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Introduction - Biodiversity - Lecture Slides, Slides of Biology

English and Foreign Languages UniversityBiology

These are the lecture slides of Biodiversity. Key important points are: Introduction, Communities, Potential Interaction, Assemblage, Community, Abundance, Different Species, Rivet Model, Redundancy Model, Populations

Typology: Slides

2012/2013

Uploaded on 01/22/2013

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•What is a Community?
•A community is defined as an assemblage of
species living close enough together for
potential interaction.
•Communities differ
in their species
richness, the
number of species
they contain, and
the relative
abundance of
different species.
Introduction
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Download Introduction - Biodiversity - Lecture Slides and more Slides Biology in PDF only on Docsity!

  • What is a Community?
  • A community is defined as an assemblage of species living close enough together for potential interaction.
  • Communities differ in their species richness , the number of species they contain, and the relative abundance of different species.

Introduction

1. Populations may be linked by

competition, predation,

mutualism and commensalism

  • Competition.
    • Interspecific competition for resources can occur when resources are in short supply. - There is potential for competition between any two species that need the same limited resource.
    • The competitive exclusion principle : two species with similar needs for same limiting resources cannot coexist in the same place.
  • Classic experiments confirm this.
  • Resource partitioning is the differentiation of niches that enables two similar species to coexist in a community.

Fig. 53.

  • Predation.
    • A predator eats prey.
    • Herbivory , in which animals eat plants.
    • In parasitism , predators live on/in a host and depend on the host for nutrition.
    • Predator adaptations: many important feeding adaptations of predators are both obvious and familiar. - Claws, teeth, fangs, poison, heat-sensing organs, speed, and agility.
  • Plant defenses against herbivores include chemical compounds that are toxic.
  • Animal defenses against predators.
    • Behavioral defenses include fleeing, hiding, self- defense, noises, and mobbing.
    • Camouflage includes cryptic coloration , deceptive markings.
  • Mimicry is when organisms resemble other species. - Batesian mimicry is where a harmless species mimics a harmful one.
  • Müllerian mimicry is where two or more unpalatable species resemble each other.
  • Mutualism is where two species benefit from their interaction.
  • Commensalism is where one species benefits from the interaction, but other is not affected. - An example would be barnacles that attach to a whale.
  • Coevolution and interspecific interactions.
    • Coevolution refers to reciprocal evolutionary adaptations of two interacting species. - When one species evolves, it exerts selective pressure on the other to evolve to continue the interaction.
  • Charles Elton first pointed out that the length of a food chain is usually four or five links, called trophic levels.
  • He also recognized that food chains are not isolated units but are hooked together into food webs.
  • Food webs.
    • Who eats whom in a community?
    • Trophic relationships can be diagrammed in a community.
    • What transforms food chains into food webs?
    • A given species may weave into the web at more than one trophic level.