BIO 2 EXAM 1 — CONCISE STUDY GUIDE

Population

Individuals of the same species in one area.

Community

Different populations/species interacting in one area.

Ecosystem

Community + abiotic environment.

Biosphere

All ecosystems on Earth.

Biological Species Concept

Species can interbreed and produce fertile offspring.

Morphological Species Concept

Species separated by physical/biochemical traits.

Phylogenetic Species Concept

Smallest distinct lineage sharing a common ancestor.

Ecological Species Concept

Species defined by its ecological niche.

Prezygotic Barriers

Reproductive barriers that occur before fertilization.

Postzygotic Barriers

Reproductive barriers that occur after fertilization.

Allopatric Speciation

Speciation that occurs due to a geographic barrier separating populations.

Sympatric Speciation

Speciation that occurs without a geographic barrier; reproductive isolation happens in the same area.

LUCA

Last Universal Common Ancestor; not the first life but the ancestor of all modern life.

Homology

Similarity inherited from a common ancestor.

Homoplasy

Similarity evolved independently, often through convergent evolution.

Niche

Species' ecological role, including resources used and interactions with other species.

Fundamental Niche

Where a species could live without competition/predation.

Realized Niche

Where a species actually lives after biotic interactions.

Generalist Species

Species with broad niches.

Specialist Species

Species with narrow niches.

Population Density Formula

Density = number of individuals / area or volume.

Dispersion Patterns

The three types are clumped, random, and uniform.

Cohort

Group of individuals born at the same time.

Exponential Growth Formula

$\frac{dN}{dt} = rN$ and $N(t) = N_0e^{rt}$.

Carrying Capacity (K)

Maximum population an environment can support long-term.

Exponential Growth

Growth that occurs with unlimited resources, J-shaped.

Logistic Growth

Growth that occurs with limited resources, S-shaped.

Type I Survivorship Curve

Most survive to old age, few offspring, high parental care.

Type II Survivorship Curve

Constant chance of death across lifespan.

Type III Survivorship Curve

Many offspring, high juvenile mortality, few survive to adulthood.

Mark-Recapture Formula

$\text{marked first time} \times N = \text{marked recaptured} \times \text{total caught later}$.

Species Richness

Number of species in a community.

Species Diversity

Richness + relative abundance/evenness.

Species Interaction Types

Competition (-/-), Mutualism (+/+), Commensalism (+/0), Predation (+/-), Herbivory (+/-), Parasitism (+/-).

Intraspecific Competition

Competition within the same species.

Interspecific Competition

Competition between different species.

Competitive Exclusion Principle

Two species with the same niche cannot coexist indefinitely.

Resource Partitioning

Species reduce competition by using different resources.

Primary Succession

Starts where little/no biological community remains.

Secondary Succession

Soil remains after disturbance.

Facilitation in Succession

Early species modify the environment for later species.

r-selected Species

Reproduce fast with many offspring in disturbed environments.

K-selected Species

Slower reproduction with stronger competitors in stable environments.

Energy Flow in Ecosystems

Energy flows; matter cycles.

Trophic Levels Order

Producer → Primary consumer → Secondary consumer → Tertiary consumer.

Energy Transfer Efficiency

Only a fraction of energy passes to the next trophic level, typically about 10%.

Food Chain vs Food Web

Food chain is one path of energy transfer, food web is all interconnected feeding relationships.

Biomass

Amount of living tissue, usually decreases as you move up trophic levels.

Gross vs Net Primary Productivity (GPP vs NPP)

GPP = total energy captured; NPP = energy remaining after producer respiration.

Carbon Cycle

Carbon is reused through the biosphere, cycling between plants, animals, and atmosphere.

Nitrogen Fixation

Atmospheric N₂ → biologically usable nitrogen compounds.

Mass Extinction

Large increase in extinction over a short geological time.

Sixth Mass Extinction Causes

Major causes include habitat destruction, pollution, invasive species, and overhunting.

Climate vs Weather

Weather = short-term conditions; Climate = long-term pattern.

Latitude Effect on Solar Radiation

As latitude increases toward poles, solar radiation decreases.

Major Biome Characteristics

Tropical rainforest: warm, wet, diverse; Desert: dry; Tundra: cold, low precipitation.

Trophic Cascade

Change at one trophic level indirectly affects another trophic level.

Biotic vs Abiotic Factors

Biotic = living factors; Abiotic = nonliving factors.

Green Revolution

Increase in agricultural productivity through high-yield varieties, fertilizers, pesticides, and technology.