SPECIATION Flashcards
Specere
“Kind”
“Appearance”
Modern classification system
Evolutionary history
Morphological and genetic characteristics
Its relatedness to other organisms
Organisms evolving independently and distinctly from other groups
Species
Scientists that built upon Darwin’s understanding of species by establishing INTERBREEDING as criteria (2)
Theodosius Dobzhansky
Ernst Mayr
When was Darwin’s origin of species?
1859
A group of individuals capable of mating and producing fertile offspring
Species
Species factors (2)
Individuals interbreed and produce fertile offspring only among themselves
members of each species resemble each other and are structurally different from other species
T or F: change in gene frequency constitutes speciation
False: It is considered evidence of evolution but does not constitute speciation
Concept that states” A species is a population or group of populations that are able to INTERBREED, under NATURAL CONDITIONS, to produce FERTILE OFFSPRING
Does not apply to all life forms*
Biological species concept
Process by which an ancestral species splits into 2 or more new species.
New species develop unique characteristics
Speciation
Three main stages of speciation
Separation - original species split into two or more groups w/ no interbreeding and cut gene flow
Divergence - independent accumulation of heritable mutations and reproduction of individuals upon heritable traits
Isolation - maintained when groups reunite and unable to breed and produce viable offspring
Types of isolation (2)
Premating isolation
Postmating Isolation
Types of Natural Speciation (4)
Allopatric speciation - result of physical separation
Peripatric speciation - subform of allopatric speciation very small
parapatric speciation -slow process by which populations separate by occupying different niches
Sympatric speciation - formation of new species from populations of original species that occupy the same geographical location
Occurs when scientists separate members of the same species into populations that form distinct species from selective breeding
Artificial speciation
Greek words for Allopatric speciation
other + fatherlands
Steps of allopatric speciation: (4)
Geographic barrier physically separates populations of the original species
Populations accumulate heritable mutations and experience selective pressures
Two populations become increasingly divergent until reproductively incompatible
Speciation is complete when interbreeding with fertile offspring is no longer possible
When small groups of individuals break off from the larger group and form a new species
one group is much smaller than the other
unique characteristics of the smaller groups are passed onto future generations
Peripatric speciation
Spatially segregate habitats
Maintain a zone of contact and do not cease the exchange of genes completely
Adjacent populations evolve into distinct species while maintaining contact along a common border
Parapatric speciation
Greek words for Sympatric speciation
Together + fatherlands
Speciation that occurs in the same area
Sympatric speciation
The fertilization of the egg produces a _____ and allows us to distinguish between _____ (before the fertilized egg) and _____ (after the fertilized egg)
zygote
prezygotic
post-zygotic
Separation of different species to keep them from creating offspring by preventing the gametes from forming a zygote
Prezygotic
Occurs after gametes have made a zygote through fertilizing the egg, isolates after
Postzygotic
Prezygotic isolation mechanisms (5)
Spatial isolation - physical distance
Temporal isolation - reproductive timing
Mechanical isolation - lack of fit between sex organs
Gametic isolation - lack of compatibility of gametes
Behavioral isolation - mating rituals or behaviors
