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Chapter 1: Understanding Biodiversity

UNIT 1.1: Biodiversity

• Biodiversity: The number and variety of species and ecosystems on Earth.

• Species: All organisms capable of breeding freely with each other under natural conditions.

• Hybridization: The crossbreeding of two different species.

• Morphology:

  • The physical appearance and characteristics of an organism.

  • Also refers to the science of studying these physical characteristics.

• Evolutionary Change: Changes that occur in an entire population over a long period.

• Genetic Diversity: Genetic variability among organisms, usually referring to individuals of the same species.

Ecological Classifications

• Heterotroph: Organism that must hunt, gather, and find its own food by consuming other living things or dead organisms to obtain nutrients and gain energy.

• Autotroph: Organism that creates its own energy (e.g. plants using sunlight and water to create glucose).

• Structural Diversity: The range of physical shapes and sizes within a habitat or ecosystem.

• Biosphere: The "zone of life" on Earth, where all living things exist across various ecosystems.

Unit 1.1: Importance of Biodiversity

Food Supply

• Species interactions: Complex relationships exist between species and their food sources.

  • Example: Bone worms feed exclusively on the bones of dead whales that sink to the ocean floor.

Reproduction

• Many species rely on others for successful reproduction.

  • Example: Trilliums produce seeds with fleshy tissues that interact with ants, which help gather and disperse the seeds.

Hygiene

• Certain species help maintain the health of others.

  • Example: Coral reefs provide "cleaning stations" where larger fish can have external parasites removed by small fish and shrimp.

Protection

• Various species depend on others for shelter and protection.

  • Example: Hermit crabs use shells from dead snails as protective homes.

Transportation

• Many species rely on other species for movement.

  • Example: Flower mites attach to the bills of hummingbirds, moving from flower to flower while feeding on nectar.

Digestion

• Species living within digestive tracts are crucial for food digestion.

  • Example: Termites consume wood but rely on a variety of bacteria and other microorganisms within their guts for digestion.

UNIT 1.2: The Nature of Classification

• Biological Classification: Systematic grouping of organisms into categories based on physical and evolutionary relationships.

• Taxonomy: The science of classifying all organisms, including both living and extinct species.

• Botanists: Scientists specializing in the study of plants, also known as plant biologists.

• Genus: A taxonomic level consisting of groups of similar species.

• Binomial Nomenclature: The formal naming system for species, assigning a genus name followed by a species name.

  • Example: Humans are scientifically named Homo sapiens.

  • Rules:

    1. Only the first word (genus) is capitalized.

    2. The name should be written in italics.

    3. Short form can be written using the first letter of the genus.

Pre-Linnaean vs. Post-Linnaean Classification

• Pre-Linnaean Classification: Divided organisms based on simple characteristics or habitats.

• Post-Linnaean Classification: Organized based on physical and behavioral characteristics.

Taxonomic Levels

• Linnaeus created various levels of classification known as taxa.

• Original 5 taxa expanded to 7 taxonomic ranks:

  1. Kingdom

  2. Phylum

  3. Class

  4. Order

  5. Family

  6. Genus

  7. Species

Human Taxonomic Ranks

• Kingdom: Animalia

• Phylum: Chordata

• Class: Mammalia

• Order: Primates

• Family: Hominidae

• Genus: Homo

• Species: Homo sapiens

Dichotomous Keys

• Tools for determining the identity of organisms through a series of choices.

• Example: Dichotomous key for birds with distinguishing features.

UNIT 1.3: Phylogeny and Modern Taxonomy

• Evolution: Theory describing changes in species over time and their shared ancestry.

• Phylogeny: Study of evolutionary relatedness between species.

• Phylogenetic Tree: Diagram tracking evolutionary history and relationships between species (taxa).

• Reading a Phylogenetic Tree:

  • Tips (Leaves): Present-day species.

  • Internal Nodes: Represent common ancestors.

  • Edges: Connect ancestors to their descendants and group species into clades.

Taxonomy Today

• Modern taxonomy utilizes DNA analysis to profile species and trace evolutionary history.

UNIT 1.4: Kingdoms and Domains

Types of Cells

• Prokaryotes: Single-celled organisms lacking membrane-bound organelles.

• Eukaryotes: Organisms (single-celled or multicellular) whose cells contain membrane-bound organelles.

Six Kingdoms

1. Animalia

2. Plantae

3. Fungi

4. Protista

5. Bacteria

6. Archaea

Domains of Life

• Proposed by Carl Woese, organisms can be classified into three domains:

  1. Eubacteria

  2. Archaea

  3. Eukarya

UNIT 2.1: The Prokaryotes (Eubacteria and Archaea)

Prokaryotes

• Single-celled organisms that lack membrane-bound organelles, typically very small (1-2 µm).

• Bacteria:

  • Infectious bacteria (pathogens) include cholera, strep throat, and tuberculosis.

  • Positive roles include atmospheric nitrogen fixation for plant use and production of vitamins K and B12 in the human intestines (mutualism).

Archaea

• Less is known about Archaea; they inhabit extreme environments (e.g., hot springs and acidic waters) and are not known to cause diseases.

Types of Eubacteria

• Proteobacteria: Diverse, some nitrogen-fixing, responsible for diseases like the bubonic plague.

• Green Bacteria: Use photosynthesis in saltwater or hot springs.

• Cyanobacteria: Photosynthetic and ancestors to eukaryotic chloroplasts.

Bacteria Characteristics

• DNA located in the nucleoid, ribosomes scattered throughout the cell, with 1-2 flagella for mobility and a pilus for attachment.

• Cell walls are made of peptidoglycan; some have a capsule aiding in survival.

Bacterial Metabolism

• Autotrophic Bacteria: Craft complex carbon molecules from inorganic materials.

• Heterotrophic Bacteria: Obtain nutrients from organic compounds.

  • Obligate Aerobes: Require oxygen for energy.

  • Facultative Anaerobes: Prefer oxygen but can survive without it.

  • Obligate Anaerobes: Cannot survive in oxygen environments.

Bacterial Reproduction

• Primarily produce asexually through binary fission.

• Increase genetic diversity through conjugation (exchange of genetic material) and transformation (uptake of DNA from the environment).

Bacteria Survival

• Many bacteria can produce endospores for survival in unfavorable conditions.

• Antibiotic Resistance: Bacteria evolve resistant strains when exposed to antibiotics.

The Domain Archaea

• Unique cell membranes and walls lacking peptidoglycan; classified into three groups:

  1. Euryarchaeota

  2. Crenarchaeota

  3. Korarchaeota

UNIT 2.2: Viruses, Viroids, and Prions

• Viruses: Small infectious particles containing genetic material (DNA or RNA) within a protein capsule (capsid) that can infect host cells, causing diseases (e.g., common cold, AIDS).

• Epidemic: A widespread outbreak of disease in a geographic area.

• Pandemic: An epidemic that spreads globally.

• Classification of Viruses: Considered non-living entities due to lack of cellular structure and function.