Download Phylogenies show Evolutionary Relationships

Phylogenies show Evolutionary Relationships
-Phylogeny is the evolutionary history of species
or a group of related species
-It is constructed by using evidence from
systematic, a discipline that focuses on
classifying organisms by their evolutionary
relationships
-Its tools include fossils, morphology, genes, and
molecular evidence
Taxonomy
-Is an ordered division of organisms into
categories based on a set of characteristics used
at assess how similar they are
Binomial Nomenclature
-Uses as two-part naming system that consist of
the genus to which the species belong as well as
the organisms’ species within the genus
Ex.: Canis familaris, the scientific name of the
common dog
The Hierarchical Classification of Organisms
consists of following levels, beginning with the
most general or inclusive:
-Domain
-Kingdom
-Phylum
-Class
-Order
-Family
-Genus
-Species (most specific)
Systematics
-Use branching diagrams called phylogenetic
trees to depict hypotheses about evolutionary
relationships
-The branches of such trees reflect the
hierarchical classifications of groups nested
within more inclusive groups
Phylogenetic Trees are inferred from
morphological and molecular data:
-Homologous structures are similarities due to
shared ancestry, such as the bones of a whale’s
flipper and a tiger’s paw
-They are used to construct phylogenetic trees,
the more structures you share with another
organism, the closer you are on the tree because
its more likely you share a common ancestor
-As new evidence about organisms becomes
available through biochemical analysis,
phylogenetic trees are constantly being revised
Shared Characters are used to construct
Phylogenetic Trees
-A cladogram depicts patterns of shared
characteristics among taxa and forms the basis
of a phylogenetic tress
-A clade, within a tree, is defined as a group of
species that includes an ancestral species and all
its descendants
Convergent Evolution
-Has taken place when two organisms developed
similarities as they adapted to similar
environmental challenges- not b/c they evolved
from a common ancestor
-It results in analogous structures between
individuals who aren’t related
-The likeness that result from convergent
evolution are considered analogous solutions to
similar problems
Ex.: the wing of a butterfly is analogous to the
wing of a bat, both are adaptations for flight
Remember Phylogenetic Trees are Based on:
-Homologous structures (because they are
showing evolutionary relationships)
-They are not based on analogous structures
(which are convergent evolution)
Molecular Systematics
-Uses DNA and other molecular data to
determine evolutionary relationships
-The more alike the DNA sequences of two
organisms the more closely related they are
evolutionarily- so the closer they are on the
phylogenetic tree
An Organism’s Evolutionary History is
Documented in its Genome:
-The rate of evolution of DNA sequences varies
from one part of the genome to another
-Comparing these different sequences helps us
to investigate relationships between groups of
organisms that diverged a long time ago
How do we classify organisms?
-Biologists have adopted a three-domain system,
which consist of the domains Bacteria, Archaea,
and Eukarya
-There domains are then separated into
kingdoms, phylum, class, order, family, genus,
and separate species
-Characteristics of the 3 domains:
The domains Bacteria and Archaea contain
prokaryotic organisms and Eukarya contains
eukaryotic organisms (kingdoms Protista, Fungi,
Plantae, and Animalia) (chart on page 30)