Unit B Evolution Flashcards
evolution is when…
the same species exposed to different environmental pressures can become so genetically different that they can no longer interbreed
______ is the mechanism by which evolution occurs.
natural selection
Jean baptise lemark proposed the theories of
Use and Disuse / Inheritance of Acquired Characteristics (1809)
the theory of use and disuse and Acquired Characteristics suggested
organs that were well developed from use would be passed onto offspring in the well-developed form
Charles Darwin
Credited with the theory of natural selection or “survival of the fittest”
the five aspects of the theory of natural selection are…
Adaptation and Natural Selection
Overproduction
Population Speciation
Gradualism
Descent with Modification
Speciation refers to the process by which…
new species are formed.
the two types of speciation is
Transformation: one species evolves into another
Divergence: a parent species evolves into more than one other species
geographic barriers are..
barriers that isolate populations and prevent them from reproducing
geographic barriers lead to…
Allopatric Speciation
reproductive barriers lead to..
Sympatric Speciation
Reproductive barriers occurs when…..
species within populations no longer mate to produce fertile offspring
reproductive barriers that occur before mating and are called
Prezygotic
reproductive barriers that occur after mating and are called
Postzygotic
Prezygotic reproductive barriers include…
Habitat: they live in different locations, areas, spaces
Temporal: breeding or activity at different times of day/season/year
Behavioural: songs, calls, or dances are not shared or recognized
Mechanical: structures are not compatible
Gametic: sperm is not able to penetrate the egg (anatomically incompatible)
Postzygotic reproductive barriers include…
Zygote Mortality: when an egg is fertilized, but the zygote or embryo dies
Hybrid Inviability: if a first generation hybrid offspring is born, but shows low fitness it may not make it to the age of being able to reproduce
Hybrid Sterility: when the hybrid offspring grows to breeding age, but is incapable of gamete formation.
Divergent Evolution describes….
two or more species that originate from a common ancestor. May happen as a result of:
Adaptive radiation
Geographic isolation
Reproductive isolation
Homologous Structures suggest
a common ancestor
Convergent Evolution describes…
unrelated species that share similar traits due to exposure to similar ecological conditions or selection pressures