Biodiversity and Taxonomy

Biodiversity

Definition of Biodiversity

  • Biodiversity refers to the vast variety of living organisms present on Earth and the complex interactions among them.
  • International Day for Biodiversity celebrated on May 25th.

Importance of Biodiversity

  • Biodiversity enhances survival through adaptation to changing environmental conditions and evolution.
Types of Diversity
  • Species Diversity: The variety of species present in a particular ecosystem.
  • Genetic Diversity: The range of genetic variation within a species, which facilitates adaptability and survival.
  • Ecosystem Diversity: The variety of ecosystems found in a specific area, interconnected with genetic and species diversity.
Interconnections
  • Genetic diversity contributes to species variety, enabling different species to thrive in distinct ecosystems.

Examples of Diversity

Genetic Diversity

  • Various dog breeds exemplifying genetic diversity:
    • Chow Chow
    • Poodle
    • Schnauzer
    • Bulldog
    • Collie
    • German Shepherd

Species Diversity in Ecosystems

  • Example of species in a grassland food web:
    • Producers: Green plants
    • Primary Consumers: Herbivores (e.g., zebras, elephants, termites)
    • Secondary Consumers: Carnivores (e.g., cheetah, hyena)
    • Scavengers: Vultures
    • Decomposers: Organisms breaking down dead material

South Africa's Biodiversity

Overview of South Africa's Biodiversity

  • South Africa is recognized as the 3rd largest country in terms of biodiversity.
  • It is categorized as a megadiverse country with high species richness and endemism.
  • Notable facts:
    • Top Rankings:
    • Among the top 10 globally for plant species richness.
    • 2nd highest in global plant endemism.
    • 3rd highest in marine species endemism.
    • Biodiversity Hotspots: Three out of 35 global biodiversity hotspots are located in South Africa.
    • Area Coverage:
    • Total landmass: 1.21 million km²
    • Marine area: 1.1 million km²
Unique Regions
  • Succulent Karoo: The world’s only arid hotspot with the highest diversity of succulents.
  • Cape Floristic Region: A World Heritage Site containing about 20% of Africa's flora within <0.5% of its land area.
  • Maputaland-Pondoland-Albany: An area with over 8,100 plant species, including 1,900 endemics, and a meeting point for six different biomes.

Species Statistics

  • Breakdown of species in South Africa and their percentage of the world total:
    • 23,420 plants (9%)
    • 6,859 marine vertebrates (8%)
    • 2,200 marine fish (15%)
    • 694 birds (7%)
    • 258 mammals (6%)
    • 363 reptiles (5%)
    • 111 amphibians (2%)
    • 96 freshwater fish (exact percentage not provided)
    • 70,000 insects (7%)

Key Species Categories

  • Key Species: Organisms that significantly influence the health and equilibrium of their ecosystem.
  • Indigenous Species: Species native to South Africa that may also be found in other areas.
  • Endemic Species: Species unique to a specific area and not found elsewhere.
  • Exotic/Alien Species: Non-native species introduced to an area (e.g., Hyacinth plants).

Biodiversity and Ecosystem Stability

Importance of Biodiversity for Ecosystem Resilience

  • Higher biodiversity enhances the ecosystem’s ability to withstand environmental changes.
  • Definitions related to ecosystem stability:
    • Resilience: The speed at which an ecosystem returns to its pre-disturbance condition.
    • Resistance: The ability to remain unchanged when subjected to disturbances.
Disturbance Models
  • Ecosystems are better equipped to handle disturbances; the more biodiverse, the higher the stability due to reduced species dependency for resources.

Human Impact on Biodiversity

Factors Reducing Biodiversity
  1. Pollution
  2. Habitat Destruction: Often for agricultural practices.
  3. Overexploitation: Includes practices like overfishing and captivity in zoos/circuses.
  4. Invasive Species: Non-native species that can outcompete local species.
  5. Climate Change: Leads to severe impacts on ecosystems.
Future Human Implications
  • Severe weather patterns.
  • Water scarcity issues.
  • Pollination failures affecting food production.
  • Risks to food security.
  • Loss of habitat and shelter options.
  • Potential decline in medication availability.

Strategies for Maintaining Biodiversity

  • Waste Reduction: Increase recycling efforts.
  • Breeding Programs: Focused on endangered species.
  • Habitat Protection: Safeguarding rare species and regenerating damaged habitats.
  • Afforestation Efforts: Replanting trees in agricultural areas to support wildlife.
  • Protected Areas: Establishing regions to prevent deforestation and conserve ecosystems.
  • Carbon Emission Reduction: Transition to renewable energy sources.

Taxonomy of Living Things

Biological Classification Hierarchy

  • Domains:
    • Eukarya
    • Prokaryota
  • Kingdom: Animalia
  • Phylum: Chordata
  • Class: Mammalia
  • Order: Primates
  • Family: Hominidae
  • Genus: Homo
  • Species: sapiens (Example: humans - Homo sapiens)

Classification Systems

  • The purpose is to organize and study life through a taxonomy based on similarities and shared characteristics.
  • Taxonomic groups are referred to as taxa.

Taxonomy Overview

  • Definition: The science of categorizing organisms and assigning a universally accepted name to each.
  • Historical Note: Aristotelian classification classified organisms simply as plants or animals over 2000 years ago.
  • Carl Linnaeus's contributions include a hierarchical system, organizing life into taxonomic ranks through 7 taxa.

Characteristics of Organisms by Group

Phylogenetic Taxonomic Overview

Polar Bear Example
  • Classification:
    • Kingdom: Animalia
    • Phylum: Chordata
    • Class: Mammalia
    • Order: Carnivora
    • Family: Ursidae
    • Genus: Ursus
    • Species: maritimus
Taxonomic Features
  • Kingdom: Animals characterized instead of plants.
  • Phylum: Chordata—organisms possessing a backbone.
  • Class: Mammalia—characteristics include lactation and specialized dentition.
  • Order: Primates—including species with enhanced sensory perception and opposable thumbs.
  • Family: Hominidae—culminates in great apes, with humans being unique among living species.

Binomial Nomenclature

  • Each species is assigned a two-part scientific name following rules:
    • Written in italics when typed.
    • Underlined when handwritten.
5 Kingdom Classification System
  • Developed as scientific knowledge advanced, proposed by Robert Whitaker and includes:
    • Body structure (unicellular/multicellular)
    • Cell structure (prokaryotic/eukaryotic)
    • Cell composition (cellulose/chitin/no cell wall)
    • Motility (mobile/immobile)
    • Nutrition mode (autotrophic/heterotrophic)
    • Reproductive methods (binary fission/asexual/sexual)

Prokaryote vs. Eukaryote Definitions

  • Prokaryote: Organisms with cells lacking true nuclei; DNA not membrane-bound, lack of organelles due to cell membrane absence.
  • Eukaryote: Organisms with true nuclei in cells; DNA is membrane-bound; cells contain true organelles.

Modes of Reproduction

  • Asexual Reproduction: Involves one parent, resulting in genetically identical offspring.
  • Sexual Reproduction: Involves two parents with gametes contributing to genetic diversity in offspring.

Organism Groups and Their Features

Monera

  • Characteristics:
    • Unicellular
    • Prokaryotic
    • Cell walls present
    • Some autotrophic, most heterotrophic
    • Reproduce asexually via binary fission
    • Example: Bacteria

Protista

  • Characteristics:
    • Some unicellular, others multicellular
    • Eukaryotic
    • Motile
    • Algae are primarily autotrophic; others are heterotrophic.
    • Reproductive methods include asexual binary fission and sexual reproduction.
    • Groups include:
    • Protozoa (animal-like, unicellular, heterotrophic)
    • Algae (plant-like, autotrophic)
    • Slime and water moulds (fungus-like)

Fungi

  • Characteristics:
    • Yeasts (unicellular), mushrooms/moulds (multicellular)
    • Eukaryotic
    • Cell walls made of cellulose and chitin
    • Composed of hyphae, which are branched filaments
    • Heterotrophic, with some being parasitic and others mutualistic.
    • Divided into three groups: Yeasts, Mushrooms, Moulds.
Structural Components
  • Macrostructure: Includes fruiting bodies and sporocarps.
  • Microstructure: Focuses on mycelium and hyphae.

Plantae

  • Characteristics:
    • Multicellular
    • Eukaryotic
    • Cell walls consist of cellulose
    • Autotrophic
    • Asexual reproduction by spores; sexual reproduction involves male and female gametes.

Animalia

  • Characteristics:
    • Multicellular
    • Eukaryotic
    • No cell walls
    • Heterotrophic
    • Can reproduce asexually, but predominantly sexually using male and female gametes.

Carl Woese and Classification

Contributions to Taxonomy

  • In the 1970s, Carl Woese discovered unique microorganisms in extreme environments (e.g., hot springs) distinctly different from typical bacteria.
  • Proposed a new classification scheme by categorizing kingdoms within overarching domains, creating a more organized structure of biological classification. Each domain encompasses several kingdoms.