BIOL300C Evolution Lecture Flashcards

Species Concepts

Overview of Species

  • Current recognition of approximately 1.75 million species.

  • Species vital to biological sciences and cultural discussions (e.g., identifying fish).

Categories of Life Forms

  • Algae: 2%

  • Protozoa: 2%

  • Fungi: 4%

  • Plants: 14%

  • Other animals: 4%

  • Chordates: 3%

  • Mollusks: 3%

  • Bacteria: <1%

  • Viruses: <1%

  • Arthropods: 67%

Questions about Species

  • What defines a species?

  • Do species exist independently of observation?

  • Can species concepts apply universally across all forms of life?

Species Concepts

  • Platonic Idealism: The belief in a perfect, unchanging ideal species.

  • Biological Species Concept: Defines species based on interbreeding capabilities.

    • A species consists of organisms that can mate and produce fertile offspring.

    • Example: Ligers (male lion and female tiger) are sterile, while female ligers are fertile when backcrossed.

  • Phylogenetic Species Concept: Focused on groups of populations sharing unique genetic traits.

  • Lineage Species Concept: Defines species as populations separated by reproductive isolation events.

Other Concepts of Species

  • Evolutionary Species Concept: A population maintaining its identity over time.

  • Recognition Species Concept: Based on common fertilization systems.

  • Cohesion Species Concept: Focuses on potential phenotypic cohesion based on intrinsic mechanisms.

  • Ecological Species Concept: Concerned with lineages adapting to specific ecological zones.

Natural Kinds

  • Derived from philosophical realism, species represent natural kinds defined by common processes (evolution, natural essences).

  • Importance of species in scientific inference and cultural understanding.

Systematics and Taxonomy

  • Systematics: The study of life diversity and relationships among organisms.

  • Phylogenetics: Explores relationships above the species level.

  • Taxonomy: Classifies and names organisms into groups (taxa).

  • Taxon: A named group of organisms.

Principles of Taxonomy

  • Universality: A single nomenclature system.

  • Uniqueness: Each taxon gets a unique name.

  • Stability: Names remain consistent over time.

  • Taxonomic Freedom: Codified guidelines for valid names without defining species.

Codes of Nomenclature

  • Governed by principles overseeing naming practices (e.g., International Code of Zoological Nomenclature, botanical, bacteria, and viruses).

Linnaean Taxonomy

  • Established by Carl Linnaeus, focusing on a hierarchical classification system.

  • Ranks include Kingdom, Class, Order, Genus, and Species.

  • Introduced binomial nomenclature where genus and species are italicized.

  • Example: Homo sapiens (Genus capitalized, species lowercase).

New Discoveries and Changes in Taxonomy

  • Names change with new discoveries influencing our understanding of relationships.

  • Taxonomy is dynamic, with ongoing discoveries highlighting new species continuously.

Conclusion: Taxonomy's Ongoing Evolution

  • Taxonomy remains an evolving field critical for understanding biological diversity and relationships despite challenges posed by emerging information.

  • Species Names

    • principle of binomial Nomenclature (“two names”)

    • genus and species names always in italics

    • genus capitalized, species noyt

    • examples: panthera tigris, homo sasapiens, passer domesticus

    • Also with author names

    • similar to cultural communication

  • Principle of types

    • name bearing types

    • Type specimen- a single specimen that bears the name of that species

    • Literature <——> type of specimen < ——> a species in nature

      species description variation

      diagnoses characteristics

      keys ecological interactions

      etc.

  • Principle of Priority

    • synonym- two names for the same taxon

    • the oldest available name is the name of the taxon

  • Principle of Homonymy

    • homonyn- the same name for two different taxa

  • New information

    • name changes because of new information about diversity and relationships

    • the rules help maintain stability but are in tension with new information.

    • taxonomic freedom- again… the codes only govern the logistics of naming, not what groups are named or theories underlying relationships between taxa