1. Origins of Biological Diversity
Chapter 15
Origins of Biological Diversity

2. 15.1 Diversity of Life
biological species concept: defines a species as a population or group of populations whose members have the ability to breed with one another in nature and produce fertile offspring.
asexual reproducers not included
fossils also not included

3. Macroevolution macroevolution: dramatic biological changes
origin of different species
extinction of species
evolution of major features
speciation: origin of a new species
Biological diversity

4. Reproductive Barriers
reproductive isolation: reproductive barrier keeps two species from breeding
Timing
different breeding seasons
Behavior
different courtship or mating behaviors
Habitat
adapted to different habitats in the same area
Others
reproductive structures incompatible
zygote fails to develop
hybrid cannot reproduce (ex. mules, wolf hybrids)

5. Geographic Isolation
geographic isolation: separation of populations as a result of geographic change or dispersal to geographically isolated places
separation of “splinter” populations is crucial to evolution; genetic drift

6. Adaptive Radiation
adaptive radiation: evolution from a common ancestor that results in diverse species adapted to different environments
Hawaiian islands; different species on each island

7. Punctuated Equilibrium
punctuated equilibrium: species often diverge in spurts of relatively rapid change
Long periods of little change in a species are broken by shorter times of speciation
Successful species last 1-5 million years; unique changes in first 50,000 years

8. 15.2 Remodeling Process Refinement of Existing Adaptations
Complex structure may have evolved from a simpler structure having the same basic function
Example: eye refinement – light-sensitive cells

9. Adaptation of Existing Structures to New Functions
chitin – forms the exoskeleton of arthropods; protection in ocean
land-dwelling – resists water loss
Penguins have modified wings for swimming

10. Evolution and Development
embryology: study of the processes of multicellular organisms as they develop from fertilized eggs to fully formed organisms
mutation in master control gene has bizarre effects; cow with head-leg
less dramatic; subtle changes in development
feet of salamanders slightly different based on habitat; trees vs. land

11. 15.3 Fossil Record
geologic time scale: organizes Earth's history into four distinct ages known as the Precambrian, Paleozoic, Mesozoic, and Cenozoic eras
Era  Period  Epoch

12. Dating Fossils
relative age: reflect the order in which groups of species existed compared to one another
absolute age: actual age in years
radiometric dating: based on the measurement of certain radioactive isotopes in objects
isotopes have fixed rate of decay
half-life: the number of years it takes for 50 percent of the original sample to decay
Uranium-238 : half-life of 4.5 billion years, has been used to date rocks of the Precambrian era and the Cambrian period
not present in living organisms
Carbon-12 and carbon-14: calculate how long the organism’s been dead
half-life of 5,730 years; only recent fossils

13. Continental Drift
Continental Drift: motion of continents about Earth's surface on plates of crust floating on the hot mantle
North America and Europe drifting apart at 2 cm per year
Explains how fossils are similar on different continents
Pangaea- supercontinent about 245 million years ago
climate change and competition; extinction of species

14. Mass Extinctions
Mass extinctions: brief episodes of great species loss
Cretaceous period, 65 million years ago, extinction of dinosaurs
1. Climate cooling and shallow seas receding
2. Meteor in the Yucatan; polluted the sky with dust, blocking sun
3. Rise of mammals
Permian period; 90% of marine animal species
Provide new opportunities for other species and new evolution

15. 15.4 Taxonomy
taxonomy: branch of biology that involves the identification, naming, and classification of species.

16. Linnaean System of Classification
Carolus Linnaeus (1707 – 1778)
1. binomial: two-part Latin name for each species
first part is genus ; first letter capitalized
second part is species; all lower case
ex. Homo sapien
2. hierarchy – broader to specific species
Kingdom
Phylum
Class
Order
Family
Genus
Species

17. phylogenetic tree: a diagram that reflects hypotheses of evolutionary relationships with a branching pattern
greater the number of homologous structures, more closely related

18. Convergent Evolution
convergent evolution: process in which unrelated species from similar environments have adaptations that seem very similar
analogous structures: similar adaptations that result from convergent evolution
ex. wings of insects and birds; no common ancestor
DNA comparisons between species increase evidence of relationships

19. Cladistics cladistics: method of determining the sequence of branching
clade: each evolutionary branch in a phylogenic tree
consists of ancestral species and all descendants
derived characters: all organisms in clade share homologous structures that do not occur outside the clade
cladogram: a phylogenetic diagram that specifies the derived characters of clades
not always accurate because birds and reptiles are similar

20. Classification Systems
Old = 5 Kingdoms
Monera
Protista
Fungi
Plantae
Animalia
New = 3 Domains
Bacteria
Archaea
Eukarya