Biology: Species and Classification Overview

Species Definition

• Organisms that can interbreed and produce fertile offspring
• Estimated 8.7 million species exist
• Only 1.2 million species have been identified (mostly insects)
• Scientific names are used to uniquely identify each species

Classification of Organisms

• Enables efficient identification and prediction of characteristics
• Necessary due to the immense diversity of species
• Two-part binomial name:
  • First part: Genus
  • Second part: Species

Population

• Group of organisms of the same species living in the same area at the same time
• Capable of interbreeding
• One species may consist of one or many populations

Community

• Collection of interacting populations within an ecosystem
• Example: Coral reef community includes interactions among coral, algae, fish, and invertebrates

Habitat

• Location where a community, species, population, or organism lives
• Described by geographical, physical, and ecosystem characteristics needed for survival
• Example: Clownfish inhabit shallow tropical reefs and live symbiotically in anemones for protection

Ecosystem

• An open system where energy and matter can enter and exit
• Consists of a community and its physical environment
• Example: Forest ecosystem includes biotic components (e.g., trees, animals, fungi) and abiotic components (e.g., sunlight, soil, water)

Ecological Niche

• The role of a species in an ecosystem
• The niche comprises all biotic and abiotic interactions that influence the growth, survival, and reproduction of a population
• Example: How food is obtained

Population Interactions

• Populations within an ecosystem interact with each other in various ways, shaping their population dynamics

Ecological Footprint

• Measures the biologically productive land and water needed to support a population’s consumption and waste
• Carrying capacity is the inverse of the ecological footprint, indicating how many people can be supported based on current consumption

Sustainability in Ecosystems

• Healthy ecosystems maintain a balance between inputs and outputs
• Closed Loop Function: Closed loop ecosystem, where inputs are balanced by outputs
• Long-Lived Ecosystems: Examples like tropical rainforests demonstrate ecosystems that have thrived for millions of years
  • Inputs: Solar radiation, organic matter, inorganic nutrients
  • Processes: Photosynthesis, energy transfer through food chains, nutrient cycling
  • Outputs: Heat, dead organic matter, gases released back into the atmosphere

Tipping Points in Ecosystems

• Human activity can lead to tipping points in ecosystem stability
• Amazon rainforest releases vast amounts of water vapor, contributing to regional rainfall patterns
• Deforestation disrupts transpiration, reducing the release of water vapor
• Deforestation leads to reduced rainfall, creating drier conditions that make the forest more prone to fires
• Continued deforestation could push the Amazon past a tipping point, transitioning it to a drier, savanna-like ecosystem

Wolf Population Dynamics in Yellowstone

• Wolves were reintroduced in 1995
• Wolf population experienced exponential growth initially
• Wolf population reached a carrying capacity around 2004
• Wolf population then exhibited overshoot and dieback in 2008
• Environmental resistance is a limiting factor, impacting wolf population growth
• Carrying capacity of wolves in Yellowstone is estimated between 100 and 200 individuals

Keystone Species

• Keystone species are crucial for the entire structure of their ecosystem
• Keystone species have a powerful influence on the community even if they are not the most abundant
• Keystone predators like wolves keep prey populations in check, preventing overexploitation of resources
• Species like beavers create habitats that benefit other organisms, altering the ecosystem