Understanding Biodiversity

• Biology studies life's structure, function, growth, origin, evolution, and distribution.

Types of Biodiversity

• Species diversity refers to the variety of different species living in a particular area.
• Genetic diversity represents the range of genetic material within a species or population.
• Ecosystem diversity is the variety of habitats, communities, and ecological processes in a given region.
• Biodiversity includes genetic, species, and ecosystem diversity.
• Genetic diversity describes variation in genes within a species.
• Species diversity describes the variety of species in an area.
• Ecosystem diversity describes the variety of ecosystems in a region.

Importance of Biodiversity to Ecosystems

• Biodiversity is essential for maintaining healthy ecosystems due to the roles and interdependence of organisms from each kingdom.
• Prokaryotes (bacteria and archaea) are vital for nutrient cycling and decomposition.
• Protists serve as a food source and play roles in various ecosystems.
• Fungi are crucial decomposers and form symbiotic relationships with plants.
• Plants are primary producers, providing energy and habitat for other organisms.
• Animals contribute to pollination, seed dispersal, and population control.
• Biodiversity provides essential ecosystem services like pollination, nutrient cycling, and water purification.
• Biodiversity contributes to human well-being through food, medicine, and other resources.
• Biodiversity loss is driven by habitat loss, climate change, pollution, overexploitation, and invasive species, with habitat loss being the most significant threat.
• Conservation protects habitats, reduces pollution, manages invasive species, and promotes sustainable resource use.
• Protecting biodiversity maintains the health and stability of our planet.
• Biodiversity encompasses evolutionary, ecological, and cultural processes that sustain life and has intrinsic value.

Prokaryotes vs. Eukaryotes

• Prokaryotic organisms lack a nucleus or other membrane-bound organelles; Eukaryotic organisms possess these.
• Prokaryotes include Bacteria and Archaea.
• Eukaryotes include Protists, Plants, Fungi, and Animals.
• The DNA of prokaryotic cell is in the cytoplasm's nucleoid.
• Eukaryotic cells are typically larger and more complex than prokaryotic cells.
• Prokaryotes reproduce asexually through binary fission, while eukaryotes can reproduce sexually or asexually.
• Prokaryotes have a cell wall made of peptidoglycan (in Bacteria) or other materials (in Archaea)
• Eukaryotes may or may not have a cell wall (e.g., plant cells have a cell wall made of cellulose, while animal cells lack a cell wall).
• Prokaryotes have smaller ribosomes than eukaryotes.
• Prokaryotic DNA is circular while eukaryotic DNA is linear and organized into chromosomes.
• Prokaryotes do not have membrane-bound organelles.
• Eukaryotes have a more complex overall structure.

Classification by Kingdom

• Prokaryotes: Bacteria, Archaea
• Eukaryotes: Protista, Fungi, Plantae, Animalia

Similarities and Differences Between Prokaryotic and Eukaryotic Cells

• Similarities: Both have DNA, ribosomes, cytoplasm, and a cell membrane.
• Differences: Eukaryotic cells are generally larger and more complex, containing membrane-bound organelles, while prokaryotic cells are smaller and simpler.

Endosymbiotic Theory

• This theory posits that mitochondria and chloroplasts in eukaryotic cells evolved from engulfed prokaryotic cells.
• Evidence includes the double membrane, similar size, and independent DNA and ribosomes of these organelles.

Classification of Living Things / Taxonomy

• Classification aims to organize and understand the diversity of life.
• Early systems were based on observable characteristics.
• Modern classification uses evolutionary relationships, genetics, and biochemistry.
• Dichotomous Key: A tool used to identify organisms based on a series of paired statements or questions.
• Taxonomy classifies and names organisms, organizing them based on evolutionary relationships.
• Phylogenetic classification reflects the evolutionary history of organisms; organisms are grouped based on shared ancestry.

Three Domains

• Bacteria: Includes the Kingdom Bacteria.
• Archaea: Includes the Kingdom Archaea.
• Eukarya: Includes the Kingdoms Protista, Fungi, Plantae, and Animalia.

Characteristics of Living Things

• Living things exhibit:
  • Organization
  • Metabolism
  • Growth
  • Reproduction
  • Response to stimuli
  • Evolution
  • Homeostasis

Linnaean System of Classification

• Based on hierarchical groups, from kingdom to species, using physical and structural similarities
• The Linnaean system is a hierarchical model.

Modern Classification

• Based on evolutionary relationships using genetic and biochemical data

Binomial Nomenclature

• A two-name naming system (genus and species) to identify related organisms
• Binomial nomenclature assigns each species a unique two-part name (Homo sapiens for humans).

Seven/Eight Taxa

• Domain, Kingdom, Phylum, Class, Order, Family, Genus, Species (remembered through mnemonics).
• The main taxonomic ranks, from broadest to most specific, are: Domain, Kingdom, Phylum, Class, Order, Family, Genus, and Species

Species Definition

• A group of organisms that can interbreed naturally and produce fertile offspring.
• Species are often defined as a group of organisms that can interbreed in nature and produce fertile offspring

Phylogeny and Cladistics

• Phylogeny: The evolutionary history of a species or group of species.
• Phylogenetic Tree: A visual representation of the evolutionary relationships between organisms.
• Phylogeny studies the evolutionary history and relationships among individuals or groups.
• It represents a hypothesis about the evolutionary relationships of organisms.
• Phylogenies are often depicted as branching diagrams or "trees".
• A phylogenetic tree is a diagrammatic representation of the evolutionary relationships among organisms.
• Cladistics classifies organisms based on evolutionary relationships.
• Cladistics constructs cladograms based on shared derived characters (synapomorphies); only shared derived characters are informative.
• Shared ancestral characters are not useful for determining evolutionary relationships.
• A cladogram is a branching diagram that depicts the evolutionary relationships among different groups.
• Each branch point represents the divergence of two or more groups from a common ancestor.
• Taxon refers to a group of one or more populations of an organism or organisms seen to form a unit.
• Sister taxa are groups of organisms that share an immediate common ancestor and are each other's closest relatives.
• A rooted tree has a single lineage (the root) to which all organisms relate.
• An unrooted tree illustrates the relatedness of the terminal taxa without specifying a common ancestor.
• Cladistics aims to reconstruct the evolutionary history of life on Earth, relying on parsimony.
• Parsimony states that the simplest explanation is the most likely to be correct; the most parsimonious tree requires the fewest evolutionary changes.

Clades

• Groups of organisms that include an ancestor and all of its descendants, sharing a more recent common ancestor.
• A clade is a group of organisms that includes an ancestor and all of its descendants

Significance of Phylogeny

• Helps understand how traits evolved and how species are related.

Building Tree Diagrams

• Based on derived characteristics or traits that appear in the most recent ancestor but not in earlier ones.