Transcript Ch 26 - MsBabbey

Phylogeny and the Tree
of Life
Chapter 26
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Key terms
 Phylogeny is the evolutionary history of a species or
group of species.
 Phylogenies are based on 3 things:
 The fossil record
 Morphological homologies
 Molecular homologies
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The fossil record
 Fossils are found in sedimentary rocks
 Older layers are at the bottom, newer ones on top
 The fossil record looks at where in the strata fossils are
found to see which organisms came first
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Morphological Homologies
 Similar numbers and arrangements of bones in the
arms of mammals show descent from a common
ancestor.
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Molecular Homologies
 Organisms who have similar DNA sequences are likely
to be closely related.
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Then what’s analogy?
 Analogy is when 2 UNRELATED species end up with
similar traits because they lived in similar
environments.
 For example: bats and birds both have wings, but these
evolved differently (bats are more closely related to
cats than birds)
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Taxonomy
 Domain (Eukarya)
 Kingdom (Animalia)
 Phylum (Chordata)
 Class (Mammalia)
 Order (Primate)
 Family (Hominid)
 Genus (Homo)
 Species (sapiens)
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Classifying Life
 There are 3 domains of life: Eukarya, Bacteria, and
Archaea
 Domain Eukarya used to be divided into 5 kingdoms:
animals, plants, fungi, protists, and monera, but this
has changed over time.
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Taxonomy
 Scientists use branching diagrams called phylogenic
trees to show evolutionary relationships.
 These are based on cladistics, which uses common
ancestry to classify organisms.
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