17 - Declining Biodiversity Flashcards
What is the IUCN? How many species threatened with extinction?
International union for the conservation of nature
Make a ‘red list’ of species that are threatened or have gone extinct
> 44,000 species threatened
Direct and indirect drivers of biodiversity loss
Direct: changes inland and sea use, direct exploitation of organisms, climate change, pollution, invasion of alien species
Indirect: human population growth, economic growth (increased energy and materials demand)
Five main threats to biodiversity
- Changes in land and sea use, including habitat loss and degeneration
- Species overexploitation
- Invasive species and disease
- Pollution
- Climate change
Slides 12, 13
Dominance hierarchies of threats
What is the current driver of biodiversity loss? Most rapidly intensifying threat?
Land/sea use changes #1
Climate change intensifying
Example of how focusing on a single driver can overlook and/or undermine targes of other drivers
Large-scale expansion of cropland bioenergy can help mitigate climate change but the loss of natural habitat will directly harm biodiversity
Stopping global biodiversity loss requires…
Policies and actions that tackle all the major drivers and their interactions
Average annual impact of a 100 kg increase of neonicotinoids on bird on bird populations
Grassland pops: 4% decline
Insectivorous pops: 3% decline
Describe changes in total flying insect biomass over 27 years
76% decline in aerial insect biomass in nature protection areas
Exceeds estimates
How threatened are insects? Most affected taxa? Main driver?
40% of insects threatened with extinction
Taxa: lepidoptera (moths, butterflies), hymenoptera (wasps, bees), coleoptera (beetles)
Driver: habitat loss
Others: agrochemical pollutants, climate change
Describe amphibian declines
Caused by two fungal species (Batrachochytriums)
Originated in Asia
90 species confirmed or presumed extinct
50 spp w pop declines
How many species have evolved on Earth? How many are extinct? Average extinction rate?
~ 4 billion species evolved over 3.5 billion years
99% extinct (balanced by speciation)
Average rate: 1 extinction per million species per year (~9 per year)
0.1 E/MSY??? confusing
On average, recognized taxa live how long?
1-10 million years
Extinction rates are how much higher than natural? Future rates?
1,000 times higher than natural
Future rates likely 10,000 times higher
Characteristics of mass extinction (5)
- Loss of 75% of species
- Geologically short interval (a few million years)
- Occurred 5x in past 540 million years
- Volcanic eruptions, depletion of oceanic oxygen, asteroid
- Millions of years required to regain number of species
Five previous mass extinctions
- Ordovician
- Devonian
- Permian
- Triassic
- Cretaceous
Slides 30-42
Look at diagrams
On average, what % of land vertebrates are considered endangered?
70%
What is a species on the brink of extinction? Examples
One with fewer than 1000 individuals on earth
e.g. Sumatran rhino, Espanola giant tortoise
How is Madagascar special biodiversly
Unique species (95% reptiles, 89% plants and 92% mammals not found anywhere else)
> 3500 species of plants and animals considered on red list of IUCN (41%)
> 30 mammalian spp (out of 250) extinct since human arrival 2500 yrs ago
Drivers of biodiversity decline in madagascar
- land use conversion for agriculture
- other forms of habitat degradation
- invasive species
- climate change
- hunting
Describe lemur biodiversity decline
- 126 spp when humans arrived 2500 yrs ago
- now 111 species
- 98% endangered (31% critically)
- drivers: habitat loss, hunting
What is environmental (e) DNA sequencing?
DNA from an environmental sample (water, air)
Where does DNA in eDNA come from? Current usage?
Originates from diverse sources (decomposing organisms, shed cells, body secretions)
Current usage: primarily aquatic systems
Relatively new field, protocols need to be standardized
eDNA screening for… Combines what?
For DNA from water, soil or air
Combines polymerase chain reaction with DNA sequencing. Uses metabarcoding
What is polymerase chain reaction
- primers bind to DNA of interest
- primers, nucleotides, bugger, thermostable DNA polymerase
- each cycle doubles amount of target DNA
- 30 cycles = 1 billion copies of target
What is metabarcoding
Parallel sequencing of complex bulk samples
Slide 58
How were frogs “lost and found”
2-30 liters of water pumped through filter (from puddles, ponds, streams and rivers)
PCR target: 12S rRNA mitochondrial sequences
eDNA readouts found DNA of some ‘disappeared’ species
Two early studies looking at eDNA from air
Both went to zoos to determine utility of eDNA from air (identifying non-native, unique DNA)
One study identified a guppy from an air sample from a rainforest house in the zoo
Detected 30 mammal, 13 bird, 4 fish, 1 amphibian and 1 reptile species
eDNA limitations
- incomplete reference databases (esp rare species)
- PCR/sequencing difficulties
- sampling rigor
- probably NOT a tool for confirming extinction
What kind of conclusion can be drawn from eDNA?
Just because it was not found does not mean it is extinct
But if you are finding the DNA you can be pretty certain the organism if present in the ecosystem
What is the earth biogenome project
Sequencing of all known eukaryotic species on earth in 10 years
1.5 million species
Plants are the only major clade that…
has more threatened species than number of genomes currently targeted for sequencing
Describe plant sequencing. What plants should be prioritized for conservation?
Plants comprise 80% of earth’s biomass
20% of vascular plants are threatened with extinction this century
Very behind on sequencing plants
Prioritize plants with unique attributes and ones under threat of extinction
Three possible solutions to biodiversity decline
- defining the drivers
- reversing or slowing the drivers
- zoological parks (breeding programs, education)
What is the species survival plan?
Cooperative, coordinated breeding programs for captive endangered species throughout the world (based on genetics of individuals)
Create captive populations that can occasionally be reintroduced into the wild
Describe the Guam rail decline
- flightless
- population decline since mid 1940s bc of brown tree snakes
- extirpated in wild in 1981, remaining 21 birds captured
- conservation breeding programs = reintroduced to wild in 1995, 2010
Describe decline of the California Condor
- extinct in wild in 1987
- 27 remaining wild birds captured
- bred in captivity (San Diego Zoo)
- Currently >500 condors (wild and captive)
How did the exhibit of the Japanese Rock Tarmigan at the Japanese zoo affect its conservation?
Not the sort of animal that typically inspires the public, but exhibit debut had impressive impact
Tarmigan web searching increased
Slides 83, 84
REad
Look over slides and graphs/diagrams
DO IT
