Communities with greater biodiversity are more resistant to ecosystem disruptions and environmental change.
Communities with greater biodiversity are more resistant to ecosystem disruptions and environmental change. (1:00) Some community interactions are permanent, having evolved dependency over many many years with symbiosis. (2:22) A niche is the role or job that an organism has within an ecosystem (4:21).
The Question of the Day asks (6:22) The clownfish hides within the anemone and excretes wastes within it. What type of symbiotic relationship is this?
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Hi and welcome to the APsolute Recap: Biology Edition. Today’s episode will recap Community Ecology
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Unit 8 - Ecology
Topic 8.5
Big idea - Energetics
Before we start, let’s review the ecology hierarchy. Organisms combine to form populations, populations of different species interact in communities, and communities interact with abiotic factors within ecosystems. Today’s episode will focus on the ways in which different populations in a community affect ecosystem stability, energy availability, and survival.
Let’s Zoom in:
The CED kicks off this section with the calculation for Simpson’s Diversity Index. Like most equations utilized in this course, they are available during the test on the formula sheet and remember, you CAN use a calculator during the multiple choice and FRQ sections. The Simpson’s diversity index compares the number for one species to the entire sample. In real science land, these values would be gathered by taking random samples from a particular habitat. Each of these ratios is squared, summed and then subtracted from one. The closer the diversity index is to 1, the more diverse the community is. And communities with greater biodiversity are more resistant to ecosystem disruptions and environmental change.
Organisms have to access energy from their environment - they can’t make it themselves. The way in which organisms accomplish this is extremely varied and influences community structure. Competition for energy and matter is a large driving force within communities. This competition can be between species groups, like different plants growing towards available sunlight or within species groups, with two male rams fighting for a female’s attention to mate.
Some community interactions are permanent, having evolved dependency over many many years with symbiosis. Mutualism is an interaction where both species benefit - like with the honeybee and the flower. The bee collects pollen for their hive while aiding in sexual reproduction of the plant as it moves from flower to flower. Commensalism is when one species benefits while the other is not harmed nor helped. For example, the golden jackal follows tigers as they hunt for prey, feeding off scraps the tiger leaves behind. Jackal gets a free meal and the tiger doesn’t care either way. Negative relationships come in a few varieties. Classic Predator (+) vs. prey (-) and parasitism with parasite (+) and host (-). Examples of parasitism include fleas on dogs, tapeworms in humans, and fungi on trees.
Word of warning - don’t make assumptions about two species interactions based on outside knowledge you may have from watching animal planet. Focus only on information given within the prompt. Oftentimes, predator prey interactions will be graphed for analysis. Additionally, follow the thread of energy. This will often be represented through a food chain, web, or trophic cascade. Even parasitic relationships can be beneficial to communities if they free up resources for other organisms or create unoccupied niches. What's a niche you ask? A niche is the role or job that an organism has within an ecosystem. Their puzzle piece if you will. If you take out an organism that was accessing sunlight at the canopy level (like a large tree), then a niche has opened for increased ground growth. Competition decreases through niche partitioning - like if two birds normally eat the same food source, but one species accesses the top of the tree while the other feeds from food that has fallen onto the ground - they are unlikely to negatively impact each other.
Time for unit connections. Let’s think back to Unit 3: Cellular Energetics where we discussed cellular respiration, photosynthesis and enzymes. Community ecology continues the transfer of energy beyond organelles and through trophic levels.
Alright - what about the exam? This is a good example topic for data analysis, especially analyzing graphs that may have error bars. Remember, if error bars overlap, there is no statistical difference between groups.
To recap……
Communities change over time as populations interact. Interactions can be positive, negative or neutral and influence how organisms access energy and matter. Diverse communities are more resistant to environmental change and have a calculated Simpson’s diversity index closer to one.
Coming up next on the Apsolute RecAP Biology Edition: Statistics
Today’s question of the day is about finding nemo.
Question of the day: The clownfish hides within the anemone and excretes wastes within it. What type of symbiotic relationship is this?