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Species Diversity
Species Diversity
Breeding bird species
Explanations for Global Patterns of
Species Richness
1) Morphological diversity, spatial heterogeneity
2) High average rarity - no monocultures – in tropics
3) Climatic constancy of tropics
4) Geological age
5) Special adaptations in extreme (harsh) environments
6) Competitive "balance"
7) Alternating competitive advantages
8) "All niches filled theory" - saturation of community
9) Productivity
from A.R. Wallace - 1878
Richness and High Average Rarity
Global Plant
Richness
Local Centers
Of Diversity
Quality of
Data
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 Hole
Ecosystem
Island
Ecosystem
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 of
Great Smoky
Mountains –
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 hole
And the pupfish
Desert Pupfish
Genetic Diversity
Ancestor of the Dog
Canis lupus arabs or Canis lupus lupus
Variation in
Brassica
oleracea
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 species
2. among populations
3. within populations
4. within individuals
Chimpanzee – Pan troglodytes
Among Species Variation - Jiggs and
Dorothy Lamour
Among Species Diversity
comparison 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 Variation
Bi-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