3.1 Biodiversity and Evolution

3.1.1 Biodiversity is the total diversity of living systems and it exists at several levels.

The biodiversity levels are habitat diversity, species diversity and genetic diversity.

Species Diversity

Species diversity in communities is a product of two variables: the number of species (richness) and their relative proportions (evenness).

Habitat Diversity

Habitat diversity refers to the range of different habitats in an ecosystem.

Genetic Diversity

Genetic diversity refers to the range of genetic material present in a population of a species.

With reference to the resource booklets, compare the biodiversity in at least two of the case study locations. Refer to all three levels of diversity.

Mapping Activity

3.1.2 The components of diversity contribute to the resilience of ecological systems.

ESQ: Explain why Costa Rican ecological systems may be considered to have greater resilience than those in London.

3.1.3 Biodiversity arises from evolutionary processes.

3.1.4 Natural selection is the mechanism driving evolutionary change.

3.1.5 Evolution by natural selection involves variation, overproduction, competition for limited resources, and differences in adaptation that affect rates of survival and reproduction.

3.1.6 Speciation is the generation of new species through evolution.

Natural Selection

3.1.7 Species diversity in communities is a product of richness and evenness.

Richness

The number of species in a community

Evenness

How similar the population sizes of each species are

3.1.8 Simpson’s reciprocal index is used to provide a quantitative measure of species diversity, allowing different ecosystems to be compared and for change in a specific ecosystem over time to be monitored.

3.1.9 Knowledge of global and regional biodiversity is needed for the development of effective management strategies to conserve biodiversity.

How is Biodiversity Data Collected (in London)?Or perhaps any case study?

HL ONLY

Selection

3.1 HL ONLY CONTENT

Geological History

3.1.15 Earth history extends over a period of 4.5 billion years. Processes that occur over an extended timescale have led to the evolution of life on Earth.

3.1.16 Earth history is divided up into geological epochs according to the fossil record.

The geological timescale is divided into eons, which are further classified into eras, periods and epochs.

Changes in these time frames are marked by major geological and biological events.

The division between one epoch and the next is marked by significant changes in fossils, indicating environmental changes causing many extinctions and the subsequent evolution of new species.

Mass Extinctions

3.1.17 Mass extinctions are followed by rapid rates of speciation due to increased niche availability.

The five mass extinctions in the past have been caused by various factors, such as tectonic plate movements, super-volcanic eruption, climatic changes, sea-level changes and meteorite impact; this is in contrast with the current anthropogenic sixth mass extinction.