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Phylogeny and Systematics

Understand phylogenetic evolution and species divergence through systematics, speciation, and taxonomy. Explore adaptive radiation, phenotypic divergence, and historical evidence in the study of ancestral and descendant species.

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Phylogeny and Systematics

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  1. Phylogeny is the evolutionary history of a group of organisms Phylogeny and Systematics

  2. Phylogeny is the evolutionary history of a group of organisms - which species are ancestral to which others… Phylogeny and Systematics

  3. Phylogeny is the evolutionary history of a group of organisms Systematics is the science of reconstructing the evolutionary history of a group of organisms Phylogeny and Systematics

  4. Phylogeny and Systematics • in order to understand phylogeny through the science of systematics, we must start at the beginning - macroevolution starts with the origin of species

  5. Speciation - ??? Phylogeny and Systematics

  6. Speciation - the evolution of reproductive isolation between once-interbreeding populations The evolutionary source of new species through adaptive evolution Phylogeny and Systematics

  7. Speciation - the evolution of reproductive isolation between once-interbreeding populations The evolutionary source of new species through adaptive evolution Taxonomy - the naming of species Phylogeny and Systematics

  8. Speciation - the evolution of reproductive isolation between once-interbreeding populations The evolutionary source of new species through adaptive evolution Taxonomy - the naming of species “New species” implies that a species is newly described by taxonomists, not that it has newly diverged from its ancestor Phylogeny and Systematics

  9. Speciation - the evolution of reproductive isolation between once-interbreeding populations The evolutionary source of new species through adaptive evolution We don’t know how many species exist - taxonomists have lots to do Taxonomy - the naming of species Phylogeny and Systematics

  10. Speciation - the evolution of reproductive isolation between once-interbreeding populations The evolutionary source of new species through adaptive evolution We don’t know how many species exist - taxonomists have lots to do Taxonomy - the naming of species Taxonomy uses “binomial nomenclature” which means naming species with two names - Genus species for instance… Phylogeny and Systematics

  11. phenotypic divergence Phylogeny and Systematics descendant species taxonomists describe species speciation Newly-evolved species to diverge from one another in a variety of characteristics, not just those that affect RI ancestral species time

  12. phenotypic divergence Phylogeny and Systematics descendant species speciation Phylogenetically closely related species diverge in characteristics over evolutionary time because they occupy different environments - this is “divergent evolution” time Ancestral species

  13. Phylogeny and Systematics derived, descendant species now A series of speciation events over evolutionary time that leads from a single ancestral species to a set of derived, descendant species is“adaptive radiation” then Ancestral species

  14. Phylogeny and Systematics • Adaptive radiation - A series of speciation events over evolutionary time that leads from a single ancestral species to a set of derived, descendant species • Divergent evolution - phylogenetically closely related species in different environments develop different phenotypic characteristics due to different environmental selection pressures

  15. Phylogeny and Systematics derived, descendant species now Taxonomists describe species - they work with what we have now Systematists sort species into categories - they try to figure out what happened in the past then Ancestral species

  16. Phylogeny and Systematics the problem for systematists is time….

  17. Phylogeny and Systematics • Phylogeny is the study of phenomena that happened in the past, sometimes deep in the past

  18. Phylogeny and Systematics • Phylogeny is the study of phenomena that happened in the past, sometimes deep in the past • Life on earth originated about 3.5 billion years ago

  19. Phylogeny and Systematics • Phylogeny is the study of phenomena that happened in the past, sometimes deep in the past • Life on earth originated about 3.5 billion years ago • vertebrates originated about 500 million years ago

  20. Phylogeny and Systematics • Phylogeny is the study of phenomena that happened in the past, sometimes deep in the past • Life on earth originated about 3.5 billion years ago • vertebrates originated about 500 million years ago • How can we understand this history?

  21. Phylogeny and Systematics • Phylogeny is the study of phenomena that happened in the past, sometimes deep in the past • Life on earth originated about 3.5 billion years ago • vertebrates originated about 500 million years ago • What are our historical texts??

  22. Phylogeny and Systematics • Direct evidence - the fossil record

  23. Direct evidence - the fossil record Paleontology Phylogeny and Systematics

  24. Direct evidence - the fossil record Indirect evidence Paleontology Phylogeny and Systematics

  25. Direct evidence - the fossil record Indirect evidence anatomical homology Paleontology Phylogeny and Systematics

  26. Direct evidence - the fossil record Indirect evidence anatomical homology Paleontology comparative anatomy Phylogeny and Systematics

  27. Phylogeny and Systematics

  28. Direct evidence - the fossil record Indirect evidence anatomical homology embryonic homology Paleontology comparative anatomy comparative embryology Phylogeny and Systematics

  29. Phylogeny and Systematics

  30. Direct evidence - the fossil record Indirect evidence anatomical homology embryonic homology molecular homology Paleontology comparative anatomy comparative embryology molecular systematics Phylogeny and Systematics

  31. Phylogeny and Systematics

  32. Phylogeny and Systematics • How do systematists make decisions about phylogeny?

  33. Phylogeny and Systematics • How do systematists make decisions about phylogeny? • Systematists compare characteristics of species whose phylogenetic relationships they are trying to determine

  34. Phylogeny and Systematics • How do systematists make decisions about phylogeny? • Comparisons of characteristics… • “ancestral” and “derived” are relative states

  35. Phylogeny and Systematics • How do systematists make decisions about phylogeny? • Comparisons of characteristics… • “ancestral” and “derived” are relative states • phylogenetic relationships are determined by shared derived characteristics

  36. Phylogeny and Systematics • Phylogenetic relationships are determined by shared derived characteristics • Think back to our discussion of mammals…

  37. Phylogeny and Systematics • Phylogenetic relationships are determined by shared derived characteristics • Think back to our discussion of mammals… • Mammals share • hair • mammary glands • three “ear ossicles” • other derived characteristics

  38. Phylogeny and Systematics • Phylogenetic relationships are determined by shared derived characteristics • Mammals share • hair • mammary glands • three “ear ossicles” • other derived characteristics • these shared derived characteristics distinguish mammals from other groups of vertebrates

  39. Phylogeny and Systematics • Derived characteristics are called “apomorphic” characteristics or “apomorphies”

  40. Phylogeny and Systematics • Derived characteristics are called “apomorphic” characteristics or “apomorphies” • An apomorphy of humans is upright posture

  41. Phylogeny and Systematics • Derived characteristics are called “apomorphic” characteristics or “apomorphies” • Derived characteristics that are shared by two or more species in a group of species are called “synapomorphies”

  42. Phylogeny and Systematics • Derived characteristics are called “apomorphic” characteristics or “apomorphies” • Derived characteristics that are shared by two or more species in a group of species are called “synapomorphies” • Eyesockets (orbits) on the front of the skull is a synapomorphy of primates

  43. Phylogeny and Systematics • Derived characteristics are called “apomorphic” characteristics or “apomorphies” • Derived characteristics that are shared by two or more species in a group of species are called “synapomorphies” • The shared derived characteristics that distinguish a group of organisms from other groups are their “unifying synapomorphies”

  44. Phylogeny and Systematics • The shared derived characteristics that distinguish a group of organisms from other groups are their “unifying synapomorphies” • The unifying synapomorphies of mammals include…

  45. Phylogeny and Systematics • Remember that “ancestral” and “derived” are relative terms

  46. Phylogeny and Systematics • Remember that “ancestral” and “derived” are relative terms • The unifying synapomorphies of mammals are derived relative to other vertebrate groups

  47. Phylogeny and Systematics • Remember that “ancestral” and “derived” are relative terms • The unifying synapomorphies of mammals are derived relative to other vertebrate groups • But the original or ancestral mammal had these characteristics

  48. Phylogeny and Systematics • Remember that “ancestral” and “derived” are relative terms • The unifying synapomorphies of mammals are derived relative to other vertebrate groups • But the original or ancestral mammal had these characteristics • So within mammals those characteristics are ancestral

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