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25.2 Part II. The Cladogram of Animals

25.2 Part II. The Cladogram of Animals. The Cladogram of animals. The features of animal body plans provide information for building a cladogram of animals The animal cladogram presents our current understanding of relationships among the animal phyla

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25.2 Part II. The Cladogram of Animals

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  1. 25.2 Part II. The Cladogram of Animals

  2. The Cladogram of animals • The features of animal body plans provide information for building a cladogram of animals • The animal cladogram presents our current understanding of relationships among the animal phyla • Animals are defined by the adult body plans and patterns of embryological development

  3. The blue boxes represent important traits that have evolved over time

  4. Difference Between Phyla • The animal cladogram represents the sequence in which important body plan features evolved • Every phylum has a unique combination of ancient traits inherited from its ancestors and new traits found only in that particular phylum • Remember just because an animal has a more complicated body system does not mean it can function better than an animal with a more simple body system • Any system found in living animals are able to function well enough to enable those animals to survive and reproduce • Example: Monkey brains are much more complicated than a fish brain, but fish brains work well enough to enable fish to survive

  5. Changes within Phyla: Themes and Variations • Within each phylum different groups represent different variations on the basic body plan themes that have evolved over time • For example: Both wings and arms evolved through changes in the standard vertebrate forelimb • Many land vertebrates typically have four limbs • In birds the front limbs have evolved into wings • In primates the front limbs have evolved into arms

  6. Evolutionary Experiments • Each phylum’s body plan can be viewed as an evolutionary experiment in which a particular set of body structures perform essential functions • Fossil records of each phylum marks the beginning of the experiment • The very first versions of most major body plans were developed hundreds of millions of years ago • Ever since a phylum’s body plan was first developed each phylum’s evolutionary history has shown variations in its body plan to adapt to changing environments • If the variation in body plan allowed the phylum to reproduce and survive than the phylum still exists • If the variation in body plan hasn’t functioned well enough over time then the phylum or particular groups within the phylum become EXTINCT

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