SYSTEMATICS Chapter 23. Systematics...Taxonomy..Classification SYSTEMATICS: The scientific study of the diversity of organisms and their evolutionary.

SYSTEMATICSChapter 23

Systematics...Taxonomy..Classification

•SYSTEMATICS: The scientific study of the diversity of organisms and their evolutionary relationships•TAXONOMY: branch of systematics

devoted to naming, describing and classifying organisms•CLASSIFICATION: process of assigning

organisms into groups based on their similarities or relationships

p497 LO#1

Taxonomy• Linnaeus 1735•Homo sapiens, H. sapiens, Homo sapiens•Binomial Nomenclature• First part: Genus -taxonomic category

made up of related species• Second: specific epithet -identifies one

particular organism (a specific species) within the genus.

Classification

5 ways to classify organisms:1. Morphologically (what they look like)2. Cell organization (single/multi cellular)3. Chemical make-up (DNA bar code)4. Ancestors (similar origin)- CLADES5. Way in which an organism develops

before birth (Embyology)

• Homo sapiens• (Man) (thinking)

Chordata

Mammalia

Primates

Hominidae

Homo

Animalia

Sapiens

• Turn this into “Tree” of relationships, with a common ancestor?

Classification of Living Things

6

KINGDOMS

3 Domains of Life

Horizontal Gene Transfer

p489p489Mitochondrial/Chloroplast endosymbiosis

Phylogenetic Trees (Cladograms)Hypothesis of evolutionary relationships

http://evolution.berkeley.edu/evolibrary

• A clade is a grouping that includes a common ancestor and all the descendants (living and extinct) of that ancestor

“Nested Hierarchies”

Phylogenetic Trees (Cladograms)

Derived Characters• A shared character is

one that two lineages have in common.

• A shared derived character is one that evolved in the lineage leading up to a clade and that sets members of that clade apart from other individuals.

Animal Kingdom Phylogeny

Homologous vs Analogous

• 4 Limbs• Wings of a bird, bat

How you classify can vary, depending on the traitsexamined: Another classification of Animals

Parsimony• The parsimony

principle is basic to all science and tells us to choose the simplest scientific explanation that fits the evidence.

• In terms of tree-building, that means that the best hypothesis is the one that requires the fewest evolutionary changes.

• (6 changes vs 7)

Molecular clocks allow scientists to use the amount of genetic divergence between organisms to extrapolate backwards to estimate dates.A-T-C-G “Oldest”A-A-C-GA-A-G-G “Youngest”

Biologists often represent time on phylogenies by drawing the branch lengths in proportion to the amount of time that has passed since that lineage arose…how do they determine the ‘timeline’?

Radiometric DatingStratigraphyMolecular clocks

KINGDOMS

Classification of Living Things

Eukaryotic vs. Prokaryotic CellsEukaryotic Cells• Large• Have chromosomes• Have membrane-bound

organelles• Nucleus• Mitochondria• Centrioles• (theory of

endosymbiosis)

Prokaryotic Cells• Small• No chromosomes,

only small circle of DNA (plasmid)• No membrane-

bound organelles.

Eukaryotic Cells are Larger than Prokaryotic cells

ARCHAEBACTERIA & EUBACTERIA

• TWO separate Kingdoms• prokaryotic organisms• Single cell (no multicellular forms)• Have a cell wall*• Peptidoglycan- Eubacteria• No Peptidoglycan- Archaebacteria

• No membrane-bound organelles • Autotrophic or Heterotrophic

PROTISTA: most diverse kingdom• The most ancient eukaryotic kingdom• Eukaryotic • Nearly ALL of the single cell

eukaryotes plus multicellular algae• heterotrophic, autotrophic, or both• Perhaps they are best defined as

eukaryotes that are NOT fungi, animals, or plants.

(Ex- Amoeba, Paramecium, Euglena, Algae)

FUNGI• Eukaryotic, usually multicellular • Heterotrophs that feed by absorption.• Cell walls with chitin (strength),

preventing bursting due to osmosis. • Played an essential role in the

evolutionary colonization of land.• Mycorrhizae- symbiotic relationships

between fungi and plant roots• Decomposers • Disease: yeast infections,

Plant-rusts, smuts, + Uses: Baking, brewing, foods, drugs Increase plant absorption of nutrients

(Ex- mushrooms, yeast)

Immobile, multicellular, autotrophic eukaryotes that have cell walls.

PLANTAE

ANIMALIA• Animals are multicellular, heterotrophic eukaryotes

that are capable of mobility at some stage during their lives, and that have cells lacking cell walls.

What are

the two

Main

Groups?

Humans?

• Homo sapiens• (Man) (thinking)

Chordata

Mammalia

Primates

Hominidae

Homo

Animalia

SapiensRelationships?

The Animal Kingdom

Main difference?

• Advanced brain • Eyes forward- stereoscopic vision/depth perception• Color vision• Acute hearing• Dental formula- same #, type, arrangement of teeth• Long slender limbs/rotate freely at hips/shoulders• 5 flexible digits with flattened nails/not claws• Opposable thumbs• Complex social behaviors• Usually 1 offspring at a time; longer parental care

Characteristics of Primates

Bipedal Skeletal Changes (Hominids)

Shape of the Spine, PelvisForamen magnum positionLeg vs arm lengthAlignment of great toe

Skull: brain, brow, jaw and teeth *Upright or Brain size first?

*Locking Knee Joint