Biodiversity & Species - Lecture

Species Interactions

  • Species compete for food, water, shelter, space, mates, sunlight

    • availability of resources influences interactions

  • Types:

    • A: competition

      • both species harmed

    • B: exploitive

      • one species benefits, one is harmed (predation), herbivory, parasitism

    • C: mutualism

      • both species benefit

    • D:commonsalism

      • one benefit, one unaffected

Tropic Levels & Energy Flow

  • Tertiary: top predation

  • Consumers: carnivores, herbivores (primary)

  • Producers: autotrophs, detrivores and decomposers, insects, plants, cyanobacteria, fungi, bacteria

  • Food Web: feeding relationships and energy flow

  • 10% Rule: each level contains about 10% of energy of level below it

    • less organisms and less biomes —> less energy

Keystone Species

  • A species that has a story or wide-reaching impact

    • modifies physical environment

    • creates trophic cascades: indirectly affects populations at lowest trophic levels

Biodiversity Basics

  • Biodiversity:

    • variety of life across all levels of biological organization

      • levels: gene-species-population-community-ecosystem

  • Evolution:

    • change overtime with modification from descent

      • genetic changes: changes in appearance, function, and behavior (small and large scale)

  • Extinction:

    • disappearance of a species from Earth

  • Natural Selection:

    • process in which traits that enhance survival are passed on more frequently to future generations

      • drives evolution

      • produces adaptations: traits that improve an organisms ability to survive

How Do We Know Evolution Exists

  • Observations and interpretations of related species

  • Geologic time and fossil record

  • Phylogenetic trees: compare organisms

    • reflect evolutionary relationships

    • physical and genetic characteristics

  • Fossil record

    • fossil: preserved remains or traces of organisms’

    • oldest: about 3.5 BYA

    • most species have gone extinct (99%)

  • 5 major mass extinctions

    • humans accelerating 6th?

    • causes: climate change, severe weather, changing sea levels, new species, destruction of habitats (habitat fragmentation)

    • 1. Ordovician: 440 MYA - ice age

    • 2. Devonian: 370 MYA - drop in O2 levels

    • 3. Perion: 250 MYA - volcanism, asteroids

    • 4. Triassic: 200 MYA - volcanoes, asteroids

    • 5. Cretaceans: 65 MYA - asteroid impact

How New Species Exist

  • Through process of speciation

  • Generated from single species

  • Allopatric speciation: species formation due to physical separation of populations

    • ex: glaciers, volcanoes, rivers, mountains

Island Biogeography

  • Explains how species are distributed among ocean islands

  • Can lead to increased or decreased biodiversity

  • Convergent evolution:

    • unrelated species acquire similar traits because of similar environments

  • Divergent evolution:

    • related species diverge in appearance and behavior

  • Distance and Area Affect

    • farther islands from a continent:

      • fewer species to colonize

    • large islands have more species than small islands

      • ex: island Royale

Importance of Biodiversity

  • 1.8 million species identified

    • 3-100 million possible

  • biodiversity is unevenly distributed

    • latitude gradient (richer at equator)

  • biodiversity affects people

    • food, fiber, medicine, ecosystem services

Ecosystem Services

  • Provides food, fuel, fiber, shelter

  • Purifies air and water

  • Stabilizes climate: moderates floods and droughts

  • Cycles nutrients

  • Renews soil fertility

  • Pollinates plants and controls pests and disease