The Tree of Life Phylogeny Phylogenetics Phylogenetic trees

The Tree of Life Phylogeny

Phylogenetics • Phylogenetic trees illustrate the evolutionary relationships among groups of organisms, or among a family of related nucleic acid or protein sequences

Each branch represents a new species which inherits many (primitive) traits from the ancestor but also has a new (derived) trait which appear for the 1 st time

Evolutionary trees depict clades. A clade is a group of organisms that includes an ancestor and all descendents of that ancestor. Phylogeny Evolutionary tree Phylogenetic tree Cladogram Are synonymous

Tree terminology a b c d d is the outgroup of abc Taxa {a, b} cluster {a, b, c} {a, b, c, d} Nodes represent the common ancestor node root

Parsimony The principle of parsimony implies that we should prefer the phylogeny that requires the fewest evolutionary changes.

Which tree is demonstrating maximum parsimony?

Phylogenetic Systematics - Introduction Phylogeny for four different taxa orangutan Gorilla Pan H. sapien

Phylogenetic Systematics - Introduction orangutan Gorilla Pan H. sapien Start at the ROOT. The root is the earliest point of time shown in this particular phylogeny… time root

Phylogenetic Systematics - Introduction orangutan Gorilla Pan H. sapien The root represents the common ancestor to orangutans, gorilla, Pan and H. sapien. time root

Phylogenetic Systematics - Introduction orangutan Gorilla Pan H. sapien time lineage gives rise to gorilla, pan, H. sapien orangutan lineage At some point this common ancestor split into two new species, one of which gave rise to orangutans and one which is the common ancestor to gorilla, Pan, and H. sapien. root

Phylogenetic Systematics - Introduction orangutan Gorilla Pan H. sapien time lineage gives rise to gorilla, pan, H. sapien orangutan lineage The common ancestral lineage to Gorilla, Pan and H. sapien eventually splits to form the lineage that leads to modern gorillas and a lineage that will give rise to Pan and H. sapien. root

Phylogenetic Systematics - Introduction time lineage gives rise to gorilla, pan, H. sapien The common ancestral lineage to Pan and H. sapien eventually splits to form the ancestors to chimpanzees and H. sapien. orangutan lineage orangutan Gorilla Pan H. sapien root

Phylogenetic Systematics - Introduction time lineage gives rise to gorilla, pan, H. sapien What is most closely related to Gorillas? orangutan Gorilla Pan H. sapien orangutan lineage In summary, there has been three splitting events (circles) that lead to four taxa at the tips of the tree. root

Phylogenetic Systematics - Introduction orangutan Gorilla Pan H. sapien Gorillas share a more recent common ancestor with Pan and H. sapien than with organutan. time root most recent common ancestor to gorilla, Pan, H. sapien.

Phylogenetic Systematics - Introduction sister taxa Pan and H. Sapien are called sister taxa because they are most closely related to each other than to any other species. orangutan Gorilla Pan H. sapien Is there a sister taxon to the Gorilla? time root most recent common ancestor to gorilla, Pan, H. sapien.

Phylogenetic Systematics - Characters and Taxa orangutan Gorilla Pan H. sapien bipedal complex language A phylogeny is a summary of both characters and taxa. use of tools Characters diagnose branches of a phylogeny. reduced hairiness time upright posture

Phylogenetic Systematics - Characters and Taxa Characters that all groups in a phylogeny share plesiomorhies orangutan Gorilla Pan H. sapien bipedal complex language use of tools Characters shared but derived are called synapomorphies reduced hairiness Characters shared only in one tip taxon are autapomorphies time upright posture

monophyletic taxon includes a group of organisms descended from a single ancestor polyphyletic taxon is composed of unrelated organisms descended from more than one ancestor paraphyletic taxon, which includes an ancestor and a group of organisms descended from it

Classification based on physical and structural similarities • • • Carolus Linnaeus (1707 -1778) Created binomial nomenclature (2 word naming system) 1 st word = Genus (genera if plural) = a group of similar species 2 nd word = specific epithet = Species Scientific name = Genus + specific epithet e. g. Homo sapiens

Rules for writing species names 1. Latin is the language of scientific names (Latin is no longer spoken, so it does not change) 2. Italicize in print and underline when hand written 3. 1 st letter of the genus is CAPITALIZED & 1 st letter of specific epithet is lowercase

Canis latrans = Coyote Canis lupus = Grey wolf

Cougar? Puma? Panther? Catamount? Mountain lion? Or… Felis concolor?

• Domain • Kingdom • Phylum • Class • Order • Family • Genus • Species

All Living Organisms are grouped into. . . 3 DOMAINS • EUBACTERIA - true bacteria • ARCHAEA - ancient prokaryotes • EUCARYA - modern eukaryotes

Six Kingdoms Eubacteria · Prokaryotic · True bacteria · RNA is simple · Have true cell walls · Unicellular Archaebacteria · Prokaryotic · RNA more complex · Unicellular Protista · Eukoryotic · Autotrophs and heterotrophs · Lacks organs systems · Lives in moist environments · Unicellular or multicellular Fungi · Eukaryotic · Heterotrophs · Unicellular or multicellular · Absorbs nutrients from organic material in its environment · Unicellular or multicellular

Plantae Six Kingdoms · Eukaryotic · Autotrophs · Multicellular · Photosynthetic Animalia · Eukaryotic · Heterotrophs · Multicellular