Challenge 1 - The Biodiversity Crisis Flashcards
what is the overriding aim of Biol 1030?
to detail fundamental concepts so to understand causes and find solutions for the most important problems facing species today
Why is BIOL1030 important? KEY POINTS TO KNOW
Biodiversity and health of the planet impact upon every aspect of our lives.
>organisms are:
-primary sources of food, fuels, drugs, shelter and clothing
- agents of disease and death
- foundation of many cultures and beliefs and of immense aesthetic value
why do vertebrates feature predominately in highlighting the biodiversity crisis?
> Many are large and visible, small population size - easier to count/assess
higher trophic position in food webs - affected more by ecosystem disturbance?
humans have knowingly caused extinctions of vertebrates
of greater significance/value as a resource to humans
-food, clothing, perfumes
- economically important
- cultural/symbolic (totem, national symbols)
-aesthetic value
-evolutionary closer ties
- they can prey upon us?
what are the number of extinctions in Australia since european settlements?
27 mammals (7.5% of 257 species)
23 birds (approx. 3% of 800 species)
4 frogs
>100 plants
what is the significance of amphibians biomedicallly?
>pregnancy testing > production of medicines > use in assays > genetic studies >model for muscle disuse atrophy and starvation
what are the causes of amphibian number declines?
> habitat destruction/fragmentation, loss of breeding sites
increased exposure to ultraviolet radition (UV-B)?
global warming and climate change
insecticide use in agriculture (aerial spraying)
introduced species: can toad, mosquito fish
emerging disease
- chytrid fungus, damages keratin in skin
over-exploitation
enigmatic decline
How is the new ‘sixth mass extinction’ different from past events?
> happening over a very short period of time
rate of species loss 100-1000x faster than previous
created by one species modifying the plant - humans
What are the main threats to species?
> habitat loss, change and fragmentation >exploitation of species/resources >invasive/exotic species and emerging disease >pollution >environmental change
What is biological diversity?
> Sum total of life on Earth
the variety of all living things, the genetic information they contain and the ecosystems they form, which creates the complexity of life on Earth
“variation of life at all levels of biological organisation
What are the three levels of biodiversity?
> species diversity (variety of species)
genetic diversity (between populations, individuals)
ecosystem diversity (e.g., rainforest, desert , coral reefs)
what is species biodiversity?
> species diversity is the variety of species in an ecosystem or throughout the biosphere.
variety and number of species
What is richness a measure of?
the number of unique life forms, i.e., how many individuals of a certain species.
What is endemism and endemic species?
> species that are confined to a specific geographical region (species found nowhere else)
endemic species are often found in geographically isolated areas.
What is the difference between native species and introduced species?
Native = their presence in the geographic region is not due to human activity introduced = their presence is due to human involvement
what is a biodiversity hotspot?
biogeographic region with significant biodiversity and high endemism, which is under threat.
How do hotspots differ from megadiverse areas?
megadiverse = large amount of different species hotspot = large amount of different species that are highly threatened.
what are the criteria for biodiversity hotspots?
1) must contain at least 1,500 species of vascular plants (>0.5 % of the world’s total) as endemics
2) to have lost at least 70% of its original habitat
What is genetic diversity?
comprises of genetic variation within a population and between populations
What important roles does genetic diversity play in the survival and adaptability of a species?
> species with less genetic variation are at a greater risk
vulnerability of a population to disease can increase with reduction in genetic diversity
problems associated with inbreeding.
What is so special about genetic variation?
Genetic variation makes evolution possible - provides the raw material for evolutionary change.
what is an example of a species where low genetic variation has had a detrimental effect?
Tasmanian Devil.
> massive pop. declines - due to devil facial tumour disease - highly contagious
>little genetic variation within pop = everyone is susceptible.
what is ecosystem diversity?
> rainforests, desert, coral reefs
assemblages/communities of organisms: microbes, plants and animals (biotic) and the physical environment around them (abiotic)
inclusive of functional traits - nutrient cycling and energy cycling
what are ecosystem functions?
ecological processes in the environment that regulate the fluxes of:
>energy
>nutrients
> organic matter
what are ecosystem serives?
the suite of benefits that ecosystems provide to humanity.
>provisioning - production of renewable resources e.g., food, wood, oxygen
>regulating - those that lessen environmental change e.g., water/air purification, carbon sequestration, disease control
how does evolution describe the unity and diversity of life?
> organisms are modified descendants of common ancestors
similar traits among organisms are explained by descent from common ancestors
differences among organisms are explained by the accumulation of heritable changes
natural selection is the overriding mechanism
what did Darwin OBSERVE?
> individuals in a population vary in their traits, many of which are heritable
more offspring are produced then survive, and competition is inevitable
species generally suit their environment
What did Darwin INFER?
> individuals that are best suited to their environment are more likely to survive and reproduce
over time, more individuals in a population will have the advantageous traits
evolution occurs as the unequal reproductive success of individuals
What is radiometric dating?
radio active decay of isotopes
>to characterise past life reliant upon:
> fossils - preserved remains of organisms
> trace fossils - traces of life, e.g., footprints, coprolites
> fossil record - documents history of life
what are the three eons?
Archean
proterozoic
phanerozoic
what are the three eras of phanerozoic?
paleozoic
mesozoic
cainozoic
what are the periods in paleozoic?
cambrian
permian
triassic
cretaceous
what were the first cells?
> heterotrophs that fed on organic molecules
>anaerobic fermentation (anaerobes) process to obtain energy
what happened in the paleozoic era?
> begins with the Cambrian explosion
arise of the many new forms of life, including the vertebrates
fishes diversity
colonisation of land - plants, simple animals and vertebrates
appearance of the reptiles
at the end of the paleozoic, the continents were joined into a single land mass, pangea
ends with a mass extinction event - “the Permian Extinction”
What happened in the Permian extinction?
> 251 million years ago
the largest madd extinction event in earth’s history
large lava eruptions, volcanic dust in the atmosphere
temperature drops
oxygen levels drop
buildup of hydrogen sulfide (produced by bacteria)
- > 95% of all species died out
what happened in the mesozoic era?
> 251 - 65 mil years ago
continental drift - split up Pangea, Laurasia and Gondwana - promoted speciation as a consequence of geographical isolation.
age of the reptiles
large living terrestrial animals, the dinosaurs
what are the modern day representatives of the reptiles of the mesozoic era?
Tuatara, turtles, Squamates (lizards/geckos and snakes), crocodilians
what happened in the cretaceous extinction ?
65 million years ago
> 75% of species lost
>dinosaurs disappeared.
What happened in the cenozoic era?
> mass extinction heralded the start of the current era
stared 65 million years ago, continues to present
mammals became the dominant life form on land. An adaptive radiation that took advantage of the sudden loss of dinosaurs.
another large group evolves : grasses
adaptive radiation of birds and flowering plants
what are the modern representatives of the cenozoic era?
Endothermy (internal heat source) > many characteristics of birds are adaptions that facilitate flight > wings > no urinary bladder > females with only one ovary > loss of teeth
what are some adaptations used for flight?
wings, feathers, hollow bones, reduced body mass, lungs
what are the three major linages of the mammals?
> monotremes (egg laying)
marsupials (pouches)
placentals (complete development in uterus)
what are the modern amphibians?
> representation of transition to land >requirement to maintain ties with water >aquatic and terrestrial existence >moist skin - prone to desiccation > eggs - no protective covering to reduce desiccation
what animals are in the amniotes?
Reptiles, birds and mammals
What are amniotes?
> appeared in Paleozoic
reptiles earliest form of amniote
scales (layers of keratin) - a waterproof barrier
shelled eggs (cleidoic)
stronger skeleton - improved locomotor ability, including bipedalism.
describe the first vertebrates
> first appeared in the fossil record during the cambrian explosion
had a basic fish-like body plan - wiyh an internal axial skeleton, based around skeletal rod (notochord)
were jawless
filter feeders
what are the modern representatives of the agnathans?
> hagfish
>lamprey
describe the jawed vertebrates
> mid-paleozoic - appearance of jaws and appendicular skeleton
added ability to chew and grind
changed from essentially a tube to somethng with arms and legs
good examples in fossil record of 1st jawed fish
diversification/radiation of “the fishes”