Conservation Biology
Humans as the biggest Threat To Nature
This last chapter isn't that significant AP Biology wise, but is important in that you know how we as humans are affecting the planet. So this won't really be the traditional study guide that you've been seeing for the past few days; I will be doing this in a more of a conversational style, because that's how the chapter should be really presented.
Humans are totally wreaking havoc on our planet. I mean, just look at the statistics presented in the book. It's positively crazy. At this rate, I'll probably guess that within our lifetimes we will see a total change in nature, such that it won't be recognizable if you took a person from a hundred years to see it. We're like a virus of sorts. If you've seen The Matrix, then you know the speech made by Agent Smith: humans are a like a cancer - they multiply and consume. We're destroying our home - the very place that nutured us. Soon this planet won't be able to support us any longer, and humans will be in a very bad situation - we have destroyed almost all ways of acquiring resources.
The Geographic Distribution of Biodiversity
Biologists and ecologists have long noticed that there are "geographic gradients" of clines in species diversity, meaning that there is a pattern between global geographic regions and species diversity.
Ecologists have proposed several hypotheses:
1. Energy availability - certain areas get more sunlight, which powers photosynthetic processes of plants, like in the tropics.
2. Habitat heterogeneity - tropics encounter a lot of regular disturbances, causing environmental patchiness (differences in local environments), so there is lots of cause for species diversity.
3. Niche specialization - the climates in the tropics allows organisms to live in a smaller niche, with narrower range of resources. This allows for resource partitioning, thus larger species diversity.
4. Population interactions - Diversity self-propagates because there are many complex interactions in any environment.
Biodiversity hot spots - small places with lots of species. Is it any wonder they have an exceptionally large amount of endemic (rare) species? That's because the more diverse a community is, the more it continues to become diverse, as stated in hypothesis number 4 above.
Conservation
Conservation, obviously, is the big topic of this chapter. Here we talk about what steps are done to protect and conserve Earth's life, and what obstructs the steps.
endangered species - a species that is in danger of being wiped out.
threatened species - species that is in danger of being endangered (sounds funny, I know).
Recipes for sustaining genetic diversity
Not only do we have to protect endangered species, we have to protect the homes of all life. What good is it to protect a species, that, once saved, has nowhere to live?
Fragmentation - human disturbances has cut up land and divided it so that former ecological communities and ecosystems are divided and fragmented into smaller pieces, causing biological islands, like discussed before. This is almost always detrimental to former species that lived in the environment, because it fragments a formerly unified group of interactions, and it totally tears everything apart.
source habitat - an area of habitat where a population's reproductive success exceeds mortality, and from which excess individuals disperse. In other words, it's a habitat that's like a factor for making individuals.
sink habitat - an area of habitat where mortality exceeds birthrates. In other words, it's a graveyard.
These two, source and sink habitats, are important in designing ecological reserves, because you can't just blindly add random area and call it a reserve - it might be a sink habitat, where individuals just die out.
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