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Speciation
the process of one species splitting into two— it connects microevolution to macroevolution
Biological Species
Group of populations whose members have the potential to interbreed in nature and produce fertile offspring
Morphological
Body shape and structural features
Two methods of speciation
Allopatric and sympatric speciation
Allopatric speciation
Population becomes isolated which cuts off the gene flow— Genetic divergence— Reproductive isolation
Sympatric speciation
due to a reduction in mating/gene flow
Biological species Concept
Group of populations whose member have the potential to interbreed in nature and produce a fertile offspring
Two types of reproductive barriers
Prezygotic barriers and postzygotic barriers
Prezygotic Barriers
Block fertilization from occurring
Postzygotic Barriers
Occurs after a hybrid zygote is formed
prezygotic barrier- Habitat isolation
Two species encounter each other rarely because they occupy different habitats
Prezygotic barriers- Temporal isolation
Species that breed at different times of the day, different seasons, or different years
prezygotic- Behavioral isolation
Courtshio rituals
Prezygotic — Mechanical Isolation
Morphological differences
Prezygotic— Gametic Isolation
Sperm cannot fertilize ( biochemical)
Postzygotic— Reduced Hybrid viability
Genes of different parent species may impair the hybrids development or survival
Postzygotic— Reduced Hybrid Fertility
Hybrids may be sterile
Postzygotic— Hybrid breakdown
Hybrids may be fertile, but their subsequent offspring are sterile
Morphological Species Concept
Focuses on body shape and structural features
Ecological species
Focuses on a species niche, can accommodate asexual and sexual organism
Hybrid zone
region where different species mate creating hybrids but some have reduced fitness— shifts with environmental changes