3.2 Origins of Biodiversity

Evolution

Evolution

is a gradual change in the genetic character of populations over many generations, achieved largely through the mechanism of natural selection

natural selection

is an evolutionary driving force, sometimes called "survival of the fittest". In this context, the meaning of "fitness" is understood to be "best-suited to the niche"

Natural Selection stages

1. Variation exists and there is overproduction so competition for resources; 2) Some individuals are thus fitter than others; 3) Fitter individuals reproduce more successfully; 4) Offspring inherit genes that give advantage

Speciation

the formation of new species when populations of a species become isolated and evolve differently from other populations.

Isolation of populations: Causes

barriers such as mountain formation; changes in rivers, sea level change, climatic change or plate movements

Plate tectonics

the surface of the Earth is divided into crustal, tectonic plates, that have moved throughout geological time. This has led to the creation of both land bridges and physical barriers with evolutionary consequences.

Mass extinction causes

tectonic plate movements, super-volcanic eruption, climatic changes (including drought and ice ages), and meteorite impact

Biogeography

the study of the distribution of species and their evolution in relation to geographical distribution

disjunct distribution

when one species or sister species are distributed in two very different locations, e.g. New Zealand and Chile

plume

location where a column of magma rises up to the surface - not associated with a plate boundary

core

the centre of the earth

mantle

molten rock between the core and the crust of the Earth's surface

Aesphenosphere

the upper part of the mantle - acts like a molten plastic

Crust

the cooled rock that floats on the mantle - divided into plates

palaeontology

the study of fossils

geomorphology

the study of the shapes of the Earth's surface

ratites

ostrich like birds that share a common ancestor, including, rhea, emu, kiwi, cassowary and extinct elephant birds and moa.

adaptive radiation

a group of closely related species that have rapidly evolved from one common ancestor, usually on islands where empty niches exist

biodiversity hotspot

biogeographic region that is both a significant reservoir of biodiversity and is threatened with destruction.

invasive species

a species not native to an area which is causing a problem to local species