This is a simulation of a population crash with introducing females into the population with artificialy modified gene that makes these females give sterile male offspring and pass on the exacts same gene to the female offspring, thus over time ensuring the population effectively dwindles down and possbily completely dies out.

CRISPR technology is a powerful tool for editing genomes. It allows scientists to easily alter DNA sequences and modify genes. Even more so it can be used to pass those altered genes to the next generation, by using Gene Drive, with 100% certainty and to all offspring instead of to just 50%.

By doing so, with gene drive you can even crash or exterminate an entire population if you successfully propagate certain genes through that population. Scientists are already experimenting with mosquitoes and rats. For example they can eradicate malaria if they crash the population of mosquitoes that carry and spread malaria.

In this simulation, we can arbitrarily introduce number of females into the population with CRISPR edited genes which ensure that their male offspring are sterile and their female offspring are carrying those same CRISPR edited genes. By doing this it is likely that sterile males and CRISPR females will propagate and spread through the population and if they reach a critical number the population may even crash.

Assumptions:

• An individual's lifespan is represented in female reproductive cycles rather than in years. So if a female has 3 reproductive cycles per year and the maximum lifespan of a member of that population is 4 years then the maximum lifespan is represented as 12 cycles.
• Females can have multiple partners as is the case in many of the species to ensure reproduction. Only if all of her partners are sterile only then the female will not have offspring during that cycle.

Parameters you can adjust for this simulation:

• REPRODUCTIVE_CYCLES - number of reproductive cycles you want this simulation to run.
• INITIAL_POPULATION - the initial size of the population.
• MAX_POPULATION - population upper limit which external forces (aging, predators, diseases, accidents, etc.) keep in check.
• MAX_OFFSPRING - maximum number of children female can have per cycle.
• MAX_LIFESPAN - maximum lifespan of the species (number of female reproductive cycles).
• MAX_PARTNERS - maximum number of partners female can have per cycle.
• CRISPR_FEMALES_PERCENTAGE - % of the initial female population with CRISPR edited gene introduced into each reproductive cycle

So, at every cycle a female mates with a number of random partners. The female gives birth to a random number of male and female children. If a female parent carries the CRISPR edited gene and at least one of her partners was not sterile they will produce female children that carry the CRISPR gene and male children that are sterile. Otherwise if the female parent has no CRISPR gene they will produce healthy offspring.

This simulation, as it is, shows that in order to crash a population, in every cycle you need to introduce as little as 1.6% females of the initial female population with edited genes.

You must first assure though that the constants are adjusted as such that the population will not crush by itself due to death rate being higher than the birth rate.

The app's UI is made possible with Streamlit.

Make sure you have python3.12+. One way of getting it is to first add a custom PPA, namely ppa:deadsnakes/ppa, to your APT package manager sources list and then install it from there. Preface these commands with sudo if you need to.

apt update &&
apt upgrade &&
apt install software-properties-common &&
add-apt-repository ppa:deadsnakes/ppa &&
apt update &&
apt install python3.12 &&
apt install python3.12-venv

Create a virtual environment, activate it and install the dependencies.

python3.12 -m venv .venv &&
source .venv/bin/activate &&
pip install --upgrade pip &&
pip install -r requirements.txt

Launch the app on localhost on port 8501.

streamlit run app.py

https://genedrive.streamlit.app