Ch. 14/15

• Speciation is the process by which one species splits into 2 or more species.
• Biological species concept defines species as a group of populations whose members have the potential to interbreed
• A hybrid is the offspring of clearly distinct species that have interbred.
• Reproductive isolation prevents genetic exchange, maintains boundary between species, and prevents interbreeding.
• Morphological species concept is classification based mainly on physical traits and other features of morphology.
• Ecological species concept identifies species based on their ecological niches.
• Phylogenetic species concept defines a species as the smallest group of individuals that have a common ancestor.
• Reproductive isolation depends on one or more types of reproductive barriers.
• Prezygotic barriers are barriers that prevent mating/fertilization
• Habitat isolation is when there is a lack of opportunities to encounter each other.
• Temporal isolation is when breeding happens at different times or seasons.
• Behavioral isolation is when there is a failure to send or receive appropriate signals.
• Mechanical isolation is when there is physical incompatibility of reproductive parts.
• Gametic isolation is when there is molecular incompatibility of eggs and sperm/ pollen and stigma
• Postzygotic barriers are barriers that happen after hybrid offspring zygotes are formed.
• Reduced hybrid viability is when the interaction of parental genes impairs the hybrid's development/survival
• Reduced hybrid fertility is when hybrids are vigorous but cannot produce viable offspring
• Hybrid breakdown is when hybrids are viable/fertile but their offspring are sterile.
• Allopatric speciation is a type of geographic barrier that isolates a population.
• Sympatric speciation has no geographic barrier.
• Polyploid cells have more than 2 complete sets of chromosomes.
• Gene flow between populations can be reduced by polyploidy, habitat differentiation, and sexual selection.
• Self-fertilization happens within a species while hybridization happens between species.
• Habitat differentiation is when a sub-species separates from initial species using other resources in the habitat.
• Sexual selection is when one biological sex chooses mates of the other biological sex based on factors and other characteristics.
• Adaptive radiation is evolution of many diverse species from a common ancestor.
• Convergent evolution is a process where unrelated organisms have similar features and come from different ancestors.
• Hybrid zones are regions in which members of different species meet and mate.
• Reinforcement is when hybrid offspring are less fit than members of both parent species.
• Fusion is when reproductive barriers are weak and species come into contact in a hybrid zone. Increased gene under the circumstances of fusion results in the speciation process reversing and 2 hybridizing species to fuse into one.
• Punctuated equilibria is long periods of little apparent morphological change interrupted by brief periods of sudden change.
• Gradualism is when new species evolve gradually from the ancestral population.
• There are 4 main stages that made the origin of life possible on Earth.
• The first stage was the abiotic synthesis of small organic molecules (ex. amino acids/bases)
• The second stage of the origin of life was the joining of small molecules into polymers.
• The 3 stage of the origin of life is packaging the polymers into "protocells" to maintain an internal chemistry different from their environment.
• The 4 stage of the origin of life is the origin of self-replicating molecules that eventually made inheritance possible.
• Condition on early Earth included immense heat, thick atmospheres, and more intense lighting/radiation etc...
• Earliest evidence of life from fossils was 3.5 billion years ago but life in its simpler form came earlier.
• Stromatolites are rocks/ stepping stones that covered the shorelines of early earth that were built up by photosynthetic prokaryotes to create layered rocks.