Biodiversity Biodiversity and Conservation n Variation in three

Biodiversity

Biodiversity and Conservation n Variation in three levels: n n n Genetic – the variety of genes within a species Species – the number of species per area Habitat –the variety of places where life exists

Genetic Diversity n Range of genes for a particular trait n n n May be different from another population of the same species Definitely different from another species Cause – sexual reproduction and mutations

Why is genetic diversity important? n n n Allows for survival from disease, changes in climate or other local environmental conditions Provides the basis for evolution by natural selection A healthy population has a high genetic diversity.

Habitat Diversity n The range of different habitats Includes microhabitat or a major community n Cause – Atmospheric circulation n

Why is habitat diversity important? n n Provides different niches Provides a variety of services n n n CO 2 Fixation Pest Control Nitrogen Fixation Soil Binding Air Pollution Absorption n n Oxygen Production Water Purification Nutrient Storage Pollination

Species Diversity n n Species – organisms that interbreed and produce fertile offspring How many different species are there? n n ~ 1. 75 million known Many more unknown n 5 – 50 million or more

Interconnection of Diversity n Increases in types of habitat leads to increase in different species which in turn increases genetic variation.

Natural Selection n n Darwin proposed that population changes are based on natural differences. “Survival of the fittest”

Five main propositions for theory of evolution by natural selection 1. More offspring are produced than will survive and reproduce. n 2. There are more individuals than can be supported by resources of the habitat There is competition for resources among offspring. n Struggle for survival based on environmental pressure

Five main propositions for theory of evolution by natural selection 3. There is variation of traits within populations of organisms. n 4. There is variety between individuals Some of these traits are more helpful than others.

Five main propositions for theory of evolution by natural selection 5. Because organisms with certain traits have greater chance of reproducing, there offspring will make up a larger part of the population n Those more fit (able)to survive, do and pass their genes on to the next generation n Changes in gene frequency lead to changes in population over time. n Over long periods of time consistent selective pressure along with reproductive isolation can lead to speciation (new species

Example of Natural Selection n Black and gray peppered moths in 19 th century England