Download Challenge 1: Biodiversity Crisis and recent

Challenge 1: Biodiversity Crisis and recent induced human actions
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Objectives of Challenge 1
o Managing and Conserving Biodiversity
o Appreciate the significance and importance of biodiversity
o Understand the importance of evolution in the unity and diversity of
life
Crocodiles and Conservation
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23 species world-wide, includes: crocodiles, alligators, caimans, gharials
Subtropical/tropical distribution
Northern Territory of Australia (Freshwater crocodile – Crocodylus johnstoni)
o 3 mts
o Regular array of teeth
o Fish, crustaceans diet
o Harmless to humans
Northern Territory, India, SE Asia (Estuanine Crocodile – Crocodylus porosus)
o Largest living reptile
o 7 mts
o Rockhampton
Globally, one of the most threatened groups of animals (10 of 23 species)
Causes of the Biodiversity Crisis
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Habitat Loss/ Fragmentation
Increased exposure to UV (amphibians)
Pollution – Global Warming and Climate Change
Exploitation
o Hunting
o Illegal Egg Harvesting
Eradication
Introduction of exotic animals
Fishing
Emerging diseases (fungus)
Vertebrates feature predominantly in highlighting the biodiversity crisis
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Large and visible, small population size
Humans have knowingly caused extinction of vertebrates value as a resource and
significance
o Food, clothing, perfumes, Cultural, Prey upon us.
Biodiversity Crisis – A focus on Australia
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Since European settlement
o 27 mammals (7.5% of 257 species)
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23 birds (3% of 800 species)
4 frogs
100 plants
**Tasmanian Tiger**
Amphibians Crisis
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More than 38 species are suspected to be extinct since the 1970s
o Of over 6400 described amphibian species:
 29% are facing extinction
 2,500 species are declined
o 435 species have declined “rapidly” since the early 1980s
History – Mass Extinctions and Causes
Era
Period
Years
Ago Percentage
(millions)
# Families
Causes
Paleozoic
Ordovician
443
86%
350
Glacial period,
carbon
dioxide stored
Paleozoic
Devonian
359
75%
400
Global
cooling,
oceans acidity
251
96%
200
Volcanic
Eruptions,
anoxic oceans
Paleozoic
Mesozoic
– Permian
Mesozoic
Triassic
200
80%
280
Increased
magma and
warming
Mesozoic
Cenezoic
– Cretaceous
65.5
75%
550
Meteorite
Impact
Requisites for Mass Extinctions
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More than 75% of species go extinct within a geologically short period of time
Sixth Mass Extinction
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Happening very short period of time
Rate for species of loss are 100x faster
Created by human modifying planet
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Biological Diversity (Biodiversity)
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The variety of all living things, the genetic information they contain and the
ecosystems they form, which creates the complexity of life on Earth
Cell is the basic unit of organization in of all life DNA are the units of inheritance
Types of Biological Diversity
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Species diversity (variety of species)
o Variety of species in an ecosystem or throughout the biosphere
o Australia has 1/10 of the species birds
o More unique life forms = Richness
Genetic diversity (between population, individuals)
o Comprises genetic variation within a population and between populations
o Important role in the survival and adaptability of a species
 Species with less genetic variation are at greater risk
 Vulnerability of a population to disease can increase with reduction
in genetic diversity
 Problems associated with interbreeding
o Genetic variation makes evolution possible- provides the raw material for
evolutionary change
Ecosystem diversity (rainforest, desert, coral reefs)
o Assemblages/communities of organisms, microbes, plants and animals
(biotic) and the physical environment around them
o Ecosystem community of organisms
 Inclusive of the functional traits of an ecosystem
Important Definitions
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Endemism
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Species that are confined to a specific geographical region (species found
nowhere else)
 Number of endemic vascular plant species
 Australia has high number of endemic species
Biodiversity Hotspot
o Biogeographic region with significant biodiversity and high endemism, which
is under threat
o Examples Tropical Andes, New Zealand, Central Chile
o Criteria
 Must contain 1,500 species of vascular plants (0.5 percent of the
world’s total) as endemics
 To have lost at least 70% of its original habitat
Endemic Species
o Found Geographically isolate areas
Native Species
o Their presence in geographic region that is not due to human activity
Introduced Species
o Their presence is due to human enrolment
Ecosystem Functions
o Ecological processes in the environment that regulate/control the fluxes of
 Energy
 Nutrient
 Organic matter
Ecosystem services
o Are the suite of benefits that ecosystem provide to humanity. Two critical
services include
o Provisioning - production of renewable resources (food, wood, oxygen)
o Regulating - those that lessen environmental change (water/air purification,
carbon sequestration, disease control)
Evolution
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Organisms are modified descendants of common ancestors, makes sense of
everything we know about biology
Explain patterns of unity and diversity in living organisms
Similar traits among organisms are explained by descent from common ancestors
Differences among organisms are explained by the accumulation of heritable changes
Evolution Natural Selection
Charles Darwin Natural Selection
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Species showed evidence of descent with modification from common ancestors
Natural selection is the mechanism behind descent with modification
Explained the duality of unity and diversity
Observed that
o Individuals in a population vary in their traits, many of which are heritable
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o More offspring are produced than survive, and competition is inevitable
o Species generally suit their environment
Inferred that
o Individuals that are best suited to their environment are more likely to survive
and reproduce
o Over time, more individuals in a population will have the advantage traits
o Evolution occurs as the unequal reproductive success of individuals
Domains of Life
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Prokaryotes Bacteria and Archaea
Eukaryotes Eukarya
LUCA
DKPCOFGS
History of Life on Earth
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First atmosphere included Carbon monoxide, water, helium and nitrate, it was said
that is a reluctant atmosphere
Evidence that hydrothermal vents existed on Earth 4.2 billion years ago indicate that
life first may have appeared at this time, and hence has evolved on Earth far
Some changes that happen are
o Land masses movement  Pangea  Actual Continents
o Major climate changes- Atmosphere, Temperature, Ice Eras
The best way to determine the age of some species or organic material is by
radiometric dating  Isotopes of Carbon or Uranium are the best ones
o Fossils the best way to generate them it’s by having a constant pressure,
water and organic material involved
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3 MAIN Eons
o Archaen
 Rsembled modern single clled organisms
o Proteorozoic
o Phanerozoic
 Paleozoic
 Meoszoic
 Cainozoic
 Cambrian
 Permina
 Triassic
 Devonian
 Cretaceous
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First Organisms – Cellularity – Set of Oxygen
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First cells were the Heterotrophs that fed on organic molecules of Anaerobic
fermentation that obtained energy
Prokaryotes dominated the Earth for most of its history due to its adaptation to harsh
environments Extremophiles
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Atmosphere of the primitive Earth, carbon dioxide, water, methane little or no free
oxygen
Oxygen in the atmosphere started isb about 2.7 billion years ago
Cyanobacteria were the photosynthetic prokaryotes organisms that used CO2 and
produced Oxygen but they got extinct because of the amount to oxygen that was
being produced.
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Importance of Oxygen
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Aerobic metabolism (using oxygen) more efficient energy production than anaerobic
metabolismEssential form of energy production for more complex life
IMPORTANT
o Increase in oxygen with photosynthetic organisms created environment
inhospitable to many groups of species (Oxygen highly reactive)
o Led to the rise of the oxygen-reliant species
Formation of the ozone layer
o UV radiation forms ozone from oxygen in the upper atmosphere
o Prevents/reduces UV from reaching Earth
o Decreased mutagenesis to live in surface water and on land
Ozone Hole
o Created as a consequence of anthropogenic release of CFCs, Cl, Br, gases
forms over poles at end of polar winter
Rise of the Eukaryotes
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Eukaryotes evolved around 2.1-2.0 billion years ago early forms unicellular
Later forms multicellular
Fossils include algae, protists & simple animals Proterozoic eon- age of eukaryotes
Characterized by membreane-bound nucleus and organelles
Eukaryotes arose from prokaryotes
o Endosymbiont Theory
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Multicellularity as an Advantage and Main History
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One of the most significant evolutionary steps in the history of life
Evolved independently several times in the eukaryotes
Three major kingdoms of multicellular organisms (evolute at least 3 times)
o Funghi
o Plants
o Animals
Even in its simplest form, multicellularity has potential advantages:
o Protection against predation
o Improved attachment to surfaces
o Greater buffering against environmental fluctuations
Allows for entirely new levels of organisation
Cambrian Explosion
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About 540 myr sudden appearance of large number of multicellular organisms
o Called the Cambrian explosion
Broad selection of body plans. Some unrelated to present –day life forms
o Some body plants disappear
The Rise of the Vertebrates
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Key Events in Life´s History
o Origin of Life
o Presence of oxygen
o Eukaryotes
o Multicellularity
o Animals
o Primitive Vertebrates: Fishes
o Colonisation of land: plants & animals
o Amphibians
o Reptiles
o Birds and Mammals
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Humans
History of life on earth – first vertebrates
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Vertebrates first appeared in fossil record around 520 myr, during the Cambrian
explosion (Paleozoic era)
Had a basic fish-like body plan-with an internal axial skeleton, based around a
skeletal rod (notochord)
Were jawless (agnathans-“no jaws”)
Filter-feeders
History of life on Earth- Agnathans
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Modern Representatives
o Hagfish
o Lamprey
o Highly modified forms of feeding
History of life on Earth – Jaws vertebrates
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Mid Paleozoic – appearance of jaws and appendicular skeleton (pectoral and pelvic)
Diversification/radiation of the fishes
Significant evolutionary innovations
o Greater diversity in body shape and size
o New feeding modes
o New modes of swimming/better control
Devonian – “Age of the Fishes”
History of life on earth – Chondrichthyes
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Modern Representatives
o Sharks, skates, rays, ratfish (chimaeras) and sawfish > 1100 species
o Cartilaginous skeleton
History of Life on Earth – Actinopterygii
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Modern Representatives
o Bony endoskeleton
o >30,000 species
o Vast array/ diversity of body shapes and sizes huge biomass
History of Life on Earth – First Land Vertebrates
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Colonisation of the land by vertebrates
Fins evolved into the limbs
Strengthening pectoral and pelvic girdles
Support weight of body on land
History of Life on Earth – Sarcopterygii
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Modern Representatives
o Lob-finned fishes
 The coelacanth
 The lungfishes
o Presence of muscular pectoral and pelvic fins, supported by extensions of
body skeleton
Evolution of Lungs
o Significant event in vertebrate evolution diverticulum of the oesophagus