Taxonomy and Classification

Taxonomy

• Taxonomy involves classifying, naming, and organizing organisms based on shared traits and evolutionary relationships.
• A standardized taxonomic system facilitates communication among scientists, organizes biological diversity, aids in identifying new species, supports conservation efforts, and enhances data organization.

Shared Derived Characteristics

• Zebra sharks, bullfrogs, kangaroos, and humans all possess vertebrae.
• Bullfrogs, kangaroos, and humans share two pairs of limbs.
• Kangaroos and humans both have mammary glands.
• Only humans possess a placenta among the listed organisms.
• A cladogram illustrates the evolutionary relationships: Zebra Shark diverges first, then Bullfrog, followed by Kangaroo, and finally Human.

Unique Characteristics of Taxonomic Groups

• Archaea have ether-linked cell membranes and thrive in extreme environments; an example is Halobacterium salinarum.
• Bacteria have cell walls with peptidoglycan and reproduce through binary fission; Escherichia coli is an example.
• Protists are eukaryotic organisms that are not plants, animals, or fungi, and they move using cilia, flagella, or pseudopodia; an example is Amoeba proteus.
• Fungi have cell walls of chitin and use absorptive heterotrophy to obtain nutrients; Saccharomyces cerevisiae (yeast) is an example.
• Plants have cellulose in their cell walls and perform photosynthesis using chlorophyll; Rosa indica (rose) is an example.
• Animals are multicellular, heterotrophic, and possess nervous and muscular systems; Canis lupus (wolf) is an example.

Evolution and Adaptation

• Evolution acts on populations, not individuals; genetic changes accumulate over generations.
• Limbs are a key trait separating amphibians from ray-finned fish.
• Birds share scales on their legs, amniotic eggs, hollow bones, similar skeletal structure, and nesting behavior with reptiles.
• Tree frogs possess ridges on their feet as an adaptation to cling to trees.
• Polar bears have thick fur and fat for insulation, white fur for camouflage, and large, webbed paws for swimming and walking on ice.

Evolution in Action

• Learning a skill is not evolution because it does not involve genetic changes.
• Human activities drive evolution, such as the development of pesticide-resistant insects due to overuse of pesticides.
• Mutations introduce genetic variation, which is essential for natural selection.
• Natural selection leads to antibiotic resistance via the survival and reproduction of bacteria with resistance mutations when non-resistant bacteria are killed by antibiotics, leading to a population of mostly resistant bacteria.

Speciation and Fossil Evidence

• Reproductive isolation can lead to speciation, as seen in Darwin's finches, where geographic isolation resulted in different beak shapes adapted to different food sources.
• The tailbone (coccyx) in humans is a vestigial structure, a remnant of an ancestral tail.
• The fossil record demonstrates gradual changes in species over time and reveals transitional forms, supporting evolution.

Evidence for Evolution

• Homologous structures, like the similar bone structures in wings, arms, and front legs of different species, point to common ancestry.
• Analogous structures, such as the wings of bats and birds, which evolved independently, demonstrate convergent evolution.
• Vestigial structures, like the non-functional leg bones in whale skeletons, indicate evolutionary history.
• Embryological development shows similarities among different species, such as gill slits and tails in fish, birds, rabbits, and mammal embryos.
• DNA comparisons, like the identical Cytochrome C DNA in humans and chimpanzees, provide molecular evidence of close relationships.

Explore the fundamentals of taxonomy, including classification, naming, and organization of organisms. Learn about shared derived characteristics and unique features of taxonomic groups. Understand cladograms and evolutionary relationships.