New Mexico Computer Science For All Population Dynamics: Birth and Death Maureen Psaila-Dombrowski

Population Dynamics What is a Population?  A group living things: Ants, bees, turtles, people…  Agent Based Modeling: Agents ( Ants, Bees,… but also molecules, cars, …) Population Dynamics - Life Science  Characterizes a population  Size, age, type, reproduction, death  Changes in Population  Population Dynamics

Population Dynamics Birth Immigration Death Emigration Population Change

Positive Feedback – Simple Birth RabbitsBunnies More Rabbits Even MORE Bunnies

Negative Feedback RabbitsBunnies More Rabbits Even MORE Bunnies Food (Not Enough) Population (Too Many or Too Few) Health (Disease) Predators

Effect of Negative Feedback Limits the population CyclicalLogistic

Modeling Population Dynamics Birth Rate Factors - Health - Food - Population BIRTH RATE Death Rate Factors - Health - Food - Population - Predators DEATH RATE DETAILED MODEL Birth Rate Factors - Health - Food - Population BIRTH RATE SIMPLE MODEL

Modeling Birth Many ways to model Birth  Agent interactions (same breeds)  Agent/Environment interactions (location, food,…)  Changes in the agent (correct age, energy,...) Energy > Birth Threshold  Need a certain energy to have birth – threshold  Energy is lost by birth ask turtles […. If (energy > BirthThreshold) [ set energy (energy – amount lost) hatch #babies [forward 1] ]

Modeling Death Many ways to model Death  Agent interactions (predator/prey, infected agent…)  Agent/Environment interactions (toxins, locations…)  Changes in the agent (disease, age, energy...) Energy < Death Threshold  When energy is less than a threshold - die ask turtles […. If (energy < DeathThreshold) [ die ]

LOOK AT models ▫Simple epidemiology ▫Rabbits and grass ▫Wolves and sheep

Summary Population: a group of living things Population Dynamics: study of the characteristics and changes in a population  Positive Feedback: results in an increase  Negative Feedback: results in a decrease Some Types of Population Growth  Exponential  Logistic  Cyclical Modeling birth and death  Agent/Agent interactions  Agent/Environment interactions  Changes in the agent