Population modification

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This article is for the PC version of Stellaris only.

See also: Traits

UI genetic modification — The genetic modification menu.

Population modification refers to the process of altering a population's traits either to change its habitability, create subspecies suited for different tasks or improving it after unlocking more trait points through research. Both organic and robotic pops can be modified and each has its own set of traits. In addition, a small number of events can modify the population of a colony.

Species with the Clone Soldier or Clone Soldier Ascendant traits cannot be genetically modified.

Number of traits[]

Trait Points[]

The number of traits of a species is limited by the total cost of those traits against Trait Points. The starting number of trait points is 2 for biological species, 1 for machine species, and 0 for robots. The cost of a trait can be negative, zero or positive.

Trait points can be gained from various sources, as listed below.

Trait Picks[]

The number of traits of a species is limited by the Trait Picks limit. Initially, trait picks are limited to 5, except for robots which are limited to 4. Traits which cost 0 points do not count against the number of trait picks.

Trait picks are increased by Ascension Paths, the Mechanist origin, or hybrid species as listed below.

Species templates[]

Population modification is done via templates, which creates a subspecies. Templates can be applied to pops per subspecies (including original species), per planet, or per subspecies on a planet. Modified pops are considered part of the same species as the original even if the name and portraits have been changed. However, it is possible to set different rights for templates and its parent species.

Templates with zero current pops can be freely modified or deleted^[1]. However, templates with at least one pop cannot be changed directly and the template modification window presents only the option to create a new one.

After a template has been applied, a special project to modify the selected pops appears in the situation log. The project timeouts in 30 days if not started. Depending on the type of modification, how severe the modification (total amount of trait point differences), and how many pops were picked, this special project can be very expensive in science. The system is currently designed towards favoring bulk modification of many traits over specific via a high base cost.

The cost to modify a species can be reduced by −50% by the following traditions: Prefabricated Components, Modular Cybernetics, or Retroviral Manipulation. Additionally, the Plentiful Fossils archaeology site can add a permanent −25% modification cost.

Type	Genetic	Robotic
Unlocked by	Gene Tailoring technology	Machine Template System technology
Advanced modification	Glandular Acclimation technology: Modify climate preference Genetic Resequencing tradition: Remove positive or Overtuned traits, add negative or advanced traits Overtuned origin: Add or remove Overtuned traits Integrated Anatomy tradition: Add or remove cybernetic traits	N/A
Cost	3000 Society Research +5 per affected Pop +20 per affected Pop per absolute Trait Point difference between the old and new templates +60 per affected Pop if climate preference is changed	1500 Engineering Research +20 per affected Pop +40 per affected Pop per absolute Trait Point difference between the old and new templates
Trait points	Gene Tailoring technology: +1 Targeted Gene Expressions technology: +1 The Omnicodex relic: +1 Genetic tradition tree (+6 total): adoption: +2 Engineered Genesis tradition: +2 finisher: +2 Modular Cybernetics tradition adds robot trait points for organic species: Machine Template System technology: +2 Cross-Model Standardization technology: +1 Fungible Circuitry technology: +1 Hybrid species: +1 Under One Rule origin (+2 total): Genome Artists leader trait: +1 Genetic Perfection leader trait: +1	Machine Template System technology: +2 for biological empires and +1 for machine empires Cross-Model Standardization / Binary Motivators technology: +1 Fungible Circuitry / Nanite Assemblers technology: +1 Solid-State Actuators tradition: +2
Trait picks	Cybernetic tradition tree (+2 total): Integrated Anatomy tradition: +1 finisher: +1 Allelic Expression tradition: +1 Hybrid species: +1 Composer of Strands covenant (starting): −1 Composer of Strands covenant (upgraded): −2	Mechanist origin: +1 Synthetic tradition tree finisher for robots: +1 Efficient Power Systems tradition for machine species: +1

Uplifting[]

For pre-sapient species, the option to create templates is replaced with the option to uplift and bring them to sapience. It requires the Epigenetic Triggers technology and costs 3000 Society research. Upon completion, the empire instantly integrates the uplifted species and gains 50 Influence. In addition, the uplifted species gains +10% Happiness when living within the borders of the empire that uplifted it. The initial ethics of the uplifted species are determined by a series of initial events. 100% Afterwards, the species is fully susceptible to ethics divergence.

Ascension paths[]

Population modification can be used in conjunction with some of the ascension tradition trees.

The Genetic tradition tree focuses entirely on genetic modification. This tradition tree grants additional trait points and trait picks, unlocks new, more powerful traits and grants more freedom when it comes to adding and removing traits.
The Cybernetic tradition tree enhances all empire species with the Cybernetic trait and eventually unlocks cybernetic traits, which are similar to robotic traits, cheaper, but with an additional energy upkeep.
The Psionic tradition tree adds the Psionic trait, which cannot be acquired or removed through genetic modification. At first, only the founding species gains it, but other species living in the empire can gain it through assimilation.
The Synthetic tradition tree focuses on robomodding and eventually replaces genetic modification with robomodding entirely.

Hybrid species[]

Xenophile empires can pick the Xeno-Compatibility Ascension Perk to allow the reproduction of two organic species into a hybrid species. Hybrid species take a portrait from one of the parent species and a mix of traits from both parent species, with at least one trait being inherited from each. They also get +1 trait point and +1 trait pick. Two species are 3× more likely to create a hybrid species if they are part of the same species group.