Evolution Flashcards
Lamarckian Evoluation
- new organs or changes in existing ones arose b/c of the needs of the organism
- amount of change was thought to be based on the disuse of the organ
Darwin’s Theory of Natural Selection
-pressure in the environment select for the organism most fit to survive and reproduce
Overpopulation
more offspring are produced than can survive
Variations
offspring naturally show differences in their characteristics compared to those of their parents
Competition
the developing population must compete for the necessities of life
Natural Selection
species have variations that give them advantage over other members of the species
Inheritance of the Variations
individuals that strive to adulthood reproduce and transmit favorable genes to offspring (genes will dominate gene pool)
Evolution of New Species
accumulation of favorable changes eventually results in such significant changes in the gene pool that we can say new species has evolved
Speciation
the evoluation of new species, which are groups of individuals that can interbreed freely with each other, but not with members of other species
demes
local populations formed within a species. if demes, become isolated, speciation may occur
phylogeny
a branching tree on which the common ancestor is found at the trunk and the modern species are found at the tips of the branches
convergent evolution
groups among the branches often develop similar traits
Parallel Evoluation
similar to convergent evolution but occurs when a more recent ancestor can be identified
Divergent Evolution
occurs when species with a shared ancestor develop differing traits due to dissimilarities between their environments
Adaptive Radiation
the emergence of a number of lineages from a single ancestral species
Population
includes all members of a particular species inhabiting a given location
Gene Pool
the sum total of all the alleles for any given trait in the population
Gene Frequency
the decimal fraction representing the presence of an allele for all members of a population that have the particular gene
The Hardy-Weinberg Principle
- evolution can be viewed as a result of changing gene frequencies within a population
- when gene frequencies of a population are not changing, the gene pool is stable and the population is not evolving.
- only true in an IDEAL population: the pop is very large, no mutations affect the gene pool, mating between individuals in the population is random, there is no net migration of individuals into or out of the population, the genes in the population are equally successful @ reproducing
Microevolution
- real populations have unstable gene pool and migrating populations
- agents of microevolution: natural selection, mutation, assortive mating, genetic drift, and gene flow
Natural Selection
genotypes with favorable variations are selected through natural selection
Mutation
gene mutations change allele frequencies in a population, shifting gene equilibria by introducing additional alleles
Assortive Mating
mates are chosen 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
Genetic Drift
refers to changes in the composition of the gene pool due to chance (also called founder effect)
Gene Flow
migration of individuals between populations will result in a loss or gain of genes
Fossil Record
direct evidence of evolutionary change
Types of Fossils
can be found in rock, tar pits, ice, and amber
Petrification
the process by which minerals replace the cells of an organism
Imprints
impressions left by an organism
Molds
form hollow spaces in rocks as the organisms within decay
Casts
formed by the minerals deposited in molds
Homologous Structures
have the same anatomical features and evolutionary origins. Although anatomical features may be similar, their functions may not be
Analogous Structures
have similar functions but may have different evolutionary origins and entirely different patters of development
Comparative Embryology
stages of development of the embryo resemble the stages in an organism’s evolutionary history
Comparative Biochemistry (Physiology)
most organisms demonstrate the same needs and metabolic processes
Vestigial Structures
have no known current function but apparently had some ancestral function
Geographic Barriers
species multiplication is generally accompanied by migration to lessen intraspecific competition
The Heterotroph Hypothesis
first forms of life lacked the ability to synthesize their own nutrients. these organisms depended upon outside sources for food
Evidence of Organic Synthesis
Stanley L. Miller stet out to demonstrate that the application of UV radiation, heat, or a combination of these to a mixture of methane, hydrogen, ammonia, and water would result in the formation of complex organic compounds
Formation of Primitive Cells
coacertive droplets (a duster of colloidal molecules surrounded by a shell of water) may have formed the first primitive cells
