Species Diversity and Succession

-Variability in genetic makeup among individuals in a pop. Genetic Diversity -Variability in genetic makeup among individuals in a pop. -If too little DNA differences, can lead to genetic bottleneck extinction. Bottleneck Effect

Causes of Bottlenecks Mass hunting Sudden, natural cause (hurricanes, tornadoes) Loss of food source/habitat

Deserts and mountain tops = LOW diversity, Low number of species Species Diversity # of Species in an Area Tropical rain forest/coral reefs = HIGH diversity, High number of species Deserts and mountain tops = LOW diversity, Low number of species

Ecotone Transitional zone where 2 or more communities meet Intertidal zones

Factors That Determine Species Diversity Habitat stress Available niches Dominance of species Geological history Mountain Lion Stress

Species Considered separate species if they cannot interbreed Same species create viable offspring YES Panda Babies! NO Dog-Cat Babies!

Exceptions to the Rule Liger

Mule

Zorse

Grolar/Pizzly Bear?

SUCCESSION

Communities Change Over Time Succession: a process of community development that involves a changing sequence of species

Species land on new material and colonize (pioneer community). Primary Succession Starts with new land. Species land on new material and colonize (pioneer community). Starts with lichens, moss, and progresses to large trees after 1,000’s of years.

1) Lichens: Can be N fixers  Put Nitrate into soil for other plants to grow! Can also measure air poll.

2) Small Shrubs and mosses (little roots), provide habitat

3) Young pine trees more habitat

4) Mature hardwood and deciduous forests climax community

Secondary Succession Starts with already formed land. Species land on disturbed material. Disturbance usually caused by fires, storms, and man.

Fire Succession in Chaparral Needed for: Reproduction Clearing out competitors Germination (seed sprouting)

As Ecosystems Mature Increase in: Diversity & pop numbers System stability Biomass Nutrient Hold Capacity