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Chapt03 Lecture

Chapt03 Lecture






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  • EVOLUTION: What are the mechanisms that promote the great variety of species on earth and that determine which species will survive in one environment but not another? SPECIES INTERACTIONS: We will look at the interactions within and between species that affect their success and shape biological communities. BIOLOGICAL COMMUNITIES: No species is an island. It always lives with other species in a biological community in a particular environment.

Chapt03 Lecture Chapt03 Lecture Presentation Transcript

  • Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Chapter 3 Lecture Outline
  • Learning Outcomes After studying this chapter, you should be able to answer the following questions:
    • • How does species diversity arise?
    • • Why do species live in different locations?
    • • How do interactions among species affect their fates and that of communities?
    • • If a species has unlimited growth potential, why doesn’t it fi ll the earth?
    • • What special properties does a community of species have, and why are they
    • important?
    • • What is the relationship between species diversity and community stability?
    • • What is disturbance, and how does it affect communities?
  • 3.1 Evolution Leads to Diversity
    • Natural selection and adaptation modify species
      • Adaptation, the acquisition of traits that allow a species to survive in its environment, is one of the most important concepts in biology.
      • The process of better-selected individuals passing their traits to the next generation is called natural selection.
  • The ecological niche is a species’ role and environment
    • Habitat describes the place or set of environmental conditions in which a particular organism lives.
    • Ecological niche, describes both the role played by a species in a biological community and the total set of environmental factors that determine a species distribution.
  • Niches: generalists & specialists
    • Generalists have a broad niche, like cockroaches.
    • Specialists have narrow niches, like giant pandas.
  • Competitive exclusion principle & Resource partitioning 3-
  • The competitive exclusion principle 3-
  • Speciation
    • The development of a new species is called speciation.
    • Geographic isolation results in allopatric speciation —species arise in non-overlapping geographic locations .
    • Behavioral isolation results in sympatric speciation —species arise in the same location as the ancestor species.
  • Directional, stabilizing, and disruptive selection 3-
  • Geographic isolation is a mechanism in allopatric speciation. 3-
  • Taxonomy
    • Taxonomy is the study of types of organisms and their relationships.
    • Genus and species compose binomials, Also called scientific or Latin names.
  • Taxonomy describes relationships among species
    • With taxonomy you can trace how organisms have descended from common ancestors.
    • Taxonomic relationships among species are displayed like a family tree.
  • 3.2 Species Interactions Shape Communities of Species
    • Competition is a type of antagonistic relationship within a biological community.
    • Organisms compete for resources that are in limited supply.
    • Competition among members of the same species is called intraspecific competition.
    • Competition between members of different species is called interspecific competition.
  • Predation affects species relationships
    • Consumers include herbivores, carnivores, omnivores, scavengers, detritivores, and decomposers.
  • Some adaptations help avoid predation
    • Toxic chemicals, body armor, extraordinary speed, and the ability to hide are a few strategies organisms use to protect themselves.
  • Coevolution
    • The response of predator to prey and vice versa, over tens of thousands of years, produces physical and behavioral changes in a process known as coevolution.
    • Coevolution can be mutually beneficial: many plants and pollinators have forms and behaviors that benefit each other.
    • A classic case is that of fruit bats, which pollinate and disperse seeds of fruit-bearing tropical plants.
  • Prey Defense Mechanisms: Batesian & Mullerian mimicry 3-
  • Prey Defense Mechanisms: Camouflage 3-
  • Types of Symbiosis: Intimate relations among species 3-
  • Types of Symbiosis: Intimate relations among species
    • Commensalism is a type of symbiosis in which one member clearly benefits and the other apparently is neither benefited nor harmed.
    • Mutualism is a type of symbiosis in which both members clearly benefit.
  • Keystone species
    • A keystone species plays a critical role in a biological community
  • 3.3 The Growth of Species Populations
    • Biotic potential— the amount of potential growth of a population with unrestrained biological reproduction.
    • Exponential (r) growth is population growth with no limits; it results in a “J” growth curve when graphed.
    • Logistic growth curves result from carrying capacity (K) limiting population growth; it results in a “S” shaped growth curve when graphed.
  • J curve of exponential growth 3-
  • Population cycles 3-
  • S curve of logistic growth 3-
  • Limits to population size
    • Density-dependent, meaning as population size increases, the effect intensifies. With a larger population, there is an increased risk that disease or parasites will spread, or that predators will be attracted to the area.
    • Density-independent limits to population are often nonbiological, capricious acts of nature. A population is affected no matter what its size.
  • Species respond to limits differently: r- and K-selected species 3-
  • Survivorship curves 3-
  • 3.4 Properties of Communities Depend on Species Diversity
    • Diversity and abundance
      • Diversity is the number of different species per unit area.
      • Abundance refers to the number of individuals of a species in an area.
  • Species patterns create community structure
    • Boundaries of species populations and communities form patterns that fit together:
      • (1) individuals and species are spaced throughout communities in different ways;
      • (2) the communities themselves are arranged over a large geographic area or landscape
      • (3) communities have relatively uniform interiors (“cores”) and also “edges” that meet.
    • Community (or ecological) structure refers to these patterns of spatial distribution of individuals, species, and communities.
  • Individuals in communities are distributed in various ways
    • Random patterns arise from random distribution of resources.
    • Uniform patterns usually arise from competition.
    • Cluster patterns help a species protect themselves.
  • Communities are distributed in patterns across a landscape
    • Core habitat- a mostly uniform environment big enough to support nearly all the plants and animals that are typically found in that community.
    • Ecotone- or border between two communities, rich in species.
    • Edge effects- where communities meet, the environmental conditions blend and the species and microclimate of one community can penetrate the other. .
  • 3.5 Communities Are Dynamic and Change Over Time
    • Climax community- The community that developed last and lasted the longest.
    • Primary succession- land that is bare of soil—a sandbar, mudslide, rock face, volcanic flow—is colonized by living organisms where none lived before.
    • Secondary succession -after a disturbance, if left undisturbed, a community will mature to a characteristic set of organisms.
    • Pioneer species -the first species to colonize a community in primary succession on land.
  • Practice Quiz
    • 1. Explain how tolerance limits to environmental factors determine distribution of a highly specialized species such as the saguaro cactus.
    • 2. Productivity, diversity, complexity, resilience, and structure are exhibited to some extent by all communities and ecosystems. Describe how these characteristics apply to the ecosystem in which you live.
    • 3. Define selective pressure and describe one example that has
    • affected species where you live.
    • 4. Define keystone species and explain their importance in community structure and function.
    • 5. The most intense interactions often occur between individuals
    • of the same species. What concept discussed in this chapter
    • can be used to explain this phenomenon?
  • Practice Quiz continued
    • 6. Explain how predators affect the adaptations of their prey.
    • 7. Competition for a limited quantity of resources occurs in all
    • ecosystems. This competition can be interspecific or intraspecific.
    • Explain some of the ways an organism might deal with
    • these different types of competition.
    • 8. Describe the process of succession that occurs after a forest
    • fire destroys an existing biological community. Why may
    • periodic fire be beneficial to a community?
    • 9. Which world ecosystems are most productive in terms of biomass
    • ( fig. 3.31 )? Which are least productive? What units are
    • used in this figure to quantify biomass accumulation?
    • 10. Discuss the dangers posed to existing community members
    • when new species are introduced into ecosystems.