Chapter 22 and 23 Flashcards
Fossil
any trace of an organism that lived in the past
extant species
species living today
phylogenetic tree
branching diagram that depicts the ancestor
homology
similarity that exists in species due to common ancestry
Evolution
Theory all organism are related by common ancestry and change over time due to natural selection
Population thinking
Way of thinking that emphasizing the importance of variation among individuals in a population
Decent with modification
Describes how species that lived in the past are the ancestors of species existing today
Sedimentary rocks
Form from sand or mud or other materials deposited in layers at locations such as beaches or river mouths
Geologic time scale
Sequence of eons, eras, and periods used to describe the geologic history of the earth.
Radioactive decay
Steady rate at which unstable “parent” atoms are converted into more stable “daughter” atoms
Genetic homology
Similarity in DNA, RNA or amino acid sequences due to inheritance from a common ancestor
Developmental homology
Similarity in embrynoic form of developmental processes due to inheritance from a common ancestor
Structural homology
Similarity in adult organismal structures due to inheritance from a common ancestor
Speciation
Process that results in new species being formed from prexisting species
artificial selection
Deliberate manipulation by humans as in animal and plant breeding, of the genetic composition of a population by only allowing individuals with desirable traits to reproduce.
Darwin’s Four Postulates
- Variation exists among individual organisms that make up a population
- Some of the trait differences are heritable
- Survival and reproductive success are highly variable
- The subset of individuals that survive best and produce the most offspring is not a random sample of the population
Variation exists among individual organisms that make up a population
Shape and size differs
Survival and reproductive success are highly variable
Many more offspring are produced than can possibly survive. Thus only some individuals in each generation survive long enough to produce offspring
Subset of individuals that survive best and produce the most offspring is not a random sample of the population
Individuals with certain heritable traits are more likely to survive and reproduce
Natural selection
Occurs when individuals with certain heritable traits produce more surviving offspring than do individuals without those traits
Two part statement of natural selection
Evolution by natural selection occurs when heritable variation leads to differential reproductive success
Evolutionary fitness
ability of an individual to produce surviving, fertile offspring relative to that ability in other individuals in the population
adaptation
Heritable trait that increases the fitness of an individual in a particular environment relative to individuals lacking the trait
turberculosis
disease of the lungs caused by infection with the Mycobacterium bacterium tuberculosis
Acclimatization
Change in an individual’s phenotype that occurs in response to a change in natural environmental conditions
Acclimation
Change in the study’s organism’s phenotype that occurs in response to laboratory conditions
Population genetics
study of processes that change the allele and genotype frequencies in populations
Genetic drift
Causes allele frequences in small populations to change randomly. May cause alleles that decrease fitness to increase in frequency
Natural selection
increases the frequency of certain alleles-ones that contribute to reproductive success in a particular environment
Gene flow
Occurs when individuals leave one population, join another, and breed.
Allele frequences may change when gene flow occurs, because arriving individuals introduce alleles to their new population and departing individuals remove alleles from their old population.
Mutation
Modifies allele frequencies by continually introducing new alleles. The alleles created by mutation may be beneficial, detrimental or neutral in their effects on fitness.
Increases genetic diversity, but usually insignificant in short term
gene pool
All of the alleles of all the genes in a certain population
What does the Hardy-Weinberg principle predict
predicts what genotype and allele frequencies will occur in the next generation.
Hardy Weinberg principle
the genetic variation in a population will remain constant from one generation to the next in the absence of disturbing factors.
Five assumptions ns that Hardy-Weinberg principle is based on
Random mating
No natural selection
No genetic drift
No gene flow
No mutation
Processes of evolution
natural selection, genetic drift, gene flow, and mutation
Inbreeding
Mating between closely related individuals. Increases homozygosity of a population and often leads to a decline in the average fitness via selection
Ecological selection
A type of natural selection that favors individuals with heritable trait that enhances their ability to survive and reproduce in a certain physical or biological environment
Genetic variation
the difference in DNA sequences between individuals within a population
Four main modes that natural selection occurs
Directional selection
Stabilizing selection
Disruptive selection
Balancing selection
Directional selection
Reduces genetic diversity and changes the average value of a trait
Individuals of one extreme are favored
Stabilizing selection
Individuals with intermediate phenotype favored
Reduces genetic diversity, but does not change mean value of a trait
Disruptive selection
Both extreme phenotypes favored
Increases genetic diversity but does not change mean value of trait
Can cause speciation
Balancing selection
Maintains variation in a trait
Purifying selection
Selection that lowers the frequency of, or even eliminates deleterious alleles
Heterozygote advantage
Occurs when heterozygous individuals have higher fitness than homozygous individuals do
Frequency dependent selection
a situation where fitness is dependent upon the frequency of a phenotype or genotype in a population
Intersexual selection
Selection of an individual of one sex for mating by an individual of the other sex
Intrasexual selection
A type of sexual selection driven by competition among family members of one sex for an opportunity to mate
sexual dysmorphism
Any trait that differs between males and females
Sexual polymorphism
presence of two or more variant forms of a specific DNA sequence that occurs on males or females
Sampling error
Occurs when the allele frequencies of a chosen subset of a population are different from those in the total population
Vestigial trait
Reduced or incompletely developed structure that has no function
Transitional features
Traits in fossil species intermediate between ancestral and derived species
Law of succession
Fossil species that are similar to living species in the same geographical area
Selection
Differential reproduction as a result of heritable variation
Deleterious
Lower fitness alleles
Inbreeding depression
Decline in average fitness when homozygosity increases and heterozygosity decreases
How inbreeding influences evolution
Increases frequency of homozygous recessive individuals
Bottleneck effect
Natural disaster kills individuals non selectively causing drastic reduction in population size
Founder effect
Small number of individuals colonize new habitat and start new population
