Biodiversity and Classification Lecture Notes

Biodiversity: Refers to the variety of life found on Earth and the complex interactions occurring between them.
Ecosystem: Defined as a community consisting of living organisms that interact both with each other and with their non-living environment within a specific geographic area.
Species: A specific group of organisms capable of reproducing with each other at random to produce viable (fertile) offspring.

High Genetic Diversity (High vs Low): * Enhanced Adaptation: Greater genetic variation allows populations to adapt more effectively to changing environments. * Ecosystem Resilience: High diversity strengthens the ability of an ecosystem to recover from disturbances. * Improved Functional Capacity: A wider range of genetic traits supports more robust biological functions. * Reduced Disease Risk: Diverse gene pools are less likely to be wiped out by a single pathogen.
Low Genetic Diversity: * Higher Extinction Risk: Limited variation makes populations more susceptible to total loss. * Inbreeding Depression: Reduced biological fitness caused by the mating of closely related individuals. * Vulnerability to Environmental Changes: Lack of genetic flexibility makes the group unable to survive shifts in climate or habitat. * Reduced Ecosystem Functionality: The overall health and efficiency of the ecosystem are compromised.

Invasive Species: * Are brought into a new area (often by human intervention). * They are notoriously hard to control. * They out-compete native species for essential resources. * They typically have no natural predators in the new environment.
Indigenous Species: * Occur naturally "everywhere" or in a variety of places. * These species occur naturally across multiple geographic areas.
Endemic Species: * Occur naturally in a very specific geographic area. * They cannot be found anywhere else in the world.

Arrival and Control: These species are introduced to an area where they are not native; they remain difficult to control due to a lack of natural predators.
Resource Competition: They steal resources from indigenous species (frequently described as "out-competing" them).
Population Decline: The presence of invasives leads to a decrease in the indigenous population.
Extinction and Emigration: Their presence can cause further local extinctions or force indigenous species to emigrate.
Trophic Impact: They impact the food chain negatively, disrupting established ecological balances.

Importance of Indicator Species: * Serve as an early warning system for environmental changes. * Assessing overall ecosystem health. * Guiding conservation efforts based on their presence or absence. * Provide cost-effective monitoring of ecological status.
Examples of Indicator Species: * Lichens * Amphibians * Macroinvertebrates * Various plants

Classification: The process of grouping organisms based on their shared similarities.
Taxonomy: The scientific study of naming and classifying organisms using a structured system.
Systematics: A field of study that researches the diversity of organisms and their relationships to each other, subsequently placing them into groups.
Nomenclature: A specific field of study focused on naming organisms according to their taxonomy.
Necessity of Classification: * It is impossible to study every living organism (totaling millions) at an individual level. * Classification facilitates easier study by organizing organisms into manageable groups. * Once classified, scientists can infer significant information about an organism based on its group traits.
Two Main Purposes of Taxonomy: 1. To identify organisms. 2. To represent the relationships among them.
Taxonomic Levels: Most taxonomists use a hierarchical system consisting of levels of classification to organize life.

Aristotle ( $384\,B.C.$ ): * A natural scientist who introduced the first classification method. * Divided life into two main groups: Plants and Animals. * Grouped these organisms according to their physical appearance. * Microorganisms were omitted as they had not yet been discovered.
Carolus Linedaeus ( $1707 - 1776$ ): * Recognized as the first modern scientist to create a reliable classifying system. * Considered the "Father of Taxonomy." * Developed the Binomial Nomenclature naming system. * Designed a hierarchical system of classification consisting of groups or "taxonomic levels" (a single group is a "taxon").
Robert Whittaker ( $1969$ ): * Proposed the 5-Kingdom Classification System: 1. Kingdom Monera 2. Kingdom Protista 3. Kingdom Mycota 4. Kingdom Plantae 5. Kingdom Animalia
Carl Woese ( $1990$ ): * Influenced by advancements in microbiology. * Proposed three domains above the kingdom level: 1. Domain Eukaria / Eubacteria 2. Ancient Domain Archiebacteria 3. Domain Eukarya

General Principles: * Each taxon contains organisms with similar characteristics. * There are various groups nested within each level. * As you move down the hierarchy, each successive taxon contains fewer types of organisms, but the organisms within those groups become more similar. * Kingdom: The largest taxon group; very broad; organisms have fewer traits in common. * Species: The smallest taxon group; very narrow; organisms have the most traits in common.
Hierarchy Mnemonic: "Dear King Philip Came Over For Good Spaghetti" 1. Dear - Domain 2. King - Kingdom 3. Philip - Phylum 4. Came - Class 5. Over - Order 6. For - Family 7. Good - Genus 8. Spaghetti - Species
Relationship Rule: Living things have more and more in common the more boxes/levels they share, showing increasing similarities as they move from Kingdom to Species.

Level	Human	Lion	House Cat
Kingdom	Animalia	Animalia	Animalia
Phylum	Chordata	Chordata	Chordata
Class	Mammalia	Mammalia	Mammalia
Order	Primate	Carnivora	Carnivora
Family	Homonidae	Felidae	Felidae
Genus	Homo	Panthera	Felis
Species	sapien	leo	domesticus

Common Names vs. Scientific Names: * All living things have common names, but these can vary by location, leading to confusion. * To avoid confusion, organisms are given Scientific Names. * Scientific names are unique to every organism and are in Latin.
Binomial Naming System: * A two-part naming system (2-naming system). * Scientific Name = $\text{Genus} + \text{Species}$ .
Rules for Writing Scientific Names: 1. Typed: Must be in Italics. 2. Written: Must be underlined. 3. Capitalization: The Genus name must start with a Capital letter. 4. Lowercase: The species name must be in lower-case.

Species Definition: A group of organisms that can reproduce with each other at random to produce viable offspring.
Classification Context: This is the smallest group into which a biologist can classify organisms.
Cross-Genera Offspring: Offspring born from two animals derived from different genera will be infertile (e.g., a mule).