12.1 Taxonomy and Phylogenetic Trees
2 min read•august 7, 2024
and phylogenetic trees help us understand life's diversity. They give us tools to classify organisms based on shared traits and evolutionary relationships. This system lets scientists organize and study the vast array of living things on Earth.
These concepts are crucial for grasping how life forms are connected. By using names, categories, and visual diagrams, we can see how relate to each other and trace their evolutionary history. It's like a tree for all living things!
Taxonomy and Classification
Taxonomy and binomial nomenclature
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- Taxonomy involves naming and classifying organisms into groups based on shared characteristics
- Linnaeus developed the modern system of classification in the 1700s which uses a two-part naming system called
- Binomial nomenclature assigns each species a two-part scientific name consisting of the and specific epithet (Homo sapiens)
- The first part of the name identifies the genus and the second part identifies the species within the genus
- Scientific names are always italicized with the genus capitalized and the species lowercase (Canis lupus)
Hierarchical classification system
- system groups organisms into increasingly broad categories
- Species is the most specific category and includes organisms that can interbreed and produce fertile offspring (Canis lupus)
- Genus is the next level up and includes closely related species (Canis)
- Family includes genera that share similar characteristics (Canidae includes wolves, dogs, and foxes)
- includes related families (Carnivora includes canines, felines, bears, and seals)
- includes related orders (Mammalia includes all mammals)
- contains animals within a with a similar body plan (Chordata includes all vertebrates)
- Kingdom is a high-level classification that includes animals, plants, fungi, protists, and bacteria
- is the broadest category and includes archaea, bacteria, and eukarya
Evolutionary Relationships
Phylogenetic trees and cladograms
- is a branching diagram that shows the evolutionary relationships among various biological species believed to have a
- is a diagram used in cladistics which shows relations among organisms
- Phylogenetic trees and cladograms are hypotheses about evolutionary relationships and history
- Both diagrams have a common ancestor at the base of the tree from which different lineages descend
- As lineages evolve independently, they diverge from their common ancestor and form new branches on the tree (birds and mammals diverged from a common reptilian ancestor)
Clades and taxa
- is a group of organisms that includes an ancestor and all of its descendants
- Clades are nested within each other and form a nested hierarchy (birds are a clade within the clade of reptiles)
- is a group of one or more populations of an organism or organisms seen by taxonomists to form a unit
- are given a taxonomic rank and can be placed at various levels in a phylogenetic tree (genus Panthera is a taxon that includes species like lions, tigers, and leopards)
Key Terms to Review (17)
Binomial nomenclature: Binomial nomenclature is a formal system of naming species by assigning each a two-part Latin name, consisting of the genus name and the species identifier. This system was developed by Carl Linnaeus and is essential for the classification and identification of organisms, allowing scientists to communicate clearly about different species without confusion.
Clade: A clade is a group of organisms that includes a common ancestor and all of its descendants, forming a branch on a phylogenetic tree. This concept is crucial in understanding evolutionary relationships, as it illustrates how species share a common lineage and the branching patterns of evolution over time.
Cladogram: A cladogram is a diagram that illustrates the evolutionary relationships among various biological species based on shared characteristics. It is a tool used in phylogenetics to represent hypotheses about the evolutionary history and lineage of organisms, emphasizing how different species branch off from common ancestors over time.
Class: In biological classification, a class is a rank in the hierarchy of taxonomy that groups together related orders sharing common characteristics. This level helps to organize living organisms into manageable categories, allowing scientists to study and understand biodiversity more effectively. Classes are vital in the context of higher-level taxonomic ranks and are essential for creating phylogenetic trees that depict evolutionary relationships.
Common ancestor: A common ancestor refers to an ancestral species from which two or more descendant species evolved. Understanding common ancestors is essential for reconstructing evolutionary relationships and helps in classifying organisms based on their shared characteristics, which is vital for understanding the diversity of life on Earth.
Domain: In biological classification, a domain is the highest taxonomic rank, above the kingdom level, used to group organisms based on fundamental similarities in their cellular organization and genetic makeup. The three recognized domains are Archaea, Bacteria, and Eukarya, reflecting major evolutionary differences among life forms.
Family: In biological classification, a family is a rank in the hierarchical system used to categorize organisms, grouping together related species that share common characteristics and evolutionary traits. This classification helps in understanding the relationships between different organisms and how they evolved over time, leading to a structured framework for organizing biodiversity.
Genus: A genus is a taxonomic rank used in the biological classification of living organisms, which groups together species that are closely related and share a common ancestor. This classification helps in organizing biological diversity and provides a framework for identifying and categorizing organisms based on their evolutionary relationships.
Hierarchical classification: Hierarchical classification is a systematic method of organizing and categorizing living organisms into ranked groups based on shared characteristics and evolutionary relationships. This approach helps scientists understand the diversity of life by placing species into a structured framework, ranging from broad categories like domains to more specific ones like species, which reveals the connections between different organisms.
Kingdom: A kingdom is a major taxonomic rank used in biological classification to group organisms that share fundamental characteristics. It is one of the highest levels of classification, positioned below domain and above phylum, and helps to organize the vast diversity of life into manageable categories, facilitating the study of evolutionary relationships and traits among living organisms.
Order: In biological classification, an order is a rank in the hierarchy used to categorize living organisms, typically grouping together families that share common characteristics. The concept of order helps to organize the diversity of life into a structured format, allowing scientists to communicate about different groups of organisms effectively.
Phylogenetic tree: A phylogenetic tree is a diagram that represents the evolutionary relationships among various biological species or entities based on similarities and differences in their physical or genetic characteristics. This tool helps visualize the lineage of organisms, illustrating how they diverged from common ancestors over time and provides insight into the historical connections between different species.
Phylum: A phylum is a major taxonomic rank in the biological classification system that groups together organisms sharing a common ancestor and significant structural features. This classification helps organize the vast diversity of life into more manageable categories, enabling scientists to understand evolutionary relationships and similarities among organisms. Each phylum consists of multiple classes, which further categorize organisms based on more specific traits.
Species: A species is a group of organisms that can interbreed and produce fertile offspring in natural conditions, sharing common characteristics and genetic similarities. Understanding species is crucial for classifying living organisms, studying biodiversity, and examining evolutionary relationships among various groups of life.
Taxa: Taxa refers to groups of one or more populations of organisms that a taxonomist designates at any rank in the biological classification system. This term is fundamental in understanding how living organisms are categorized, as it includes everything from species to higher-level categories like families and orders, reflecting evolutionary relationships and lineage.
Taxon: A taxon is a group of one or more organisms that share common characteristics and are classified together in the biological classification system. Taxa can vary in size and scope, ranging from a single species to a broader grouping that encompasses multiple species, genera, families, and higher ranks. The classification of organisms into taxa is essential for understanding the relationships among different species and their evolutionary history.
Taxonomy: Taxonomy is the scientific discipline concerned with classifying and naming organisms based on shared characteristics and evolutionary relationships. This classification system helps organize biological diversity into hierarchical categories, such as domain, kingdom, phylum, class, order, family, genus, and species, which aids in understanding the evolutionary history of life.