Biological Communities in the World Around Us Big Idea #4 Interactions Big Idea #4 Interactions Chapter 54 : Community Ecology

What is a biological community? A group of populations of different species living close enough to interact Biome = community with a characteristic climate

Think outside the box… What are the members of this community? Are you a biological community?

Interactions within a community (54.1) Competition – Intraspecific – Interspecific: competitive exclusion Predation – Including Herbivory Symbiosis – Mutualism – Commensalism – Parasitism

Competitive Exclusion Principle defines an organisms niche How might this play out in the human body? What conditions in the human body cause a different member of the community to be successful?

Also important… Dominant Species: usually most abundant…what if they change? Keystone Species: not usually abundant…why might you start seeing them? Ecosystem engineers: foundation species…drives change in other species.

Succession Changes in community composition – Primary Succession – Secondary Succession

Does ecological succession occur when you take antibiotics? How might this change impact the human body? (27.5)

Nitrogen cycling in a biological community What types of organisms play a critical role? (27.5) How might changing the members of the community affect nitrogen cycling? What events might cause succession/change?

How can succession be measured? Species biodiversity is used to characterize a community---so-called “climax communities” have stable, distinctive organisms Higher biodiversity = greater succession The impact of events on a community may be evaluated by studying changes in biodiversity

Shannon Diversity Index The biodiversity of an area can be calculated using the equation: H = -(p A ln p A + p B ln p B + p C ln p C ….) Higher values of H indicate greater biodiversity We will practice using this equation in a separate activity See 54.2 Example two forest communities.

What’s this all got to do with cheese? Cheese is the scaffold for a microbial community – a microbiome. The process of making cheese involves an understanding of biology.

New England Cheese Economy From these Chronicle clips, appreciate an understanding of why biologists (yes…ones at that big University in Cambridge, MA) might be interested in the cheese making process. Part 1: Cheese-Trail-Part-1/-/ / /-/ute169/- /index.html Part 2: cheese-trail-part-2-chronicle-wcvb-home/ Part 3: Cheese-Trail-Part-3/-/ / /-/13v2y1t/- /index.html

Experimental Design Experimental Question: – How can humans impact the microbial community growing on cheese?

What background do you need to know? How is cheese made? What types of conditions is cheese cultured under? What types of bacteria usually grow on cheese?

Designing an experiment What is an independent variable? – What could be an independent variable in this lab…what do you need to know?!?! What is a dependent variable? – What qualitative results might you observe? – Is there a quantitative dependent variable that would be appropriate to this lab?