Chapter 12 and 13

April 16, 2012

• Domestication – process by which plant and animals species come to depend on humans for survival while providing humans with some benefit

teosinte

Humans and Extinction

• Humans are responsible for 6th extinction on Earth– Predation– Trophic cascades– Alien species– Habitat destruction– Agriculture

• Prehistoric extinctions

• Historic extinctions

• Easter Island palm (Paschalococos disperta)» Chilean wine palm

Historic Extinctions

Historic Extinctions

• Iceland - northern birch (Betula pubescens)

Historic Extinctions

Omilteme cottontail

Great auk

• Historic extinctions of small, endemic populations

• Passenger pigeon – 5 billion killed

Tasmanian tiger

Historic Extinctions

Passenger pigeon

Pandemics and Endemics

• Pandemics – having a widespread distribution between and within biogeographic regions

• Endemics – restricted to 1 geographic area• Neoendemics – species that just recently

evolved• Paleoendemics – endemics that had a much

larger range in the past

Silversword (Argyroxiphium sandwicense sandwicense)

Redwood (Sequoia sempervirens)

Distribution Types• Dispersal disjunctions – when a jump dispersal

event allows a population of a plant or animal species to become established a long distance from the main population

Least bittern (Ixobrychus exilis)

Figure 13.7

• Climatic disjunction – occurs when climatic change makes a portion of a species’ range uninhabitable and splits a once continuous distribution

Distribution Types

Figure 13.7

Magnoliaceae family

Climatic Disjunction

Gorilla (Gorilla gorilla)

• Geologic disjunction – when geologic processes split once continuous ranges into two or more separate parts

Distribution Types

Superorder Ratites

• Evolutionary disjunction – when 2 new species develop in different portions of the geographic range of a widespread common ancestor

Distribution Types

Biogeographic Relicts• Biogeographic relicts are taxa that once had larger

distributions but have become narrow endemics– Climatic relicts – species whose geographic ranges are

restricted due to recent climate changes – aka glacial relicts

Torrey pine (Pinus torreyana)

– Evolutionary relicts – paleoendemics that are survivors of formerly more widespread and diverse evolutionary lineages

Biogeographic Relicts

Tuatara (Spenodon punctatus)