Introduction to Ecology and Conservation Biology: Study Notes

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Introduction to Ecology

Overview of Ecology

Ecology is the scientific study of interactions between organisms and their environment. Ecologists investigate the distribution and abundance of organisms, the interactions among them, and the flow of energy and matter through living communities.

Key Questions in Ecology:
- Why is a particular species found in one habitat but not another?
- Why does the species composition in a location change over time?
- How does the presence of one species affect another?
- How can the biotic environment affect the abiotic one?

Species Range and Niche

The range of a species is its geographic distribution, while a niche is the range of biotic and abiotic conditions a species can tolerate.

Abiotic Factors: Light, oxygen, nutrients, temperature, rainfall.
Biotic Factors: Competitors, prey distributions/food supplies, predators, pathogens/hosts, pollinators.

Note: Variability, extremes, and averages of these factors all influence species distributions.

Climate vs. Weather

Weather: Short-term atmospheric conditions (e.g., temperature, precipitation).
Climate: Long-term prevailing weather patterns in an area.

Global Temperature and Rainfall Patterns

Shaped by variation in temperature and moisture.
Key factors:
- Average annual temperature and precipitation.
- Annual variation in temperature and precipitation.

Seasonality

Caused by Earth's axial tilt as it orbits the sun.
Surface angles to the sun change over seasons, leading to temperature variability.

Global Wind Patterns

Shaped by the Coriolis Effect (deflection of air and water due to Earth's rotation):
- Deflection to the right (clockwise) in the Northern Hemisphere.
- Deflection to the left (counterclockwise) in the Southern Hemisphere.
- Determines prevailing wind directions.

Regional Rainfall Patterns

Mountains: Cause air to rise, cool, and release water on windward side; dry air descends on leeward side (rain shadow effect).
Hadley Cells: Global air circulation cells at the equator, causing high rainfall at the equator.

Oceans and Climate

Oceans moderate temperature due to water's high specific heat.
Water absorbs heat in summer (stays cooler than air) and releases heat in winter (stays warmer than air).
Hydrogen bonds in water require significant energy to break, contributing to temperature moderation.

Net Primary Productivity (NPP)

Net Primary Productivity (NPP) is the total amount of biomass generated through carbon fixation minus the amount oxidized during respiration.

Determines the organic material available to consumers.
Formula: where GPP = Gross Primary Productivity, R = Respiration

Major Terrestrial Biomes

Biomes are large ecological areas with distinct climate, flora, and fauna. Key characteristics include productivity, species diversity, and dominant vegetation.

Biome	Precipitation	Temperature	Productivity	Dominant Vegetation
Tundra	Very low	Very low	Low	Grasses, mosses, lichens, low shrubs
Boreal Forest (Taiga)	Low	Low, high variation	Low	Coniferous trees (spruce, fir, pine)
Temperate Deciduous Forest	Moderate	Moderate, seasonal	Moderate	Deciduous trees
Temperate Grassland (Prairie)	Moderately low	Moderate, seasonal	Moderate	Grasses
Subtropical Desert	Extremely low	High, extreme	Extremely low	Xerophytes (e.g., cacti)
Tropical Wet (Rainforest)	High	Constant, moderate-high	High	Broadleaf trees

Major Ocean Zones

Zone	Location/Description
Intertidal	Coastline, exposed at low tide
Neritic	Above continental shelf (up to 200 m deep)
Oceanic	Open ocean
Photic	Sunlit zone
Aphotic	No sunlight
Benthic	Ocean bottom

Light Penetration in Water

Water depth reduces sunlight availability.
Distribution of wavelengths changes with depth, affecting photosynthesis.

Major Lake Zones

Zone	Description
Littoral	Near shore, where plants can root
Limnetic	Offshore, too deep for rooted plants

Seasonal Turnover in Lakes

Winter Stratification: Dense 4°C water at bottom (nutrient-rich), colder water at surface (oxygenated).
Spring Turnover: Surface water warms to 4°C, sinks, carrying O2 down and nutrients up.
Summer Stratification: Dense 4°C water at bottom (nutrient-rich), warmer water at surface (oxygenated).
Fall Turnover: Surface water cools to 4°C, sinks, mixing O2 and nutrients.
Without turnover, nutrients would remain at the bottom, limiting productivity.

Conservation Biology

Measuring Biological Diversity

Genetic Diversity: Number and frequency of alleles in a species or group.
Species Diversity: Combines species richness (number of species) and evenness (relative abundance).
Phylogenetic Diversity: Number of independent evolutionary lineages, measured by branch lengths in a phylogeny.
Functional Diversity: Ecological distinctiveness based on functional traits.
Ecosystem Diversity: Number of distinct ecosystems in a region.

Conservation Priorities and Evolutionary Significant Units (ESUs)

Conservation biologists identify which populations, species, or lineages to conserve to maximize genetic, species, and ecosystem diversity.
Evolutionary Significant Units (ESUs): Populations considered distinct for conservation based on genetic and ecological criteria.

Case Studies

Kemp’s Ridley Sea Turtle: Population declined from ~40,000 nesting females (1947) to <1,000 (1985). Major conservation efforts justified by ESU status have increased numbers, but species remains critically endangered.
Dusky Seaside Sparrow: Subspecies extinct in the wild by 1987. Not considered an ESU (closely related to other seaside sparrows), so not prioritized for conservation. Officially declared extinct in 1990.

Conservation Hotspots

Regions with at least 1,500 endemic vascular plant species and >70% loss of primary vegetation.
Represent 17% of Earth's land area, home to 50% of known species, 77% of terrestrial vertebrates, and 42% of endemic terrestrial vertebrates.

Threats to Biodiversity and Conservation Strategies

All-Taxa Surveys: Comprehensive efforts to catalog all species in a region (e.g., Great Smoky Mountains National Park ATBI, Census of Marine Life).
Biological Inventories: Document species diversity and abundance to inform conservation.
Global Efforts: Census of Marine Life involved 2,700 scientists, 540 expeditions, and 30 million records, identifying 6,000 potentially new species and estimating 250,000 marine species.

Importance of Biodiversity

Current extinction rates are 100–1,000 times higher than historical averages.
Earth is experiencing a sixth major extinction event, primarily due to human activity (unlike previous events caused by climate change, volcanic activity, or asteroid impacts).

Ecosystem Services

Ecosystem services are the benefits that humans derive from ecosystems, including provisioning (food, water), regulating (climate, disease), supporting (nutrient cycling), and cultural services (recreation, spiritual value).
Biodiversity enhances ecosystem productivity, stability, and resilience.

Additional info: Ecosystem services are often categorized as provisioning, regulating, supporting, and cultural services. Conservation strategies may include protected areas, restoration, sustainable resource management, and policy interventions.