SYSTEMATICS: Taxonomy, Phylogeny, and Evolution PDF

SYSTEMATICS is the science that integrates taxonomy Uses a hierarchical system with ranks, where each (description, identification, nomenclature, and classification of rank includes all lower ranks organisms) with the goal of reconstructing the phylogeny...

SYSTEMATICS is the science that integrates taxonomy Uses a hierarchical system with ranks, where each (description, identification, nomenclature, and classification of rank includes all lower ranks organisms) with the goal of reconstructing the phylogeny (evolutionary history) of life. Systematics focuses on identifying Phylogeny the unique modifications and patterns that arise through evolution. Phylogeny is the study of the evolutionary history of a By studying these evolutionary changes, systematics provides a group of organisms—basically, figuring out how framework to understand life's diversity and evolutionary different species are related and how they evolved over relationships. time. This scientific discipline ties together the principles of taxonomy, To represent this, scientists use a diagram called a phylogenetics, and evolutionary biology, making it foundational to cladogram (or phylogenetic tree). our understanding of the natural world. The Lines (Lineages): The lines on the cladogram represent lineages, Some consider taxonomy and systematics as separate but which are groups of organisms that share a overlapping fields. common ancestor. Despite this, systematics is widely accepted as These lineages show the flow of evolution over encompassing the broader field. time, with each line representing a sequence of Systematics is rooted in evolutionary principles, with populations that passed down traits from the major premise that life has one phylogeny (shared ancestors to descendants. evolutionary lineage). Branching (Divergence): Broadly, evolution means change since the universe's When the line splits (branches), it means one origin (~14 billion years ago). group of organisms split into two or more Biological evolution: Defined by Darwin as “descent groups. This process is called lineage with modification,” involving changes in genetic divergence. material (DNA) over time. It shows how species became different from one another but still share a common ancestor. Evolution, at its broadest, refers to "change" over time. In Relative Time: biological terms, it was defined by Charles Darwin as The cladogram has an implied time scale, "descent with modification." meaning that the branching order shows which Descent groups diverged earlier and which diverged o Refers to the transfer of genetic material later. However, it's not exact like a calendar— from parent(s) to offspring over generations. it's relative. Modification For example, if two branches are close o Involves changes in the genetic makeup together, it means those species share a more (DNA) of populations or species over time. recent ancestor compared to species on a more Mechanisms of Descent distant branch. Representation: o Clonal reproduction: Simple processes like Cladogram (or phylogenetic tree): bacterial fission or vegetative propagation in A branching diagram that represents the evolutionary plants. pattern of descent. o Sexual reproduction: Complex processes Lines in a cladogram represent lineages, which trace involving meiosis and the fusion of gametes ancestral-descendant populations over time. (e.g., sperm and egg) from two parents. Branching points indicate lineage divergence from a To identify unique modifications resulting from common ancestor. evolutionary changes. Implied Time Scale: Here’s a highlighted summary of the key points about Cladograms include a relative time scale, indicating the taxonomy: sequence of evolutionary events. Taxonomy Importance of Cladograms: A major part of systematics that involves Description, Serve as an end goal for understanding phylogeny. Identification, Nomenclature, and Classification Can be used to create a classification system (DINC). (taxonomy’s goal). Taxonomy studies taxa (singular: taxon), which are Enable exploration of biological questions, such as: defined groups of organisms. Iogeographic or ecological history. Four Components of Taxonomy Processes of speciation. Adaptive character evolution. Description: Assigning features or attributes (characters) to a taxon. Character states are different forms of a character (e.g., ASPECT PHYLOGENY TAXONOMY "petal color" with states like "yellow" and "blue"). FOCUS Evolutionary Grouping organisms Identification: relationships into categories Associating an unknown taxon with a known one or PURPOS Explains how Provides a system for recognizing it as new. E organisms evolved naming and classifying Begins by noting and describing the unknown taxon’s characteristics. VISUAL Phylogenetic tree Hierarchical list Nomenclature: OUTPUT The formal naming of taxa according to standardized DATA Genetic, fossil, and Observable traits and systems. USED evolutionary data features Rules for naming plants, algae, and fungi are governed Taxonomy provides the names and categories for by the International Code of Botanical Nomenclature. organisms. Scientific names are typically in Latin. Phylogeny explains how those organisms are related through evolution. Classification: Organizing taxa into a specific order to express relationships. D. WHY STUDY SYSTEMATICS? 1.2. Greeks and Romans The rationale and motives for engaging in a study of Aristotle (384–322 BC): systematics are worth examining. Introduced basic classification of animals, dividing them into vertebrates (with blood) and invertebrates (without 1. For one, systematics is important in providing foundation blood). of information about the tremendous diversity of life. First to classify all living things in Western scientific Virtually all fields of biology are dependent on the taxonomy. correct taxonomic determination of a given study Further divided these groups, with classifications still in organism, which relies on formal description, use today (e.g., insects, crustaceans, mollusks). identification, naming, and classification. Theophrastus (370–285 BC): 2. Systematic research is the basis for acquiring, cataloging, Authored De Historia Plantarum (480 plant species), and retrieving information about life’s diversity. Essential laying the groundwork for plant classification. to this research is documentation, through collection and Student of Aristotle and Plato. storage of reference specimens, Many of his plant genera (e.g., Narcissus, Crocus, e.g., for plants in an accredited herbarium. Computerized Cornus) are still recognized today, as Carl Linnaeus data entry of this collection information is now vital to adopted many of his names. cataloging and retrieving the vast amount of information Dioscorides (40–90 AD): dealing with biodiversity. Wrote De Materia Medica (600 species), used medicinally for centuries. E. GOALS OF SYSTEMATICS Greek physician who studied medicinal plants across the 1. To provide an inventory of the world’s flora and fauna Roman and Greek world. (flowers & animals) 2. To provide a convenient method of identification and This work was influential in medicine until the 16th century. communication. Plinius (23–79 AD): 3. To provide a system of classification which depicts the evolution within the group. Roman naturalist, wrote Naturalis Historia, a 160- 4. To provide an integration of all available information. To volume work describing plants and assigning them Latin gather information from all the fields of study, analyzing names. this information using statistical procedures with the help He is often called the Father of Botanical Latin of computers, providing a synthesis of this information because Latin became the standard for botanical naming. and developing a classification based on overall Several of his plant names (e.g., Populus alba, Populus similarity nigra) are still in use today. 5. Elucidating evolutionary relationships between organisms. 1.3. The Herbalists 6. Constructing hierarchical classifications that reflect these The Herbalists relationships Book Printing Revolution: The invention of book 7. To detect evolution at work; to reconstruct the printing in Europe allowed for the mass production of evolutionary history of the plant kingdom books, including herbals by various herbalists. 8. To provide new concepts, reinterpret the old, and develop Notable Herbalists: new procedures for correct determination of taxonomic Brunfels, Bock, Fuchs, Mattioli, Turner, L'Obel, Gerard, affinities, in terms of phylogeny and phonetics. L'Ecluse. Many plants were later named in honor of these F. 7 Component Fields of Systematics herbalists (e.g., Brunfelsia, Mattiolia, Turnera, Lobelia, 1. Biodiversity – number and kinds of organisms Gerardia, Fuchsia). 2. Taxonomy - art & science of describing organisms Early Herbals: Initially, these herbals didn't feature 3. Classification - methods of grouping organisms – could much classification and were mostly copies of works by be artificial, natural, or evolutionary - based on Theophrastus and Dioscorides. homology Later Developments: Over time, herbals became more 4. Nomenclature -science of naming organisms original and included elaborate woodcut illustrations of 5. Biogeography - studies the distribution of organisms plants. aims to reveal where organisms live, at what abundance, These herbalists played a key role in preserving and expanding and why they are (or are not) found in a certain botanical knowledge, especially through the popularization of geographical area. printed herbals. 6. Evolutionary Biology - seeks to classify organisms using a combination of phylogenetic relationship and 1.4. Early Taxonomists overall similarity - considers taxa rather than single 16th Century Advancements: By the end of the 16th century, species, so that groups of species give rise to new groups. taxonomic works began to move beyond ancient Greek 7. Phylogenetics - study of evolutionary relatedness among classifications, thanks to optical lenses and the collection of groups of organisms (e.g. species, populations), which is specimens. The focus shifted from medicinal uses to taxonomic discovered through molecular sequencing data and classification. morphological data matrices Caesalpino (1519–1603): 1. Pre-Linnaean Taxonomy An early taxonomist from Italy, often called "the first 1.1. Earliest Taxonomy taxonomist". Taxonomy began with human language and the need to In 1583, wrote De Plantis, which classified 1500 species identify edible and poisonous plants. based on growth habit and fruit/seed form. Eastern Contributions: Recognized plant families like Brassicaceae and Shen Nung (3000 BC): Father of Chinese medicine; Asteraceae, which are still acknowledged today. wrote the Divine Husbandman's Materia Medica with Bauhin Brothers (1541–1631; 1560–1624): 365 medicinal substances. Published Pinax Theatri Botanici in 1623, listing 6000 Egyptian medicinal plants were documented in Ebers species. Papyrus (1500 BC), featuring local plant names like Introduced synonyms to resolve confusion caused by "celery of the hill country." multiple names for the same species.  Recognized genera and species as major taxonomic Introduced taxon names still in use today, such as levels. Mammalia. Linnaeus' work set the foundation for modern taxonomy, turning botany and zoology into systematic sciences. John Ray (1627–1705): English naturalist who emphasized species as the fundamental unit of taxonomy. Post-Linnaean Taxonomy - Natural System Emerging in France In 1682, published Methodus Plantarum Nova, listing Resistance to Linnaean System: 18,000 plant species based on a narrow species concept. In France, the Linnaean system was not widely accepted; Made significant contributions to entomology and sought French scientists favored developing a natural system for to create a complete classification system. classification. Joseph Pitton de Tournefort (1656–1708): French Scientists: French botanist who developed a classification system Georges-Louis Leclerc de Buffon (1707–1788): based on floral characters. Criticized Linnaeus' artificial classification system. In 1700, published Institutiones Rei Herbariae, listing Focused on describing nature rather than classifying it. 9000 species in 698 genera. Explored ideas of species development, infraspecific His system, which emphasized genera, influenced variety, and inherited acquired characters, paving the way Linnaeus, though Linnaeus expanded on it by including for evolutionary theories. sexual reproduction in plants. Michel Adanson (1727–1806): These early taxonomists laid the groundwork for modern Authored Familles des Plantes (1763). taxonomy through their systematic approaches to Advocated using a wide range of characters for classifying plants and establishing foundational concepts. classification rather than emphasizing specific traits. Criticized Linnaeus and supported Tournefort’s Linnaean Era classification. Starting Point of Modern Taxonomy: Antoine Laurent de Jussieu (1748–1836): Carl Linnaeus (1707–1778) is considered the father of modern Published Genera Plantarum (1789). taxonomy. Introduced a natural system based on many characters. Two of his key works set the foundation for botanical and Divided plants into acotyledons, monocotyledons, and zoological taxonomy: dicotyledons. Species Plantarum (1753) - focused on plants. Established the family rank between genus and class, Systema Naturae (1758, 10th edition) - included animals. foundational to modern classification. Linnaeus’ Contributions: Jean-Baptiste de Lamarck (1744–1829): introduced the binomial nomenclature system, where Proposed the theory of Lamarckism, which introduced each species is given a genus name and a trivial (species) the concept of inheritance of acquired traits. name. Anticipated the evolutionary theory later presented by The trivial name was meant for fieldwork and education, Charles Darwin and Alfred Russel Wallace in 1858. making it easier to identify species in practical settings. The French contribution to taxonomy emphasized a Before Linnaeus, species were often named with long natural, comprehensive approach, influencing the phrase names, which became cumbersome as more development of modern classification and evolutionary species were discovered during 17th and 18th-century theories. expeditions. Linnaeus' Species Count: Development of Botanical and Zoological Nomenclature By 1753, Linnaeus had identified and cataloged 8530 Botanical Nomenclature species of flowering plants. Augustin Pyramus de Candolle (1778–1841): Linnaeus’ work revolutionized taxonomy, simplifying Proposed rules for botanical taxonomy in Théory species identification and establishing a systematic élémentaire de la botanique (1813). approach still used today. Introduced the idea of priority of names based on publication date (starting with Linnaeus). Transforming Botany and Zoology into a Science Alphons de Candolle (1806–1873): Carl Linnaeus’ Early Career: Published Lois de nomenclature (1867), officially Published Systema Naturae in 1735, introducing the adopting naming rules. sexual system of plants, which classified plants based on Otto Kuntze (1843–1907): stamens and pistils (sexual parts of flowers). Published Revisio generum Plantarum, applying strict The idea of plant sexuality was controversial at the time nomenclature rules. but gained acceptance due to Linnaeus' practicality and Changed 1,000 generic names and 30,000 species names, careful observations. creating confusion. Influence Beyond Science: This led to the Vienna Congress (1905), which: Linnaeus' system became popular even outside the Set 1753 (Linnaeus' Species Plantarum) as the starting scientific community, marking a significant cultural point for botanical nomenclature. impact. International Code of Botanical Nomenclature (ICBN): Foundational Works and Contributions: American botanists introduced concepts like type Critica Botanica (1735): Introduced rules for generic specimens and allowed tautonyms (e.g., Grus grus). names. Unified European and American systems merged into Genera Plantarum (1735): Listed all known genera at one code in 1935. the time. Zoological Nomenclature Fundamenta Botanica (1736) & Philosophia Botanica Strickland Code (1842): (1751): Created by Hugh Edwin Strickland (1811–1853) with a Created rules for species descriptions and terminology. committee, including Charles Darwin. Provided instructions for building a herbarium cupboard. Adopted by British and American zoologists within three Terms and Taxon Names: years. Linnaeus coined key botanical terms like corolla, stamen, Challenges to Uniformity: filament, and anther.  The Strickland Code was modified in 1881 to include fossils. The PhyloCode and Its Emergence Multiple codes were proposed by different groups Introduction to PhyloCode (French, German, American), leading to taxonomic Origins: chaos. Initiated in the 1990s by Kevin de Queiroz and Jacques International Code of Zoological Nomenclature (ICZN): Gauthier, two American zoologists. The need for an international standard led to its Theoretical groundwork was laid, and a framework for acceptance at the Moscow Congress (1892). the PhyloCode emerged after a meeting at Harvard in Significance 1998. The development of botanical and zoological A draft PhyloCode was published online in 2000. nomenclature created a structured system for naming organisms. This ensured global consistency and Philosophical Shift in Taxonomy minimized confusion, forming the foundation for modern From Traditional Linnaean System: taxonomy. Traditionally, taxonomy names species and then classifies them into hierarchical ranks (genus, family, order, etc.). Evolution of Systematics from Phenetics to Phylogenies To Clade-Based Nomenclature: Introduction of Evolutionary Theory Species and clades are the only entities given names. Charles Darwin (1809–1882) and Alfred Russel Wallace (1823– Higher ranks (like genus or family) are excluded from 1913): nomenclature. Introduced the theory of evolution in 1858, but it did not Stability is built on clades rather than traditional ranks. immediately influence systematics. Pioneers of Evolutionary Trees: Goals of PhyloCode Ernst Haeckel (1834–1919): Coined the term phylogeny and Minimize Change: began constructing evolutionary trees. Strives to retain existing names as much as possible. August Wilhelm Eichler (1839–1887): Contributed to the Focuses on naming taxa based on their position within development of evolutionary classifications. phylogenetic trees. Replace Ranks with Clades: Dominance of Phenetics in the 20th Century Removes dependence on artificial hierarchical ranks. Phenetics (Extended Comparison of Similarities and Differences): Controversy and Reception Systematics focused on comparing morphology, Debate Among Taxonomists: anatomy, chromosomes, pollen, biochemistry, and The PhyloCode is controversial, sparking global debates. proteins. Critics question its practicality and departure from Plant and animal systems grew immensely, with centuries of Linnaean tradition. flowering plants reaching ~250,000 species. Adoption and Future: Notable Figures in Plant Systematics: Its success depends on the willingness of taxonomists to Eugen Warming (1841–1924) adopt it. John Hutchinson (1884–1972) Currently remains a draft and is not universally accepted. Armen Takhtajan (1910–2009) Arthur Cronquist (1919–1992) Significance Robert F. Thorne (1920–2015) The PhyloCode represents a revolutionary approach to biological Rolf Dahlgren (1932–1987) nomenclature, aligning taxonomy with evolutionary relationships. While promising in theory, its widespread adoption hinges on Each developed systems based on various characters, but these resolving debates about practicality and preserving historical often relied on subjective expertise, making them hard to test. continuity. Cladistics and the Rise of Phylogenetics G. Contributions of Systematics to Biology Willi Hennig (1913–1976): Systematics has made remarkable contributions across Founded cladistics in 1966, introducing two key principles: various domains of biology and has significantly Use only shared derived traits (synapomorphies) for classification. impacted human life in diverse ways: Taxa must include all descendants from a single ancestor (monophyly). 1. Foundation of Evolutionary Studies Cladistics provided a testable framework for hypotheses Before the rise of genetics, systematists led the study of in systematics. organic diversity and solved major evolutionary Challenges and Adoption: problems. Initially controversial, cladistics gained traction by the They continue to reveal new evolutionary questions and 1980s after a decade of debates. provide the basis for evolutionary research. Limitations included the difficulty of obtaining sufficient 2. Unveiling Patterned Diversity data for high-resolution phylogenies. Systematists uncover patterns in organic diversity and Technological Advances: explore their causes. Polymerase Chain Reaction (PCR): Enabled economical Example: Similarities between rodents and lagomorphs amplification of DNA sequences for phylogenetic (e.g., rabbits) are analyzed to determine whether they are studies. due to common ancestry or adaptive convergence. Computational Tools: Advanced software handled large datasets, making cladistics the standard in systematics. A sound taxonomic foundation is essential for studying evolutionary processes. Significance 3. Applications in Biology The shift from phenetics to cladistics marked a revolution Medicine, public health, agriculture, and conservation in systematics, integrating evolutionary theory and benefit directly and indirectly from systematics. enabling precise, testable classifications through the use 4. Epidemiology of DNA and computational methods.  A classic case is the discovery of sibling species in Photosynthetic Cyanobacteria: Released oxygen as a Anopheles maculipennis, resolving malaria transmission byproduct, transforming Earth’s atmosphere. mysteries in Europe. Impact: Enabled the evolution of aerobic (oxygen- This insight allowed targeted control measures, saving dependent) organisms. significant resources and lives. Marked the beginning of major evolutionary shifts. 5. Biological Pest Control 3. Rise of Eukaryotes (2 Billion Years Ago) Systematists identify parasites of insect pests, facilitating Origin of Complex Cells: Eukaryotes evolved through the use of natural predators instead of harmful chemicals. endosymbiosis (e.g., mitochondria and chloroplasts This approach mitigates the adverse effects of pesticides derived from engulfed bacteria). on human health and the environment. Fossil evidence: Grypania spiralis (an early eukaryotic 6. Wildlife Management organism). By identifying endangered species, systematists Systematics Contribution: Distinguished between the contribute to environmental protection and biodiversity domains Eukarya, Bacteria, and Archaea. conservation. Led to the classification of kingdoms like Protista, They help address issues arising from deforestation and Plantae, Fungi, and Animalia. indiscriminate killing of animals. 4. Multicellularity (1 Billion Years Ago) 7. Dating Geological Events Emergence of Multicellular Organisms: Simple Systematists assist in dating sedimentary rocks by multicellular algae appeared, later evolving into more identifying enclosed flora and fauna. complex plants and animals. This has been vital for industries such as oil exploration. Systematic Implications: Enabled more detailed 8. Tackling Environmental Problems phylogenetic analysis based on morphological and Indicator species identified by systematists help monitor genetic diversity. pollution and trace non-biodegradable pollutants in ecosystems. 5. The Cambrian Explosion (541 Million Years Ago) 9. Enhancing Soil Fertility Rapid Diversification of Life: Most major animal phyla Systematists identify species of animals and microbes appeared, including arthropods, mollusks, and chordates. that improve soil fertility, aiding in sustainable Fossil evidence: Burgess Shale (preserves diverse agricultural practices. Cambrian organisms). 10. Introducing Commercially Important Species Systematics Role: Established the foundation for modern Systematics enables the correct identification and successful animal classifications. introduction of species like: Allowed for detailed study of morphological traits and Apis mellifera (Italian honey bee) evolutionary lineages. Cyprinus carpio (common carp) 6. Colonization of Land (500–400 Million Years Ago) Such introductions have boosted economic productivity in countries like India. Plants and Fungi: Early land plants (e.g., mosses, ferns) 11. Contributions to Theoretical Biology evolved, followed by vascular plants. Systematics has contributed to population thinking and Fungi formed symbiotic relationships with plants. population genetics. Animals: Arthropods (e.g., insects) and vertebrates (e.g., It solved the problem of species multiplication and amphibians) adapted to terrestrial environments. emphasized the role of natural selection. Systematic Relevance: Biogeographical studies explore 12. Advancing Behavioral Studies how species adapted to new ecosystems. Taxonomists contributed to the development of ethology 7. Age of Dinosaurs (Mesozoic Era: 252–66 Million Years Ago) (study of behavior) and the phylogeny of behavior, emphasizing the evolutionary role of natural selection. Conclusion Rise and Extinction: Dinosaurs dominated terrestrial Systematics has provided a foundation for evolutionary biology, ecosystems, while mammals and birds began to diversify. environmental management, agriculture, and beyond. Its Extinction event (asteroid impact) marked the end of the contributions ensure a balanced, sustainable, and scientific era. approach to biological and ecological challenges. Systematics: Fossil evidence helps trace evolutionary connections between dinosaurs and modern birds. The History of Life on Earth for Systematics 8. Mammalian and Flowering Plant Evolution (Cenozoic Era: The history of life on Earth is integral to systematics, as 66 Million Years Ago–Present) it provides the evolutionary timeline that informs how Radiation of Mammals: Mammals diversified into species are classified, named, and understood in relation various ecological niches after the dinosaurs' extinction. to one another. Here’s a breakdown of key events and Angiosperms (Flowering Plants): Dominated terrestrial their significance to systematics: plant ecosystems, co-evolving with pollinators (insects, birds). 1. Origins of Life (3.8–4 Billion Years Ago) Systematics: Molecular phylogenetics explores co- First Life Forms: Simple, single-celled organisms evolution between plants and animals. (prokaryotes) emerged in Earth's primordial oceans. 9. Emergence of Humans (2–3 Million Years Ago) Fossil evidence: Stromatolites (layered structures formed Evolution of Homo sapiens: Humans evolved from by cyanobacteria). primate ancestors in Africa. Significance to Systematics: These early organisms form Key developments: tool use, language, and cultural the root of the phylogenetic tree of life. evolution. Prokaryotes were later divided into two domains: Systematic Implications: Humans are classified in the Bacteria and Archaea. order Primates and share a common ancestor with other 2. The Great Oxygenation Event (2.4–2.5 Billion Years Ago) apes.  Genetic studies reveal humans’ relationships with extinct relatives like Neanderthals. 10. Biodiversity and Modern Systematics Current Biodiversity: Millions of species exist, many yet to be discovered. Rapid loss of biodiversity due to human activities emphasizes the importance of systematics. Role of Modern Tools: Molecular techniques (e.g., DNA sequencing) revolutionize the understanding of evolutionary relationships. Databases like GBIF (Global Biodiversity Information Facility) catalog life on Earth. Significance of History in Systematics Reveals Evolutionary Pathways: Helps classify organisms based on shared ancestry. Informs Conservation Efforts: Identifies unique evolutionary lineages for protection. Advances Biological Research: Facilitates studies on evolution, adaptation, and speciation. The history of life provides the framework for systematics, linking the diversity of life to its evolutionary origins and ensuring we can preserve and understand it for future generations.