General Biology Study Guide: Ecology, Evolution, and Biodiversity

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Ecology and Conservation

Introduction to Ecology

Ecology is the scientific study of interactions between organisms and their environment. It encompasses various levels, from individuals to populations, communities, ecosystems, and the biosphere.

Ecology: The study of how organisms interact with each other and their environment.
Population ecology: Focuses on populations of organisms, especially regarding population size, density, and factors affecting growth.
Restoration ecology: The science of restoring damaged ecosystems to a more natural state.
Conservation: The protection and management of biodiversity to prevent extinction and maintain ecosystem services.

Scientific Method in Biology

The scientific method is a systematic approach to understanding natural phenomena through observation, hypothesis formation, experimentation, and analysis.

Steps: Observation, Question, Hypothesis, Prediction, Materials and Methods, Results, Conclusions.
Hypothesis: A testable statement that explains an observation or answers a question.
Controlled experiment: An experiment in which only one variable is changed at a time.
Variables: Independent variable (manipulated), Dependent variable (measured), Control variables (kept constant).

Example: Testing the effect of sunlight on plant growth by varying light exposure (independent variable) and measuring plant height (dependent variable).

Key Terminology

Term	Definition
Inquiry	Process of asking questions and seeking answers through investigation
Hypothesis	Testable explanation for an observation
Controlled experiment	Experiment with controlled variables
Independent variable	Variable that is manipulated
Dependent variable	Variable that is measured
Theory	Broad explanation supported by evidence
Prediction	Expected outcome based on hypothesis
Peer-review	Evaluation by other scientists
Sample size	Number of observations or replicates
Statistics	Mathematical analysis of data

Ecological Principles

Climate and Species Distribution

Climate, the long-term pattern of weather in a region, is a major factor influencing species distributions. Weather refers to short-term atmospheric conditions.

Factors affecting species distribution: Latitude, sunlight intensity, global circulation, precipitation, seasonality, mountains, water bodies, vegetation, microclimate, and global climate change.
Biotic factors: Living components (e.g., competition, predation).
Abiotic factors: Non-living components (e.g., temperature, water, sunlight, rocks, soil).
Ecological niche: The role and position a species has in its environment.

Population Ecology

Population ecology studies the dynamics of species populations and how they interact with the environment.

Population size is affected by births, deaths, immigration, and emigration.
Exponential growth: Population increases rapidly under ideal conditions.
Logistic growth: Population growth slows as it approaches carrying capacity (K).

Key equations:

Exponential growth:
Logistic growth:

r (intrinsic rate of increase): Maximum per capita growth rate of a population.
K (carrying capacity): Maximum population size an environment can support.
Ecological footprint: Measure of human demand on Earth's ecosystems.

Key Terminology

Term	Definition
Annual rate of increase	Yearly population growth rate
Cohort	Group of individuals of the same age
r (intrinsic rate of increase)	Maximum per capita growth rate
K (carrying capacity)	Maximum sustainable population
Logistic growth	Growth with carrying capacity limit
Exponential growth	Unlimited population growth
Ecological footprint	Human impact on environment

Ecosystems and Energy Flow

Ecosystem Structure and Function

An ecosystem consists of all organisms in a community and the abiotic factors with which they interact. Energy flows through ecosystems, while matter cycles within them.

Producers (autotrophs): Organisms that produce their own food (e.g., plants, algae).
Consumers (heterotrophs): Organisms that obtain energy by eating other organisms.
Decomposers: Break down dead organic matter, recycling nutrients.
Primary production: Amount of light energy converted to chemical energy by autotrophs.
Net Primary Production (NPP): , where GPP is gross primary production and R is respiration.
Biomass: Total mass of living organisms in a given area.
Trophic pyramid: Diagram showing energy flow through trophic levels.

Key Terminology

Term	Definition
Primary producers	Autotrophs (e.g., plants)
Primary consumers	Herbivores
Secondary consumers	Carnivores that eat herbivores
Tertiary consumers	Carnivores that eat other carnivores
Detritus	Dead organic matter
Decomposers	Organisms that break down detritus
Heterotrophs	Organisms that consume others for energy
Autotrophs	Organisms that produce their own food
Net Primary Production (NPP)	Energy available to consumers
Net Ecosystem Production (NEP)	Total biomass accumulation
Production efficiency	Efficiency of energy transfer
Trophic pyramid	Energy flow diagram
Eutrophication	Nutrient enrichment of water bodies
Bioremediation	Use of organisms to detoxify environments
Biological augmentation	Adding organisms to restore ecosystems

Biodiversity and Conservation

Biodiversity and Its Threats

Biodiversity includes genetic, species, and ecosystem diversity. It is threatened by habitat loss, introduced species, overharvesting, and global change.

Genetic diversity: Variation within a species.
Species diversity: Variety of species in an ecosystem.
Ecosystem diversity: Variety of ecosystems in a region.
Threats: Habitat loss, introduced species, overharvesting, nutrient enrichment, toxins, plastics, climate change.
Conservation strategies: Protecting habitats, restoring ecosystems, sustainable resource use.

Key Terminology

Term	Definition
Introduced species	Non-native species that disrupt ecosystems
Endangered species	Species at risk of extinction
Threatened species	Species likely to become endangered
Nutrient enrichment	Excess nutrients in ecosystems
Diversity (genetic, species, ecosystem)	Levels of biodiversity
Ecosystem services	Benefits humans obtain from ecosystems
Habitat loss	Destruction of natural habitats
Biological magnification	Increase in toxin concentration up food chains
Overharvesting	Excessive removal of species
Extinction	Loss of a species
Biodiversity hotspot	Area with high species diversity and threat
Greenhouse effect	Warming due to atmospheric gases

Evolution and Phylogeny

Introduction to Evolution

Evolution is the process by which populations of organisms change over generations. It is driven by mechanisms such as natural selection, genetic drift, gene flow, and mutation.

Natural selection: Process where individuals with advantageous traits survive and reproduce more successfully.
Adaptation: Trait that increases an organism's fitness in its environment.
Speciation: Formation of new species.
Phylogeny: Evolutionary history and relationships among species.

Key Figures in Evolutionary Thought

Darwin: Proposed natural selection as a mechanism for evolution.
Wallace: Independently conceived the theory of evolution by natural selection.
Lamarck: Proposed inheritance of acquired characteristics (not supported today).
Lyell, Hutton: Developed ideas about gradual geological change.

Mechanisms of Evolution

Mutation: Random changes in DNA that introduce new genetic variation.
Genetic drift: Random changes in allele frequencies, especially in small populations.
Gene flow: Movement of alleles between populations.
Non-random mating: Mating that is not random with respect to genotype or phenotype.
Selection: Differential survival and reproduction.

Hardy-Weinberg equilibrium: Describes a non-evolving population. The equation is:

Where p and q are the frequencies of two alleles in a population.

Types of Selection

Directional selection: Favors one extreme phenotype.
Disruptive selection: Favors both extreme phenotypes.
Stabilizing selection: Favors intermediate phenotypes.

Key Terminology

Term	Definition
Allele frequency	Proportion of a specific allele in a population
Gene flow	Movement of alleles between populations
Genetic drift	Random change in allele frequencies
Founder effect	Genetic drift in a new, small population
Bottleneck effect	Genetic drift after a population reduction
Genotype	Genetic makeup of an organism
Phenotype	Observable traits
Heterozygote advantage	Greater fitness of heterozygotes
Sexual selection	Selection for traits that increase mating success
Artificial selection	Human-directed breeding
Historical constraints	Limitations due to evolutionary history

Phylogenies and Classification

Phylogenies depict evolutionary relationships among species. They are constructed using morphological and molecular data.

Homology: Similarity due to shared ancestry.
Analogy: Similarity due to convergent evolution.
Cladistics: Method of classifying species based on common ancestry.

Summary Table: Major Concepts

Topic	Key Points
Ecology	Interactions, climate, distribution, niche, biotic/abiotic factors
Population Ecology	Population growth, carrying capacity, ecological footprint
Ecosystems	Energy flow, trophic levels, nutrient cycling
Biodiversity	Genetic/species/ecosystem diversity, threats, conservation
Evolution	Natural selection, adaptation, speciation, phylogeny

Additional info: These notes are based on the Campbell Biology 12th edition and cover key concepts in ecology, evolution, and biodiversity, suitable for college-level General Biology courses. For further study, refer to the chapters and resources listed in your syllabus.