The Tree of Life. Phylogeny

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1 The Tree of Life Phylogeny

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

4 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

5 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

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

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

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

12 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

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

14 lineage gives rise to gorilla, Phylogenetic Systematics - Introduction 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. orangutan Gorilla Pan H. sapien time root pan, H. sapien

15 lineage gives rise to gorilla, Phylogenetic Systematics - Introduction 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. orangutan Gorilla Pan H. sapien time root pan, H. sapien

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

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

18 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.

19 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.

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

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

22 MRP (Matrix Representation Parsimony) 3 Homo sapiens Pan paniscus Gorilla gorilla Pongo pygmaeus Hylobates 0 0 0

23 n species Example Input: m characters C 1 C 2 C 3 C 4 C 5 A B C D E Possible output: C 3 (00000) (00100) D (00110) B (00100) E (01000) zero-root (01000) (11000) A (11000) C 2 C (11001) 23

24 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

25 Classification based on physical and structural similarities Carolus Linnaeus ( ) 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

26 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

27 Canis lupus = Grey wolf Canis latrans = Coyote

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

29 Domain Kingdom Phylum Class Order Family Genus Species Did Kinky Phil Come Over For Good Sex

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

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33 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

34 Plantae Eukaryotic Autotrophs Multicellular Photosynthetic Animalia Eukaryotic Heterotrophs Multicellular