Species Diversity

Species Diversity

Breeding bird species

Explanations for Global Patterns of Species Richness

1) Morphological diversity, spatial heterogeneity2) High average rarity - no monocultures – in tropics3) Climatic constancy of tropics4) Geological age5) Special adaptations in extreme (harsh) environments6) Competitive "balance"7) Alternating competitive advantages8) "All niches filled theory" - saturation of community9) Productivity

from A.R. Wallace - 1878

Richness and High Average Rarity

Global PlantRichness

Local CentersOf Diversity

Quality ofData

Richness and High Average Rarity

Endemic Plant Species Globally

Richness and High Average Rarity

Endemic Plants in Africa

Function of Species in Ecosystems – the airplane analogy

Function of Species in Ecosystems – the airplane analogy – are species the rivets or the passengers?

What happens when we lose too many pieces?

Ecosystem Diversity

What is an Ecosystem?

• An ecosystem is a group of interacting organisms (often called the community) in a particular location and the physical environment they inhabit

Walden Pond Shoreline

Pond Ecosystem

Ecotone between pine forest and grassland

Tree HoleEcosystem

IslandEcosystem

Lake Superior Ecosystem – from space

Lake Superior Ecosystem – at night

Biosphere

Steppe Grasslands

North Dakota

Masai Mara, Kenya

Ecosystem as Superorganism?

Ecosystem as Collection of Individuals?

Ecosystems of Great Smoky Mountains – from R.H. Whittaker

Ecosystems ofGreat SmokyMountains – elevation vs.moisture

Tree species distributions in Great Smoky Mountains

Caption for preceding three figures

Value of Ecosystems

Strategic Values

Value of Ecosystems

Uniqueness Value

Devil’s Hole – landscape and the holeAnd the pupfish

Desert Pupfish

Genetic Diversity

Ancestor of the DogCanis lupus arabs or Canis lupus lupus

Variation inBrassicaoleracea

Variation in Brassica oleracea

What is Genetic Diversity?

• Genetic diversity is the diversity that occurs in genes of individuals and species

• Genetic diversity originates with mutations • It is probably best to think of genetic diversity as

occurring at 4 different levels:1. among species2. among populations3. within populations4. within individuals

Chimpanzee – Pan troglodytes

Among Species Variation - Jiggs and Dorothy Lamour

Among Species Diversitycomparison of mitochondrial DNA

Among Populations – Achillea lanulosa

Among Populations – Achillea lanulosa

Within Population - Diversity in shell patterns in a population of Garden Snails - Cepaea

Within Individual VariationBi-colored eyes in Siberian Huskies

Measuring Genetic Diversity

• Among and within populations we often measure genetic diversity by measuring polymorphism - the percentage of genes that are polymorphic (have several alleles) within a population

• Polymorphism is sometimes also considered to be a process - the maintenance of genetic diversity within a population

• We can also measure genetic diversity by measuring heterozygosity - the percentage of genes at which the average individual is heterozygous

Origin of Genetic Diversity• Genetic diversity

originates with mutations

• Genetic diversity fuels evolution by allowing organisms to differ from their ancestors and thus be subject to different selection pressures

Selection for white spotting in Dutch Rabbits

Cause of Continuous Variation

• The genetic cause for these changes are genes with small phenotypic effect called multiple factors or polygenes –

• Polygenes are where several genes interact to produce a quantitative phenotypic effect on a character