BIOL 1442 Ch 47 The Biodiversity Crisis

ecologist have measured biodiversity by

taking into account both the number of species and their relative abundance to eachother

adaptive radiation

rapid branching through speciation of a phylogenetic clade into many related species

extinction

the disappearance of a species

The rate of species loss today is comparable with

the five periods of mass extinction

Three human activities have a major impact on the current extinction:

destruction of habitat, introduction of exotic species, and over-harvesting

genetic diversity/genetic variation

defines the raw material for evolution and adaptation in species

the species with the most genetic potential for subsequent evolution is the most

genetically diverse one

genetic diversity can be measured as chemical diversity in that

different species produce a variety of chemicals in their cells

ecosystem diversity

the number of different ecosystems on the planet of within a given geographic area

The loss of an ecosystem means

the loss of interactions between species, the loss of unique features of coadaptation, and the loss of biological productivity

Endemic species

only found in one location

biodiversity increases

closer to the equator

The hypothesis for why biodiversity increases closer to the equator include

the greater age of ecosystems in the tropics and the increased direct energy the tropics receive from the sun

Tropical ecosystem complexity may promote speciation by increasing the

heterogeneity (number of ecological niches) in the tropics relative to higher latitudes

The tropics have been perceived as being more stable than

temperate regions

Norman Myers developed the concept of

biodiversity hotspots

Biodiversity hotspots

geographical areas that contain high numbers of endemic species

The number of species on the planet are the result of

speciation and extinction

Five strata in the fossil record that appear to show sudden and dramatic losses in biodiversity are called

mass extinctions

The Ordovician-Silurian extinction is the

first recorded mass extinction and the second largest, killing 85% of marine species

The main hypothesis for the Ordovician-Silurian extinction is

a period of glaciation then warming

The late Devonian extinction may have occurred ( ) and mostly affected ( )

over a relatively long period of time; marine species

The end-Permian extinction was the ( ) in the history of life

largest

In the end-Permian extinction, ( ) of all marine species and ( ) of all terrestrial species were lost

96%, 70%

The leading suspect for the end-Permian extinction is

extended and widespread volcanic activity that led to a global-warming event

In the end-Permian extinction, the oceans became largely ( ), suffocating marine life

anoxic

The Triassic-Jurassic extinction may have been caused by

climate change, asteriod impact, and volcanic eruptions

The end-Cretaceous extinction event was the result of a

cataclysmic impact of a large meteorite off the coast of the Yucatan peninsula

The Pleistocene extinction was one of the ( ) extinctions and was ( )

lesser; recent

In North America, the Pleistocene extinction losses included

woolly mammoths, mastodon, giant beavers, giant ground sloths, saber-toothed cats, and the North American camel

The timing of the Pleistocene extinctions coincided with the arrival of

paleo-humans

The Holocene extinction is the ( ) and is largely do to activities of ( )

sixth mass extinction; modern homo sapiens

Some examples of animals going extinct during the Holocene extinction include the

dodo bird, Steller’s sea cow, passenger pigeon, Carolina parakeet, Japanese sea lion, and Carribean monk seal

The International Union for Conservation of Nature keeps a list of extinct and endangered species called the

red list

Estimation of extinction rates are hampered bu the fact that

most extinctions are probably happening without observation

background extinction rate is estimated to be about

one per million species per year

species-area relationship

the rate at which new species are seen when the area surveyed is increased