight cell

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cops but then something else mutations

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might affect this process so that they

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couldn't separate after that great thank

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you

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but they don't look like it's in the

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other questions I have a question Green

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now is a bicones and all know this other

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organism say unique wants so is there

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any way that you can try to do any

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Studies on some single seller unicorns

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and try to see if you can do sort of

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explore the origin of multicellularity

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it's a fool major clades of eukaryotic