All Rat Species: Overview of the Muridae Family

The Grand Scope of Muridae

Classification Within Rodentia

The order Rodentia comprises the most diverse group of mammals, with the family Muridae representing the largest lineage. Within Muridae, rats are classified through a hierarchical system that distinguishes subfamilies, tribes, and genera based on morphological and genetic criteria.

The primary subfamily containing true rats is Murinae. This subfamily is divided into several tribes, each grouping genera that share evolutionary traits:

Rattini – includes the genus Rattus, which contains the majority of globally distributed rat species such as R. norvegicus and R. rattus.
Arvicolini – encompasses genera like Microtus and Myodes, which, while not traditional rats, are closely related within the murid clade.
Apodemini – comprises genera such as Apodemus, representing field mice that occupy a similar ecological niche.

Within the genus Rattus, species are further differentiated by geographic range, dentition patterns, and chromosomal arrangements. Key species include:

Rattus norvegicus – widespread in temperate regions, characterized by a robust skull and large body size.
Rattus rattus – adapted to tropical and subtropical habitats, distinguished by a slender build and long tail.
Rattus alexandrinus – confined to North African and Middle Eastern deserts, notable for its pale fur and reduced whisker length.
Rattus exulans – island specialist found throughout the Pacific, exhibiting a compact stature and high reproductive rate.

Molecular phylogenetics has refined these classifications, revealing cryptic lineages and prompting revisions of traditional morphological groupings. DNA sequencing of mitochondrial and nuclear markers provides resolution at the species level, supporting the delineation of subspecies and informing conservation priorities.

Overall, the taxonomic framework of rats within Muridae reflects a structured hierarchy that integrates anatomical features, genetic data, and biogeographic distribution, enabling precise identification and comparative research across the rodent order.

Distinguishing Murids from Other Rodent Families

Murids, the family that includes true rats and mice, can be separated from other rodent lineages by a combination of skeletal, dental, genetic, and ecological characteristics.

The skull of a murid displays a relatively short rostrum and a well‑developed infraorbital foramen that allows the passage of the masseter muscle. This feature contrasts with the elongated rostrum typical of squirrels (Sciuridae) and the reduced infraorbital opening found in many cricetids.

Dental morphology provides a second diagnostic set. Murids possess a single pair of continuously growing incisors with enamel limited to the labial surface, creating a self‑sharpening chisel edge. Their molars are brachydont, with three longitudinal rows of cusps (the so‑called “tri‑cusp” pattern). In contrast, dipodids exhibit multiserial cusps, while beavers (Castoridae) have flattened, gnawing incisors with enamel on both faces.

Chromosomal analyses reveal a conserved karyotype within Muridae: most species have a diploid number ranging from 38 to 44, with a distinctive telocentric chromosome structure. Comparative genomics shows a high proportion of repetitive DNA elements shared among murids, distinguishing them from the more variable genome organization of hystricognath rodents.

Ecologically, murids are primarily omnivorous and display high reproductive rates, traits reflected in their short gestation periods (≈ 20 days) and large litter sizes. Other families often specialize: beavers are strict herbivores, while jerboas (Dipodidae) are adapted to desert locomotion with elongated hind limbs.

Key distinguishing criteria:

Skull morphology: short rostrum, large infraorbital foramen.
Incisor structure: labial enamel only, chisel‑shaped.
Molar pattern: three longitudinal cusp rows, brachydont.
Karyotype: diploid number 38–44, telocentric chromosomes.
Reproductive strategy: rapid breeding, large litters.
Dietary breadth: omnivorous, flexible feeding habits.

These attributes collectively enable reliable identification of murid rodents and separate them from the diverse adaptations observed in other rodent families.

Global Distribution Patterns

Rat species belonging to the Muridae family occupy every continent except Antarctica, forming a complex mosaic of native, endemic, and introduced populations. Distribution reflects historical land connections, human-mediated transport, and ecological flexibility.

North America: Rattus norvegicus and Rattus rattus dominate urban and agricultural habitats; the prairie vole (Microtus ochrogaster) represents native murids in grassland ecosystems.
South America: Andes‑originated species such as Thomasomys spp. inhabit high‑elevation cloud forests, while Rattus spp. colonize lowland tropical regions and coastal cities.
Europe: Rattus norvegicus thrives in temperate zones, especially near waterways; Rattus rattus persists in Mediterranean ports and islands.
Africa: Diverse genera (Mastomys, Arvicanthis) occupy savannas and wetlands; Rattus spp. are common in urban centers across sub‑Saharan nations.
Asia: Highest species richness occurs in Southeast Asian rainforests, with genera such as Niviventer, Chiromyscus, and Rattus displaying narrow endemism; Rattus norvegicus spreads through agricultural and industrial zones.
Oceania: Endemic murids (Uromys, Melomys) inhabit Australian and New Guinean rainforests; introduced Rattus species dominate many Pacific islands, often displacing native fauna.

Distribution patterns reveal three dominant trends. First, temperate regions host primarily commensal Rattus species that exploit human settlements, whereas tropical zones sustain a broader array of native genera with specialized habitat requirements. Second, island ecosystems exhibit high endemism among murids but also suffer extensive invasive Rattus incursions, leading to rapid biodiversity loss. Third, anthropogenic expansion correlates with the global spread of Rattus norvegicus and Rattus rattus, establishing continuous corridors between formerly isolated populations.

These geographic arrangements influence ecosystem dynamics, predator‑prey relationships, and pathogen transmission. Understanding the spatial distribution of murid rodents provides a foundation for biodiversity conservation, biosecurity planning, and public‑health interventions worldwide.

Diversity and Phylogenetic Relationships

Subfamily Organization

The murid family is divided into several subfamilies that structure the diversity of rat species. Each subfamily groups genera that share morphological traits, ecological niches, and geographic ranges.

Murinae – the largest subfamily, encompassing the genus Rattus and related genera such as Bandicota and Berylmys. Members exhibit robust bodies, omnivorous diets, and a worldwide distribution, with many species adapted to commensal life alongside humans.
Deomyinae – primarily African and Asian taxa, including Acomys (spiny mice) and Lophuromys (brush‑furred mice). Species display distinctive pelage and specialized dentition, occupying arid and rocky habitats.
Gerbillinae – comprises gerbils, jirds, and sand rats (Gerbillus, Meriones). Adaptations include elongated hind limbs and efficient water conservation, supporting survival in desert and steppe environments.
Dendromurinae – contains climbing and forest-dwelling mice such as Dendromus and Malacomys. Members possess prehensile tails and arboreal locomotion, inhabiting tropical woodlands across sub‑Saharan Africa.

Subfamily classification reflects evolutionary lineages validated by molecular phylogenetics, providing a framework for comparative research on rat biology, disease ecology, and conservation status.

The Murinae Subfamily: The «True Rats and Mice»

The Murinae subfamily, commonly referred to as the “true rats and mice,” constitutes the most diverse lineage within the Muridae family. Members share a set of morphological traits: elongated snouts, continuously growing incisors, and a well‑developed auditory bulla. Their dental formula (1.0.0.3 / 1.0.0.3) distinguishes them from other rodent subfamilies and underpins the ability to gnaw a wide range of materials.

Geographically, Murinae occupy every continent except Antarctica. Species adapt to habitats ranging from tropical rainforests to arid deserts, demonstrating ecological flexibility that drives their evolutionary success. Distribution patterns reflect both ancient dispersal events and recent anthropogenic introductions.

Key genera within Murinae include:

Rattus – encompasses the brown rat (R. norvegicus) and black rat (R. rattus), both globally commensal.
Mus – contains the house mouse (M. musculus) and related species, notable for laboratory use.
Apodemus – forest-dwelling field mice prevalent across Eurasia.
Micromys – the harvest mouse, distinguished by its diminutive size and arboreal nesting.
Niviventer – Southeast Asian forest rats with robust bodies and long tails.

Reproductive strategies vary, but most Murinae exhibit rapid breeding cycles, short gestation periods (≈ 20–30 days), and large litter sizes. These traits facilitate swift population growth under favorable conditions, contributing to their status as prominent pest species in human settlements.

Phylogenetic analyses based on mitochondrial and nuclear DNA place Murinae as a monophyletic group, with divergence estimates suggesting a Miocene origin (~ 12–15 million years ago). Molecular data corroborate morphological classifications, confirming the subfamily’s internal cohesion while revealing cryptic speciation in several widespread taxa.

Ecologically, Murinae serve as seed dispersers, prey for a variety of predators, and vectors for zoonotic pathogens. Their role in disease transmission, particularly hantaviruses and leptospirosis, underscores the importance of monitoring population dynamics in both natural and urban environments.

Evolutionary Success and Rapid Speciation

The Muridae family contains more than 800 described rat species, representing the most species‑rich rodent lineage on the planet. Their evolutionary trajectory is marked by high reproductive output, flexible diet, and adaptive physiology that enable colonization of diverse habitats ranging from arid deserts to tropical forests.

Key traits that underpin this success include:

Rapid maturity and short gestation periods, allowing multiple generations per year.
Omnivorous dentition and digestive enzymes that process seeds, insects, carrion, and human waste.
Genetic plasticity that supports quick physiological adjustments to temperature, moisture, and pathogen pressures.
Social structures that promote cooperative breeding and efficient resource sharing.

Rapid speciation within the group results from a combination of geographic isolation and ecological opportunity. Island colonization, riverine barriers, and urban expansion create fragmented populations that experience reduced gene flow. In these isolated groups, mutations affecting coat color, body size, and metabolic rate become fixed, producing distinct species in relatively short evolutionary intervals.

Examples of recent diversification:

The Rattus rattus complex, which split into at least five cryptic species following global trade routes.
The Rattus norvegicus lineage, showing divergent forms in temperate versus subtropical zones.
Several Rattus species confined to the Indonesian archipelago, each adapted to specific altitude and forest type.

Overall, the combination of high reproductive capacity, dietary breadth, and genetic adaptability fuels both the widespread presence and the swift emergence of new rat species across the globe.

Notable Genera and Iconic Species

Rattus Species: Global Invaders

Rattus norvegicus: The Brown Rat

Rattus norvegicus, commonly known as the brown rat, is the most widely distributed member of the Muridae family. Originating in the plains of northern China and Mongolia, it has colonized every continent except Antarctica through human-mediated transport. The species thrives in close association with urban environments, where it exploits abundant food waste and shelter.

Key biological attributes include:

Average body length 20–25 cm, tail length comparable to body.
Weight range 250–500 g, with sexual dimorphism favoring larger males.
Omnivorous diet comprising grains, fruits, insects, and carrion.
High reproductive capacity: gestation 21–23 days, litter size 6–12, up to five litters per year.
Strong nocturnal activity patterns, with keen olfactory and tactile senses.

Ecologically, the brown rat functions as both predator and prey. It regulates populations of insects and small vertebrates while providing a food source for raptors, snakes, and carnivorous mammals. Its burrowing behavior alters soil structure, influencing nutrient cycling in both natural and built habitats.

From a taxonomic perspective, Rattus norvegicus belongs to the subfamily Murinae, sharing a common ancestor with other Rattus species such as R. rattus (black rat) and R. losea (Indonesian rat). Genetic analyses reveal low mitochondrial divergence among global populations, reflecting recent expansion facilitated by commerce and travel.

In public health, the brown rat is a vector for pathogens including Leptospira spp., hantaviruses, and Yersinia pestis. Control measures prioritize habitat modification, sanitation improvements, and targeted rodenticides, aiming to reduce population density and limit disease transmission.

Rattus rattus: The Black Rat

Rattus rattus, commonly known as the black rat, belongs to the family Muridae and the genus Rattus. It is the type species for the subgenus Rattus (Rattus) and is recorded under the synonym Rattus norvegicus in some older literature. Native to Southeast Asia, the species now occupies a global range, thriving in coastal ports, urban settlements, and tropical islands.

Adult black rats measure 16–24 cm in head‑body length, with a tail of comparable length. Fur is typically blackish‑brown, interspersed with lighter patches on the ventral side. The skull exhibits a narrow rostrum and well‑developed auditory bullae, distinguishing it from the brown rat (Rattus norvegicus).

Omnivorous diet: grains, fruits, insects, carrion, and human food waste.
Nocturnal activity: peak foraging occurs during twilight hours.
Reproductive capacity: gestation lasts 21–23 days; litters average 5–7 pups; females may produce up to 10 litters per year.
Social structure: colonies form around abundant resources, with hierarchical dominance observed among males.

The species serves as a reservoir for several zoonotic pathogens, including Yersinia pestis, Leptospira spp., and hantaviruses. Transmission to humans occurs through flea bites, contaminated food, or aerosolized urine. Urban infestations correlate with increased incidence of these diseases.

Control strategies prioritize integrated pest management: sanitation to reduce food sources, structural exclusion to block entry points, and targeted rodenticides applied according to regulatory guidelines. Conservation assessments list Rattus rattus as “Least Concern” due to its extensive distribution and adaptability, though island ecosystems may experience biodiversity loss from introduced populations.

Mus Species: Small but Widespread

The genus Mus comprises the true mice, a group of small rodents positioned within the Muridae family. Individuals typically measure 6–10 cm in head‑body length, with a tail of comparable length, and exhibit a body mass that rarely exceeds 30 g. Their distribution spans continents, covering temperate, tropical, and subtropical zones across Europe, Asia, Africa, and the Americas.

Key species within the genus include:

Mus musculus – the common house mouse, found worldwide in association with human settlements.
Mus spretus – the western Mediterranean mouse, inhabiting coastal scrub and woodland.
Mus minutoides – the African pygmy mouse, occupying savanna and semi‑arid environments.
Mus pahari – the Gairdner’s mouse, restricted to forested regions of South‑East Asia.
Mus cervicolor – the brown mouse, occurring in lowland forests of the Indian subcontinent.

Adaptability characterizes the group: diet ranges from seeds and insects to anthropogenic waste; reproductive cycles produce multiple litters per year, each containing 4–8 offspring; and nesting behavior tolerates both natural burrows and artificial structures. These traits underpin the genus’ capacity to colonize diverse habitats and maintain stable populations under fluctuating environmental conditions.

Most Mus species are classified as Least Concern by the IUCN, reflecting broad ranges and high reproductive output. Localized threats—habitat loss, pesticide exposure, and competition with invasive rodents—affect certain populations, prompting targeted monitoring in regions where agricultural expansion encroaches on native ecosystems.

Specialized and Endemic Genera

The Muridae family contains several genera that have evolved distinct adaptations to narrow ecological niches and are restricted to specific geographic regions. These specialized and endemic lineages illustrate the evolutionary plasticity of rat-like rodents.

Nesokia – occupies arid and semi‑arid habitats of the Middle East and South‑west Asia; morphological traits include elongated hind limbs and reduced fur density, facilitating burrowing in loose soils.
Bandicota – found primarily in South‑East Asia’s cultivated fields; robust skulls and strong incisors enable consumption of hard seeds and tubers.
Niviventer – restricted to forested highlands of the Himalayas and southern China; elongated tails and agile limbs support arboreal foraging among bamboo and shrub layers.
Chiropodomys – limited to tropical forests of Indo‑Malesia; prehensile tails and flattened paws allow movement along slender branches and leaf litter.
Sundamys – endemic to the Sunda Shelf islands; dense fur and enlarged auditory bullae reflect adaptation to humid, low‑lying swamp environments.
Papagomys – isolated to the island of Sulawesi; oversized body size and powerful forelimbs correlate with a diet of large fruits and nuts unavailable to mainland relatives.

Each genus demonstrates a combination of morphological, behavioral, and physiological features that align with the constraints of its native habitat. The convergence of such traits across unrelated lineages underscores the role of environmental pressure in shaping rat diversity within the Muridae family.

Ecological Roles and Adaptations

Habitat Versatility and Niche Occupation

Rat species within the Muridae family exhibit remarkable habitat versatility, thriving in environments that range from dense tropical forests to arid deserts, high‑altitude plateaus, urban infrastructure, agricultural fields, wetlands, and coastal dunes. This adaptability stems from physiological tolerance to temperature extremes, flexible water requirements, and the ability to exploit both natural and anthropogenic resources.

Key habitats occupied by murid rats include:

Tropical and temperate woodland understories, where dense leaf litter provides shelter and abundant invertebrate prey.
Grassland and steppe regions, offering seed caches and open foraging grounds.
Desert scrub and semi‑arid zones, where nocturnal activity reduces exposure to daytime heat.
Freshwater margins and marshes, supporting semi‑aquatic species that forage on aquatic insects and vegetation.
Urban districts, characterized by abundant refuse, structural cavities, and constant human presence.
Agricultural landscapes, where crop residues and stored grain serve as primary food sources.

Niche occupation reflects this ecological breadth. Murid rats function as opportunistic omnivores, consuming seeds, fruits, insects, carrion, and human waste. Their foraging behavior contributes to seed dispersal, soil aeration through burrowing, and the regulation of invertebrate populations. Some species specialize in climbing, exploiting arboreal niches and accessing canopy insects, while others excel at swimming, occupying riparian and floodplain habitats. Predatory pressure from birds of prey, snakes, and carnivorous mammals shapes their nocturnal and cryptic habits, reinforcing their role as prey within food webs.

Collectively, the habitat flexibility and niche diversity of these rodents underpin their global distribution and ecological impact, highlighting the adaptive success of the Muridae lineage.

Dietary Habits and Feeding Strategies

Rats within the Muridae family exhibit highly adaptable feeding habits that enable survival across a broad spectrum of habitats. Their diets are fundamentally omnivorous, incorporating plant material, animal protein, and anthropogenic sources. Primary components include:

Grains, seeds, and nuts, which provide carbohydrates and lipids.
Invertebrates such as insects, arachnids, and mollusks, supplying protein and essential micronutrients.
Small vertebrates, carrion, and eggs, contributing additional protein and fat.
Human-derived waste, processed foods, and refuse, offering high‑calorie options in urban and agricultural settings.

Feeding strategies vary among genera and reflect ecological niches. Species such as Rattus norvegicus and Rattus rattus demonstrate opportunistic foraging, exploiting temporal windows of food availability and displaying nocturnal activity patterns that reduce competition with diurnal mammals. Bandicota spp., adapted to rice paddies, practice selective grazing on young shoots and seed heads, while also scavenging fallen grain. Niviventer and Chiromyscus species, inhabiting forest floors, employ ground‑level foraging combined with occasional arboreal excursions to access fruits and insects.

Several behavioral adaptations enhance resource acquisition:

Gnawing of hard substrates to access concealed seeds or break open shells.
Food caching in concealed locations, allowing retrieval during periods of scarcity.
Use of tactile and olfactory cues to locate hidden prey or edible fungi.
Seasonal dietary shifts, with increased plant matter during wet seasons and greater reliance on animal protein when invertebrate populations rise.

Collectively, these dietary patterns and foraging tactics illustrate the ecological flexibility that characterizes the rat clade within Muridae, underpinning their success in both natural ecosystems and human‑altered environments.

Reproductive Output and Population Dynamics

Rats across the Muridae family exhibit high reproductive capacity, with most species reaching sexual maturity between 5 and 12 weeks. Females produce 5–12 litters per year, each containing 4–10 offspring, depending on species and environmental conditions. Gestation periods range from 21 days in the common brown rat (Rattus norvegicus) to 23 days in the black rat (Rattus rattus). Lactation lasts approximately 21 days, after which juveniles become independent and may breed within a few weeks.

Population growth hinges on three quantitative factors:

Litter size: Directly influences the number of new individuals per reproductive event.
Breeding frequency: Determines the interval between successive litters, with some species capable of continuous breeding in favorable climates.
Survival rate: Affected by predation, disease, and resource availability; higher juvenile mortality reduces effective reproductive output.

These parameters interact to produce rapid exponential increases when mortality is low. In temperate zones, seasonal fluctuations suppress breeding during winter, lowering overall growth rates. Tropical environments permit year‑round reproduction, resulting in higher steady‑state densities.

Density‑dependent mechanisms regulate populations. As numbers rise, competition for food and nesting sites intensifies, leading to reduced litter sizes and longer inter‑litter intervals. Social stress can elevate cortisol levels, decreasing fertility. Conversely, abundant resources in agricultural or urban habitats often eliminate such constraints, allowing populations to reach densities exceeding 500 individuals per hectare.

Long‑term dynamics are shaped by stochastic events such as disease outbreaks (e.g., hantavirus, plague) and habitat disturbances. These can cause abrupt declines, followed by recovery driven by the species’ intrinsic reproductive vigor. Management strategies that limit food availability, disrupt nesting sites, or introduce biological control agents exploit the predictable relationship between reproductive output and population resilience.

Murids and Humanity: Interactions and Conflicts

Economic Impact on Agriculture and Infrastructure

Rats belonging to the Muridae family affect agricultural production and built environments through direct consumption, contamination, and physical damage. Species such as the brown rat (Rattus norvegicus) and the black rat (Rattus rattus) are responsible for the majority of losses reported worldwide.

In crop fields, rodents feed on grains, fruits, and vegetables, reducing yields by 5–15 % in temperate regions and up to 30 % in tropical zones where storage facilities are less secure. Post‑harvest losses increase when rats gnaw packaging, spread pathogens, and contaminate produce with urine and feces. Economic estimates attribute annual global damage to food crops at $19 billion, with the United States accounting for roughly $2 billion of that total.

Infrastructure suffers from rat activity in several ways:

Burrowing undermines foundations, road embankments, and irrigation channels, leading to settlement and collapse.
Gnawing on electrical wiring triggers short circuits, fire hazards, and costly repairs in residential and commercial buildings.
Blockage of sewer and drainage systems occurs when rats accumulate debris, causing flooding and increased maintenance expenses.

Urban utilities experience recurring costs from rat‑related repairs. In major cities, municipal budgets allocate between $10 million and $30 million annually for rodent control, pipe replacement, and damage mitigation. The transport sector reports losses from compromised structural components in bridges and tunnels, with repair expenses ranging from $0.5 million to $5 million per incident depending on the scale of damage.

Preventive measures—integrated pest management, secure storage, and infrastructure design that limits access—reduce economic impact. Studies show that implementing comprehensive control programs can cut agricultural losses by up to 40 % and lower infrastructure repair costs by 25 % within five years.

Murids as Vectors for Zoonotic Disease

Muridae rodents comprise a taxonomically diverse group that thrives in urban, agricultural, and wild environments. Their proximity to human habitations and high reproductive rates generate abundant opportunities for pathogen exchange.

Rodent populations maintain and amplify infectious agents because individuals shed microorganisms in urine, feces, and saliva, while frequent contact with stored food and surfaces facilitates environmental contamination. These biological and ecological traits enable murids to act as reservoirs and amplifiers of zoonotic agents.

Leptospira interrogans – bacterial spirochete causing leptospirosis; transmission occurs through contact with contaminated water or soil.
Hantavirus – hantavirus pulmonary syndrome and hemorrhagic fever with renal syndrome; inhalation of aerosolized rodent excreta is the primary route.
Yersinia pestis – bacterium responsible for plague; fleas feeding on infected rodents transmit the pathogen to humans.
Salmonella enterica serovars – foodborne bacterial infections; contamination of foodstuffs occurs via rodent droppings.
Bartonella spp. – agents of cat‑scratch disease and trench fever; transmission through ectoparasites such as fleas and lice.
Seoul hantavirus – a specific hantavirus variant prevalent in dense rodent populations; spreads via aerosolized excreta.

Pathogen transfer follows three principal mechanisms: direct handling of rodents, indirect exposure to contaminated materials, and vector‑mediated transmission by ectoparasites that feed on murids. Each pathway contributes to the persistence of disease cycles in both rural and urban settings.

Surveillance data indicate that murid‑borne infections account for a measurable fraction of global zoonotic disease burden, with seasonal peaks aligning with rodent population surges. Outbreak investigations repeatedly identify rodent control failures as critical factors in disease emergence.

Effective mitigation relies on integrated pest management, including habitat modification, exclusion techniques, population reduction through baiting, and routine monitoring of rodent‑borne pathogens. Public health programs combine sanitation improvements, community education, and rapid diagnostic response to limit spillover events.

Ethical Considerations in Scientific Research

Research on the extensive range of rat species belonging to the Muridae family demands rigorous ethical oversight. Ethical frameworks protect animal welfare, ensure scientific validity, and maintain public trust.

Replace animal models whenever feasible.
Reduce the number of individuals required for statistically robust results.
Refine procedures to minimize pain, distress, and lasting harm.
Apply humane endpoints that halt experiments before irreversible suffering occurs.

Compliance with national legislation and institutional review boards, such as Animal Care and Use Committees, is mandatory. Documentation must include justification for species selection, justification of sample size, and detailed protocols for anesthesia, analgesia, and post‑procedure monitoring.

Species‑specific considerations influence housing, enrichment, and handling. Differences in social structure, auditory sensitivity, and metabolic rate require tailored environments and procedural adjustments. Failure to address these variables compromises data integrity and violates welfare standards.

Transparent reporting of ethical decisions, including justification for any deviations from the 3R principles, strengthens reproducibility and accountability across the scientific community.