Convergence
the evolution of similar adaptations in unrelated species. (i.e., birds and bats both have wings, solving a similar environmental challenge through completely separate processes)
Analogy
the similarity between traits resulting from convergent evolution, not common descent. (i.e., humans and kangaroos are both bipedal; birds, bats, and bees all fly)
Divergence
the evolution of different adaptations based upon the same structures in related species. (i.e., dogs and humans have the same bones in the forelimb/arm, using the same base anatomy to solve different environmental problems)
Homology
similarity resulting from common ancestry
Variant
: a particular form of a trait. (i.e., blonde vs. brunette, blue or brown eye color)
Genes
a segment of chromosome that produces a recognizable effect on phenotype.
Gametes
germ cells that unite with opposite sex for reproduction - in animals, sperm and egg.
Mitosis
ordinary cell division; chromosomes "copied
Meiosis
: cell division leads to gamete production; chromosomes split apart
diploid
homologous pairs
haploid
one chromosome
Zygote
new, diploid cell bundle (to become offspring) formed by joining of gametes
Alleles
specific forms of genes.
Recombination
creation of new genotypes as a result of random segregation of chromosomes and cross over; nature's way of "shuffling" the genetic deck.
Linked genes
genes that are on the same chromosome; the closer the loci (positions) of the genes, the more likely they will be linked.
Unlinked genes
genes that are on different chromosomes.
Base pairs
A-T
G-C
Protein-coding genes
specifc structure of proteins. Many proteins are enzymes (catalysts) that regulate biochemistry.
...
...
Proteins
large molecule that consists of a long chain amino acid; may be enzyme catalysts or perform structural functions
Amino acids
molecules linked in a chain to form proteins.
Primary structure
makes one protein different from another.
Tertiary structure
the 3-dimensional shape of the folded protein.
Codons
:three-letter "words"
64 possible combinations
61 code for the 20 amino acids (redundancy)
3 code for "punctuation marks" (i.e., start, stop)
Introns
non-coding DNA sequences
Exons
protein-coding DNA sequences
Transcription
DNA - mRNA making a mold
Translation
Process by which mRNA is decoded and a protein is produced
Regulatory gene
DNA sequence that regulates expression of a gene, often by binding to an activator or repressor.
Activator
protein that increases transcription of a regulated gene
Repressor
protein that decreases transcription of a regulated gene.
Combinatorial control
control of gene expression in which more than one regulatory protein/gene is used and expression is allowed only in a specific combination of conditions.
Population genetics
study of the processes that change the genetic composition of populations through time.
Genotypic frequency
fraction of individuals in a population that have a particular genotype.
Environmental variation
phenotypic differences between individuals that exist because those individuals developed in different environments
Mutations
spontaneous change in the chemical structure of DNA.
Sex ratio
the relative number of males and females.
Canalized
describing traits that are insensitive to environmental conditions resulting in consistent phenotypes.
Plastic
describing traits that are very sensitive to environmental conditions resulting in varying phenotypes.
Taxonomy
naming and classifying organisms.
Microevolution
evolution of populations within a species
Macroevolution
evolution of new species, families, and higher taxa.
Gene flow
movement of genes from one population to another, or from one part of a population to another, as the result of interbreeding.
Allopatric speciation
two or more populations of a single species are fully isolated by geographical boundaries and diverge to form two or more new species
Character displacement
result of competition between two species that causes members of different species to become morphologically or behaviorally different from each other.
Reinforcement
process of selection that acts against likelihood of interbreeding.
Parapatric speciation
two-step process of speciation.
1. partially isolated by geographical boundaries
2. become reproductively isolated as a result of reinforcement
Sympatric speciation
selection pressures favor different phenotypes within a population without requiring geographic isolation.
Niche
way of life or "trade" of a species - what foods it eats and how the food is acquired.
Adaptive radiation
single lineage diversifies into several species, characterized by distinct adaptations.
Phylogeny
evolutionary relationships among groups of species, usually diagrammed as a "family tree.
Cladistic taxonomy
a system for classifying organisms based on patterns of descent only; genetic distance.
Evolutionary taxonomy
system for classifying organisms that use patterns of descent AND patterns of overall similarity.