Introduction to Population Dynamics

1. Introduction to Population Dynamics

2. Ecosystems and their Components • A population is a group of organisms of one species that lives in the same place, at the same time, and can successfully reproduce. • All populations that interact in a given area form a community

3. Ecosystems and their Components • Ecosystems are made up of all the interacting parts of a community and its environment. • Ecosystems are composed of both biotic (living) and abiotic (non-living) components

4. Ecosystems and their Components • An area with a particular set of biotic and abiotic components, in which an organism is able to survive is that organism’s habitat • The role an organism has within its habitat, including its biotic relationships and theabiotic resources it uses makes up its ecological niche

5. Interactions between Organisms • Interactions that occur between organisms in ecosystems are called biotic interactions • Biotic interactions include: • Predation • Competition • Symbiosis http://fany.savina.net/2010/03/ecological-relationships-in-nature-populations/ http://www.treesforlife.org.uk/forest/ecological/predation.html

6. Interactions between Organisms • Symbiosis includes: • Parasitism • Mutualism • Commensalism

7. Interactions between Organisms • Organisms at different trophic levels interact in feeding relationships called a food chain • Numerous interacting food chains make up a food web http://www.sciencebob.com/questions/q-food_chain_web2.php

8. Interactions between Organisms • Energy is transferred from one trophic level to another within a food chains and food webs. • Only 10% if the energy available at one trophic level is transferred to the next • 30% of the energy is used for life functions • 60 % is lost as waste and heat http://www.eduweb.com/portfolio/earthsystems/food/foodweb2.html

9. Biodiversity • Biodiversity refers to the number and variety of organisms found within a specific region • The more biodiversity an ecosystem has the healthier and more resilient it is • More biodiversity is always better

10. Biodiversity • Threats to biodiversity include: • Habitat loss • Alien or invasive species • Ecosystem fragmentation • Overexploitation http://king.portlandschools.org/files/houses/y2/animalmaineia/files/species/rnpheasantkh/habitat%20loss/habitat_loss.html

11. Evolution • Organisms face environmental challenges that affect their ability to survive and reproduce • Adaptations that help organisms survive these challenges include: • mimicry • variations among individuals • camouflage http://falkenblog.blogspot.com/2010/07/batesian-mimicry-explanation-of.html http://science.howstuffworks.com/environmental/life/zoology/all-about-animals/animal-camouflage.htm

12. Evolution • Species that do not overcome challenges will become extinct • Natural selection is a process by which characteristics of a population change over generations http://evolution.berkeley.edu/evolibrary/article/evo_51

13. Evolution • Natural selection occurs when individuals that have inherited a trait that helps them survive environmental changes are able to reproduce more often • The alleles that are responsible for the trait are passed on • Genetic change that results over time is called evolution

14. Population Change • Populations that exhibit exponential growth have accelerated growth that produces a J-shaped curve when population size is graphed against time http://math.tutorvista.com/algebra/exponential-growth.html

15. Population Change • Limiting factors limit population size as well as the growth or distribution of a population within an ecosystem http://cfpub.epa.gov/ncer_abstracts/index.cfm/fuseaction/display.abstractDetail/abstract/6127/report/2004

16. Population Change • Carrying capacity refers to the size of the population that can be supported indefinitely by the resources and services available in an ecosystem

17. The End