By: Mariama Koroma and Bethiel Fesseha

 Charles Darwin proposed the mechanism that is accepted today  “Survival of the Fittest” – inherited traits favorable to survival in a given environment tend to be preserved, and unfavorable ones are eliminated  Adaptation: evolutionary modification that improves chances of survival and reproductive success of the population in a given environment The Origin of Species by Means of Natural Selection More favorable genes increase in successive generations, and fewer unfavorable genes survive

1. Overproduction: more offspring produce than will survive to maturity 2. Variation: individuals have unique combinations of traits that make them more/less “fit” for their environment 3. Limits to Population Growth(Struggle for Survival): environment can’t support everyone (Competition for resources, predation, or disease) 4. Differential Reproductive Success: Those individuals with the most “fit” traits for their environment are more likely to survive, reproduce, and pass their traits on to the next generation

 Directional Selection: One extreme of a specific trait is more advantageous than both the other extreme and average trait  Ex. Peppered Moth  “Pays to be DIFFERENT ”  Stabalizing Selection: Tends to eliminate individuals on both ends of the genetic spectrum  Ex: Birth Weight  “Pays to be AVERAGE ”  Diversifying (Disruptive) Selection: environmental conditions favor individuals at both extremes of the genetic spectrum and eliminate or sharply reduces individuals with intermediate genes  Ex: Green v. Brown Anole  “Pays to be (either) EXTREME ”

 Convergent Evolution : two totally different species become similar due to their same type environment for each species  Ex. Dolphin and Sharks  Divergent Evolution : two of the same species move to different environmental and evolve to two different species  Ex: Penguin and Puffin  Adaptive Radiation: Darwin’s Finches  Co-Evolution: A form of evolution where two different species evolve in the same fashion  Ex: Rabbit and Wolf

Primary Succession: originates from a lifeless habitat (bare rock, lava flow, etc.) Secondary Succession: occurs where a disturbance eliminates most organisms but does not destroy soil Super Subject 4: Succession- the gradual change in species that occupy a given area

 Early  GPP is LOW because: LOW PRODUCER DENSITY  R is LOW because: LOW PRODUCER DENCITY & FEWER PRODUCERS  NEP is MEDIUM meaning: MASS IS ACCUMULATING; SYSTEM IS GROWING  Middle  GPP is MEDIUM because: MEDIUM PRODUCER DENSITY  R is MEDIUM because: MEDIUM PRODUCER DENSIT AND MEDIUM # OF PRODUCERS CAN SUPPORT MORE CONSUMERS  NEP is MEDIUUM meaning: MASS IS STILL ACCUMULATING; SYSTEM IS STILL GROWING  Late: CLIMAX COMMUNITY  GPP is HIGH because: HIGH PRODUCER DENSITY  R is high because: HIGH PRODUCER AND MANY CONSUMERS CAN NOW BE SUPPORTED  NEP is LOW meaning: STABLE COMMUNITY, NOT GROWING; PRODUCTION RESPIRATION RATIO APPROACHES 1

 Keystone Species : Species that are more crucial to the maintenance of their ecosystems, vital in determining the nature and structure of the entire ecosystem (not most abundant organisms)  Symbiotic Relationships  Mutualism (+/+): both organisms benefit Ex. Nitrogen Fixation Bacteria and Legumes  Commensalism (+/0): one benefits, one is not affected Ex. Remora Fish and Shark  Parasitism (+/-): one benefits, one is harmed Ex. Tapeworm and Human  Predation: consumption of one species (prey) by another (predator)  Strategies (Pursuit and Ambush)  Adaptations for Plants: spines thorns, tough leaves, protective chemicals  Adaptations for Animals : fight, camouflage, mechanical & chemical defenses  Warning Coloration & Mimicry : Ex. Monarch and Viceroy Butterflies

 Niche: role of an organism in their ecosystem- “its job”  Includes abiotic and biotic factors  NO TWO SPECIES CAN SHARE THE SAME NICHE!  Fundamental VS. Realized Niche

 Limiting Factors: forces that slow the growth of a population  Density Dependent: dependent on population size; related to competition. (ex. Food supply, living space, and water availability)  Density Independent: affects the same % of a population regardless of size (ex. Climate and natural disasters)  Competition: Intraspecific VS Interspecific  Intraspecific: competition within two individuals of the SAME species; Ex. A big cardinal and a little cardinal fight for the same seed  Interspecific: competition between two DIFFERENT species; Ex. Cardinals and Finches compete for same bird seed

Factors that affect species richness: 1. Abundance of potential ecological niches 2. Proximity to margins of adjacent communities - ECOTONE = transitional zone where 2 or more communities meet 3. Geographical Isolation 4. Dominance of one species over others 5. Habitat Stress 6. Geological History

 Summary: Species richness is great when…  There are MANY potential ecological niches  You’re CLOSE TO adjacent communities  The community isnot isolated  The community isnot severely stressed  There is LOW species dominance over others  Communities have STABLE geologic history