Let the Genes Fall Where They May

Dimitri DaMommio; Jayson Paulose

Let the Genes Fall Where They May

Dimitri DaMommio and Jayson Paulose

let the genes fall where they may cover

Transcript

Overview

A hand drawn comic, inked in thin, precise lines and finished with vivid watercolor and gouache. Text is added digitally on top of the art.

Cover

Let the Genes Fall Where They May

Written by: Jayson Paulose

Drawn By: Chloe DaMommio

References:

Oskar Hallatschek and Daniel S Fisher, Acceleration of Evolutionary Spread by Long-Range Dispersal. Proceedings of the National Academy of Sciences Vol. 111, pp. E4911-E4919 (2014).

Jayson Paulose and Oskar Hallatschek, The Impact of Long-Range Dispersal on Gene Surfing. Proceedings of the National Academy of Sciences Vol. 117, pp. 7584-7593 (2020).

Page 1

The page is split vertically down the center into two columns, with one sequence of visuals on the left and one sequence of visuals on the right. The center line separating the left and right sequences is a DNA double helix.

Left panel 1: A close up on shiny purple grapes on the vine. “What is the purpose of life?”

Right panel 1: A many-sided purple polygon with lines sticking out from the vertices with small tulip-like flower shapes on the ends. “It’s a question that has stumped poets and philosophers through the ages.”

Left panel 2: A bunch of grapes on a vine.

“But as far as evolution is concerned, there’s a simple answer:”

Right panel 2: Several purple polygons floating on a yellow background, there is a red blob encroaching on the right side of the panel.

Left panel 3: A tanager, a red bird, perches on the grape vine and bites into a grape.

“Living beings exist to propagate genes through space and time…”

Right panel 3: A tired and cold looking woman with dark skin and light hair huffs out a cloud of purple smoke.

Left panel 4: The tanager soars.

Right panel 4: The woman continues huffing out smoke as a person with short hair in a stripped scarf approaches on the sidewalk.

“…through whatever means they can find.

Page 2

This page is also split into vertical columns separated by a double helix.

Left panel 1: “Unsurprisingly, evolution has dreamed up myriad ways to disperse genetic replicas far and wide:” The tanager perches on a telephone wire and poops. “Seeds gobbled up in delicious fruit; sneeze-inducing pathogens.”

Right panel 1: The person with the stripped scarf sits on a bus breathing out purple air that wafts toward a woman in a winter hat sitting next to him and a woman in a headscarf sitting further down the bus.

Left panel 2: “But where the tanager flies, or the sick host travels, is not up to the hitchhiker –” A small plant sprouts next to a fence, another plant sprouts in a field.

Right panel 2: The woman with the hat breathes purple air on the sidewalk. The woman with the headscarf breathes purple air as she gets off the bus and walks past a woman with a suitcase. “It is purely a matter of chance.”

Left panel 3: “And the broader the range of possible outcomes of every dispersal event the bigger the role of random chance in charting out the fate of the spreading species.” A small grape vine grows in front of the fence and a squirrel eats the grape. In the field another vide grows and a squirrel eats one of those grapes.

Right panel 4: The woman in the hat sits at a cafe exhaling purple air, it floats towards a bearded man sitting at a table. The woman with the suitcase naps at an airport gate exhaling purple air that drifts towards a child sitting at the gate.

Page 3

The top two panels are divided by a double helix into two vertical columns, then the helix splits and forms one large panel that takes up the rest of the page. The two panels divided by the double helix are each split into four quadrants.

Left quadrants 1-4: A possum eats grapes from a vine. A small bird with a red body and black wings flies, carrying a grape. A larger bird with a dusty read body soars with a grape in its mouth. A coyote holds a bunch of grapes in its mouth.

Right quadrants 1-4: A train travels through the night with purple breath clouding out of it. An audience watches a movie in a theater full of purple breath. An airplane flies, surrounded by purple breath. A stadium full of people is engulfed in purple breath.

“Any single dispersal event, ending up in one of many possible random outcomes, appears inconsequential.”

Large panel: “Yet, as scores of dispersal events occur across generation after generation they combine to determine the fate of the growing population. Can we find order in this mess of random events, to understand how dispersal impacts evolution? One way to make sense of a complex phenomenon is to strip it down to the basics: no grapes or viruses, no tanagers or travelers, just dots generating more dots which spread out into a featureless landscape via random jumps—many over short distances, but some long and a rare few very long.” In the background of the panel is a large bunch of purple grapes and a collection of blown-up purple viruses.

Page 4

Two series of three panels run across the top of the page, “Turn these basic rules into a computer program; let it run and watch the population of dots expand.” In the first panel of the first series is a green dot with a few purple dots around it. There are more purple dots in the second panel, and many in the third. In the second series there is a similar, but slightly different, progression of just a few purple dots expanding to a larger mass of purple dots around a green center.

“Run it again, and observe new rolls of the virtual die combining to form a different splatter of dots.”

“Run it again, and again, and again; overlay scores of generated patterns…” Nine small panels show nine different patterns of splattered dots, the splatters are uneven, and oblong in different ways. An arrow points to a single large panel where all the patterns are overlayed to form an even gradient where the dots are concentrated around the center and taper off around the edges.

“…And a smooth pattern emerges.”

“The average patterns have a simpler structure than any single outcome of the expansion process, and provide answers to questions about dispersal-driven growth such as: How quickly might we expect the population to expand?

A graph with population size on the y-axis and time on the x-axis has an exponential line on it and a large question mark next to it.

Arrows show the progression from one crocus blooming, to three, to an entire patch of crocuses.

Page 5

The top half of the page is one large open panel, then a double helix splits the bottom half into two panels.

Top half: “How would altering the odds of traveling near or far affect population growth?” There are two bats, a purple bat and a green bat, that are flying around two graphs. The first graph has probability on the y axis and dispersal distance on the x axis. There is a purple line and a green line. Both lines start high on the y axis and then have a sharp dip and curve down to the x axis, but the purple Iine starts higher and dips sooner and lower. Purple bat: “Cool wings, bro!” Green bat: “Wait ‘til you see what they do to my population growth curve!” The second graph has population size on the y axis and time on the x axis. Both the green and purple lines start at the origin and curve up exponentially but the green line curves up much more sharply.

“How might different mutations fare during a dispersal–driven expansion?” In a small panel there is a yellow culture and a purple culture both in the same area. An arrow points from the panel to a graph with “fraction” on the y axis (starting at 0% and going to 100%), and “time” on the x axis. There are two lines, a purple line labeled “Mutation 1” and a yellow line labeled “Mutation 2, which both start at 50%. Mutation 1 slowly decreases to close to 0% as Mutation 2 increases to close to 100%.

“By answering such questions, simple models of dispersal reveal how random jumps across time and space impact biological processes of all shades and stripes…”

Lower panel 1: “from ecological expansions…” A grape vine grows on a fence, dropping grapes into the street.

Lower panel 2: “to pandemics…”” A woman stands on a balcony coughing while looking out over a bustling city, viruses float around her head.

Page 6

“…to the evolution of dispersal itself, in its abundant forms.”

A full page spread of animals and other organisms. At the top of the page the double helix from the previous page ends. The organisms include a quail, a water bear, a dragonfly, various fungi, a squid, moths and flowers, a toad, a camel, a hare, coral and other sea creatures.