Systematics

1. Systematics Discovering and classifying organisms or Study of biodiversity

2. Taxonomy = discovery and description of species

3. 2. Phylogenetics = study of evolutionary relationships among species A B C

4. Species General agreement exists that there are entities in nature correctly referred to as species, and we share a feeling that we really understand the term and use it knowingly. Largemouth bass vs. smallmouth bass vs. rock bass, etc.

5. Species Historically….

6. Species Historically…. Carl von Linné, (Carolus Linnaeus) a Swedish botanist, binomial nomenclature, the combination of a genus name and a specific epithet, which together uniquely identify each species of organism

7. Species Historically…. Carl von Linné, a Swedish botanist, Published “Systema Naturae” 1759 10th edition is the starting point of zoological nomenclature

8. Species More recently…. Rules of Zoological Nomenclature The naming of an animal species and higher categories are governed by rules in the International Code of Zoological Nomenclature.

9. Species Including… Law of priority – 1st valid name is the name of the species

10. A species is given a binomen consisting of a genus name and a species name. E.g., Etheostoma flabellare • The genus name relates it to its closest relatives (if any), and the species name (specific epithet) usually describes some characteristic of the species

11. A species is given a binomen consisting of a genus name and a species name. E.g., Etheostoma flabellare • The genus name relates it to its closest relatives (if any), and the species name (specific epithet) usually describes some characteristic of the species • E.g., Etheostoma flabellare Rafinesque 1819 •  Catonotus flabellare (Rafinesque 1819)

12. A subspecies is given a trinomen - 3 part name Etheostoma flabellare flabellare Etheostoma flabellare lineolatum Etheostoma flabellare flabellare Rafinesque 1819 Etheostoma flabellare lineolatum (Agassiz 1854)

13. With the assignment to a genus, the species also assigned to a family, order, class, phylum, and kingdom as well. • The ending idaeis standard for animal families (Cyprinidae)

14. With the assignment to a genus, the species also assigned to a family, order, class, phylum, and kingdom as well. • The ending idaeis standard for animal families (Cyprinidae) The ending iformesis standardized for orders for many groups (Perciformes)

15. Note that both the genus and species names are italicized or underlined; other names are not • All names except the specific epithet are capitalized

16. Species General agreement exists that there are entities in nature correctly referred to as species, and we share a feeling that we really understand the term and use it knowingly. Largemouth bass vs. smallmouth bass vs. rock bass, etc.

17. Species But, when we begin looking at variation – i.e., at the population level and become cognizant of temporal and geographic variation, things become much more muddled.

18. Species But, when we begin looking at variation – i.e., at the population level and become cognizant of temporal and geographic variation, things become much more muddled. So, what is a species?

19. Biological Species Concept “Species are groups of actually or potentially interbreeding populations which are reproductively isolated from other such groups.” E. Mayr

20. Biological Species ConceptProblems: • Recognizing reproductive isolation between allopatric populations 2. Deciding whether infrequent mating is a result of hybridization between species, or mating between two populations of a species

21. Biological Species ConceptProblems: • In paleontology, there is no way of determining whether or not two forms separated by time were reproductively isolated 4. In uniparental (apomictic) species, individuals do not mate with one another and therefore do not fit the definition as biological species

22. Other Species Concepts Phylogenetic Species Concept: A species is a population (sexual reproduction) or lineage (asexual reproduction) that is diagnosable by a unique combination of character states

23. Other Species Concepts • Evolutionary Species Concept: “A species is a lineage with its own evolutionary role and tendencies” G. G. Simpson • 20 concepts

24. Where are we? • Biological species: Most conceptually satisfying. • Phylogenetic species: Operationally most accurate.

25. Speciation • How do species originate? Isolation of populations --> Differentiation --> Speciation

27. Differentiation

28. Differentiation= genetic • May be result of selection - natural or sexual • or genetic drift

29. Isolation • May occur allopatrically or sympatrically We speak of sympatric and allopatric speciation

30. Sympatric speciation? • In fact, is probably very rare in animals • Perhaps occurring only with changes in ploidy or as a result of hybridization

31. Allopatric speciation • Prevalent mode of speciation in animals • Founder effect, or peripatric, speciation • Vicariance, the splitting of populations by geological phenomena

32. Founder effect, or peripatric, speciation New species arise as populations become isolated on the periphery of a wide-ranging species. A A A

33. Founder effect, or peripatric, speciation New species arise as populations become isolated on the periphery of a wide-ranging species. A A B

34. Founder effect, or peripatric, speciation This model most easily explains the origin of species on islands where genetic change follows dispersal of individuals from continents or other islands Analogously, patchy habitats on continents may foster new species. Genetic change following isolation may lead to speciation.

35. Vicariance New species after populations are isolated by geological phenomena such as continental drift, orogeny, and glaciation.

36. Vicariance • For example, a headwater stream and its fishes might be transferred from one river system to another as changes occur in the earth’s crust. Following the transfer, fishes in the headwater stream are isolated from conspecifics in the drainage where they formerly occurred.

37. Stream Capture

38. Vicariance • One of the predictions of the vicariance model is that distributional patterns shared by several species groups are more likely to be the result of vicariant events than individual dispersal events.

39. Phylogeny A B C