Lecture 21: Biodiversity & Global Ecology: Global biodiversity & history Flashcards
define biodiversity
variation among ecological systems at all scales
Biodiversity research is especially focused on explaining how the ___________________ of organisms in ecological systems ___________________________
- abundance and richness
- changes across the planet
Gradients of global plant diversity - What global patterns of biodiversity can we identify?
- Strong latitudinal gradients in biodiversity
- At the same latitude, different regions do not all have the same level of biodiversity
Gradients of biodiversity for different organisms in the same location (North America)
All have a general latitudinal gradient, but lots of variation in diversity at the same latitude within and across different organisms
Why are there so many species in the tropics? - historical perspective
- “museum” hypothesis
- “cradle” hypothesis
“museum” hypothesis
Biodiversity accumulates without limits, and the tropics are older and have more time to accumulate species
“cradle” hypothesis
Diversity reaches an equilibrium that is higher in the tropics
Why are there so many species in the tropics? - modern view
- Biodiversity accumulates over time, but rates of accumulation can vary by region, latitude, and age of that group
- The biodiversity in any one place is a balance between the historical accumulation of species and the equilibrium from abiotic and biotic interactions
On short time-scales, _____________ of colonization and local extinction ___________ from the _________________________
- local processes
- sort species
- “regional species pool”
Biodiversity of the ________________________ is ultimately constrained by the number of species that have ________________________________
- regional species pool
- evolved in the region and have yet to go extinct
___________________ that influence __________________________ at biogeographical scales are ____________________________________
- Historical processes
- species production and extinction
- critical for understanding present-day biodiversity
Major influences on historical species accumulation
- time
- landmass size and location
- isolation
- historical climate change (major but slow shifts)
Major influences on historical species accumulation - time
More time allows more species to be produced and accumulate
Major influences on historical species accumulation - landmass size and location
More area allows more opportunity for speciation
Major influences on historical species accumulation - isolation
Facilitates speciation and independent evolution
Major influences on historical species accumulation - Historical climate change (major but slow shifts)
Drives large-scale changes in the other influences (time, landmass size and location, isolation)
Life remained ___________________________, and __________________ were strikingly ___________________
- basic for most of earth’s history
- ecological systems
- different from today
_______________________ produced ______________________________________ – the original ecosystem engineers
- Photosynthetic microbes
- oxygen byproduct that shifted the atmosphere
_____________________ made ______________________________ forms possible
- Atmospheric oxygen
- more complex metabolism and life
______________ cell is the product of the ____________________________
- Eukaryotic
- last billion years of evolution
____________________ phyla appeared about _______________________ – arthropods (e.g., crabs), mollusks (e.g., snails), brachiopods (e.g., clams), echinoderms (e.g., sea stars)
- Modern invertebrate
- 540 million years ago
Diversification of ___________ has proceeded mostly________________ for about the ____________________ (after dinosaur extinction)
- modern groups
- uninterrupted
- last 65 million years
because of diversification of modern groups being mostly uninterrupted, __________________________________________________ are therefore ___________________________________
- Modern species pools and ecological systems
- composed of life that accumulated in this relatively recent time frame
Major __________________ have had their own ________________ that have further ________________________________
- geographical regions
- more recent histories
- influenced speciation and extinction
what is reflected in modern biodiversity patterns?
Regional histories and interactions between regional biodiversity in the last 65 million years
Landmass area and location ________ to determine species accumulation
interact
_________ land masses generally allow for ____________________, but area being equal, __________ of landmass determines __________________________________ – for all the reasons we know about in hot, wet locations
- Larger
- more species to evolve and coexist
- location
- climate and rate of species accumulation
define microevolution
change over time within a population
define macroevolution
evolutionary change that results in the production of new species
two contrasting modes of speciation
- Sympatric speciation
- Allopatric speciation
define sympatric speciation
The evolution of new species within a population, without any geographical isolation
Sympatric speciation - especially important in what?
Especially important in contributing to species accumulation in highly productive (hot and wet) regions
define allopatric speciation
The evolution of new species via geographic isolation of subpopulations
Allopatric speciation - geographical isolation
“Geographical isolation” may actually be on very small scales for many organisms, so landmass changes can cause many fine-scale isolation barriers
_________________ followed by __________________________ in distinct ecological niches results in sympatric speciation
- Disruptive selection
- reinforcing reproductive isolation
_________________ in isolated locations _______________________________, results in allopatric speciation
- Directional selection
- reinforced by reproductive isolation
define vicariance
the splitting of a widely distributed ancestral population by continental drift or other major geological barrier to dispersal
vicariance - what does it “seed”?
new landmasses with similar diversity
__________________ evolution created ______________________________
- Subsequent independent
- divergent patterns of biodiversity
After vicariance, __________________ between long-isolated regions can drive ___________________________
- new connections
- radical changes in biodiversity
Vicariance example: Army ants and Driver ants - _______________________________________ with rudimentary version of raiding behavior, followed by _____________________________ of similar complex biology on different continents
- Similar biology is from common ancestor
- vicariance and remarkable convergent evolution
the major zoogeographical regions are based on what?
based on the distinct distributions of modern animals
The distributions of animals reflect ______________________________ followed by ______________________________________
- historical, biogeographical separation
- accumulated influences of more modern interactions
What major, and fairly modern land-connection event shaped North and South American biodiversity that we see today?
The isthmus of Panama and the great American interchange between north-south America
The land-bridge between north and south American, known as the ________________, stabilized about 3 million years ago
Isthmus of Panama
Isthmus of Panama ___________ areas that had been _________________________________
- reconnected
- largely isolated for tens of millions of years
Allowed _____________________ and exchange of organisms that had _______________________________ – “great American interchange”
- large scale movement
- evolved in isolation from each other
The exchange was ________: more north American lineages successfully spread south than vice versa
uneven
Many distinct _______________________________, including many marsupial lineage
South American lineages went extinct
Cats (felids) are a __________________________ that persisted in the north and ____________________________________
- North American lineage
- invaded South America and diversified
50-35 mya, large parts of _________________ were covered in tropical forests and _____________ had rich temperate forests
- North America
- Antarctica
With climate shift, ________________________, creating distinct temperate and tropical biotas
cold intolerant taxa retreated to the south
Historical stratification (distinct zones) of climate are matched by what?
stratification of biodiversity
About 2mya, gradual cooling of the earth drove large climate oscillations – the __________
ice age
Expansion of range ice retreat, but different tree groups ____________________ to the retreat of the ice, resulting in _____________________________________
- responded differently
- distinctly different present-day distributions
