Macroevolution Flashcards
(40 cards)
What is adaptive radiation?
The rapid diversification of a lineage into many species, each adapted to different ecological niches.
Define mass extinction.
A relatively short interval of geological time in which a very large percentage of species go extinct globally.
What role does continental drift play in macroevolution?
It reshapes habitats and geographic barriers, driving speciation and extinction by isolating or connecting populations.
What is co-evolution?
Reciprocal evolutionary change in interacting species (e.g., predator–prey, host–parasite, mutualists).
What are homeotic genes?
Genes that regulate the development of anatomical structures, determining the identity of body parts.
What is the estimated total number of species on Earth?
Around 15 million.
What percentage of terrestrial species remain undescribed?
About 86%.
What is a “living fossil”? Give an example.
A species that has persisted with little change over geological time, e.g., the coelacanth.
What triggered the Great Oxygenation Event?
Photosynthetic cyanobacteria releasing oxygen into the atmosphere around 2.4 billion years ago.
Name the “Big Five” mass extinctions and their approximate ages.
Ordovician (~500 MYA), Devonian (~350 MYA), Permian (~250 MYA), Triassic (~180 MYA), Cretaceous–Paleogene (~65 MYA).
What caused the end-Cretaceous (K–T) extinction?
Likely a combination of a giant meteorite impact and volcanic activity (Deccan Traps) around 66 MYA.
How did mammals survive the K–T event?
Their burrowing habits and diets (roots, invertebrates) buffered them against harsh surface conditions.
What is the Holocene (Sixth) Mass Extinction?
The ongoing, human-driven loss of species since the start of the Holocene epoch.
List three human activities driving the Sixth Extinction.
Overharvesting, deforestation, habitat fragmentation.
What is Wallace’s Line?
A biogeographic boundary separating Asian and Australasian faunas in Southeast Asia.
Who proposed continental drift and when?
Alfred Wegener, in 1912.
Why does continental drift produce disjunct species distributions?
Formerly contiguous landmasses separated, isolating populations.
During which period did trilobites flourish?
Ordovician (~500 MYA).
What are Pleistocene refugia?
Areas where species survived glacial maxima, such as southern European peninsulas.
Define “southern richness, northern purity.”
Post-glacial recolonization yields higher genetic diversity near refugia and lower diversity in newly colonized areas.
How many major ice ages have occurred?
At least five.
What was the Last Glacial Maximum?
The peak of the Pleistocene glaciation around 18,000–20,000 years ago.
Give one genetic consequence of ice-age-driven refugia.
Population bottlenecks that reduce allelic diversity in recolonized regions.
What is adaptive radiation following mass extinction called?
Competitive release.
