What happens to the world now that we are in the picture?

 A niche describes ALL of the characteristics that any species needs to survive  Examples:  amount of space  type of food  climate conditions  If humans change any of these in any place, they make a species die off or move, because they have changed its niche

 bio- living  diversity- differences  the number of different living things in an area  more biodiversity gives the ecosystem a better chance for overall survival when changes occur

 Most populations grow exponentially until they reach their carrying capacity  the maximum number of individuals that area can hold  Something limits their growth  this is their limiting factor  may be amount of space, food, or number of predators

 Many human activities create or change different areas’ limiting factors  *All of these are because of increasing human populations!  overconsumption  habitat fragmentation  invasive species  global warming  ozone depletion  biomagnification

 Humans take more than they need  overharvesting of tuna  population crash  overhunting of bison, wolf  overharvesting of shrimp  If too few are left in too large an area, they cannot find mating pairs  Often, products are taken without regard for other items around them  Direct harvesting- picking of only the best or most desired crops, leaving the others behind

 Breaking up large areas of land so humans can use them

 species introduced to an area where they do not belong  THEY HAVE NO NATURAL PREDATORS, so they are better competitors and take over!

 Gases put into the atmosphere trap heat around Earth, making a “blanket”  guilty gases:  carbon dioxide  water vapor  methane  Increase in global temps by 1-2 degrees celcius  could make oceans rise by as much as 20 feet!

 DIFFERENT FROM GLOBAL WARMING!  Certain chemicals in the air act to break down a layer in our atmosphere that protects us from the sun’s radiation.  this makes us cooler BUT increases our risks for cancers

 (or biological magnification)  Any toxic substance that begins in an ecosystem will get passed up in higher and higher concentrations as it works its way up the food web

 We have changed the Earth in so many ways that we are causing:  species to MOVE  ex. maple trees  species to go extinct (no longer in existence anywhere)  ex. dodo bird  6 th extinction???  5 times in Earth’s history there have been massive die-offs of species.  Are we the cause of #6?

 List three positive and three negative things humans have done to the environment