199103 2-14

• Small genetic changes can alter the way that genes are expressed and regulated during development, these changes can have both positive and negative effects on an organism's survival and reproductive success - Changes in timing of developmental processes can affect the final size, shape and function of organs, as well as the overall phenotype of the organism - Small changes to the genome can alter gene expression and regulatory networks, leading to changes in development and phenotype
• Evolution is not goal oriented - there is no intrinsic drive towards a particular phenotype, many branches are extinct
• Aristotle viewed species as fixed and unchanging, and put them on a scale called "Scala Naturae", and believed that organisms were created by god and therefore perfectly crafted to be fit for their purpose
• Analogous Structures


  Structures that are independently evolved
• Sources of Genetic Variation


  • The formation of new alleles via mutations
  • Altering gene number or position
  • Rapid reproduction
  • Sexual reproduction
• Vestigial Traits


  Remnants of features that served important functions in an ancestral species
• 'Decent with Modification'


  That all organisms are related to one another having descended from a common ancestor that lived in the remote past and populations change over time and diverge from one another
• Taxon


  A group of organisms in a category
• Binomial Nomenclature


  Capitol letter Italics
• Divergent Evolution


  Interbreeding species diverged into 2 or more evolutionary groups
• Morphological Stasis


  When there is minimal biological change, ie morphologically unchanging
• Punctuated Equilibrium


  A pattern of evolution in which long stable periods are interrupted by brief periods of rapid change
• Synapomorphy


  A characteristic in ancestral species shared by it's evolutionary descendants
• Molecular Clock Theory


  Genetic mutations, although random, occur at a relatively constant rate
• Taxonomic Hierarchy


  • Domain
  • Kingdom
  • Phylum
  • Class
  • Order
  • Family
  • Genus
  • Species
• Types of Mutations that Maintain Variation


  • Neutral mutation: no advantage or disadvantage in reproductive frequency
  • Adaptive mutation: mutation will increase the frequency of reproduction with in a population
  • Maladaptive mutation - will reduce the increase of reproduction with in a population
• Phylogeny vs Systematics


  A phylogeny is the evolutionary history of a species or a group of related species - A systematic is a scientific discipline, that classifies organisms by their evolutionary relationships
• Abiotic vs Biotic Factors


  • Biotic factors are living things within an ecosystem; such as plants, animals, and bacteria
  • Abiotic are non-living components; such as water, soil and atmosphere. Abiotic and biotic factors determine whether or not an organism will survive, these are called selection pressures - Disease - Food - Habitat availability - Predation - Access to light - Water - Oxygen
• Genetic diversity is important because it reduces the likelihood of harmful recessive alleles being expressed, provides populations the ability to adapt to abiotic and biotic factors, helps avoid predators, competition with other predators, and increases chance of resisting new diseases and changes with in an environment
• The term 'species' is arbitrarily given given for the sake of convenience to a set of individuals closely resembling each other, and does not differ from the term variety, which is given to describe, less distinct and more fluctuating forms
• will a singular adaptation always be helpful to an individual ?No, a singular adaptation will not always be helpful to an organism, as advantageous traits may be disadvantageous in other environments, eg white mouse, but suddenly soot filled town, white mouse will no longer have selection advantage
• Defining Features of Planarians (flatworms) Clade Lophotrochozoa Phylum Platyhelminthes

  • Many flat worms are parasites, such as flukes and tape worms
  • Flatworms are triploblastic, but lack a body cavity
  • Flatworms have a gastrovascular cavity with one opening
  • Possess a central nervous system
• Life has existed on earth for approximately 3.5 - 4 Billion years
• Synapsid vs Diaspid

  Major divisions in the amniotes is based on skull structure

  - Holes for muscle attachment

  - Diaspid - Two holes in their skull

  - reptiles and their ancestors and descendants

  - Diverged into lepidosaurs and archosaurs

  - Synapsid - One hole lower in the skull

  - Mammals and others more closely related to mammals than reptiles and avians
• Gnathostome

  Vertebrates that have a jaw
• Tripoblastic

  3 germ layers:

  Ectoderm - Epidermis, Nervous system, Lens, Hair, Mammary glands - Mesoderm - Skeleton, Skeletal muscle, Dermis, Connective tissue, Urigenital system, Heart, Blood, Kidneys, Spleen

  Endoderm - Epithelial lining of the digestive tract, Intestines, Colon, Pancreas, Stomach, Liver, Lungs
• Vertebrate

  A Chordate with a back bone
• Amphibian Respiration

  Most amphibians have moist skin that complements the lungs in gas exchange

  - Respiration involves 3 surfaces: Skin, Mouth, Lungs

  - Oxygen can come form the skin and mouth (systemic route) as well as the lungs (pulmonary route)

  - Three-chambered heart can divert blood to one or other system

  - Uses a buccal pump (mouth) instead of the chest to inflate
• Jaw Articulation and Hearing Evolution in Synapsids

  Teeth became more specialised

  - Dentary bone in the lower jaw was expanded

  - Existing jaw bones are incorporated in to the ear

  squamosal- Shift from articular/quadrate to denture/squasmosal
• One-Way (Avian) Respiration vs Tidal Ventilation

  One-Way (Unidirectional) Respiration

  - When the respiratory medium flows in at one point and exits via another

  - Birds have a one- way airflow system through the lungs

  
  

  
  

  Tidal Ventillation

  - When the external media moves in and out of the respiratory system in a back and forth movement
• Sea Star Movement and Feeding

  They use their water vascular system for both movement and feeding. It is a Hydraulic system

  - System is composed of canals connecting to numerous tube feet

  - Sea stars feed on bivalves by prying them open with their tube feet, everting their stomach, and externally digesting their prey with digestive enzymes
• Mammalian Lung Ventilation

  Rib Ventilation with diaphragms to help ventilate the lungs

  - Rib cage expands as the muscles contract

  - Rib cage gets smaller as the rib muscles relax
• Tidal Ventillation

  1. Breathe in, air passes through the lungs into the anterior sacs

  2. Breathe out, the anterior sacs contract (1) air is pushed out
• Sea stars

  • They use their water vascular system for both movement and feeding
  • It is a Hydraulic system
  • System is composed of canals connecting to numerous tube feet
  • Sea stars feed on bivalves by prying them open with their tube feet, everting their stomach, and externally digesting their prey with digestive enzymes
• Mammalian lung ventilation

  1. Rib cage expands as the muscles contract

  2. Rib cage gets smaller as the rib muscles relax
• Anatomy of birds

  • No Uranary bladder
  • One ovary
  • Gonads regress after mating
  • Toothless
  • Hollow bones = Many features to reduce the overall weight of the bird
• Tetrapod adaptations to terrestrial life

  • Fusion of pelvic girdle to backbone
  • Enlarged ribs for support
  • Shift from limb locomotion to body locomotion
  • Double circulation to avoid blood pooling, due to gravity > High blood pressure needed for the separation of the systemic (body) and pulmonary (lung) circuits
  • Neck and shoulder allow for head movement
• Avian pectoral girdle movement

  1. Pectorals pull wings down

  2. Supracoracoideus raises wings up

  3. Coracoid bone is a brace between the shoulder and keel
• Phylum Mollusca

  • Coelomates
  • Soft-bodied
  • Most secrete a hard shell made of calcium carbonate
  • Most molluscs have separate sexes with gonads located in the visceral mass, but many snails are hermaphrodites
  • Slugs, squids and octopi have a reduced internal shell or have lost their shell completely during their evolution
  • Muscular foot
  • Visceral mass (contains most organs)
  • Mantle
  • Many molluscs also have a water-filled mantle cavity (has gills, anus and excretory glands) and feed using a strap-like radula (strap like organ scrapes food)
  • The larval stage is called trochophore, which is a characteristic shared with some annelids and some lophotrophozoans
  • Four major classes of molluscs are: Polyplacophora (chitons), Gastropoda (snails and slugs), Bivalvia (clams, oysters, and or bivalves), Cephalopoda (squids, octopi, cuttlefish and chambered nautiluses)
• Phylum Annelida

  • Coelomates
  • Live in the sea, fresh water, or damp soil
  • Distinguished by serial segmentation (metameric)
  • Body systems are repeated in each segment (eg. Circulation, nervous, excretion)
  • Segments are divided by a septum except in leaches
  • Have chitinous bristles called stetae that provide anchorage for swimming (except leeches)