BIO102_SYSTEMATICS

    Cards (32)

    • Macrotaxonomy is the branch of taxonomy that establishes rules to the classification of superior taxa
    • Naturalistic systematics - naturalists sought to classify nature in a way that reflected nature, rather than the ways humans use nature
    • Darwin's Theory of Natural Selection suggested that all organisms are related by descent
    • Classification is the grouping of organisms often on the basis of simple observable traits
    • Taxonomy - study of biological classification
    • Artificial classification divides organisms by what is useful at that time
    • Natural classification is based on evolutionary relationships between organisms and their evolutionary descents
    • The goal of systematics is to determine the phylogeny - evolutionary history - of a species or a group of related species
    • Phylogenies are inferred by identifying organismal features and characters that vary among species
    • Characters can be morphological, molecular, chromosomal, and behavioral or ecological
    • Homologous characters are shared characters that result from common ancestry
    • Homoplasies are shared characters that are NOT a result of common ancestry, but of independent evolution
    • Convergent evolution occurs when natural selection, working under similar environmental pressures, produces similar (analogous) adaptations in organisms from different evolutionary lineages
    • Shared primitive character is a homologous structure that is older than the branching of a particular clade from other members of that clade
    • A shared primitive character is shared more than just the taxon that is being defined
    • An example of a shared primitive character is that all mammals have bones, but so do other vertebrates
    • A shared derived character is a new evolutionary feature unique to a particular group
    • Shared derived characters are most useful for determining evolutionary relationships
    • Ancestral character state is the FORM of the character that was present in the common ancestor of the group
    • Derived character state is the variations of that character that arose later
    • All mammals have hair, but no other animals have hair is an example of a shared derived character
    • Polarity (which version of the trait is ancestral) is determined by outgroup comparison
    • An outgroup is CLOSELY RELATED, but NOT part of the group being examined (ingroup)
    • Ancestral character is found in both the study group and the outgroup
    • Derived character groups are found in the study group, but not the outgroup
    • Clades are groups that share derived characters and form a subset within a larger group
    • The unit of common evolutionary descent is a clade
    • Synamorphy is a derived character that is shared by all members of the clade
    • Using synamorphies to define clades will result in a nested hierarchy of clades
    • Ancestral character states for a taxon are called plesiomorphic
    • Symplesiomorphies are shared ancestral characters
    • Symplesiomorphies do not provide useful information for forming a nested series of clades