Diversity of Living Things

1.1: Biodiversity

Biodiversity

• Number and variety of species and ecosystems on Earth

• By the end of 2010, 1.7 million species have been identified

Levels of Biodiversity

• Genetic diversity: variety of genes among organisms belonging to one species (environmental adaptation and evolution)

• Review Species: Members of groups or populations that can interbreed to produce viable and fertile offspring.

• Species diversity: quantity of each species as well as variety of different species in an ecosystem

Levels of Biodiversity

• Structural diversity: the range of physical shapes and sizes within a habitat or ecosystem

• Greater species diversity and greater structural diversity increases biodiversity

Biodiversity At Risk• Loss of biodiversity

-threatens our food supply

- eliminates sources of medicines

- economic impact on tourism and forestry

- cause serious problems in cycles

Diversity of Living Things

1.2: Classification

Taxonomic Systems• Biological classification: systematic

grouping of organisms into biological categories based on physical and evolutionary relationships

• Taxonomy: science of classifying organisms

• Aristotle (Greek, 384-322 B.C.)-“ladder of nature” - simplest organisms at the bottom of the ladder, most complex (i.e.humans) at the top

Taxonomic Systems

• Carl Linnaeus (Swedish, 1707-1778)- Father of Taxonomy

-classification system based on physical and structural features of organism

-binomial nomenclature: method of naming organisms by 2 names (genus + species), e.g., Homo sapiens-indicates similarities in anatomy, embryology, evolutionary ancestry

Levels of Classification

•The most accepted system has seven levels of classification (taxa)

Levels of Classification

1. Kingdom

2. Phylum

3. Class

4. Order

5. Family

6. Genus

7. Species

Dichotomous Keys

• dichotomous key = two-part key to identify organisms

*See textbook for examples:

- birds, page 18, Figure 8

-fish, page 32-33, Investigation 1.2.1

Dichotomous Key: Limitations• More complex when classifying a lot of

organisms• Plants: Can observe features by dissection

only at certain times of the year• Criteria used for classification (Example:

Horseshoe crab is more closely related to spiders than true crabs based on internal blood chemistry

• Average bird family contains 50 species whereas there are 60,000 species of parasitic wasp in Ichneumonidae

Diversity of Living Things

1.3: Phylogeny and Modern Taxonomy

Phylogeny• Phylogeny: evolutionary history of a

group of organisms

• Phylogenetic tree: indicates relationships, from ancestral forms of organisms to all descendants

• Clade: taxonomic group that includes a single ancestor species and all its descendants

• See Tutorial 1 on p. 22 for example

Phylogeny

Taxonomy Today

• Morphological criteria of classifying organisms may overlook evolutionary relatedness

• Phylogenetic analysis can help in unravelling evolutinary relationships

• DNA barcoding (Paul Herbert): DNA profile of every species in the form of a barcode

Diversity of Living Things

1.4: Kingdoms and Domains

Domains of Life

• Carl Woese in 1996 proposed three distinct groups- Eubacteria: Kingdom Eubacteria- Archaea: Kingdom Archaea- Eukaryotes: Protista, Animalia, Plants and Fungi

• See p. 28• See Table 1 on p. 27