Topic 8 Flashcards
What is broad patterns of evolutionary change above species level?
Macroevolution
What is the Biological Species Concept?
A species consists of a group of actually or potentially interbreeding individuals
What are two limitations of the Biological Species Concept?
i) Cannot be applied to fossils or asexual organisms
ii) It emphasizes the absence of gene flow
What concept defines a species by structural features?
Morphological species concept
What is the ecological species concept?
A species is a set of organisms adapted to a particular set of resources, called a niche, in the environment
What concept defines a species as the smallest group of individuals on a phylogenetic tree?
Phylogenetic species concept
T/F: The biological species concept emphasizes reproductive isolation
True
What is reproductive isolation?
The existence of biological factors that impede two species from producing viable, fertile offspring (hybrids)
What do you call offspring of crosses between different species?
Hybrids
What do prezygotic barriers do?
They block fertilization from occurring
What are the five prezygotic isolation mechanisms?
i) Habitat isolation
ii) Temporal isolation
iii) Behavioral isolation
iv) Mechanical isolation
v) Gametic isolation
What type of isolation occurs when two species encounter each other rarely or not at all because they occupy different habitats?
Habitat isolation
What is temporal isolation?
Species that breed at different times of the day, seasons, or years cannot mix their gametes
What type of isolation occurs when courtship rituals and other unique behaviors create barriers?
Behavior isolation
What is mechanical isolation?
Morphological differences that prevent mating
What is gametic isolation?
When the gametes of one species may not be able to fertilize eggs of another species
What are postzygotic barriers?
They prevent a hybrid zygote from developing into a viable, fertile adult
What are the three types of postzygotic barriers?
i) Reduced hybrid viability
ii) Reduced hybrid fertility
iii) Hybrid breakdown
What is reduced hybrid viability?
Occurs when genes of the different parent species may interact and impair the hybrid’s development
What process describes hybrids that are sterile?
Reduced hybrid fertility
What occurs when some first generation hybrids are fertile but when they breed the next generation are feeble or sterile?
Hybrid breakdown
What are the two ways speciation occurs?
i) Allopatric speciation
ii) Sympatric speciation
What is allopatric speciation?
Occurs when gene flow is interrupted when the population is divided into geographically isolated subpopulations
What are two ways allopatric speciation occur?
i) Dispersal: results in the establishment of a new and distant population
ii) Vicariance: the range of a species is split by a change in the environment
What is sympatric speciation?
Takes place in geographically overlapping populations if individuals in the subgroup stop mating with individuals of the larger population
Sympatric speciation can occur by three factors. What are they?
i) Polyploidy
ii) Habitat differentiation
iii) Sexual selection
What is polyploidy?
It is the presence of extra chromosome sets due to errors during cell division
What is the result of a polyploidy?
It can produce new sympatric biological species within a single generation
What is the difference between an autopolyploid and an allopolyploid?
An autopolyploid is an individual with multiple chromosome sets derived from one species and an allopolyploid is a species derived from different species
What is habitat differentiation?
Sympatric speciation resulting from the appearance of new ecological niches
What is sexual selection?
It involves the evolution of traits that increase an individual’s access to members of the opposite sex
What do you call a region in which members of different species mate and produce hybrids?
Hybrid zone
What are the three outcomes of hybrid zones?
i) Reinforcement: of barriers occurs when hybrids are less fit than the parent
ii) Stability: continued formation of hybrid individuals
iii) Fusion: weakening reproductive barriers
What are the two patterns for the rate of speciation seen in fossil records?
i) Punctuated equilibrium
ii) Gradualism
