Please enable JavaScript.
Coggle requires JavaScript to display documents.
The Origin of Species and The History of Life on Earth - Coggle Diagram
The Origin of Species and The History of Life on Earth
Reproductive Isolation
The existence of biological factors (barriers) that impede members of two species from producing viable, fertile offspring
biological species concep
t is based on the potential to interbreed, not on physical similarity
*limited to what it can be applied to
*prevent gene flow and limit formation of hybrids
prezygotic barriers
reproductive barrier that blocks fertilization from occurring
postzygotic barriers
may contribute to reproductive isolation after the hybrid zygote is formed
morphological species concept
distinguishes a species by body shape and other structural features
ecological species concept
defines a species in terms of its ecological niche, the sum of how members of the species interact with the nonliving and living parts of their environment
allopatric speciation
populations are geographically isolated VS
sympatric speciation
populations are NOT geographically isolated, but are not longer able to reproduce
sypatric speciation
occurs if gene flow is reduced by -polyploidy -sexual selection -habitat diferentation
Hybrid Zones
a region in which members of different species mate and produce hypbrid offspring
if hybrids do NOT become reproductively isolated from their parent species these are possible
reinforcement
hybrids are less strong than parent species, reduces hybrid production
fusion
there can be substaintial gene flow between species if hybrids are as fit as their parents
stability
extensive gene flow from outside the hybrid zone can overwhelm selection for increased reproductive isolation inside the hybrid zone (hybrid out # the parents)
Early Earth
Origins -reduced atmosphere -no oxygen
small organic molecules formed, molecules joined into macromolecules
first genetic material, self replicating
FOSSILS and MOLECULAR DATA give us this information
Major Milestones
-prokaryotes -oxygen -Eukaryotes -Multicellular eukaryotes -Cambrian Explosion -Colonization of Land -Tetrapods
BIG Changes over time
Continental Drift
leads to altered habitats, climate change, allopatric speciation
Mass extinction wiping out 50% of species
Adaptive Radiation: Rapid speciation following mass extinctions