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

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Presentation on theme: "Phylogenetics Phylogenetic trees illustrate the evolutionary relationships among groups of organisms, or among a family of related nucleic acid or protein."— Presentation transcript:

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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 abc d {a,b} {a,b,c} {a,b,c,d} Nodes represent the common ancestor

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

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

12 orangutan Gorilla Pan H. sapien time Phylogenetic Systematics - Introduction

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

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

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

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

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

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

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

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

21 orangutan Gorilla Pan H. sapien time 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 upright posture use of tools reduced hairiness bipedal complex language Phylogenetic Systematics - Characters and Taxa

22 Homo sapiens11 1 Pan paniscus 1 1 1 Gorilla gorilla 1 1 0 Pongo pygmaeus1 0 0 Hylobates 0 0 0 123123 1 2 3 MRP (Matrix Representation Parsimony)

23 23 A E D C B (11000) (00100) (01000) (00110) (11001) m characters n species Example C 1 C 2 C 3 C 4 C 5 A 11000 B 00100 C 11001 D 00110 E 01000 Input: Possible output: (00000) (11000) (01000) (00100) C2C2 C3C3 zero-root

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 (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

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

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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


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