Macroevolution Flashcards
How are micro- and macroevolution typically distinguished? In what way is speciation important in this discussion?
Micro-within a population
Macro- changes above the species level
Speciation is the link between these two concepts
What is the basic question of the long-term role of directional natural selection in evolutionary trends?
Do we see trends in phenotypic changes through time?Are certain directions of change favored in the long run?
How does this relate to Gould’s left wall of biocomplexity?
Gould’s left wall refers to the trend of increasing complexity over time
What are some ways that passive and driven trends are distinguished?
Driven- both ends of the distribution change in the same direction
Passive- the minimum remains unaltered
What is Cope’s Rule, and do the basic observations that spawned it support a widespread driven trend across animal taxa?
Cope’s rule- observation that body size appears to increase in lineages over time
What are the some of the basic questions asked about macroevolutionary patterns of diversity?
How has biodiversity changed over the history of life? Are there patterns of diversity that are indicative of macroevolutionary phenomena? Has diversity been steadily increasing? Did it saturate early? As the taxonomic composition of diversity changed, did diversity stay constant or were there major changes?
What determines the diversification rate of lineages?
The balance between speciation rate and extinction rate
Why have marine invertebrates been important to this field?
Marine invertebrate fossils are very abundant and provide a very complete picture of the fossil record
What are extinction rates and (in basic terms) how are they calculated?
The proportion of geological lifespans that end over a given time interval
What are mass extinctions and why are they important in understanding macroevolutionary patterns?
Period with a high rate of extinction associated with major shifts in fauna and restructuring of biosphere
What were some of the causes and consequences of the two mass extinctions we discussed specifically?
K-pg extinction- giant asteroid, ended the Cretaceous period/160 million years of terrestrial vertebrae dominance
Permian-Triassic extinction- widespread, dramatic environmental change, likely due to massive volcanism (Siberian traps). 96% of animal species died, followed by slow recovery in Triassic
What are the two basic models for how the taxonomic composition of diversity can shift? What are some examples of each that we discussed (one came up in a later lecture)?
Biotic exchange and punctuated equilibrium
Why do some lineages become numerically dominant following mass extinctions? What does this say about the deterministic nature of macroevolution? Was the evolution of human inevitable?
A particular species may have a number of traits that puts it at an advantage following a mass extinction. This illustrates that macroevolution is deterministic, as it is due to external/environmental forces. Human evolution was not inevitable
What is the punctuated equilibria model? What does it attempt to describe? What other concepts from class does it relate to?
A model that features periodic increases in diversity followed. Attempts to describe the lack of diversity in the fossil record as opposed to what may be expected. Wright’s Shifting Balance Theory is similar
What is convergent evolution and what does it potentially tell us about the long-term role of natural selection in macroevolution?
Organisms from different clades develop similar traits due to natural selection favoring those traits. ie marsupial/placental comparisons
