Transcript Diversity of Living Things

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