Final Exam Flashcards
Speciation
The process by which one species splits into two species
Microevolution
Changes in allele frequency in a population over time
Macroevolution
Broad patterns of evolutionary change above the species level
How do new species originate from existing species
Over time, populations of a single species connected by gene flow can diverge genetically, giving rise to a new species
Reproductive isolation results when
biological barriers impede members of two species from interbreeding and producing viable, fertile offspring
Zygote
the diploid cell produced by the union of haploid gametes during fertilization
Prezygotic barriers: Habitat Isolation
Two species that occupy different habitats within the same area may encounter each other rarely, if at all
Prezygotic barriers: Temporal Isolation
Species that breed at different times of the day, in different seasons, or in different years cannot mix their gametes
Prezygotic barriers: Behavioral Isolation
Courtship rituals and other behaviors unique to a species are effective barriers to mating
Prezygotic barriers: Pollinator Isolation
Species of plant that attract different types of pollinators have a barrier to reproduction
Prezygotic barriers: Mechanical Isolation
Mating is attempted but morphological difference prevent its successful completion
Prezygotic barriers: Gametic Isolation
The sperm of one species may not be able to fertilize the eggs of another species
Postzygotic Barriers: Reduced Hybrid Viability
Genes of different parent species may interact in ways that impair the hybrid’s development or survival in its environment
Postzygotic Barriers: Reduced Hybrid fertility
Meiosis may fail to produce normal gametes, resulting in sterility, if the parent species have chromosomes of different numbers of structure
Postzygotic Barriers: Hybrid Breakdown
First Generation hybrids are viable and fertile, but offspring in the next generation are feeble or sterile
Speciation
the formation of a new species over geological time
Geographic Isolation
process of which the evolution of new species
Allopatric Speciation
over time, the populations become so different that they cannot interbreed and they evolve into new species
Geographic separation
creates two populations who are isolated from each other and result to no genetic exchange can occur between them
Divergence
involves accumulation of independent genetic differences between groups
Sympatric speciation
the evolution of new species without geographic isolation
Factoes that reduce the gene flow
- polyploidy
- sexual selection
- habitat differentiation
Polyploidy
the presence of extra set of chromosome that can accidentally occur during cell division
Drivers of sympatric speciation: Polyploidy
- Can form a new species within a single generation without geographic separation
Drivers of sympatric speciation: Habitat Differentiation
- result from the exploitation of new habitats or resources
