Biogeography_and_Zoogeography Flashcards
Q: Biogeography vs zoogeography
Biogeography: the geographical distribution of plants and animals (over time).
Zoogeography: the geographical distribution of animals (over time).
Q: How is biogeography a source of evidence for evolution?
The geographic distribution of organisms on earth follow patters that are best explained by evolution in conjunction with the movement of tectonic plates over geological time.
Q: Factors affecting (changing) distribution of animals over time
continental drift
climates
longitude
altitude
topographic changes
introduction of artificial or natural barriers to dispersal
Q: Describe how Australia exemplifies what can happen in island ecosystems over time
Long isolation (due to island separation) is reflected by
- abundance of endemic species (typical of islands whose isolation by expanses of water prevents migration)
- over time, these species diverged evolutionarily into new species that look very different from their ancestors that may exist on the mainland
- the diversification of the marsupials
- the absence of other mammals
Q: Examples of island ecosystems isolated over time
- abundance of endemic species in Australia (details on separate card)
- abundance of endemic species on Madagascar (isolated for 88 M years; 90% of all plant & animal species on madagascgar are endemic)
- the finches on the Galapagos
Q: Zoogeographic regions
-Earth is divided into six regions based on the distinctive fauna present in each section.
-Nearctic, Neotropical, Palaearctic, Afrotropical, Oriental, Australasian
-Some scientists include two others- Antarctic, and Oceanic
-Proposed by Alfred Russel Wallace in 1876
-Has been the backbone for our understanding of global biodiversity.
-Regions largely delineate by what we now know as the continental plates.
-Each region possesses distinctive and uniform taxonomic groups, and some familes are shared between regions. Regions that were together longer before the continents separated share many types of species.
-Similar biomes in different zoogeographic regions usually have completely different species
Q: Continental Drift
The theory that continental plates are in constant motion and have changed their positions over time.
Theory proposed by Alfred Wegener in 1912
Proposed based on zoogeographic observions, but lacked explanation for the mechanism of drift
Q: Plate Tectonics
The theory that Earth’s cooler outer skin is divided into several plates that glide over the hot molten mantle. Continents rest on tectonic plates.
Proposed in 1960s as we started deep sea exploration
Q: Geological phenomena explained by plate tectonics
earthquakes
volcanic eruptions
mountain range formation
mid-ocean ridges
oceanic trenches
movement of the continents
Q: Pangea
A supercontinent formed during the late Paleozoic Era that included all current land masses.
Lasted millions of years.
Broke up around 175 MYA and drifted apart.
Q: Endemic vs. indigenous vs. native species
Native: found naturally in a particular area/ecosystem.
Indigenous: native, but also found elsewhere.
Endemic: native, and restricted to a certain country or area. Not found anywhere else.
Q: What were the landmasses that formed when Pangea broke apart?
Laurasia
- Land mass that broke away from Pangea and drifted north to form North America, Europe, and Asia
Gondwanaland
- A southern supercontinent, the remainder of Pangea that formed all southern continents, Antarctica, South America, Africa, Australia, subcontinent India, and part of southern Asia.
Pangea broke up about 175 MYA
Q: Why is one broad reason that some species distributed worldwide and some limited to certain continents?
- Animal species which were present before the breakup of the continents would be worldwide in their distributions (e.g., opossums are found in North and South America; this was an early marsupial that evolved before the split)
- As continents separated and species became isolated, their distributions were limited only to those regions
- Populations can be separated by barriers, which may lead to the evolution of subspecies if groups remain isolated over long periods of time, and new species over millions of years.
Q: Two reasons a species may be endemic to a region
- Vicariance - they have always been there; they descended from ancestors that inhabited the same region.
(The ancestral population may divide into subpopulations when a barrier appears that they cannot cross. Through natural selection, there was a change in these two subpopulations; given enough time, these two separated subpopulations evolve into two different species.) - Dispersal - the ancestral species originally occurred somewhere else and later dispersed into new ranges resulting in isolation from an original population. Dispersal may be affected by resources, climate, etc.
