Biodiversity and Evolution

Biodiversity and Evolution

Key Concepts of Biodiversity

  • Biodiversity (or biological diversity): The variety of life on Earth.

Four Components of Biodiversity

  1. Functional Diversity

    • Refers to the biological and chemical processes such as energy flow and matter recycling needed for the survival of species, communities, and ecosystems.
    • Involves:
      • Heat
      • Decomposers: (bacteria, fungi)
      • Chemical nutrients: (carbon dioxide, oxygen, nitrogen, minerals)
      • Producers: (plants)
      • Consumers: (plant eaters and meat eaters)
      • Solar energy: Essential for energy transformation and sustenance of life.

  2. Ecological Diversity

    • The variety of terrestrial and aquatic ecosystems found on Earth.

  3. Genetic Diversity

    • The variety of genetic material within a species or a population.

  4. Species Diversity

    • The number and abundance of species present in different ecosystems.

Ecological Niche and Habitat

  • Ecological Niche: Refers to the role of each species within the ecosystem it inhabits.
    • Generalist Species: Has a broad niche (e.g., raccoon, cockroaches, rats).
    • Specialist Species: Occupies a narrow niche (e.g., giant panda).
  • Habitat: The place, or type of ecosystem, in which a species lives and obtains what it needs for survival.

Specialized Feeding Niches in Bird Species

  • Various bird species in coastal wetlands occupy specialized feeding niches. This specialization reduces competition and allows for sharing of limited resources:
    • Black Skimmer: Seizes small fish at water surface.
    • Brown Pelican: Dives for fish which it locates from the air.
    • Avocet: Sweeps bill through mud and surface water in search of small crustaceans, insects, and seeds.
    • Dowitcher: Probes deeply into mud in search of snails, marine worms, and small crustaceans.
    • Herring Gull: A tireless scavenger.
    • Ruddy Turnstone: Searches under shells and pebbles for small invertebrates.
    • Flamingo: Feeds on minute organisms in mud.
    • Scaup and other Diving Ducks: Feed on mollusks, crustaceans, and aquatic vegetation.
    • Louisiana Heron: Wades into water to seize small fish.
    • Oystercatcher: Feeds on clams, mussels, and other shellfish by prying with its narrow beak.
    • Knot (Sandpiper): Picks up worms and small crustaceans left by receding tide.
    • Piping Plover: Feeds on insects and tiny crustaceans on sandy beaches.

Major Ecosystem Roles of Species

1. Native Species

  • Those that normally live and thrive in a particular ecosystem. Examples include:
    • Tamaraw (Bubalus mindorensis)
    • Philippine Eagle (Pithecophaga jefferyi)
    • Philippine Tarsier (Carlito syrichta)
    • Narra (Pterocarpus indicus)
    • Waling-waling (Vanda sanderiana)

2. Nonnative Species

  • Other species that migrate into or are introduced into a new ecosystem, either accidentally or deliberately.
  • Invasive Species: Compete with and reduce an ecosystem’s native species. Examples include:
    • Mahogany (Swietenia macrophylla)
    • Gmelina (Gmelina arborea)
    • Acacia mangium
    • Madre de cacao (Gliricidia sepium)

3. Indicator Species

  • Species that provide early warnings of environmental change in a community or ecosystem.
  • Examples:
    • Amphibians: Indicators of water and habitat quality.
    • Philippine Eagle: Indicator of old-growth forest health.

4. Keystone Species

  • Species that have a large effect on the types and abundance of other species in an ecosystem.
  • Examples:
    • Pollination of flowering plants by butterflies and honeybees.
    • Top predators that control population dynamics.

Evolution

  • Evolution: The process by which species change genetically over time.
    • Occurs through Natural Selection: Individuals with certain genetic traits are more likely to survive and reproduce.
    • Proposed by Charles Darwin and Alfred Russel Wallace.

Process of Evolution by Natural Selection

  1. Genetic Variability: A variety in the genetic makeup of individuals in a population, arising primarily through mutations.
  2. Selection of Certain Individuals:
    • Adaptations: Traits in individuals that provide an advantage over other individuals in the population.
  3. Survival and Reproduction: Populations that are better adapted to survive and reproduce under existing environmental conditions evolve over time.

Example of Evolution through Natural Selection

  • A population of bacteria is exposed to an antibiotic:
    • (a) Initial population includes normal and resistant bacteria.
    • (b) The antibiotic kills all non-resistant bacteria.
    • (c) The resistant bacteria survive and multiply.
    • (d) Eventually, the resistant bacteria replace most or all of the non-resistant bacteria.

Speciation

  • Speciation: The process by which one species evolves into two or more different species.
    • Happens in two phases:
    1. Geographic Isolation: Different groups of the same species become physically isolated from one another for an extended period.
    2. Reproductive Isolation: Mutation and change through natural selection operate independently in the gene pools of geographically isolated populations.

Artificial Selection and Genetic Engineering

  • Artificial Selection: Used to change genetic characteristics of populations with similar genes.
    • Steps:
    1. Selecting one or more desirable genetic traits in the population.
    2. Selective breeding or crossbreeding: Controlling members of the population to reproduce.
  • Genetic Engineering: Also known as gene splicing; changes genes by adding, deleting, or altering segments of DNA to produce desirable traits or to eliminate undesirable traits.
    • Genetically Modified Organism (GMO): An organism whose genetic information has been modified in a way not found in natural organisms.

Extinction

  • Biological Extinction: Occurs when an entire species ceases to exist.
    • Species that are found only in one area, referred to as endemic species, are especially vulnerable to extinction.