AP biology: 24 origin of species Flashcards
(35 cards)
Darwin explored the Galápagos Islands
And discovered plants and animals found nowhere else on Earth
The origin of new species
or speciation
Macroevolution
Refers to evolutionary change above the species level
A species is
a population or group of populations
whose members have the potential to interbreed in nature and
produce viable, fertile offspring
unable to produce viable fertile offspring with members of other populations
Reproductive isolation
Prevents organisms from producing offspring
Is a combination of various reproductive barriers
Prezygotic barriers
Prevent mating or fertilization of ova from two different species
Postzygotic barriers
Often prevent the hybrid zygote from developing into a viable, fertile adult
The biological species concept cannot be applied to
Asexual organisms
Fossils
Organisms about which little is known regarding their reproduction
Speciation can take place with or without
geographic separation
Speciation can occur in two ways
Allopatric speciation
Sympatric speciation
In allopatric speciation
Gene flow is interrupted or reduced when a population is divided into two or more geographically isolated subpopulations
Once geographic separation has occurred
One or both populations may undergo evolutionary change during the period of separation
In sympatric speciation
Speciation takes place in geographically overlapping populations
Polyploidy
Is the presence of extra sets of chromosomes in cells due to accidents during cell division
Has caused the evolution of some plant species
An autopolyploid
Is an individual that has more than two chromosome sets, all derived from a single species
An allopolyploid
Is a species with multiple sets of chromosomes derived from different species
Sympatric speciation
Can also result from the appearance of new ecological niches
In cichlid fish
Sympatric speciation has resulted from nonrandom mating due to sexual selection
In allopatric speciation
A new species forms while geographically isolated from its parent population
In sympatric speciation
The emergence of a reproductive barrier isolates a subset of a population without geographic separation from the parent species
Adaptive radiation
Is the evolution of diversely adapted species from a common ancestor upon introduction to new environmental opportunities
The Hawaiian archipelago
Is one of the world’s great showcases of adaptive radiation
Niles Eldredge and Stephen Jay Gould
Used fossils to develop theory
describe these periods of apparent stasis punctuated by sudden change
The punctuated equilibrium model
Contrasts with a model of gradual change throughout a species’ existence