Transcript Biodiversity and Evolution

Biodiversity and
Evolution
Chapter 4
Biodiversity: Definition
• The variety of earth’s species, their genes, the
ecosystems, energy and matter cycling
• It is a renewable resource!
Species’ Origin
1. Biological Evolution: how life changes over time
2. Natural Selection – traits that survive
1. Genetically based traits that enhance survival
are passed on
2. Results in a change in a population’s genetic
characteristics
3. Six kingdoms of life: eubacteria,
archaebacteria, protists, plants, fungi,
animals
Kingdoms
Species’ Origin
3. Evidence is in fossil records
4. Populations, not individuals, evolve
a. Mutations: random changes in DNA
structure/number
b. Mutagens: agents that enhance mutations
c. Mutations that take place in gametes are
passed on
Species’ Origin
5. Beneficial Traits
a. Adaptation: heritable trait that enables survival &
reproduction
b. Differential Reproduction: leave more offspring (ex.
– thick coats in wolves)
c. Genetic Resistance: ability of 1 or more organisms in
a population to tolerate chemicals designed to kill it
(ex. Antibiotic resistant bacteria)
Climate and Geologic Effects
1. Geological Processes
a. Plate Tectonics: continent location
determines climate allowed for species to
move and adapt →→→ new species
b. Earthquakes: can separate and isolate
species
c. Volcanoes: disrupt/destroy habitat
Climate and Geologic Effects
2. Climate & Catastrophes
a. Ice Ages, warm periods change things
b. Ecosystems change with climate
c. Asteroid Collisions! Duck!
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Speciation, Extinction, Human
Activities
1. Speciation: a new species evolves; Occurs in
2 “phases”:
a. Geographic Isolation (migration,
geographic barriers, wind)
b. Reproductive Isolation: mutation & change
by natural selection
c. These are mutually exclusive
Speciation, Extinction, Human
Activities
2. Human Role: artificial selection and genetic
engineering
3. Extinction:
a. Endemic Species: found in one area only; very
vulnerable
b. Example of recent extinction: Golden Toad
4. Background Extinction: low rate; 1-5
species/million
Speciation, Extinction, Human
Activities
5. Mass Extinctions: large groups, wide-spread
a. Makes way for new species to emerge
Species Diversity
1. Definition: Number of different species in an
ecosystem (richness) and relative abundance
of individuals in a species (evenness)
2. Examples:
a. Rain forest: rich but low evenness
b. Aspen forest: low richness, high evenness
3. Geographic location determines richness; rich
near equator, decreases to north/south
Species Diversity
4. Rich Ecosystems are productive and
sustainable
a. Supported by research
b. Greater variety of producers = ↑ biomass
c. Greater variety/food web = stable
The Roles of Species
1. Each species has a distinct role to play in its
own ecosystem
2. Role = Ecological Niche; a way of life
a. Includes all things that affect survival: water,
sunlight, space, temperature
3. Generalist Species have broad niches; can live in
a variety of places, eat a variety of foods, are
tolerant of extreme conditions
a. cockroaches, mice, deer, humans
The Roles of Species
4. Specialist Species have narrow niches; can live in
one type of habitat, few types of foods, etc.
a. Ex. – tiger salamander, panda
5. Native Species: normally live in a specific
ecosystem
6. Non-native species: introduced to or migrate to
a different ecosystem (killer bees of Brazil)
7. Indicator Species: provide early warnings of
ecological damage frogs, trout, birds,
butterflies)
The Roles of Species
8. Keystone Species have a large effect on types
and abundances of other species
a. Vulnerable (few numbers)
b. Include pollinators and top predators
9. Foundation Species create and/or enhance
habitats for certain other species
a. Ex. – elephants, clear trees; promotes grassland
b. Ex. - beavers