CHAPTER 8 Flashcards
who first conceived the theory of evolution
Charles Darwin
the four principles of life the evolution is based on
- Many of the traits of an organism are heritable
- Sometimes organisms have heritable traits that are new, not copied from parents =mutation.
- An organisms traits effect how successfully that organism is able to reproduce
- There’s competition for limited resources, allowing only some individuals to reproduce before they die.
The theory of evolution combines these four basic principles of life together:
the DIFFERENTIAL SUCCESS of certain VARIATIONS of a HERITABLE trait, because of the COMPETITION for limited resources, leads to change over time (evolution) of that trait.
organisms are grouped together based on there most ______
organisms are grouped together based on their most recent shared common ancestor.
How can we figure out which dinosaurs share a more recent common ancestor, and, therefore, should be grouped together?
This is done by studying characters.
character
A character is any heritable trait that can be described and labeled
A shared derived character
A shared derived character is a character that is present in two or more groups and their common ancestor, but is not present in any more distantly related groups.
synapomorphy
A shared derived character is also called a synapomorphy.
What is one of the biggest challenges to determining evolutionary relationships?
One of the biggest challenges to determining evolutionary relationships is the common phenomenon of convergent evolution.
Ouranosaurus
Ouranosaurus is an Iguanodont with a:
- Beak
- Grinding teeth
- Hoofed toes
- Long processes on the vertebrae of the back that form a sail.
Spinosaurus
Spinosaurus is a theropod with a:
- Long snout
- Sharp teeth
- Clawed fingers
- Long processes on the - vertebrae of the back that form a sail.
convergent evolution.
The evolution of similar traits in two different or separate lineages is termed convergent evolution.
parsimony OR Occam’s razor
The idea that “all other things being equal, the simplest answer is usually the right one” is called parsimony. Parsimony is also referred to as Occam’s razor.
how to paleontologists determine evolutionary relationships between large numbers of species, many of which may be closely related, and to take into consideration a large number of characters
they use computer programs that analyze a list of characters which is compelled by the researcher.
what is the list of characters called
a matrix
which principle does the computer apply and why?
the principle of parsimony and its to that they could arrange the sequence of relationships that require the fewest instances of convergence evolution
phylogenetic trees
The resulting arrangements look like diagrams of a “family tree” and are called phylogenetic trees.
what are the phylogenetic trees composed of ?
nodes and branches
what’s a node ?
A node is where two branches diverge, and shows the point at which two linages shared a common ancestor.
what’s after the node?
After a node, the pattern of subsequent branches and nodes shows how the descendants of that common ancestor continued to diverge from each other
what’s a clade?
A group of species that share a common node is called a clade.
what must a clade contain?
A clade must contain the ancestor of a group and all of its descendants. A group that does not include all of the descendants of a common ancestor is therefore not a clade.
Linnaean Hierarchy
was formed before ideas like evolution and natural selection. It classifies organisms as belonging to a Kingdom, Phylum, Class, Order, Family, Genus, and Species
“missing links”
organisms that show an evolutionary connection between two major groups of organisms by displaying a mosaic of traits and characteristics from both groups.
