Name: how dna defines microbial species
Uploaded: 2026-03-12T13:57:40.000Z
Duration: 1 min 22 s
Channel: JoVE

El concepto filogenético de especie define a una especie como el grupo más pequeño de organismos que comparten un ancestro común y tienen rasgos genéticos únicos.Los microbios se reproducen asexualmente, muestran una diversidad morfológica limitada y participan en la transferencia genética horizontal. Por tanto, no se pueden usar definiciones tradicionales de especie.El concepto filogenético de especie es adecuado para la clasificación microbiana, ya que compara secuencias génicas o genomas completos para mostrar relaciones evolutivas.Por ejemplo, si dos secuencias de ADN tienen aproximadamente un 98,7% de similitud en su secuencia del gen 16S rRNA, generalmente se consideran que pertenecen a la misma especie.La Identidad Media de Nucleótidos, o ANI, compara genomas completos y se considera un método más preciso.Un umbral de 95–96% de ANI, que indica una similitud genómica del 95-96%, es ampliamente aceptado para la identidad a nivel de especie.El concepto de especie filogenética suele combinarse con rasgos ecológicos y metabólicos para definir con mayor precisión una especie microbiana.

concepto de especie filogenética en microbiología

Phylogenetic Species Concept in Microbiology

El concepto filogenético de especie (PSC) es un marco utilizado para delimitar especies basándose en relaciones evolutivas, enfatizando la ascendencia compartida y rasgos genéticos diagnosticables. A diferencia de los conceptos morfológicos o biológicos de especies, la PSC es especialmente ventajosa para la taxonomía microbiana, donde los criterios tradicionales reproductivos o fenotípicos a menudo no se cumplen debido a la prevalencia de la reproducción asexual, la mínima diferenciación morfológica y la amplia transferencia horizontal de genes entre los procariotas.Una piedra angular del PSC en microbiología es el análisis comparativo de secuencias genéticas para inferir relaciones filogenéticas. El gen de ARN ribosomal 16S (ARNr) ha servido históricamente como marcador molecular principal debido a su presencia en bacterias y arqueas y a sus regiones conservadas intercaladas con segmentos variables. Una similitud de secuencia de genes 16S rRNA de aproximadamente el 98,7% se utiliza comúnmente como umbral para designar a dos organismos como pertenecientes a la misma especie. Sin embargo, este umbral no es definitivo, ya que puede no capturar completamente la diversidad genómica o la divergencia evolutiva.Para mejorar la resolución y la precisión, las comparaciones de genomas completos utilizando la Identidad Media de Nucleótidos (ANI) se han convertido en estándar. La ANI mide la identidad media de todos los pares de genes ortólogos compartidos entre dos genomas. Un umbral de 95–96% de ANI es ampliamente aceptado como indicativo de la relación a nivel de especie, ofreciendo una métrica a escala más fina que las comparaciones de un solo gen. Los análisis ANI son especialmente efectivos para identificar especies crípticas y resolver relaciones taxonómicas complejas en poblaciones bacterianas.Aunque las métricas genéticas proporcionan una clasificación fundamental, incorporar roles ecológicos y capacidades metabólicas es crucial para una definición holística de la especie. Rasgos como la especificidad del hábitat, las vías metabólicas y las interacciones ambientales complementan los datos genómicos, ayudando a identificar especies microbianas funcionalmente y ecológicamente distintas. Así, cuando se integra con información fenotípica y ecológica, la PSC permite una comprensión robusta y multidimensional de la diversidad microbiana.

Concepto de especie filogenética en microbiología

The phylogenetic species concept (PSC) is a framework used to delineate species based on evolutionary relationships, emphasizing shared ancestry and ...

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phylogenetic-species-concept-in-microbiology

Education

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JoVE Core

Microbiology

Microbiología

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Unidad

Microbial Evolution

Evolución microbiana

KEY TERMS AND CONCEPTS

TÉRMINOS Y CONCEPTOS CLAVE

how dna defines microbial species

The phylogenetic species concept helps define microbial species by looking at DNA and evolutionary relatedness. It focuses on shared ancestry and genetic traits that can be diagnosed in different organisms. This approach is especially useful in microbiology, where other species concepts often do not work well.

Traditional morphological and biological species concepts rely on body form or reproduction. Those methods can fall short for microbes because many reproduce asexually, show little visible difference, and exchange genes through horizontal gene transfer. As a result, scientists use sequence data to compare microbes and trace their phylogenetic relationships.

The 16S ribosomal RNA, or 16S rRNA, gene has long been a key marker in this work. It is found in bacteria and archaea and contains conserved regions mixed with variable segments. A 16S rRNA similarity of about 98.7% is often used to place two organisms in the same species, although this cutoff is not perfect because it may miss deeper genomic diversity or evolutionary divergence.

To improve species resolution, scientists also use whole-genome comparisons such as Average Nucleotide Identity, or ANI. ANI measures the average identity of orthologous gene pairs shared by two genomes. A value of 95 to 96% ANI is widely accepted as a sign of species-level relatedness, and it can help reveal cryptic species and resolve difficult bacterial relationships.

Genetic data are not the only part of species definition. Ecological roles and metabolic capabilities also matter in a fuller view of microbial diversity. Habitat specificity, metabolic pathways, and environmental interactions can help distinguish microbes that are genetically close but functionally different. When genomic, phenotypic, and ecological information are combined, the phylogenetic species concept gives a stronger picture of microbial species.

How DNA Defines Microbial Species

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How Microbes Gain New Traits

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Reading Microbial Family Trees

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phylogenetic species concept in microbiology

The phylogenetic species concept helps define microbial species by looking at DNA and evolutionary relatedness. It focuses on shared ancestry and genetic traits that can be diagnosed in different organisms. This approach is especially useful in microbiology, where other species concepts often do not work well. Traditional morphological and biological species concepts rely on body form or reproduction. Those methods can fall short for microbes because many reproduce asexually, show little...

key terms and concepts

Learn how microbial species are classified with DNA evidence, from 16S rRNA and ANI thresholds to ecology, metabolism, and shared ancestry.

How DNA Defines Microbial Species | JoVE K12

JoVE Core Microbiology provides an engaging introduction to the microbial world and its influence on health, industry, and the environment. This comprehensive collection covers key concepts such as microbial structure, metabolism, genetics, and ecology. It introduces essential laboratory techniques and microscopy methods through visually engaging animations. Corresponding scientist-in-action videos bridge classroom concepts with real-world research and applications.

microbiology

How DNA Defines Microbial Species

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