Final Exam BIO 192 flash cards

Population Dynamics

• Population size change over time is influenced by:
  • Per capita birth rate (b): births per individual.
  • Per capita death rate (d): deaths per individual.
  • Per capita rate of increase (r): $r = b - d$

Scenarios based on r:

• If r > 0, population increases.

• If r < 0, population decreases.

• If $r = 0$, zero population growth, constant population size.

  • Example: If $b = 0.4$ and $d = 0.4$, then $r = 0$

Logistic Growth Model

• S-shaped curve: Population size increases over time but levels off at carrying capacity (K).

• Equation: $\frac{dN}{dt} = r_{\text{max}} N \frac{(K - N)}{K}$ where:

  • N = Population size
  • K = Carrying capacity

• Impact of N on growth rate:

  • Small N: Fast growth, steep slope.
  • Large N (close to K): Slow growth, resources limited.

Species Interactions

• Competition: Negative impact for one or both species.
• Neutral impact.

Niche Concept

• Niche: Combination of abiotic and biotic factors used by an organism.

Niche Factors

• Single-factor niche.
• Two-factor niche (e.g., temperature).
• Three-factor niche (e.g., salinity, temperature).

Types of Niches

• Fundamental niche: Physiological niche under ideal conditions.

  *Ideally, where a species could be found.

• Realized niche: Actual niche where a species is found.

  • Realized niche is smaller than the fundamental niche.

Competition

• Competition: Two species require the same resource in limited supply.

• In nature: Results in competition or avoidance of competition.

• Experimental evidence: Lab-based study on two different species of paramecium demonstrates logistic growth under limited resources.

• Competitive Exclusion Principle: Trade-off between tolerating drying out and competitive ability.

  • Example: Barnacles (Balanus and Chthamalus).
  • Chthamalus from that lower region competitive ability

Avoiding Competition

• Strategies:

  • Evolve to use a different resource.

  • Occupy different niches.

  • Example: Anolis lizards occupying different microhabitats.

• Competitive exclusion does not always lead to extinction.

• Example: Invasive Argentine ant species compete with native ant species.

Competitive Exclusion Principle

• Niche overlap: Species competing for the same resources.

• Evolutionary adaptation: Occupy different niches to coexist or go extinct.

• Character Displacement: Trait differs between two species when found in sympatry (same geographic region).

  • Sympatry vs. allopatry: Species inhabiting the same geographic region at the same time vs. species isolated by an external barrier.

  • Trait differing is directly related to competition.

  • Example: Beak depth in finches on islands.

    • When multiple species on 1 island, this is what we don't see when compared to different islands.

    • Beak depth influenced by competition.

Keystone Species

• Highly influential to their ecosystem; removal can dramatically decrease diversity.

  • Example: Yellowstone wolves.

Predator-Mediated Coexistence

• Keystone predator (e.g., seastar) allows two species to coexist by:

  • Selective predation favoring coexistence.

  • Example: Barnacles and mussels.

    • Without seastar: Mussels competitively exclude barnacles.
    • With seastar: Predation prevents mussels from taking over, promoting coexistence.

  • Higher species diversity when the predator is present, preventing competitive exclusion.

Ecological Succession

• Predictable change in community over time, associated with disturbance.

Types of Succession

• Primary succession: Occurs in a "lifeless" area with no soil due to disturbance.
• Secondary succession: An earlier community is disturbed and returns to an earlier stage in the successional sequence.

Life-History Trade-offs

• Species present are characterized by trade-offs in their life-history:
  • r-selected traits: Species that show up early, smaller size, colonize quickly; not very competitive (e.g., weeds).
  • K-selected traits: Species that show up later, larger size, colonize slower, grow slowly; very competitive (e.g., larger seeds, red woods, oaks, maples).

Ecological Succession and Diversity

• Early and late stages: Lowest species diversity.
• Intermediate stages: Highest species diversity.

Whale Carcass Example

• Complex "mini" ecosystem.

  • Early stages: Low species diversity.
  • Intermediate stages: 178 species on a single vertebra.

Ecosystem Energy Flow

• Energy flows through ecosystems.

Autotrophs

• At the base of the energy: Autotrophs (e.g., plants, green algae, cyanobacteria) produce energy through photosynthesis.

Trophic Structure

• Describes the feeding relationships of organisms.

• Producers (Autotrophs):

  • Terrestrial systems: Plants.
  • Aquatic systems: Phytoplankton.
  • Deep ocean: Chemosynthetic prokaryotes (energy from chemicals).

• Consumers:

  • Herbivores: Eat producers.

  • Carnivores: Eat other consumers.

  • Omnivores: Eat producers and consumers.

  • Detritivores/Decomposers: Feed on dead/decaying matter (detritus).

    • Examples: millipedes, sea cucumbers.

  • Decomposers: Feed on dead plant/animal matter (fungi, bacteria, earthworms).

  • Scavengers: Eat dead animals (Vultures).

Food Chain

• Linear sequence of feeding relationships describing energy transfer.

Food Web

• Network of food chains; more realistic.

Trophic Levels

• Primary consumers.

• Secondary consumers.

  • Example: Crabeater seals (2° consumers).

Energy Transfer and Energy Pyramids

• Energy is lost between trophic levels due to:

  • Respiration.
  • Waste.

• The rest of the energy makes the transition used in secondary production growth of an individual.

• 90% reduction in energy at each trophic level

  • Energy Pyramids
    • If producers (phytoplankton) have $100,000 J$, then the Primary consumer (zooplankton) has $10,000 J$, the Secondary consumer has $1000 J$, the tertiary consumer has $100 J$, and the Quaternary consumer has $10 J$

Chemical Cycling

• Chemical elements are available only in a limited amount and must be recycled.
• Biogeochemical cycles: Nutrient cycles with living (biotic) and non-living (abiotic) components.

Reservoirs

• Overall reservoirs:
  • Organic (O): Living material (must contain carbon).
  • Inorganic (I): Non-living components (soil, atmosphere).
• Availability:
  • Available (A): Accessed directly (e.g., eating, uptake from water/air).
  • Unavailable (V): Not accessed directly (e.g., rock, minerals).

Carbon Cycle

• Important because it forms the framework for all organic molecules.
• $CO_2$ is used in photosynthesis by plants (1° producer) and the carbon is available for consumers.
  • Grasshoppers eat Plants (1° consume) -> Mouse (2° consumer) eats grasshopper

Nitrogen Cycle

• Importance:

  • Part of amino acids, proteins, nucleic acids.
  • Often a limiting plant nutrient.

• 80% of $N_2$ is in the atmosphere, but plants can't access it.

• Nitrogen-fixation done by bacteria (prokaryotes): Convert $N<em>2$ to ammonia ($NH</em>3$) + ammonia.

• Plants use inorganic forms of nitrogen: $NH<em>4$, $NO</em>3$

Phosphorus Cycle

• $P$ is part of ATP, nucleic acids, RNA, and DNA.
• Plants use inorganic form (phosphate; $PO_4$).
• Largest reservoir: Sedimentary rock (phosphate minerals).

Diversity of living Organisms

• Unity of life – Similarities in organisms

  • all have same 20 a.a ATP
  • DNA as genetic material
  • homologies in bone structure

• Diversity of Life - Many different species that exist, is driven by evolution + natural Selections

  • Causing new traits

• Some Sort of metabolism (to process energy)

• reproduce. - asexual VS Sexval

• Organized structure - cells have a different Structure

• movement I response to enviroment - plants change

• grow develop - in response to enviroment change

• evolutionary adaptation - to Survive

• Regulate internal enviroment - homostasis.

Prokaryotes

• Most abundant life form on Earth.

  • Most are bacteria - Rhizobia, Bacillus sp.
  • Also Archaea - thermophiles, halophiles, methanogens

• Small (0.5-5 mm in length).

• Single-celled - no nucleus (no membrane bound organelles).

• Asexual reproduction- binary fission (one bacterial cells divides its DNA in half)

• Undergo rapid evolution because of their quick reproduction.

• Use flagella for movement (not all but some).

• pathogenic bacteries

Archaea or Bacteria?

• Cell Walls:

  • Bacteria: have peptidoglycan in their cell wall (rigid envelope for protection)
  • Archaea: no peptidoglycan in cell wall

• Growth at temperature > 100°C in cell wall

  • Bacteria: no
  • Archaea: yes for some species (extremophiles)

• Variation in Bacteria and Archaea

  • mutation because no sexval reproduction -> Change in DNA sequence
  • Horizontal transfer some genetic material -> exchanging of sance spp.

Prokaryotes - Source of Carbon

• • Heterotrophs: get Some Organic compound from their source from Sume other organism
  • Autotrophs: absorb + take in things from exviroment for example, Sunlight to Sulfur)

Prokaryotes Ecology

• Critical role in chemical cycling:

  • Nitrogen cycle (by fixing $N_2$ = make it available to plants).
  • Carbon cycle through decomposition & photosynthesis.

Protists

• Eukaryotes meaning they have membrane-bound organelles.
• Typically unicellular with a complex organization within their cells.
• Cell wall made of cellulose.
• Phylogenetic Velationships are often unclear because of this huge complexity within protists.
• Varied modes of reproduction -> is binary fission -> asexually- mitosis / Sexually-meiosis

What are fungi?

• heterotrophs - get nutrients from outside themselves
• Cells Walls have Chitin.
• Asexual / Sexual reproduction produce many spores. - Type III
  • Spores - produced by reproductive structure
    1. Wind disposual
    2. Water droplets disposual
    3. Attract insects - through scent
  • asexually- Stoday honeydew substance
• have diverse Roles
  • Mutulists
    • Lichen - relationship between fungus, bacteria, photosynthetic protist
• - Lichen is vary important Panar Species on Ground when species are not many
  - often found on rocks / trees. role in Succession
• Mutualist + (mycorrhizae) fungi and plant roots fungi and plant roots.
  - fungi help root absorption + give nutrient / Plant give Carbohydrates fungi through Photosynthesis