Learning Targets. 1. I can describe how to reduce my carbon footprint. 2. I can explain how populations change in an environment.

Transcription

1 Learning Targets 1. I can describe how to reduce my carbon footprint. 2. I can explain how populations change in an environment.

2 Population Ecology

3 WHAT IS ECOLOGY? Ecology- the scientific study of interactions between organisms and their environments, focusing on energy transfer Ecology is a science of relationships

4 Organism - any unicellular or multicellular form exhibiting all of the characteristics of life, an individual. The lowest level of organization

5 POPULATION a group of organisms of one species living in the same place at the same time that interbreed Produce fertile offspring Compete with each other for resources (food, mates, shelter, etc.)

6 Community - several interacting populations that inhabit a common environment and are interdependent.

7 Ecosystem - populations in a community and the abiotic factors with which they interact (ex. marine, terrestrial)

8 Biosphere - life supporting portions of Earth composed of air, land, fresh water, and salt water. The highest level of organization

9 Ecology Organization organism population community ecosystem biosphere

10 Factors that affect Population Size Abiotic (non-living) factors sunlight / temperature precipitation / water nutrients Biotic (living) factors food competitors predators disease Intrinsic factors adaptations

11 Population Size Changes to population size Add individuals Birth Immigration New organisms arrive from somewhere else Remove individuals Death Emigration Organisms leave for somewhere else

12 Exponential growth rate Characteristic of populations WITHOUT limiting factors introduced to a new environment or rebounding from a catastrophe Whooping crane coming back from near extinction African elephant protected from hunting

13 Number of cladocerans (per 200 ml) Number of breeding male fur seals (thousands) Carrying capacity Exponential growth NOT sustainable Carrying capacity = Maximum population size that environment can support Time (years) Time (days)

14 Regulation of population size What keeps populations in check? competition: food, mates, nesting sites predators, parasites, pathogens abiotic factors sunlight (energy) temperature rainfall marking territory = competition competition for nesting sites swarming locusts

15 Introduced species Non-native species transplanted populations grow exponentially in new area out-compete native species loss of natural controls Don t have predators, parasites, or competitors reduce diversity examples African honeybee in the Americas Kudzu in Southern US Rabbits in Australia kudzu

16 Rabbits in Australia Introduced in 1859 by Thomas Austin (he wanted to hunt them) No natural predators Mild temperature meant they could breed year-round Population grew exponentially Erosion because rabbits ate vegetation Mass extinction of native species Tried to stop the spread with rabbit-proof fence Unsuccessful (why?)

17 Changes in Carrying Capacity Population cycles At what population level is the carrying capacity? predator prey interactions

18 Human population growth What factors have contributed to this exponential growth pattern? 2011 = 7 billion people! adding 82 million/year ~ 200,000 per day! Significant advances in medicine through science and technology billion Industrial Revolution Is the human population reaching carrying capacity? Bubonic plague "Black Death" million

19 Human Population Growth Grows at a rate of about 80 million yearly Why doesn t environmental resistance take effect? (Why doesn t the environment affect the population?) Altering their environment Technological advances The cultural revolution The agricultural revolution The industrial-medical revolution

20 The Human Population Doubled three times in the last three centuries About 6.1 billion and may reach 9.3 billion by the year 2050 Improved health and technology have lowered death rates