Chapter 26 Flashcards
What is the genetic change taking place in a group of organisms?
evolution
What is evolution taking place in a single lineage over time?
anagenesis
What is the splitting of one lineage into two?
cladogenesis
What is the theory that proposes that much molecular variation is adaptively neutral (individuals with different molecular variants have equal fitness)?
neutral-mutation hypothesis
What is selection that maintains genetic variation?
balancing selection
What are different kinds or types of living organisms?
species
What is the widely used definition of a species that states that a species is a group of organisms whose members are capable of interbreeding with each other but are reproductively isolated from the members of other species?
biological species concept
What is any biological factor or mechanism that prevents gene exchange?
reproductive isolating mechanism
What are mechanisms that prevent gametes from two species from fusing and forming a hybrid zygote?
prezygotic reproductive isolating mechanisms
What is the isolation mechanism where species do not encounter one another?
ecological isolation
What is the isolation mechanism where species have differences in behavior that prevent interbreeding?
behavioral isolation
What is another type of isolation when reproductive activities do not take place concurrently?
temporal isolation
What is the isolation caused by anatomical differences?
mechanical isolation
What are isolations caused by gametes being unable to form zygotes?
gametic isolation
What are isolation mechanisms that see a lack of gene flow after the creation of a viable zygote?
postzygotic reproductive isolating mechanisms
What is a form of separation between species where a hybrid cannot complete development?
hybrid inviability
What is the form of separation where hybrids develop fully but are sterile?
hybrid sterility
What is the form of separation where species can reproduce, but they cannot continue to reproduce (F2 is either inviable or sterile)?
hybrid breakdown
What is the process by which new species arise?
speciation
What is the form of speciation caused by geographic barriers splitting populations?
allopatric speciation
What is the form of speciation that arises in the absence of any external barrier to gene flow?
sympatric speciation
What is the evolutionary relationships among a group of organisms?
phylogeny
What is a graphical representation of a phylogeny?
phylogenetic tree
What are the evolutionary connections in a phylogenetic tree?
branches
What are the points where the branches split (representing a common ancestor) in a phylogenetic tree?
nodes
What is a description of the phylogenetic tree where one node represents a common ancestor to all other nodes?
rooted
What are trees that depict the evolutionary relationships among DNA sequences?
gene tree
What is the time deduced from the number of molecular changes that a protein has gone through in a certain amount of time?
molecular clock
What is the process where exons of different genes are exchanged?
exon shuffling
What are groups of genes that are similar in sequence but encode different products?
multigene families
