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BIO 126 Lecture Notes - Lecture 25: Overgrazing, Allopatric Speciation, Primary Succession

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lemonleopard146
26 May 2016
School
Drexel University
Department
Bioscience & Biotechnology
Course
BIO 126
Professor
Kevin Smith

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Document Summary

When allopatric, they have the same food sources and their beak sizes are the same. When sympatric, they have different food sources so one gets smaller, one gets bigger. Disturbance: an event, such as a storm, fire, flood, drought, overgrazing, or human activity that changes a community by removing organisms from it or altering resource availability. The gradual, sequential regrowth of an area following a disturbance. Primary succession: the development of a community in an area that has not previously supported life. Examples might include: a bare rock, a sand dune, or an island formed by volcanic eruption. Primary succession often occurs very slowly: minerals necessary for plant growth are unavailable. Over time, rocks will begin to break down due to weathering. Lichens help break down the rock into soil. Lichens are usually the first to colonize these barren areas: a lichen is the mutualistic relationship between an algae and a fungus.

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Related Questions

1. Compare and contrast micro- and macroevolution.

2. For the following situations, state the likely outcome of thehybrid zone described.

a. Two species of butterfly live on Haleakalā; the silverswordbutterfly lives at higher elevations and the rainbow eucalyptusbutterfly lives at lower elevations. A thin hybrid zone between thetwo butterflies exists. The hybrids produced are more successfulthen their parent species during el niño years when weatherconditions are warmer but during normal years, the hybrids are notas successful as their parent species.

b. Two different species of rockmover cichlid fishes live inLake Victoria but they also reside in different lakes where theother species are not found. In allopatric populations, the malesresemble each other but in sympatric populations the males lookvery different. Every so often, allopatric populations are able tocome into contact with one another through flooding and hybrids areformed but in sympatric populations, the two species never formhybrids.

c. In the Artic National Wildlife refuge (ANWAR) two populationsof reindeer: Northern Territory and Southern Territory Reindeer. Alarge glacier isolated the two populations but in the last 50years, the glacier has retreated to a point where the populationscan access mutual feeding grounds. As a result they have started tointerbreed more frequently.

1.

What is a method that some ecologists have proposed to protectspecies from extinction in the face of global climate change?

  1. natural attenuation
  2. assisted migration
  3. bioremediation
  4. mitigation
  5. adaptive management

2.

Why is it usually not possible to restore a community to itspre-altered state?

  1. It is not always possible to determine the kinds of speciesthat populated a community.
  2. Invasive species compromise restoration.
  3. Climate change complicates restoration.
  4. Evolutionary trajectories cannot be predicted.
  5. All answers are correct.

3.

How is ecological restoration different from restorationecology?

  1. It considers cultural and societal concerns.
  2. It does not rely on ecological principles.
  3. It cannot be predicted.
  4. It does not involve manipulation of the environment.
  5. All answers are correct.

4.

What is the goal of assisted migration?

  1. to help species respond to climate change
  2. to help species learn new seasonal migration routes
  3. to help migrating species avoid human-made structures
  4. to help native species tolerate restoration efforts
  5. All answers are correct.

5.

Which of the following might serve to enhance habitat in arestoration project?

  1. a dead log in a stream
  2. a concrete water control structure in an estuary
  3. removal of a dam
  4. an artificial nesting box
  5. All answers are correct.

6.

Biologists want to restore a region that experienced stripmining. How will bacteria assist in the restoration?

  1. They will restore the biotic parts of a community.
  2. They will enhance adaptive management.
  3. They will remove harmful metals.
  4. They will improve revegetation.
  5. They will remove the source of the disturbance.

7.

A barge has leaked a small amount of oil in the middle of LakeMichigan. What might be the best solution to clean it up?

  1. Add molasses to stimulate bacterial action.
  2. Leave it alone.
  3. Introduce engineered bacteria.
  4. Add microorganisms not normally found in the lake.
  5. Launch a comprehensive restoration effort.

8.

Before deciding on an appropriate restoration strategy for aparticular degraded ecosystem, which information would be LEASTimportant to have?

  1. the goals of the restoration, in terms of biodiversity andecosystem functioning
  2. the degree to which the ecosystem has been degraded whencompared to a reference ecosystem
  3. the types of species that were present before thedegradation
  4. the social, political and economic constraints on therestoration
  5. None of the answers are correct.

9.

A biologist works to restore habitat during a restorationproject. Which of the following might serve to enhance thehabitat?

  1. a dead log in a stream
  2. a concrete water control structure in an estuary
  3. removal of a dam
  4. an artificial nesting box
  5. All answers are correct.
  6. 10.
  7. Restoration ecologists want to restore a landscape to itsoriginal state before humans arrived and altered it, but they donot know what species of plants lived there historically. What isthe best alternative?
  8. Import plants from other ecosystems at the same latitude.
  9. Bioremediate the soil.
  10. Use plants growing nearby.
  11. Use assisted migration.
  12. Let nature take its course.

11.

Biologists begin collecting native seeds in a seed bank in aregion that experienced considerable alteration. Describe thebenefits of taking this action for the future.

  1. It is important to collect samples of native seeds for culturalpurposes.
  2. Biologists can use the seeds to restore other regions atsimilar latitudes.
  3. If the region is heavily altered, it may take time and multiplesteps to restore the region. Collecting the seeds while they areavailable ensures that the biologists can use them later in therestoration process.
  4. The see bank will promote the assisted migration of plants fromhabitats made unsuitable by climate change.
  5. All answers are correct.

12.

Although disturbance is often thought of as a detriment tonatural ecosystem functioning, one type of disturbance, fire, isoften used to restore ecological communities. In what way(s) canfire restore ecological communities?

  1. Fire is an effective way to "clean the slate" of the ecosystemby burning plants and sterilizing the soil so that appropriatemitigation and bioremediation plans can be implemented.
  2. In ecosystems where fire is a natural periodic event, fire cankill many non-native plant species while leaving native speciesless influenced.
  3. Fire can suppress the growth of competitive dominant plants,such as shrubs and trees, increasing the diversity of certainecosystems.
  4. All answers are correct.
  5. None of the answers are correct.

My question is:

Do all strands of the same length have the same sequenceof base pairs? I wouldn't think so, and this would be a problem inthe next step, determining the sequence of one size fragment byusing special base pairs that are lacking a hydroxyl group. Isn'tit possible I could have two strands that are 50 base pairs long(for example) that have the same beginning and same end and arethus cut by the restriction enzymes to a length of 50, but are mostassuredly not the same within their sequence

The text says that once the different size strands are separatedby electrophoresis, you can just cut out one of the bands and workwith that. That makes sense if you are guaranteed to only have 1strand at that level of the gel agar or if the multiple strands areall the same exact sequence.

If you read this far, thank you. I think more generally I needto know how many of these segments are produced when you userestriction enzymes and how long the average one is. And is thereany guarantee for one chromosone (or all 46 chrmosones) having allthe segments be unique sizes (I wouldn't think so)?

And even more generally :), I need additional sources thatexplain DNA sequencing in simple to understand terms.