genes
short segment of a chromosome that encodes for a specific protein
Alleles
different types of the same gene
Homozygous
the alleles are identical
Heterozygous
the alleles are different
Dominant
a trait that will mask the expression of any other allele
Recessive
masked by a dominant allele, invisible will only express itself in the homozygous
Simple Patterns
alleles obey the law of segregation and independent assortment, inheritance patterns of traits affected by a single gene that is found in 2 variants
Pisum sativum
common garden pea that Mendel studied it had many varieties differing in characteristics
True Breeding Line
organisms with a given phenotype that produce offspring with the same phenotype generation after generation
Phenotype
the physical appearance of an organism controlled by the genotype
Genotype
An organism's genetic makeup, or allele combinations.
Cross - Fertilization
removal of pollen from plant and selectively pollinating the female reproductive structures of different plants
Monohybrids
offspring of true breeding parents that differ in only one character
Mendels Law of Segregation
Mendel always observed a 3;1 ratio between dominant and recessive traits in the F2 generation
which chromosome has more information on it
X chromosome
Males
XY
Females
XX
Y chromosome
gene for testis determining factor (TDF)
Sex Linked Traits
coded for by genes located on the sex chromosomes, mostly X
Incomplete Dominance
both alleles are partially expressed in the heterozygote
Codominance
if 2 dominant alleles for a given trait are inherited both will be fully expressed
Epistasis
a type of gene interaction in which the alleles of one gene masks the effects of an allele of another gene
Continuous Variation
inheritance pattern in which offspring display a continuous range of phenotypes
Autosomal Linkage
all the genes that are located on the same chromosome are said to be linked may be broken up during meiosis
X chromosome Inactivation
in female mammals, one X sex chromosome is inactivated in the somatic cell, RANDOM
Evolution
change in gene frequencies in a population over time
Carolous Linnaeus
father of modern taxonomy, classified organisms based on their similarities
LaMarck
first to propose a mechanism for evolution (inheritance of acquired characteristics)
Inheritance of acquired characteristics
if your dad cuts your pinky off you won't be born without a pinky
Charles Darwin
English natural scientist who formulated a theory of evolution by natural selection (1809-1882)
HMS Beagle
charted coastlines in the Southern Hemisphere and brought Darwin to the Galapagos Islands
Darwins Theory of Evolution
Those individuals that are best adapted to the environment will survive and reproduce; those traits that help them, become more common in a species and maladaptive traits die out. This is called natural Selection.
Fossil Records
some fossils show a change in a species overtime EX horses hoof
Convergent Evolution
unrelated species that evolve similar characteristics under similar circumstances
Selective Breeding
animals can only breed with other animals of the same species
Vestigial structures
organs which appear to not be used by one species but are highly developed in another
Macroevolution
evolutionary changes creating new species and groups of species, accumulation of microevolutionary changes
Morphological Traits
physical characteristics, disadvantage is you don't know how dissimilar traits are
Reproductive Isolation
inability to breed in nature, disadvantage is sometimes different species can interbreed in nature
Molecular Features
comparisons of DNA sequences of genes and location of genes, disadvantage is you don't know how different the features need to be
Ecological Factors
related to an organisms habitat, EX some warbler species characterized by where they forage for food
Evolutionary Relationships
MOST ACCURATE, based on fossil record and DNA analysis
Species Concepts
a way to define concept of a species and/or provide approach to distinguish different species
Biological Species Concept
group of individuals capable of interbreeding with one another in nature to produce viable, fertile offspring, can't interbreed with members of other species
Evolutionary Lineage Concept
species defined based the separate evolution of lineages
Ecological Species Concept
each species occupies an ecological niche (unique set of habitat resources)
General Lineage Concept
each species forms a group with a particular set of characteristics, DNA sequences can be applied to all organisms
Reproductive isolating mechanisms
mechanisms that prevent interbreeding between different species
Prezygotic Isolating mechanism
prevents a zygote from forming
Zygote
a single cell formed when an egg is fertilized by a sperm
Habitat Isolation
species can't breed because they occupy different habitats, never come in contact with each other
Temporal isolation
reproduce at different times of the year
Behavioral Isolation
differences in behavior or physiology prevent attraction between males and females even if they live in the same habitat
Mechanical isolation
body parts don't fit together to exchange gametes
Gametic isolation
games fail to unite successfully,
protein called binding allows sperm to attach to the ova but this doesn't happen in gametic isolation
Postzygotic isolating mechanisms
reduced viability or reproductive capacity of hybrid offspring, less common in nature
Hybrid inviability
egg of one species is fertilized by a sperm from a different species, development of zygote stops during early embryonic stage
Hybrid sterility
a viable hybrid is produced but sterile EX mule
Hybrid Breakdown
interspecies hybrids are produced and are fertile but subsequent generations harbor detrimental genetic abnormalities
Speciation
Formation of new species which happens because the environments affects the phenotype which affects the genotype
Anagenesis
SINGLE species transformed into different specieS over the course of many generations
Cladogenesis
division of a species into 2 or more species (original may still be alive)
Allopatric Speciation
The formation of a new species as a result of an ancestral population's becoming isolated by a geographic barrier.
Genetic Drift
A change in the allele frequency of a population as a result of chance events rather than natural selection.
Adaptive radiation
one species evolves into many descendent species differing greatly in habitat, form or behavior
Sympatric Speciation
The formation of a new species as a result of a genetic change that produces a reproductive barrier between the changed population (mutants) and the parent population. No geographic barrier is present.
Timespan of Speciation
rate of evolutionary change and speciation not constant
Gradualism
new species evolve continuously over long spans of time
Punctuated Equilibrium
long periods of evolutionary stasis are interrupted by short rapid bursts of changes in phenotypic frequencies (rapid evolutionary change)