From Biol301

Notes generously supplied by Alice.

Contents 1 Distribution! 1.1 Factors that Limit Distribution 1.2 Historical influence on current distributions 1.3 Climate and Range Expansion 1.3.1 Other Factors Necessary for Change Range 1.4 Inter-specific competition: competition between species

Distribution!

• Explanation of topic: Today we will be looking why organisms are located where they are!
• Ex. Salamanders.

Factors that Limit Distribution

1. Geographic range

• Is limited by availability of suitable habitat.
• A suitable habitat is an area where the organism has high fitness.
• Ex. Sugar Maple
  • It is not found on the east because of the Atlantic Ocean, on the west due to aridity (pattern of rain fall), on the north because of cold winter, and one the south because of the hot summers

2. Different ages/stages often have different requirements to maintain regional persistence.

• Ex. Salmon. When they are young, they need to live in streams. However when they are adults, they live in the ocean.
• Note: there is not a decrease of salmon due to over fishing but due to a decrease in juvenile salmon runs = not as much baby salmon around to grow up
• Ex. Organisms that spend time in pond and land, ponds during baby stage, land during adult stage. (e.g. frogs)
• Note: pond may dry up which effects the number of species in a range.

Historical influence on current distributions

• Shelford’s Law of Tolerance: physiological performance of a species based on the variable weather conditions for the organism
• Physiological ecology: a science to explore physiological factors that limits the range of a species (e.g. temp and moisture)

Glaciations

• last glacial period forced people to move south
• species may move with glacial period due to resources available
• ex. Tiger beetle
  • they moved northward and into the mountains
• ex. Bog turtle
  • the gulf current moved them to the eastern shore because it was warmer

Climate and Range Expansion

• if ranges were determined purely by climate, species would shift their range in response to climate changes.
• Ex. Skipper butterfly
• Ex. Moth – moved south and north in the UK
• Ex. Parasites in the Chesapeake Bay- they are currently killing oysters and their range is going south

Other Factors Necessary for Change Range

• Nutrient food
• Soil availability
• Competition
• Dispersal ability of species
• Genetic factors

Inter-specific competition: competition between species

MISSING INFO ON GROUP WORK WITH THE # QUESTIONS