1 / 19

Ecology Primer: Biological Interactions

Ecology Primer: Biological Interactions. Nicklaus Kruger NISL nicklaus@webmail.co.za. An Optional Graphic can go here. Biological Interactions. Ecology is the study of the interactions between living organisms and their environments Other organisms are part of that environment

tan
Download Presentation

Ecology Primer: Biological Interactions

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript


  1. Ecology Primer: Biological Interactions Nicklaus Kruger NISL nicklaus@webmail.co.za An Optional Graphic can go here

  2. Biological Interactions • Ecology is the study of the interactions between living organisms and their environments • Other organisms are part of that environment • The interactions between organisms are numerous, but they can all be fitted into a framework of a handful of interactions

  3. Interspecific Interactions

  4. Competition • The concept of competition is fundamental to the science of ecology • Competition occurs when two (or more) organisms require the same limiting resource • Intraspecific competition refers to competition between conspecifics • Interspecific competition refers to competition between members of different species • The more similar the fundamental niche of two organisms, the more potential for competition between them

  5. Competition (cont) • Competition leads to niche differentiationn or competitive exclusion • Competitive release occurs when one of the competitive species is removed the area, and its competitor species expands its niche and occupation of the habitat • Laboratory experiments demonstrate that two species cannot coexist if they require similar resources

  6. Competition (cont…) • Closely related species rarely coexist for long in the laboratory • If two species are forced to live off the same resource, inevitably one persists and the other dies out • The competitive exclusion principle holds that two species cannot coexist on the same limiting resource • Only resources that limit population growth can provide the basis for competition • Non-limiting resources are superabundant compared to the needs of organisms

  7. Predator/Prey Dynamics • Organisms must consume food to survive • Some organisms are able to derive chemical energy from inorganic molecules • Other organisms get their carbon from living organisms • Predation has received more attention from ecologists than any other form of biological interaction (except competition)

  8. Predator/Prey Dynamics • When prey is plentiful, predator numbers can increase • But predators have an obvious adverse effect on prey population numbers • Ecologists debate whether ecosystems are regulated more by the dynamics within predator populations, or the dynamics within the populations of their prey • Individual predators tend to be larger than their prey, and also less abundant

  9. Herbivores and Plants • While we often view herbivore relationships differently from classic predator/prey relationships, functionally they are rather similar • Herbivores tend to be larger than carnivores, or to have larger populations, as a result of the way energy flows through an ecosystem

  10. Herbivores and Plants (cont) • The nature of the plant has profound effects on the evolution of its herbivores • Plants also adapt to the pressures of herbivory, and develop strategies to escape predation • Plants and herbivores are locked in a coevolutionary arms race

  11. Parasitism • Parasitism is similar to predation, except that the parasite tends not to kill its host as swiftly (if at all) • Endoparasites live within the tissues or their hosts • Ectoparasites live outside the tissues of their hosts, but attached to them • Epiparasites are parasites that parasitise parasites • Social parasites exploit the interactions between members of their host species

  12. Parasitism: The malaria parasite

  13. Mutualism • In mutualism, both of the interacting species benefit • When the species form a lifelong association in close physical and biochemical content, this form of mutualism is known as symbiosis • Obligate mutualism occurs when both species are dependent on their partners, and cannot survive without them • Facultative mutualism occurs when the partners are capable of surviving separately under certain conditions

  14. Symbiois: Lichens • Lichens are symbiotic associations between algae and fungi • They are more successful together than apart • Many lichens are obligate mutualists

  15. Endosymbiosis • Obligate mutualism can sometimes lead to the evolution of a new unity • Endosymbiogenesis is the theory that this has happened several times in the evolution of the eukaryotic cell • The mitochondria that power our cells are thought to have once been bacterial endosymbionts

  16. Commensalism • In this form of interaction, one species benefits, while the other is not affected at all • Real and well-attested examples of commensalism are hard to come by • Certain epiphytes are thought to be involved in commensal relationships with their hosts (algae covering barnacles, for example)

  17. Coevolution • Co-evolution is the mutual evolutionary influence between two or more species • In a co-evolutionary relationship, organisms exert selective pressure on one another • Effectively, co-evolution refers to biological interactions on an evolutionary timescale

  18. Coevolutionary arms races • Co-evolutionary arms races are positive feedback loops • The evolution of one participant leads to the evolution of the other, which in turn feeds back to the original participant • The classic example of this is in predator-prey relations • Below is an illustration of positive feedback and its involvement in the greenhouse effect

  19. Bibliography • Dark green font Arial at least 18 point this colour is 70 70 0 • Use animation and the effects of BLINDS for TEXT and DISSOLVE for IMAGES– they are quick and effective and bring in by paragraph and then dim after mouse click to a mid grey colour 150 150 150 • Give your presentation a header … there is space in the top and it also uses the colour 150, 150, 150 this uses Word Art and can be stretched. Use VIEW / MASTER/ SLIDE MASTER to access • If you need to hyperlink such as this is the URL for NISL if you use this as a template the colour is already set and is 96 132 113. For a visited Hyperlink use this colour which is 204 102 0 • Keep within the frame … this ensures it will not get clipped when projecting. • Use Bullet Points as indicated (Square colour is 128 128 0 )

More Related