Biology Taxonomy Flashcards

Taxonomy and Species

• Taxonomy is the science of classifying organisms based on their relationships and distinguishing characteristics.
• A species is a fundamental grouping in biological classification, defined as a population that breeds and produces fertile offspring under natural conditions.
• Inherited variation is the foundation of evolution.

Variation in Species

• Members of a species may exhibit differences in appearance; not all look alike.
• Polymorphism occurs when multiple forms exist within a single population.
• Geographic variation arises when a species spreads across diverse environments, leading to distinct physical traits.

Reproductive Isolation

• Species remain separate due to three main mechanisms:
  • Lack of interaction among potential mates
  • Mates interact but do not breed
  • Mating occurs, but offspring are not viable or fertile.

Limitations of Species Concept

• The species concept has limitations, especially for organisms that reproduce asexually.
• Some sexually reproducing species may still have partial barriers to interbreeding.
• Slow, measurable changes in species over time challenge the applicability of the species concept.

Classification Characteristics

• Organisms are classified using structural, biochemical, behavioral, and genetic characteristics.
• Stable traits are crucial for animal classification, with structural features being particularly significant.

Structural Relationships

• Structural similarities that indicate a shared ancestry are known as homologies.
• Homologous structures, such as the flipper of a whale, bird wing, and human arm, arise from common ancestry.
• Similarities in appearance and function that do not derive from shared ancestry are called analogies, exemplified by moth and bird wings.

Classification System

• Carl von Linne, also known as Carolus Linnaeus, formulated the system for classifying organisms.
• Classification utilizes homologies to categorize species into broader groups.
• Species with similar traits are classified within the same genus, with the plural form being genera.
• Similar genera belong to the same family; distinctive animals are grouped in an order.
• Classes contain groups with basic similarities, such as mammalia for fur and milk-producing attributes.
• After class, organisms are sorted into phylum (or divisions for botanists).
• All animals fall under the kingdom Animalia.

Evolution and Classification

• Charles Darwin's work transformed Linnaeus's classification approach, correlating it with evolutionary relationships.
• Binomial nomenclature, established by Linnaeus, uses a two-word naming system (first word: genus, second word: species) to identify organisms.

Phenetics in Taxonomy

• Phenetics analyzes organisms based on a wide range of characteristics and assigns similarity scores based on shared traits.
• It treats all characteristics equally, although it may overlook important phylogenetic relationships.