Exam 1 Flashcards
Descent with Modification
Species that lived in the past are the ancestors of the species existing today and that descendant changes through time
Population thinking
Variation among individuals in a population is the key to understanding the nature of species(Darwin)
Fossil
Trace of an organism that lived in the past
Fossil record
Consist of all fossils that have been found
Extant
Species living today
Transitional feature
Trait in fossil species that is intermediate between those of older and younger species
Vestigial trait
Reduced or incompletely developed structure that has no function or reduced function
Phylogeny
Family tree of population or species
Homology
“Study of likeness” similarity that exists in species because they both inherited the trait from a common ancestor
Biological fitness
Ability of an individual to produce surviving offspring
Acclimation
Changes in individual phenotype that occur in response to changes in environment
Genetic correlation
Constraint caused by pleiotropy(single allele affects multiple traits)
Fitness trade-off
Compromise between traits in terms of how those traits perform in the environment
Mechanisms that shift allele frequencies
Natural selection
Genetic drift
Gene flow
Mutation
Gene pool
All gametes produced in a generation and combine at random to produce offspring
Hardy-Weinberg principle
No trend toward both alleles reaching frequency of 0.5
Hardy-Weinberg rules
1) no natural selection
2) random allele frequency changes
3) no gene flow
4) no mutation
5) random mating for gene in question
Genetic variation
Number of relative frequency of alleles present in a particular population
Directional selection
Average phenotype of the populations change in one direction
Purifying selection
Disadvantageous alleles decline in frequency
Stabilizing selection
Reduce both extremes in a population, no change in average trait and genetic variation reduced
Disruptive selection
Favors phenotypes on the extreme
Heterozygote advantage
Heterozygous individuals have higher fitness than homozygous
Balancing selection
No single allele has a distinct advantage and increases in frequency
Frequency dependent selection
When alleles are favored when rare but not common
Genetic drift
Any change in allele frequencies on a population due to chance
Sampling error
Allele frequencies change due to blind luck
Genetic marker
Specific allele that causes a distinctive phenotype
Founder effect
Change in allele frequencies by occurs when a new population is established
Genetic bottleneck
Sudden reduction in numbers of alleles in a population
Gene flow
Movement of alleles from one population to another
Mutation
Change in genetic code
Deleterious
Alleles that lower fitness
Beneficial
Allele that allows individuals to produce more offsprig
Interbreeding depression
Decline in average fitness takes place when homozygosity and heterozygosity decrecreses
Sexual selection
Individuals within a population differ in their ability to attract mates
Territory
Area actively defended as provides exclusive use by owner
Sexual dimorphism
Any trait that differs in males and females
