Biology and Biodiversity

• Biology 


  is the study of living things. All living things, including us, interact with other living things and non-living things on our planet.
• Biology


  The study of living things
• Biodiversity


  The great variety of life that exists in our biosphere (any area on Earth that living things inhabit)
• All living things, including us, interact with other living things and non-living things on our planet
• Biodiversity hotspot


  • A relatively small area with numerous endemic (native) species and a large number of endangered and threatened species
  • To qualify as a biodiversity hotspot, an area must contain at least 1500 species of vascular plants found nowhere else on Earth (known as 'endemic' species)
  • It must have lost at least 70% of its primary native vegetation
• Ecosystem


  The biotic and abiotic factors in an area, and their interactions
• Biodiversity


  The number, variety and variability of organisms present in a specified area or grouping
• Biological classification


  Classification is hierarchical and is based on molecular sequences, levels of similarity of physical features (morphology) and methods of reproduction
• Classification systems


  Provide methods of sorting, so that similar or related organisms are grouped together
• Classification helps us distinguish between native and invasive species that look similar
• Levels of classification


  • Domain
  • Kingdom
  • Phylum
  • Class
  • Order
  • Family
  • Genus
  • Species
• Binomial name


  All organisms have a binomial (scientific) name consisting of two parts: the first denotes the genus and the second is specific to the species
• Characteristics used to classify organisms


  • Methods of reproduction
  • Molecular sequences
  • Morphology
• Porifera (sponges)


  • Asymmetrical (no definite symmetry)
  • Body is multicellular, with few tissues and no organs
  • Cells and tissues surround a water-filled space but there is no true body cavity
  • All are sessile (as an adult, live attached to something)
  • Reproduce sexually or asexually
• Cnidaria (jellyfish, sea anemones and corals)


  • Radially symmetrical (body plan is circular with structures that radiate out)
  • Gastrovascular cavity with single opening that serves as both mouth and anus
  • Reproduce sexually or asexually
  • Simple, net-like nervous system
  • Live in aquatic environments, mostly marine
• Platyhelminthes (flatworms)


  • Bilaterally symmetrical (left and right halves of body are mirror images)
  • Gastrovascular cavity with single opening that serves as both mouth and anus
  • Body has three layers of tissues, with organs
  • Body without cavity
  • Body has blind gut (mouth but no anus)
  • A flattened body shape
• Mollusca (molluscs)


  • Bilaterally symmetrical
  • Body without cavity
  • Body has through gut (with mouth and anus)
  • Uses muscular foot for locomotion
  • Open circulatory system with heart and aorta
• Annelida (segmented worms)


  • Bilaterally symmetrical
  • Body has more than two cell layers, tissues and organs
  • Body cavity, nervous system and closed circulatory system
  • Body has through gut (with mouth and anus)
• Nematoda (roundworms)


  • Bilaterally symmetrical
  • Cylindrical morphology
  • Body covered by tough cuticle (of collagen and chitin)
  • Alimentary canal (digestive system) with mouth and anus, but no circulatory system
  • Found in most aquatic habitats, soil, moist tissues of plants, and body fluids and tissues of animals
• Arthropoda (arthropods)


  • Usually bilaterally symmetrical
  • Segmented
  • Hard exoskeleton (external skeleton) of protein and chitin
  • Most have through gut (with mouth and anus)
  • Jointed appendages (body parts attached to main trunk such as arms, legs, wings); have 3–400+ pairs of jointed legs
• Echinodermata (starfish)


  • Five-rayed symmetry, mostly radial, sometimes bilateral
  • Body has more than two cell layers, tissues and organs
  • Thin epidermis covering an endoskeleton; most species prickly due to skeletal bumps and spines
  • Most have short, through gut (with mouth and anus)
  • Body shape highly variable, but with no head
• Chordata (vertebrates)


  • Ninety per cent are vertebrates (have backbones), but Chordata does include two invertebrate groups
  • Have the following features during development (possibly as embryo): pharyngeal slits, dorsal nerve cord, notochord, post-anal tail
  • Closed circulatory system with blood transported in arteries, veins and capillaries
  • Bilaterally symmetrical
• Vertebrate classes


  • Mammals
  • Birds
  • Reptiles
  • Amphibians
  • Fish
• Plant kingdom


  Members are eukaryotic, mainly terrestrial and photosynthetic. They are divided into two main groups depending on whether or not they contain vascular tissue.
• Plant groups


  • Monocotyledons
  • Dicotyledons
• Dichotomous key


  A tool used to identify organisms, involving choosing between a series of two options until an organism is identified
• Organisms are classified into groups that reflect their evolutionary history, based on the fact that related organisms share characteristics
• Phylogenetic tree


  A visual representation of the evolutionary relationships between organisms
• Cladistics


  A technique used to construct phylogenetic trees, based on the assumption that the more closely related two organisms are, the more characteristics they will share
• Parts of a phylogenetic tree


  • Lines (branches showing related groups)
  • Tips (species/groups)
  • Nodes (ancestors and descendants)
  • Clades (groups and their descendants)
• Biodiversity


  The diversity of species, genetic variation within species, and the variety of ecosystems
• Importance of biodiversity


  • Not only has importance and relevance from scientific perspective
  • Vital factor for long-term survival of all life on Earth, including human societies
  • Essential for ecosystem processes
  • Delivers educational and cultural benefits
  • Contributes to production of food, purified water and air, fibre products, fuels, climate control and pharmaceuticals
  • Attracts tourism and contributes to the economy
• Levels of biodiversity


  • Species
  • Ecosystem
  • Genetic
• Species


  • Fundamental component of biodiversity, representing the variety of life forms on Earth
  • Each species has unique traits, behaviours, and ecological roles, contributing to the overall richness and complexity of life
  • Preserving biodiversity means protecting the multitude of species that inhabit our planet, as they collectively form the web of life upon which ecosystems depend
• Ecosystems


  • Rely on the variety of species within them to function properly
  • Biodiversity, which encompasses the diversity of species, genetic variation, and habitats, provides essential services to ecosystems such as pollination, nutrient cycling, and pest control
  • Each species plays a unique role in maintaining the balance and health of the ecosystem
  • When biodiversity decreases due to factors like habitat loss or species extinction, ecosystems become less resilient and may struggle to provide these vital services
  • Preserving biodiversity is crucial for the stability and sustainability of ecosystems
• Genetics


  • Genetic diversity within species contributes to overall biodiversity
  • Genetic diversity refers to the variety of genes within a population or species, which allows them to adapt and survive in changing environments
  • The more genetically diverse a population is, the better it can respond to threats like diseases or climate change
  • Higher biodiversity, which includes genetic diversity, leads to healthier ecosystems and more stable communities
  • Genetics is a crucial component of biodiversity, influencing the resilience and sustainability of ecosystems and the survival of species
• Biological species


  A group of organisms who are able to interbreed in nature and produce viable, fertile offspring
• Biological species


  • Individuals within a species are reproductively isolated from individuals not belonging to that species
  • Definition has an important link to the processes of evolution
  • When populations of individuals become unable to interbreed, the evolution of new species can occur
• Morphological species


  Defined based on observable physical characteristics, such as body shape, size, colour, and other anatomical features
• Morphological species classification may not always reflect true evolutionary relationships, as organisms with similar appearances may not necessarily be closely related genetically