Test 3 Flashcards
Founder effect
After being displaced, a small population evolves in new environment to become a distinct species
Allopatric speciation
May take place when a physical barrier is divides a large population (the ocean) or when a small population is displaced from their natural environment (frogs to Hawaii, for example)
Species cluster
A cluster of species related by a common ancestor
Hybrid zones
Locations where two separate populations may mate with each other after being separated for a short time. Prezygotic reproductive isolation must not be complete.
Reinforcement
When postzygotic reproductive isolation limits the offspring of species in hybrid zone, “finishing the job” and making the species distinct.
Parapatric speciation
Speciation occurring between adjacent populations as a result of a change in one populations environment.
Sympatric Speciation
Speciation that divides two subgroups of a single population into two different species
Dispersal
A form of disjunct distribution as a result of a small group of a population traveling from original habitat. Can result in allopatric speciation.
Biological species concept
The idea that individuals belong to the same species if their progeny are capable of reproduction under natural conditions.
Morphological species concept
The idea that all individuals of a species share measurable traits that distinguish them as individuals of that species.
Phylogenetic species concept
The idea that a phylogenetic species shares recent evolutionary history with other members.
Dobzhansky-Muller Model
The idea that changes in at least two loci are required to cause hybrid incompatibility, or at least a decrease in fitness between individuals from two ancestrally identical, but allopatric populations
Node
Branching point on a phylogenetic tree
Clade
Branch of phylogenetic tree
Monophyletic taxa (group)
Comprises only one clade, an ancestral species and all of its descendants, but no other species.
Paraphyletic taxa
A taxa that include an ancestor species and some, but not all, of its descendants
Polyphyletic taxa (group)
A phylogenetic tree the comprises of different clades, but not their common ancestor.
Linnaean system of naming
Binomial nomenclature. Is weak because of homoplasies (traits that evolved similarly but independently)
Define homology. Why is homology important for reconstructing evolutionary relationships? How do we evaluate whether two taxa share a trait that is homologous? Can we use non-homologous traits to construct phylogeny?
Homology are similar traits in species that were inherited from a common ancestor. Thus, tracking homologous traits is essential for constructing a phylogenetic tree. We evaluate the structure of the trait to determine if it is functionally derivative or simply yields a similar trait. We cannot use homoplastic traits to construct phylogeny, though they may appear.
Be able to use phylogenetic information to identify the source of emerging diseases. Describe what phylogenetic analyses of SIV/HIV phylogeny tell us about how often HIV has been transmitted to humans from non-human primates. 29 October.
The clade that infects chimpanzees includes HIV-1, and one of the clades that infect monkeys includes HIV-2. Thus, the two strains of HIV apparently originated in separate non-human hosts. Scientists suspect that the transmission to humans occurred multiple times when hunters who were butchering bush meat—chimpanzees in central Africa and sooty mangabey monkeys in West Africa— acquired the virus through cuts on their hands.
