Zoogeography Flashcards
Define cosmopolitan
Found in many places or areas
Define endemic
Found in only one place
Define disjunct
Found in several seemingly unrelated areas
Define biogeographic realm
Areas of land or water that correspond with particular fauna or flora
Define vicariance
The result of one population that separated
Define dispersal
Ancestor of a group moved to another place
How do plate tectonics and historical positions of continents explain fresh and marine fish distributions?
Disjunct distributions of fish used to confuse fish scientists. Before 1960, the idea of a continental drift was not widely accepted but dispersal via land bridges was more accepted. This means that fish that are disjunct had to be explained by a terrestrial ancestor who moved via land bridge. Once continental shift was accpected, vicariance was used to explain disjunct distributions: a once continuous distribution was disturbed/altered by geographic barriers (continental drift). Plate tectonics explains that deep ocean ridge rocks spread apart causing the plates to move, which are holding the continents. Continents were once all connected during the Permian in a land mass called Pangea. They have since drifted which explains the disjunct distribution of organism we sometimes see on different continents.
A fish example would be the African/Asian elephant fishes which are disjunctly distributed. The three hypotheses are that they 1) dispersed when the continents were connected as water from India carried fish into Asia, 2) there was a continuous population in Africa and Asia, or 3) recent dispersal over land from Africa to Asia. There is no modern day dispersal of freshwater fish across continents.
What % of all fish are marine?
50%
Where are marine fish the most diverse?
The greatest diversity of marine fish is in the tropical shallows, such as the Caribbean. Being near the continents/shore, tropics, and the surface allows for more nutrients, productivity, light, a bigger temperature gradient, and more ecological niches allowing for even mooore diversity.
Compare and contrast the typical distributions of epipelagic, deep benthic, and littoral fish.
Epipelagic fish live in the open ocean and are have the widest distribution. They are found at the surface to about 200m below. Ex: Scombridae with partial endothermy to help swim through cold open oceans/depths. As well as modified fusiform for rapid locomotion and high metabolism
Deep benthic fish live below 200m depth. They are limited by shallow sills and temperature. Often adapted to low light and for hunting: photophores, large eyes, lures etc. Some have modification to with stand pressure or live near thermal vents for heat and food.
Littoral fish are also localized to tidal zones and continental shelves but live are found from the surface to 200m depth. This area has 95% of species and are limited by temperature, salinity, productivity and habitat. Ex: Cottidae with modified body to help with stand tidal movements: large low pectorals, inferior mouth, no gas bladders
What are the four zoogeographrical regions of nearshore tropical marine fishes?
1) Indo-west Pacific (3000sp)
2) Western Atlantic (1500sp)
3) Eastern Pacific (750sp)
4) Eastern Atlantic (500sp)
Indo-west Pacific and Western Atlantic are the most diverse because they have warmer water currents/T, closer to continents, and located near tropics.
What are the freshwater fish trends?
The farther downstream, the more diversity. In headwaters or cool streams, you start with trout, trout and sculpins, and then trout, sculpins and dances. Mid reaches add more minnows, suckers, sunfishes, darters and small catfish. Larger river have deep-bodied fish with larger catfish.
How did the Pleistocene glaciations determine the present distribution and diversity of fish in North America?
There used to be water connections between drainage basins and connections between continents. The Intermountain West used to contain huge lakes. These previous geological features allow current fish to be related to fish between areas that are no longer connected.
What are the impacts of major freshwater rivers on marine fish distributions?
Interactions of freshwater flows with tides, winds and costal currents can create unique ecosystems with different salinity, water temperature, water circulation, and levels of nutrients within estuaries and coastal areas.
Freshwater rivers can also act as physical barriers to marine species. For example, their are different species on the Northern and Southern sides of the Amazon River.
Define antitropical distribution
Fish that are present in temperate waters on either side of the equator
