REVIEW FOR CUMULATIVE FINAL Flashcards
Homology
forms related by common ancestry as a result of divergent evolution
Homologous structures
Structures derived by a common ancestor but they may be modified for different function
Convergence
unrelated species have similar adaptations due to being under similar environmental conditions
Allele
one of a number of alternate forms of a DNA sequence at a specific physical location of a gene on a chromosome
Morphological species concept
Organisms that have significant and anatomical differences are different species
Biological species concept
members of the same biological species:
- share the same gene pool
- have gene flow between two populations
- are reproductively isolated from other spp. by biological barriers
Temporal isolation
species have different breeding schedules
Habitat isolation
members of species move or are otherwise seperated (cant mate because they do not meet)
Behavioral isolation
certain actions or behaviors impact reproduction
- gametic isolation where differences in gametic cells prevent fertilization
- mechanical isolation where incompatibility is due to sexual organs
Hybrid in viability
nonviable embryo is produced
Hybrid sterility
produces off spring but they hybrid cannot produce off spring
Hybrid break down
2nd generation of hybrids are feeble or sterile
Genetic variation
new genes and alleles arise by mutation or gene duplication
Microevolution
a change in allele frequencies in population over generations
Relative fitness
reproductive success of individuals and is relative to other individuals in the population.
Directional selection
one extreme phenotype is more fit than the others phenotypes. Shifts variance towards the new and more fit phenotype
Diversifying / Disrupted selection
both extreme phenotypes are more fit than those in the middle. This maintains diversity and increases genetic variance
Stabilizing selection
intermediate phenotype is considered more fit than the extreme ones. This then decreases genetic variance
Mechanisms of microevolution
- natural selection
- genetic drift (founder effect / bottleneck effect)
- Gene flow
Natural selection
- acts non-randomly on phenotypes of individuals
- always leads to adaptation of population
Genetic Drift
- genetic frequency changes due to random events
- often occurs in small populations
- often reduces genetic diversity
- allele may become fixed while others are lost
Gene flow
alleles move in/out of a population
- tends to add genetic diversity to one population
- overall reduces the genetic differences between both populations