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