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Evolution and Biodiversity. Chapter 3 Pages 46-62. Evolution: All species descended from earlier ancestral species. Changing genetic make- up in a population over time. Accepted scientific explanation of how animals adapt and survive. Evolution and Adaptation.

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Evolution and biodiversity

Evolution and Biodiversity

Chapter 3

Pages 46-62

Evolution and biodiversity

Evolution: All species

descended from earlier

ancestral species.

Changing genetic make-

up in a population over


Accepted scientific

explanation of how

animals adapt and


Evolution and adaptation
Evolution and Adaptation

Macroevolution – long term, large scale changes

Microevolution – small genetic changes

Gene pool – all genes in a population

Mutation – random change in structure of DNA. Every so often, a mutation is beneficial for survival.

Natural selection – individuals that have traits that benefit survival.

Natural selection
Natural Selection

Microevolution is changes in the gene pool of a population over time that result in changes to the varieties of individuals in a population such as a change in a species' coloring or size.

Macroevolution If the changes are over a very long time and are large enough that the population is no longer able to breed with other populations of the original species, it is considered a different species.

Evolution and adaptation1
Evolution and Adaptation



Natural selection1
Natural Selection

Three things must happen:

1. Genetic variability in a trait within population

2. Trait is heritable

3. Differential reproduction – must enable individuals with the trait to leave more offspring than others without the trait.

Adaptive (heritable) trait helps survival and reproduction under current conditions

Ecological niches and adaptation
Ecological Niches and Adaptation

Ecological niche – role in ecosystem. Includes interaction with biotic and abiotic factors.

Habitat – physical location

In other words:

Niche – species occupation

Habitat - address

Evolution and biodiversity

Stratification of niches, habitats allows many different

species to coexist. This is biodiversity.

Broad and narrow niches
Broad and Narrow Niches

Generalist species

Specialist species

What is better? Depends…

Environmental conditions consistent – favors specialists. Fewer competitors, food plentiful

Rapidly changing environmental conditions – favors generalists… More adaptable.

Speciation extinction and biodiversity how species evolve
Speciation, Extinction, and BiodiversityHow Species Evolve


Geographic isolation

Reproductive isolation

Fig. 5-7 p. 94


  • When Environmental changes occur, species must evolve to adapt. If not…

  • Background extinction – slow rate

  • Mass extinction – quickly, large groups

  • Mass depletion – higher than mass (Ice Age)

    • 99% of species that have existed on earth are now extinct.

Changes in Earth’s biodiversity – has leveled off during the last 1.8 million

Years. Is this due to human influence?


Adaptive radiation – after mass extinctions, numerous new species evolve to fill vacated niches. Takes 1-10 million years for adaptive radiation to rebuild biodiversity.

Human impacts – accelerated extinction

Human impacts on evolution
Human Impacts on Evolution

Artificial Selection – artificially selecting superior genetic traits




Genetic Engineering

Gene splicing

Species creation in laboratories

Takes less time than artificial selection

Concerns about Genetic Engineering

Many failures (1% success rate)

Lead to more abortions? Only for the wealthy?

Biomes life on land
Biomes: Life on Land

major vegetation types on land – based on different climates and atmospheric conditions

forests, grasslands, deserts

tropical, temperate, polar

temperature and precipitation determine overall patterns

What biome do we live in?

Evolution and biodiversity

Biomes across 39th parallel

Altitude and latitude
Altitude and latitude

The two most important factors influencing vegetation in the

formation of biomes are precipitation and temperature.

Aquatic life zones saltwater 71 of the earth
Aquatic Life Zones: Saltwater71% of the Earth

Coastal zone

majority of marine species (90%)

most commercial fisheries and interaction with land and humans

Open ocean

90% of ocean area


where rivers meet ocean

Coral reefs and mangrove forests

Freshwater life zones
Freshwater Life Zones

Standing water

Flowing water

Stream systems
Stream Systems



Drainage basin