an evolutionary tendency to increase in size over time
the "derived group" that evolved from the stem group
Early stage ancestors
done by radiometric dating, measures decay of radioactive elements each type decays at a specific rate (1/2 life) U-235 = 0.7bya
A method used to determine the age of rocks by comparing them with those in other layers
slow steady change in a phylum with a steady accumulation of small changes
short periods of rapid change and macroevolutionary events during which new taxa arise (speciation) interrupt long periods of little change (stasis). *requires speciation
Hypothesis applies to the abrupt appearance of closely related species, not the appearance of higher taxa.
The theory that species evolve during short periods of rapid change
-characters may evolve in between long-stable states in populations that do not undergo speciation.
-Random fluctuation in a character may result in a gradual net change over time.
-Consistent directional change is seldom recorded, perhaps because it often occurs too quickly to be preserved in a coarse fossil record
Geologic Time Scale
scale used by paleontologists to represent evolutionary time
similar stages of related organisms
complex characters once lost, are not regained. This law is not universal and depends upon changes in the genetic code controlling development.
largest scale of biogeographic division of the earth's surface; based on historic distribution patterns of plants and animals.
represent large areas of the earth's surface where plants and animals developed in relative isolation over long periods of time, and are separated from one another by geologic barriers to migration
two or more groups that are related but widely separated from each other geographically
the one-way movement of a species from the site of origin to new habitats. This expands the range of the species.
evolutionary separation of species by barriers such as those formed by continental drift may account for the presence of related taxa in disjunct areas
species formation without branching of the evolutionary line of descent.
can cause disjunct distributions.
uses present ecological factors (climate, soil, etc.) to explain distributions of animals
studies past geological events to understand present distributions, e.g. connection between South America and Africa explains the distribution of some taxa in those two continents
fundamental Ecological niche
the set of environmental conditions in which a species can maintain a stable population size.
realized ecological niche
the actual niche occupied by the species due to the influence of competitors, predators, etc.
Phylogenetic niche conservatism
Related species often have similar ecological requirements presumably due to their common ancestry. Species tend to retain their ancestral niche characteristics.
Native or confined to a particular region
studies the processes and principles that control the geographic distribution of lineages of genes especially within species and closely related species
relies strongly on phylogenetic analysis of variant genes within species (gene trees, Ch. 2) to infer population history.
provides insights into the past movements of species
different forms of the same gene.
unequal crossing over
can occur between two homologous sequences or chromosomes not perfectly aligned resulting in tandem duplication in one chromosome and deletion in the other.
polyploidy formed between two related, but separate species
an individual with more than two chromosome sets, derived from one species
Occurs when a gene that has undergone a mutation reverses to its original
Process in which homologous chromosomes exchange portions of their chromatids during meiosis.
gene mutation in which a single base pair in DNA has been changed
replaces one nucleotide and its partner with another pair of nucleotides
result in no changes in the amino acid sequence.
result in the wrong amino acid; They may or may not have consequences in the phenotype
groups of genes that have similar sequences and related functions
Having too many or too few copies of a particular chromosome
condition in which an organism has extra sets of chromosomes
Alleles that produce detectable phenotypic differences useful in genetic analysis
An exchange of material between homologous sequences that differ at two or more base pairs can form new combinations in the DNA
A single gene having multiple effects on an individuals phenotype
A short, highly repeated, untranslated DNA sequence.
Two or more DNA sequences of base pairs that are repeated
substitutions of purine to purine or pyrimidine to pyrimidine
substitutions of a purine to a pyrimidine or vice versa
when a piece of DNA is relocated to a different locus
genetic element that moves from one location to another in a genome always include genes that code for the enzyme that accomplishes the transposition 3 types: insertion sequences, transposons, retroelements
An individual with the normal (most common) phenotype.
Lower jaw dentary only, single jaw joint, enlargement of brain Hadrocodium Mammals
Morganucodon (first mammals during Triassic, a gradual transition not a distinct point) Teeth like mammals, more developed dentary squamosal joint, beginning of hammer and anvil