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The American alligator is an important ______ species in southern wetland ecosystems, and has made a significant comeback since the 1960s. It contributes significantly to the Louisiana economy, and continues to provide many ecosystem services in Louisiana’s coastal marshes and freshwater swamps.
keystone
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_______is a renewable resource, and as the book says, includes not only the planet’s species, but the linkages among those species, the ecosystems they live in, and the ecosystem processes (energy flow and nutrient cycling) and services that keep these populations productive
Biodiversity
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Species diversity is important, but _____ diversity may be even more important; the variability in the genetic composition of individuals within populations is the basis of evolution and adaptation to changing environmental conditions.
genetic
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Ecosystem Diversitis..y
Ecosystem diversity is obvious as you look around the world at the various biomes and aquatic life zones on the planet - all of these ecosystems contain unique and potential important (to the ecosystem and to us, either directly or indirectly) organisms that need to survive if the planet is to continue to function as it has for thousands of years
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Functional diversity is...
is also important, how all of the biotic and abiotic components of an ecosystem interact with one another. Maintaining all of these diversities is a cornerstone of conservation; we have a responsibility to future generations to protect our biodiversity heritage.
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Earth’s biodiversity resulted from 3 billion+ years of ____, the process whereby Earth’s species emerge, change, and become extinct.
evolution
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Charles Darwin and Russel Wallace proposed____ ____ as the process whereby organisms become adapted to a particular environment and thrive.
natural selection
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Small environmental changes probably do not alter species too much, as the genetic diversity within populations allows them to persist. However, as environments change rapidly, or new species evolve from a_____ ____, some individuals will survive better and produce more offspring, hence future generations will resemble the more “fit” individuals, and species, communities, and ecosystems change.
genetic mutations
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As you can see in Figure 4-3, we now classify organisms into...
6 kingdoms, 2 prokaryotes and 4 eukaryotes.
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The fossil record allows us to see how some populations change and evolve through time. These changes generally occur through ______, changes in DNA structure which, if they are in reproductive cells, result in “new” offspring.
mutations
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Many, if not most, mutations are deleterious, i.e., they harm the individual, but some are probably neutral, and some allow individuals to perform better in certain habitats, or under certain environmental conditions, which are called ______.
adaptations
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These are _____ (passed on from parent to offspring through DNA) traits upon which natural selection acts. If a trait leads to greater reproductive output or survival of your, those adaptations will be selected for, and those traits will increase in the population.
Note therefore that natural selection acts upon individuals (and their genetic composition), causing evolution in populations as conditions (and favorable adaptations) change.
The books talks about fur thickness in wolves, and genetic resistance in bacteria (a huge problem in the medical world).
heritable
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Remember that survival of the fittest, means ...., and fitness is measured in....
evolutionary fitness, not strength, how many offspring you leave behind that survive to reproduce.
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As the book points our, movement of the continents on the planets_____ _____ has had a significant effect on climate, and particularly biodiversity. As the continents have moved from Pangaea to where they are today, communities have been separated and have species have evolved as environments on the plates changed. Volcanoes have also helped this process, such as the Hawaiian Island chain, which has resulted in some very unique species (unfortunately, as humans move rats, cats, snakes, etc., around the planet, these unique species face a highly increased rate of extinction - see Australia and New Zealand for good examples).
tectonic plates
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You can see, therefore, that species arise through _____ and _____ _____, whereby individuals of a species that historically interbred are now unable to do so.
geographic and reproductive isolation
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Talk about Extinction
is a natural process as well, although rates and causes of extinction seem to be changing. On p. 87, the book talks about the golden toad being one the first species to become extinct due to global warming in Costa Rica, changing rainfall, and loss of the cloud forests. I doubt this is the case, this same scenario may have gone on hundreds of times in the Earth’s history - but the causes of global warming seem to have shifted, and now we control the fate of thousands or millions of unique species around the globe.
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Species diversity includes _____ and _______. The example of evenness on p. 89 in the book is WRONG: a community with many species is rich, but evenness depends on the relative abundance of each species, not the total abundance of each species. Therefore, …with a large number of different species (high species diversity) generally has only a few members of each species (low species evenness)…is WRONG. If each of 500 species has only 10 individuals, the community is still very even…if 499 species have 5 individuals, and one species has 10,000, it has very low evenness - got it?
richness (the number of species), evenness (the relative abundance of species).
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The theory of _____ _____ developed by MacArthur and Wilson appears to be generally true, as species colonize and become extinct on islands, depending on the size of the island (more species on larger islands) and the distance from the nearest mainland (source of colonizers).
As I said before, we are changing this ecological principle as we move animals and plants around the globe much more quickly that they would have naturally, and the consequences to many endemic island species has been catastrophic.
island biogeography
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We generally believe that biodiversity is .... and there is research to support this (p. 90-91). Unfortunately, human activities tend to reduce biodiversity, and we don’t really know the consequences of these changes on a global scale
related to ecosystem stability, sustainability, and resilience after disturbance,
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Each species has a ____, the role of that species in the ecosystem, or all of the resources that an organism needs to survive
niche
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Some species are ____, like the rat, and some are _____, like most of the threatened or endangered species on the planet, they have one or more
resources that are limiting.
generalists, specialists
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As opposed to native species, nonnative, alien, or exotic species move into a new environment, and, depending on their ____, can either fail, hang on, or thrive.
niches
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Some species have niches that reflect the quality of their environment, and we call these species_____ ____, i.e., the health of their populations indicate the health of the environment.
We often use these “canaries in the coal mine” to assess environmental quality, trying to separate natural factors that affect these species from
human-induced environmental changes.
For example, when water quality declines, mayflies (Ephemeroptera) often decline as well. If we go to a stream in Pennsylvania and find no
mayfly larvae, it is an indication that something is wrong and needs to be investigated.
indicator species
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Talk about Keystone species
- are particularly important in ecological communities. The more we look for them, the more we see species that are crucial to the ecology of other species as well as ecosystem function.
- The book also mentions foundation species, one that modifies habitats for the benefit of other species, but this seems to be splitting hairs a little to me, a keystone is a keystone, regardless of the roles it plays.
- The section on sharks is interesting, they are probably important keystone species in most oceanic ecosystems, yet we are destroying them at an
- alarming rate - shark finning is a particularly nasty and stupid business, and the example of shark reductions causing increases in rays and skates and decreases in the abundance of scallops (an important commercial species) is a good example of the Principle of Ecosystem Relationships that we talked about.
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