Biodiversity and Biodiversity and EvolutionEvolution

Chapter 4Chapter 4

Biodiversity: DefinitionBiodiversity: Definition

• The variety of earth’s species, their genes, the ecosystems, energy and matter cycling

• It is a renewable resource!

Species’ OriginSpecies’ Origin

1. Biological Evolution: how life changes over time2. 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

KingdomsKingdoms

Species’ OriginSpecies’ Origin

3. Evidence is in fossil records4. Populations, not individuals, evolve

a. Mutations: random changes in DNA structure/number

b. Mutagens: agents that enhance mutationsc. Mutations that take place in gametes are

passed on

Species’ OriginSpecies’ Origin

5. Beneficial Traitsa. Adaptation: heritable trait that enables survival &

reproductionb. 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 EffectsClimate and Geologic Effects

1. Geological Processesa. 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 EffectsClimate and Geologic Effects

2. Climate & Catastrophesa. Ice Ages, warm periods change thingsb. Ecosystems change with climatec. Asteroid Collisions! Duck!

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Speciation, Extinction, Human Speciation, Extinction, Human ActivitiesActivities

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 Speciation, Extinction, Human ActivitiesActivities

2. Human Role: artificial selection and genetic engineering

3. Extinction:a. Endemic Species: found in one area only; very

vulnerableb. Example of recent extinction: Golden Toad

4. Background Extinction: low rate; 1-5 species/million

Speciation, Extinction, Human Speciation, Extinction, Human ActivitiesActivities

5. Mass Extinctions: large groups, wide-spreada. Makes way for new species to emerge

Species DiversitySpecies 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 evennessb. Aspen forest: low richness, high evenness

3. Geographic location determines richness; rich near equator, decreases to north/south

Species DiversitySpecies Diversity

4. Rich Ecosystems are productive and sustainable

a. Supported by researchb. Greater variety of producers = ↑ biomassc. Greater variety/food web = stable

The Roles of SpeciesThe Roles of Species

1. Each species has a distinct role to play in its own ecosystem

2. Role = Ecological NicheEcological Niche; a way of lifea. 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 conditionsa. cockroaches, mice, deer, humans

The Roles of SpeciesThe 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, panda5. Native Species: normally live in a specific

ecosystem6. 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 SpeciesThe 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