Lab 7 - Invert Diversity - Student

Lab 7 - Invert Diversity - Student - BSC 2011 Laboratory 7...

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1 Modern systematics organizes life in a hierarchy based on available evidence for shared ancestry. The hierarchy is composed of groups that reflect increasing degrees of similarity. These groups include Domain , Kingdom, Phylum, Class, Order, Family, Genus and Species . This classification culminates in an organism’s binomial , which is a name created by combining both its genus and species group (e.g., Homo sapiens ). The Kingdom Animalia (also known as the Metazoa ) is a monophyletic group that is thought to have derived from an ancestral flagellated protist. A long history of systematic work based on morphology and developmental traits has been used to build a phylogeny. More recently, molecular research has been used to build a phylogeny of the Metazoa. These phylogenies do not entirely match – a great example of how science works! What we thought we knew is confronted with new evidence that has also been carefully collected and verified. These discrepancies must be reconciled based on the combined evidence. The two phylogenies represent a current debate in the science of biology (it's a great time to be a biologist!). Which one is correct? OBJECTIVES In today's lab, you will: 1. (with a partner and then your table) compare (i.e., find similarities) and contrast (i.e., find differences) the morphological and molecular phylogenies. 2. (with a partner) examine some evidence for the morphological & developmental phylogeny, based on selected major phyla only. Before you begin, it will help to be familiar with terminology. Read and refer to the glossary on the next page before you begin, and refer to it during lab – the lab will be easier if you can use the terms. Invertebrate Diversity BSC 2011 Laboratory 7
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2 GLOSSARY Acoelomate : a body plan without a body cavity. Each of three germ layers occur in order (ectoderm then mesoderm then endoderm) with no body cavity in between. Annelida : a large phylum (~17,000 species) composed of segmented worms, where some organs repeat in segments. Includes earthworms, leeches, polychaete worms, and other groups. Arthropoda : the most diverse phylum (~1 million species, >80% of described living species). All members have jointed appendages, an exoskeleton, and a segmented body. Includes Subphylum Chelicerata (e.g., spiders, scorpions, horseshoe crabs), Subphylum Myriapoda (e.g. centipedes, millipedes), Subphylum Hexapoda (e.g., insects), and Subphylum Crustacea (e.g., crabs, crayfishes and lobsters, shrimps, barnacles, copepods). Bilateral symmetry : An organism with a left side and a right side. There is only one way to cut these organisms in half and obtain two matching halves. For example, humans exhibit a bilateral body plan. Also see radial symmetry.
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Lab 7 - Invert Diversity - Student - BSC 2011 Laboratory 7...

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