Ch 5

• • Evolution occurs when heritable characteristics of a species change
• • The fossil record provides evidence for evolution
• • Selective breeding of domesticated animals shows that artificial selection cancause evolution
• • Evolution of homologous structures by adaptive radiation explains similarities in structure when there are differences in function.
• • Populations of a species can gradually diverge into separate species by evolution.
• • Continuous variation across the geographical range of related populations matches the concept of gradual divergence.
• • Application: Development of melanistic insects in polluted areas
• • Application: Comparison of the pentadactyl limb of mammals, birds, amphibians and reptiles with different methods of locomotion.
• • Natural selection can only occur if there is variation among members of the same species.
• • Mutation, meiosis and sexual reproduction cause variation between individuals in a species.
• • Adaptations are characteristics that make an individual suited to its environment and way of life.
• • Species tend to produce more offspring than the environment can support.
• • Individuals that are better adapted tend to survive and produce more offspring while the less well adapted tend to die or produce fewer offspring
• • Individuals that reproduce pass on characteristics to their offspring
• • Natural selection increases the frequency of characteristics that make individuals better adapted and decreases the frequency of other characteristics leading to changes within the species.
• • Application: Changes in beaks of finches on Daphne Major
• • Application: Evolution of antibiotic resistance in bacteria
• • The binomial system of names for species is universal among biologists and has been agreed and developed at a series of congresses.
• • When species are discovered they are given scientific names using the binomial system.
• • Taxonomists classify species using a hierarchy of taxa
• • All organisms are classified into three domains
• • The principal taxa for classifying eukaryotes are kingdom, phylum, class, order, family, genus and species
• • In a natural classification, the genus and accompanying higher taxa consist of all the species that have evolved from one common ancestral species.
• • Taxonomists sometimes reclassify groups of species when new evidence shows that a previous taxon contains species that have evolved from different ancestral species.
• • Natural classifications help in identification of species and allow the prediction of characteristics shared by species within a group.
• Plant Example (Medow Buttercup):

   

  Eukaryota

  Plantae

  Angoiospermatophyta

  Eudicotyledons

  Magnoliidae

  Ranunculales

  Ranunculus

  Acris
• Animal Example (Humans):         

   

  Eukaryota

  Animalia

  Chordata

  Mammalia

  Primates

  Hominidae

  Homo

  Sapiens
• • Application: Recognition features of bryophyta, filicinophyta, coniferophyta and angiospermophyta
• • Application: Recognition of features of birds, mammals, amphibians, reptiles and fish.
• • Skill: Construction of dichotomous keys for use in identifying specimens
• • Viruses are not classified as living organisms
• • A clade is a group of organisms that have evolved from a common ancestor
• • Evidence for which species are part of a clade can be obtained from the base sequences of a gene or the corresponding amino acid sequence of a protein
• • Sequence differences accumulate gradually so there is a positive correlation between the number of differences between two species and the time since they diverged from a common ancestor.
• • Traits can be analogous or homologous.
• • Cladograms are tree diagrams that show the most probable sequence of divergence in clades.
• • Evidence from cladistics has shown that classifications of some groups based on structure did not correspond with the evolutionary origins of a group or species.
• • Application: Cladograms including humans and other primates
• • Application: Reclassification of the figwort family using evidence from cladistics.
• • Skill: Analysis of cladograms to deduce evolutionary relationships