biology chapter 16 Flashcards
evolution
the change in the genetic makeup of a population with time
fossils
are the most direct evidence of evolutionary change
actual remains
including teeth, bones, etc,. Found in rock, tar pits, ice and amber (the fossil resin of trees)
petrification
is the process in which minerals replace the cells of an organism
imprints
are impressions left by an organism, i.e. footprints
molds
form in hollow spaces of rocks, as the organisms within decays
casts
are formed by minerals deposited in molds
homologous structures
have the same basic anatomical features and evolutionary origins. They demonstrate similar evolutionary patters with late divergence of form due to differences in exposure to evolutionary forces
analogous structure
have similar functions but may have different evolutionary origins and entirely different patterns of development. Analogous organs demonstrate superficial resemblance which cannot be used as a basis for classification
vestigial structures
are structures that appear to be useless but apparently had some ancestral function
Darwin’s theory of Natural Selection
- overpopulation 2. variations 3. competition (struggle for survival) 4. natural selection 5. inheritence of the variations 6. evolution of new species
population
includes all members of a particular species inhabiting a given location
gene pool
of a population is the sum total of all the alleles for any given trait in the population
gene frequency
is the decimal fraction representing the presnece of an allele for all memebers of a population that have this particular gene locus.
p
is used for the frequency of the dominant allele of a particular gene locus
q
represents the frequency of the recessive allele
Hardy-Weinberg Principles
- the population is very large 2. there are no mutations that affect the gene pool 3. mating between individuals in the population is random 4. there is no net migration of individuals into or out of the population 5. the genes in the population are all equally successful at reproducing
Hardy-Weinberg equation
p2 + 2pq + q2 = 1
agents of microevolutionary change
natural selection, mutation, assortive mating, genetic drift, and gene flow
natural selection
genotypes with favorable variations are selected through natural selection, and the frequency of favorable genes increases within the gene pool. Genotypes with low adaptive values tend to disappear
mutations
gene mutations change allele frequencies in a population, shifting gene equilibria
assortive mating
if mates are not randomly chosen, but rather selected according to criteria such as phenotype and proximity, the relative genotype ratios will be affected, and will depart from the predictions of the Hardy-Weinberg equilibrium. On the average, the allele frequencies in the gene pool remain unchanged
genetic drift
refers to changes in the composition of the gene pool due to chance. Genetic drift tends to be more pronounced in small populations, where it is sometimes called the founder effect
gene flow
migration of individuals between populations will result in a loss or gain of genes, and thus change the composition of a population’s gene pool
speciation
is the evolution of new species, which are groups of individuals who can interbreed freely with each other, but not with members of other species.
deme
is a small local population
adaptive radiation
is the emergence of a number of lineages from a single ancestral species
heterotrophs
depend upon outside sources for food
