Classifying Life's Diversity

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Classifying Life's Diversity

• The morphological species concept classifies organisms based on their appearance and physical traits.
• The biological species concept classifies organisms based on their ability to interbreed and produce fertile offspring.
• The phylogenetic species concept classifies organisms based on shared ancestry but with distinct evolutionary paths.
• Binomial nomenclature involves a two-name system (Genus + species) for classifying organisms.
• Taxonomy is the science of classifying organisms.

How Species are Related

• Anatomical evidence, such as bone structure and physical traits, shows relatedness.
• Physiological evidence, including internal processes like metabolism indicates relatedness.
• DNA evidence, or genetic similarities, shows how species are related.
• Phylogenetic trees show evolutionary relationships between species.

Kingdoms and Domains

• The three domains of life are Bacteria, Archaea (both prokaryotic), and Eukarya (eukaryotic).
• The six kingdoms are Bacteria, Archaea, Protists, Plants, Fungi, and Animals.
• Prokaryotic cells are simple cells lacking a nucleus.
• Eukaryotic cells are complex cells containing a nucleus.
• Dichotomous keys identify organisms through a series of choices.

Biodiversity

• Biodiversity is the variety of life on earth, and includes: Species diversity (variety of species in an ecosystem), Genetic diversity (variety of genes within a species), and Ecosystem diversity (variety of ecosystems in a region).
• Genetic diversity allows species to adapt to environmental changes, increases disease resistance, and prevents extinction.
• A biodiversity crisis is the rapid loss of species due to human activities.

Viruses

• Viruses are not considered living because they cannot reproduce on their own, grow, develop, or produce energy.
• Viruses classification is based on shape and size of capsid and the diseases they cause.

Viral Reproduction:

• Lytic cycle (active phase) involves rapid replication and host cell destruction.
• Lysogenic cycle (dormant phase) involves viral DNA integrating into the host's genome.

Bacteria Characteristics

• Bacteria shapes include cocci (spherical), bacilli (rod-shaped), and spirilla (spiral).
• Bacteria arrangements include pairs (diplo-), clumps (staphylo-), and chains (strepto-).
• Types of Bacteria Habitats: Thermophiles (heat-loving), Acidophiles (acid-loving), and Halophiles (salt-loving).

Bacteria Reproduction

• Binary fission is asexual reproduction where a cell elongates, replicates DNA, and divides.
• Conjugation is sexual reproduction where bacteria exchange genetic material through a conjugation bridge, increasing genetic diversity and resistance.

Classifying Bacteria

• Gram staining differentiates bacteria: Gram-positive bacteria have a thick peptidoglycan layer and stain purple, while Gram-negative bacteria have a thin layer and stain pink.

Eukaryotic Evolution and Diversity

• Endosymbiotic theory explains the evolution of eukaryotic cells from simpler prokaryotic cells, where larger cells engulfed smaller cells.
• Mitochondria and chloroplasts provide the strongest evidence for endosymbiosis because they resemble ancient prokaryotic cells.
• Other membrane-bound organelles likely originated from inward folding of the cell membrane.

Protists

• Animal-like protists (heterotrophs) are classified by movement: pseudopods (amoeba), flagella (flagellates), and cilia (ciliates).
• Plant-like protists perform photosynthesis (e.g., diatoms, dinoflagellates, euglenoids).
• Fungus-like protists absorb nutrients from other organisms.

Protist Structures and Movement

• Paramecium has cilia for movement, a nucleus, and vacuoles.
• Amoeba moves using pseudopodia.
• Protists move using cilia, flagella, or pseudopodia.

Multicellular Diversity: Evolution of Terrestrial Plants

• Terrestrial plants evolved from algae.
• Multicellular algae (seaweeds) are classified into brown, red, and green algae.
• Green algae are most like plants, with similar chlorophyll, cellulose cell walls, and starch storage.
• Both algae and plants contain chlorophylls a and b, have cellulose-based cell walls, similar genetic information, & store food as starch.
• Adaptations for land survival include protection from drying out, water transport systems, and support structures.

Types of Plants

• Non-vascular plants (mosses, liverworts, hornworts) lack true roots, stems, and leaves, and are small in size.
• Vascular plants have tissues for transporting materials. Seedless vascular plants, seed producing vascular plants that are either angiosperms like monocot and dicot and then gymnosperms.

Fungi Kingdom

• Fungi are eukaryotic, heterotrophic, multicellular organisms composed of hyphae, with mycelium in the soil and have both sexual and asexual reproduction.
• Fungi can be parasitic (absorbing nutrients from living hosts), predatory (trapping prey), mutualistic (partnering with other organisms), or saprobial (feeding on dead organisms).
• Zygospore fungi (mold) reproduce via zygospores.
• Sac fungi (yeast) are single-celled and develop spores.
• Club fungi (mushrooms) are typical mushrooms.

Animal Kingdom

• Animals are classified as invertebrates (without a backbone) or vertebrates (with a backbone), with arthropods being the largest group.
• Animals are classified based on differences in structure, tissues, and organ systems.
• Body layers include ectoderm, mesoderm, and endoderm.
• Symmetry can be bilateral (equal halves) or radial (circular arrangement).
• Acoelomates lack a body cavity, while coelomates have a fluid-filled body cavity.
• Segmentation involves division of the body into sections.
• Reproduction is primarily sexual, with zygotes produced by external or internal fertilization, although some animals reproduce asexually.
• Animals are multicellular, eukaryotic heterotrophs lacking cell walls.

Phylogenetic Trees

• Phylogenetic trees are constructed to show evolutionary relationships based on characteristics.

Explore methods of classifying life's diversity, including morphological, biological, and phylogenetic species concepts. Learn about binomial nomenclature and taxonomy. Discover how anatomical, physiological, and DNA evidence reveal species relatedness, and study phylogenetic trees to visualize evolutionary relationships across the three domains of life.