1. Chapter 7
Biological Diversity

2. Biological Diversity and Biological Evolution
The variety of life-forms commonly expressed as the number of species in an area
Biological Evolution
The change in inherited characteristics of a population from generation to generation
One of the features that distinguishes life from everything else in the universe
Due to natural selection and mutation

3. Four Processes that Lead to Evolution
Mutation (radiation, chemicals, viruses)
Natural Selection (most “fit)
Migration (over geologic time)
Genetic Drift (chance)
Each of these four processes leads to changes in gene frequency.

4. Mutation A chemical change in a DNA molecule
Affects the expressed characteristics when cells or individual organisms reproduce

5. Natural Selection 4 Characteristics:
Genetic Variability (inheritance of traits)
Environmental Variability
Differential Reproduction
Environmental Influence
Species:
a group of individuals that reproduce with each other

6. Natural Selection: DDT
Malaria: parasitic microbes
Microbes carried by mosquitoes and transferred to people
1957: DDT (mosquitoes) and chloroquine (protozoa)
resistance through natural selection
must attack completely at outset before natural selection leads to resistance
Biotechnology

7. Migration
Two populations of the same species become geographically isolated from each other for a long time (Alaska and Siberia)
Can no longer reproduce
Two new species evolve from an original species due to isolation
Loss of geographic isolation can also lead to a new species (alters gene frequency in new habitat)

8. Genetic Drift
Random changes in the frequency of a gene in a population due to chance
May determine which individuals become isolated from larger group (bighorn sheep)
Can be a problem for rare or endangered species
characteristics that are less adapted to existing environmental conditions may dominate (survival less likely)
small size reduces genetic variability thus ability to adapt to future changes

9. Basic Concepts of Biological Diversity
Genetic Diversity: total number of genetic characteristics of a specific species, subspecies or group of species
Habitat Diversity: different kinds of habitats in a given unit area
Species Diversity:
Species Richness: total number of species
Species Evenness: relative abundance of species
Species Dominance: most abundant species

12. Evolution of Life on Earth
Fossils
3.5 – 2 billion years ago: microbial life
atmospheric changes
600 million years ago: multicellular life in oceans (Cambrian period)
land plants, fish, amphibians
reptiles and mammals
evolution and catastrophes

15. The Number of Species of Life on Earth
No one knows the exact number
About 1.4 million species have been identified and named
Eukaryota
Bacteria
Archaea
Insects and plants make up most of these species
Number will increase

16. The Competitive Exclusion Principles
2 species that have exactly the same requirements cannot coexist in exactly the same habitat
Ex) introduction of the gray squirrel into Great Britain

19. Professions and Places: The Ecological Niche and the Habitat
Habitat: where a species lives
Ecological Niche: a species profession
The reason more species do not die out from competition is that they have developed a niche, and thus avoid competition (adaptive radiation – when a species becomes adapted to a specialized role)
Species that require the same resources can coexist by utilizing those resources under different environmental conditions

21. Species Engage in 3 Basic Interactions
1. Competition
2. Symbiosis
3. Predation-Parasitism
Each affect evolution, persistence of a species and the overall diversity of life
Organisms have evolved together and therefore adjusted to one another
Human interventions upset these adjustments

22. Symbiosis
The relationship between 2 organisms that is beneficial to both and enhances each organisms chances of persisting
Obligate symbionts:
a symbiotic relationship between two organisms in which neither by themselves can exist without the other
Ex) stomach of a reindeer

24. Predation and Parasitism
Predation occurs when an organism (predator) feeds on other live organisms (prey), usually of another species.
can increase diversity
Parasitism occurs when one organism (parasite) lives on, in, or within another (host) and depends on it for existence but makes no useful contribution to it or may harm it.

25. Environmental Factors that Influence Diversity
Increase Diversity:
diverse habitat
moderate disturbance
small environmental variations
high diversity at one trophic level
mid-succession
evolution
Decrease Diversity:
environmental stress
extreme environment
severe limitation in essential resource
extreme disturbance
exotic species
geographic isolation

27. Ecological Gradient
change in the relative abundance of a species over an area
tolerance (altitude, pollutants, etc.)
physiological tolerance: adjusts to pollutant level
genetic tolerance (adaptations): some individuals are more resistant than others; pass resistance to future generations