Biodiversity

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Biodiversity
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Biodiversity

• The variety of Earths species, the genes they
  contain, the ecosystems in which they live,
  their functions in energy flow nutrient cycling

Destroying the rain forest for economic gain is
like burning a Renaissance painting to cook a
meal. E. O. Wilson
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Three Components
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What affects biodiversity?

• Natural Selection/Evolution
• Speciation
• Extinction

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Evolution

• Change in a species genetic makeup over time

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Natural Selection

• Individuals with certain traits are more likely
  to survive and reproduce under a particular set
  of environmental conditions than those without
  the traits
• Begins with mutations

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Adaptation Video
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Resistance
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Limits to Natural Selection

• When a change in environmental conditions occurs,
  a gene/mutation must already occur in the
  population
• Reproductive capacity
• Fast reproduction quicker adaptation
• Slow reproduction slow adaptation

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r Selected

• Unstable environments
• Small body size
• High fecundity
• Early maturity
• Short generation time
• Less parental care

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K selected

• Stable environments
• Large body size
• Long life expectancy
• Later maturation
• Few offspring
• More parental care

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Reproductive Strategies
R- strategists K-strategists
Mature rapidly Mature slowly
Short lived Long lived
Tend to be prey Tend to be both predator and prey
Have many offspring and overproduce Have few offspring
Low parental care High parental care
Generally not endangered Most endangered species are K-strategists
Wide fluctuation in population density (booms and busts) Population stabilizes near carrying capacity
Population size limited by density-independent factors (climate, weather, natural disasters, requirements for growth) Density-dependent limiting factors to population growth stem from intraspecific competition and include predation, parasitism, and migration
Tend to be small Then to be larger
Type III survivorship curve Type I or II survivorship curve
Examples most insects, annual plants, bacteria, rodents Examples humans, elephants, cacti and sharks
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Survivorship Curves

• Show age distribution characteristics of species,
  reproductive strategies and life history.
• Reproductive success means how many organisms
  make it to maturity and reproduce

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Survivorship Curves
Type Descriptions
I Late Loss Reproduction occurs fairly early in life. Most deaths occur at the limit of biological life span. Low mortality art birth. High probability of surviving to advanced age. Advances in prenatal care, nutrition, disease prevention and cures mean longer life spans for humans. Examples humans, annual plants, sheep and elephants.
II Constant Loss Individuals in all age categories have fairly uniform death rates. Predations affecting all age categories is primary means of death. Typical of organisms that reach adult stages quickly. Examples rodents, perennial plants and songbirds.
III Early Loss Typical of species that have great numbers of offspring and reproduce for most of their lifetime. Death is prevalent for younger members of the species (environmental loss and predation) and declines with age. Examples sea turtles, trees, internal parasites, fish and oysters.
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Speciation

• One species splits into two of more different
  species
• Two mechanisms
• 1. Geographic Isolation
• 2. Reproductive Isolation

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Geographic Isolation

• Occurs when a population become physically
  isolated from one another for a long period of
  time
• mountains rivers landslides

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Reproductive Isolation

• Differences in isolated groups become so great,
  they can no longer interbreed
• Behavioral changes
• Physical changes
• Genetic changes

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Speciation in Action

• California Salamanders

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Extinction

• Two Types
• 1. Biological
• The process in which an entire species ceases to
  exist
• Local
• A population of a species becomes extinct over a
  large region but not globally

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Passenger Pigeon

• 3-5 billion first European settlers
• Last died 1914
• Cincinnati zoo - Martha
• Caused by
• Habitat destruction
• Over hunting

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Endemic Species

• Species only found in one area
• Highly vulnerable to extinction

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Types of Biological Extinction

• Background extinction
• Species disappearing at a slow rate
• Mass extinction
• Significantly high rate of extinction
• 25-95 of global species gone
• Largest Permian 96 of species died
• Promotes evolution

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Endangered Species

• So few individuals that the species could become
  extinct
• Reasons
• Habitat loss/fragmentation
• Loss of keystone species
• Invasive species
• Climate change
• Pollution
• Overcosumption

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Keystone Species

• A species that plays a critical role in ecosystem
  structure whose impact on the community is
  greater than expected based on abundance
• Removal greatly affects
• the food web

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Keystone Species

• Sea Otters

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Keystone Species
Grey Wolves
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Invasive Species

• A non native (introduced) species that adversely
  affects a habitat they invade ecologically and/or
  economically

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Invasive Species

• Where do they come from?
• Horticulture
• Conservation
• Accidental

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Invasive Species Characteristics

• Tolerate a variety of habitat conditions
• Reproduce rapidly
• Short generation time
• Great competitors
• generalist
• Lack of predators
• Genetic variability

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Indicator Species

• Species that provide early warning signs of
  damage to an ecosystem
• Examples
• Lichens (air quality)
• Stoneflies (aquatic DO)
• Pika (climate change)

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Levels of Diversity

• Ecosystem Diversity
• Different habitats, niches, interactions
• Species Diversity
• Different types of organisms
• Genetic Diversity
• Different genes combinations within a population

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Measuring Species Diversity

• Two components
• Species richness
• Number of unique species
• Species evenness
• Number of individuals of each species in an area

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Monoculture

• Opposite of biodiversity
• Growing only one species of organism
• Problem?
• disease

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Which do you think is more diverse?
A
B
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Which do you think is more diverse?
B
A
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Which do you think is more diverse?
A
B
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Leaf Litter
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