Ch 24: Origin of Species Flashcards
What is the biological concepts?
a population or populations of organisms that are capable, or potentially capable of interbreeding with one another. Results of matings produce viable, fertile offspring.
What is reproductive isolation?
is the existence of biological factors (barriers) that impede two species from producing viable, fertile offspring
What are hybrids?
the offspring of crosses between different species (ex. donkey + horse = mule)
What are prezygotic reproductive barriers?
prevent or reduce the probability of mating ot fertilization
What are the four examples of prezygotic reproductive barriers?
habitat isolation, behavioral isolation, mechanical isolation, and temporal isolation
What is habitat isolation?
members of two populations evolve two different habitat preferences
What is behavioral isolation?
populations of one species evolve different courtship behaviors
What is mechanical isolation?
incompatibility of body structures which prevents mating
What is temporal isolation?
different timing of reproductive events
What are postzygotic reproductive barriers?
inability of hybrid zygotes to develop into a viable, fertile adult
What are the three examples of postzygotic reproductive barriers?
reduced hybrid viability, reduced hybrid fertility, and hybrid breakdown
What is reduced hybrid viability?
the offspring dies quickly
What is reduced hybrid fertility?
the offspring are fertile
What is hybrid breakdown?
low-quality offspring
What are the limitations of the biological species concept?
the biological species concept is difficult to apply to asexually reproducing organisms and situations where gene flow does occur between populations of distinct species
What are the three alternatives to the biological species concept?
morphological species concept, ecological species concept, and phylogenetic species concept
What is allopatric speciation?
populations become isolated from one another due to separation by a geographical barrier
What is sympatric speciation?
genetic isolation occurs without geographic isolation. Genetic isolation occurs as a result of “accidents” during cell division (ex autoploidy and allopalyploidy)
What is polyploidy?
presence of extra sets of chromosomes due to accidents during cell division (much more common in plants than in animals)
What is autoploidy?
an individual with more than two chromosomes sets, derived from a single species
What is allopolyploid?
a species with multiple sets of chromosomes derived from different species
What is a hybrid zone?
region where members of different species mate and produce hybrids
What are the three possible outcomes of a hybrid zone?
strengthening of reproductive barriers, weakening of reproductive barriers, and continued formation of hybrids
What is punctuated equilibrium?
speciation characterized by periods apparent stasis punctuated by sudden change
