Systematics: Seeking Order Amidst Diversity Chapter 18: Systematics: Seeking Order Amidst Diversity

1 2 3 Systematics: The science of reconstructing phylogeny Chapter 18: Systematics Systematics: The science of reconstructing phylogeny Evolutionary history Three natural processes underlie evolution: 1) Genetic variation exists among members of a population 2) Such variation is inherited to the next generation 3) Natural Selection: The survival and enhanced reproduction of members with favorable variations. 1 2 3 Birds like red frogs

Taxonomy: The science of naming organisms and placing Chapter 18: Systematics Taxonomy: The science of naming organisms and placing them into categories based on their evolutionary relationships (Table 18.1) Bacteria Archaea Prokaryotes (no nucleus) Eukarya Eukaryotes (true nucleus) Domain Eukarya Animalia Chordata Reptilia Squamata Colubridae Thamnophis Sirtalis Kingdom Phylum Class Order Family Genus Species Scientific Name

Thamnophis sirtalis Thamnophis marcianus Thamnophis radix Chapter 18: Systematics Thamnophis sirtalis Thamnophis marcianus Thamnophis radix

Based work on Aristotle (~ 350 B.C.) Introduced scientific names Chapter 18: Systematics “Father” of Taxonomy Carl von Linne (1707 - 1778) (Carolus Linnaeus) Based work on Aristotle (~ 350 B.C.) Introduced scientific names Basis for Classification: 1) Anatomical structures (Homologous = same evolutionary origin) 2) Developmental stages 3) Genetic comparisons (DNA)

Chromosome comparison Sequence comparison (Figure 18.3) Chromosome comparison Chapter 18: Systematics Sequence comparison

system (plants / animals) 1) Monera (single-celled prokaryotes) Chapter 18: Systematics The Kingdoms (Proposed by Robert Whittaker - 1969): 2) Protists (single-celled eukaryotes) 3) Fungi (multicellular; absorptive digestion) 4) Plantae (Multicellular; photosynthsis) 5) Animalia (Multicellular; ingestion) Replaced 2 kingdom system (plants / animals)

The Domains (Proposed by Carl Woese - 1990’s): Chapter 18: Systematics The Domains (Proposed by Carl Woese - 1990’s): Archaebacteria Eubacteria (Figure 18.5)

Chapter 18: Systematics (Figure 18.6)

? Taxonomies Do Change (more common further down spectrum): Chapter 18: Systematics Taxonomies Do Change (more common further down spectrum): 1) Emergence of New Information: Baltimore Oriole Bullock’s Oriole ? Biological Species Definition

~ 2/3 of Earth’s biodiversity Chapter 18: Systematics Taxonomies Do Change (more common further down spectrum): 1) Emergence of New Information: 2) Asexual Reproducing Organisms: Do not fit Biological Species Definition (Interbreeding) Phylogenetic Species Concept: The smallest discernable group that contains all the descendants of a single common ancestor Currently 1.4 million species are named 7000 - 10,000 new / year 5% prokaryote / protists 22% plants / fungi 63% animals Tropical Rain Forest: 6% of Earth’s land area ~ 2/3 of Earth’s biodiversity Why? Ease of locating them...