macroevolution- 8.5 Flashcards
macroevolution
large-scale evolutionary changes
includes periods of stasis, character change, speciation and extinction events
evidence of macroevolution comes from
fossils
comparisons from living organisms
diversification/diversification events definition
an increase in speciation events and biodiversity on Earth (groups of organisms undergo divergent evolution as they move to occupy many ecological niches)
cambrian explosion
the biggest diversification event on earth
541 million years ago, start of the cambrian period, most of the major animal phyla are first seen in the fossil record
mass extinction definition/explanation
rapid and widespread decrease in biodiversity on Earth
99.999% of all species on Earth have gone extinct
there have been 5 mass extinction events in Earth’s history
gradualism (gradualism vs. punctuated equilibrium)
evolution occurs due to the gradual accumulation of small changes
punctuated equilibrium (gradualism vs. punctuated equilibrium)
evolution consists of long periods of “stasis” by rapid periods of change
cladistics
determining evolutionary relationships based on the presence or absence of recently evolved (derived) traits
synapomorphy
a derived trait shared by two or more species