conservation bio ONE Flashcards
Science of Conservation
conservation is a scientific endeavor to understand the natural world to minimize extinctions. The scientific method is used to formulate and test hypotheses to answer research questions
hypothesis– answer to a research question that makes testable predictions
- research question
- hypothesis
- prediction
- new data
- compare data
- reject or support hypothesis
individuals
populations
species
communities
individual: male, female, juvenile, etc
population: made up of individuals
species: can have many populations and subspecies
communities: have many different species
why is it hard to define “species”
because speciation is a continuous process
allopatric speciation
isolation leads to unique populations via mutations and differential selection which can lead to new species with a unique evolutionary history
biological species concept (BSC)
species: groups of interbreeding populations which are reproductively isolated from other such groups
subspecies: distinct populations of species, which are unique but still have gene flow
subspecies are incipient species
time and isolation for differences can develop, but are still not reproductively isolated
biodiversity
diversity of and within species over some defined area– species and their genetic variation
species richness
total number of species in an area (common metric for biodiversity)
why do we want to prevent extinction and preserve biodiversity, what is their value
philosophical and ecological
2 philosophical values to save species
- Inherent (intrinsic) value: they are valued just because they exist, most often seen in charismatic species
- Utilitarian value: they provide direct and indirect benefits to humans
- direct benefits: food, fuel, material, medicine (vincristine and aplidin)
- indirect benefits (ecosystem services): crop pollination, water purification, erosion regulation, pest regulation, soil formation, climate regulation
- overall $33 billion/year estimated benefit
Ecological reason to save species
High diversity ecosystems function better (are more productive and resilient) than depauperate (low diversity) ecosystems
ecosystem function increases with community diversity
Tilman Prairie Biodiversity Experiment
- low and high diversity plots established and compared
- high diversity plots had: higher biomass (more productive), retained soil nutrients, more resilient to drought and disease, less herbivory by grasshoppers, fewer weedy invadors
diverse systems being more productive and “healthier” has implications for agriculture, range land, and forestry
why is there a biodiversity crisis
- people do not understand/appreciate the value of species and biodiversity
- economic externalities exist, leading to environmental degradation
(externality: hidden cost in economic transaction; hidden cost: environmental degradation; environment pays for this hidden cost)
environment is damaged unless the government gets involved
examples of externalities
- byproducts of industrial production– toxins
- released into air, water, ground
- toxins degrade the environment (reduce survival and reproduction of organisms)
5 mass extinctions that dramatically reduced global diversity.
Which was the most intense?
- 443– Ordovician (26, 60, 86)
- 359– Devonian (22, 57, 75)
- 251– Permian * (51, 82, 96)
- 200– Triassic (22, 53, 80)
- 65– Cretaceous (16, 47, 76)
Permian was most intense, with a 51% family, 82% genera, and 96% species extinction
Overall, D— Pleases The C—
what was the cause of these extinctions
what about in the cretaceous
Temporal
extra-terrestrial: massive volcanic eruption with associated changes in oceanic and atmospheric chemistry and climate change. toxic gas in the air changes global chemistry, hurting survival and reproduction. Asteroid, earthquakes, tidal waves
how many species are formally described
how many new ones are described per year
1.5 million
~ 15,000
undescribed species and total species estimate
10 million, 5-15 million
(most are insects
biodiversity hotspots
unusually high levels of biodiversity
(tropical forests, tropical lakes, coral reefs, temprate shrublands with mediterrean climate– wet winter, dry spring summer fall)
how much of the area is made up of biodiversity hotspots and how many species do they have
5-10 percent contain over 25 percent of all species
latitudinal diversity gradient
highest diversity near the equator and declines as you move towards the poles, has been this way for millions of years
on a graph, 0 is the equator
hypotheses for the LDG
- based on evolutionary NOT ecological time
1. stability
2. productivity (energy)
3. area
2 mechanisms that cause change in diversity over evolutionary time
and the LDG hypotheses must explain these
- speciation increases diversity
- extinction decreases diversity
ecological time is
within the lifespan of a species
evolutionary time is
over many thousands of generations (millions of years)
stability hypothesis
- the tropic regions have been the most climatically stabilized for many years
- increased stability promotes lower extinction rates
- evidence: climate has fluctuated globally, how is it at the equator? hard to know
productivity (energy) hypothesis
- productivity = rate of conversion of solar energy to biological energy (photosynthesis). measures by change in plant biomass
- since the earth is tilted, the tropics have the most solar radiation
- more resources = higher pop sizes and lower extinction rates
how was the productivity hypothesis tested ?
- productivity increased by feeding nutrients
- but increase led to decreased diversity, oops
- but, this was done in ecological time, so maybe its not a fair test
Area Hypothesis
- based on data
- more species are found in larger areas
- slope shows how quickly you pick up species
how to do the area hypothesis
- divide the globe into biomes (tropical, temperate, artic/boreal) for all latitudes
results of area hypothesis
- tropic biome has largest area and most species, temperate, then boreal
- tropical north and south biomes are contiguous, hence why its area is greater than all others
what does area hypothesis have to do with speciation and extinction
more area -> species move -> vicariance (something breaking area) -> split -> allopatric speciation -> greater speciation rate
greater area = more resources = higher population sizes = lower extinction risk
support for area hypothesis
vicariance in tropics has increased due to cooling. and speciation is higher on larger islands
what type of animals were extinct during the pleistocene extinctions
large-bodied mammals and big birds; bigger than 100 lbs
where and when was the pleistocene extinction
North and South America, about 12,000 years ago
how many mammals went extinct in NA pleistocene
34/37
- 50% of 70 pound ones gona
- and all 2100 ones extinct
- bison was only big survivor (2000)
how many mammals went extinct in SA pleistocene
80% big bois
what were the large species during Pleis called
megafauna
what about Pleis in Eurasia and Africa
not many– some in Eurasia and very few in africa
what to understand to answer these extinction patterns ?
- why clustered towards the end
- why in just NA and SA
- why just big bois and birds
2 proposed Pleis extinct hypotheses
- climate change
- human overkill
climate change hypothesis
- ice ages, prolonged cooling and warming periods
- glacial maximum and global warming at the end
- changes in climate at the end of the Pleis led to habitat changes that negatively affected species
- big bodies need more resources and have lower repro rates
- endotherms (birds and mammals) are most vulnerable to climate change, as they need very specific foods and climates
- many guys lived in grass and savannah, which were reduced as the earth warmed. thus species-area relationship
support for climate change hypothesis
- evidence that habitats changed as climate did
- ex: there used to be boreal places in missouri that now are in north canadal
limitations of climate change hypothesis
- there were many changes, so why just the end ?
- why only big bois
- why werent they global
human overkill hypothesis
- human hunting led to extinctions via overharvesting of megafauna, as humans target big bois and birds
- humans came to NA and SA around ~ 25,000 years ago
- has human pops increased, hunting increased
- animals in NA and SA were not familiar with human hunters, so not adapted to them
- some went extinct as their prey went extinct
support for the overkill hypothesis
- archeological sites have found hunting tools
- most happened when humans arrived and sites show this
- many extinctions have followed the arrival of humans
how to test the overkill hypothesis
- plant and fungal spores and pollen
- lake sediment can be dated
- plants show herbivores, charcol shows widespread firew
what a specific spore and what does it tell us abt both extinction hypotheses
Sporomiella (fungal) was found in only dung of large herbivores
- climate: extinctions during or after vegetation change, plants changed from cold ones to warm ones
- overkill: decline when humans arrive
lake sediment study supports which hypothesis
overkills, because no veggie change found until 13k years ago, and human hunting was evident 15k years ago
how many extinctions since 1600
over 800 globally
- 200 molluscs
- 100 insects
- 100 birds
- 50 mammals
- 30 fish
- 25 reptiles
most happened on islands
why are recent extinctions different than Pleis
they are global and not as related to human consumption as the last
3 threats to biodiversity
- habitat loss, modification, degradation, and fragmentation
- overharvesting
- exotic species
(hoe)
habitat loss / modification
- humans modify habitats from one type to another
- most species are just adapted to one, so the conversion reduces their fitness (survival and reproduction) and can lead to extinctions
eastern deciduous forest birds
- by 1870, characterized by the industrial revolution and western migration, 50% of the habitat was converted from forest to non-forest
- 3.99 went extinct
- there were 23 species, but with 50% loss, only about 19 can be supported
- 17% loss
habitat loss and species capacity graph
x– habitat loss
y– how many species it can handle
what are grassland, wetlands / aquatic places, and coral reefs converted to
- grassland: converted to agriculture
- wet / aqua: filled or drained for development, channeled for flood control, or polluted
- coral reefs: sandy bottoms
how many tropical and temperate forests are turning into non-forest spaces for agriculture, logging, and pasture
67% in asia and africa
habitat degredation
no structural change, but reduced quality with pollution and toxins
industrial pollution, toxic heavy metals, chemical pesticides (DDT), lead, nitrates, and sulfates for acid rain
eutrophication
fertilization of aquatic habitats
Eutrophication of Lake Washington
- used lake washington instead of the pacific ocean for sewage treatment
- 20 million gallons of treated sewage pumped into lake in 1920s (fertilizers and detergent)
- sewage was treated with N and P
- the added nutrients to the treated sewage caused algal growth
- summer algal blooms started
- in fall, algal death and decomposition was followed by fish death due to reduced O2 levels
- plan to save the lake changed dumping to the pacific ocean
Ocean Eutrophication
1970s “dead zone” in Gulf of Mexico started occurring every fall in the 1980s, and the size was increasing
caused by N and P runoff from Midwest agriculture (fertilizer) and cities (sewage)
caused by hypoxic conditions where O2 was too low to support marine life
habitat fragmentation
habitat patches in a sea of other kinds of habitats
2 effects of habitat fragmentation
- movement is impeded
- edge effects are created
movement during habitat fragmentation
- individuals are adapted to specific environments which they prefer to move in
- when they are converted, movement is reduced
- reduced movement can negatively affect the number of species
model of island biogeography
used to predict the number of species on an island
colonization/immigration and extinction relationship
as colonization rate decreases, extinction rate increases, equilibrium is at S*
x axis– number of species
y axis– rate
5 key assumptions in the model of island biogeography
- based on ecological time, NOT evolutionary
- number of species on an island affects extinction rate
- number of species on an island affects immigration rate
- island size affects extinction rates– Erate declines as size increases
- island distance to mainland affects immigration rate– Irate declines with longer distance
fragmentation impedes movement -> immigration curve lowered -> reduced number of species
what does this imply
small island -> fewer species due to high extinction rates
+
farther distance -> fewer species due to lower immigration curve
=
both reduce the predicted # of species
movement also aids population persistence– population structures
- a species can exist as a metapopulation (a set of populations) and many separate populations connected by movement of individuals
- existing populations can go extinct each year
- unoccupied sites can be colonized each year
what is population persistence
persistence (population does not go extinct) of entire metapopulation (across all sites) is a function of colonization
high dispersal -> most sites occupied -> low extinction rate for metapopulation
colonization and persistence relationship
add fragmentation in there
high colonization means high persistence
fragmentation reduces colonization, thus persistence
what happens to species without immigration
present species will decline and go extinct
hence reserves, which are set aside to keep human interaction away from animals; however, the low immigration leads to extinction
Edge effects– ecotones
habitat conservation creates leads to ecotones– abrupt transition from one habitat to another
edge– transition
how can edge effects look
the edge of a habitat can differ from the center/core
this affects fitness of those adapted to the core
what happens to species interactions at the edge
- new species interactions occur
- mixing species adapted to different habitats
- can hurt those adapted to the core
- ex: brown-headed crowbirds are open habitat, brood parasites. These expanded into forest areas where others nest, and they would put their eggs into these nests. this hurt other chicks (such as the kirtland warbler), reducing their fitness
overexploitation
2nd most important human activity responsible for the conservation crisis
k =
carrying capacity
k / 2 = p*
maximum sustainable yield (MSY): where you can use animals without harming their population
calculated by the slope of the log -> line curve with x– pop size and y– change in pop size
how to use MSY model for sustainable harvest
- determine P*
- harvest MSY each year, to keep pop size at P*
- maximize harvest without causing population to change
- goal– keep population size to P*
MSY model successes
- terrestrial species
- need permits to hunt deer, elk, doves, etc
- state agency sets a quota of how much can be harvested per year
- designed to stay at P*
MSY model failures
- we overexploit ocean animals (whales, oysters, fish)
- not too good at preventing this
- many ocean populations have collapsed due to overfishing
why does MSY fail to protect ocean species
- political pressures to set higher quotas for more food and money
- model assumes that people know the actual population, but that can be hard to predict in the ocean. so, we need to estimate, but that can lead to over-optimistic estimates
why does MSY fail to protect ocean species, graph terms
unstable equilibrium
- if the actual population size is lower than K/2, then overharvest will occur and MSY harvest will exacerbate this decline. all the while, you still think k/2 is the population
how to modify the MSY to reduce overharvestin
- set target population size to higher than P*
- new target population, S2, results in a lower quota, but higher population
- it is a stable to poor estimate of the true population size
- need to keep population size larger than K/2 to set lower harvest than MSY
- unstable below the stock size and stable above the stock size (P*) on the x-axis
MSY modification effects on overexploutation and harvest quotas
- decreases overexplotation
- lowers harvest quotass
sustainable seafood
- alaskan halibut and salmon
- clams, mussels, oysters
- crabs
- pacific cod
- pacific sardines
- striped bass
- albacore tuna
poorly managed seafood (near k/2)
- atlantic fish
- chilean sea bass
- mahi mahi
- orange roughy
- bluefin tuna
- imported shrimp
- shark
exotic species
species evolved in one place and moved to another place on earth by human activities
invasive species
an exotic species that attains high abundance and negatively affects native species
ex: invasive squirrels now outcompeting native ones
Unintentional introductions
ships and planes
rats, mice, snakes
fire ants and zebra mussels that make up the ballast
Intentional introductions
for sport
to improve pastureland for livestock (plants)
as a biological control (predators) to reduce abundance of other exotic species (foxes to control rabbits, but it went bad cause they ate other animals instead)
how many exotic species are successful
only 1%, but humans bring so many
4 major problems of exotic species
- carry novel diseases
- super predators
- super competitors
- alter disturbance regimes
novel disease examples
Japanese chestnut tree introduced to the US, resulted in decline of American chestnut.
the JC had a fungus that killed AC
exotic mosquitos from hawaii brought malaria to birds
exotic livestock from africa brought rinderpest virus to native wildbeest
super predator examples
eat prey who have no evolutionary adaptations to this redation
brown tree snake from asia to guam which caused the extinction of 10-12 birds and lizards
burmese python in the everglades
super competitor example
exotics can outcompete native species
zebra mussel competes for space in the great lakes
kudzu overgrows and outcompetes other plants for light
disturbance regimes examples
exotic grasses enhance fires
feral hogs create soil disturbances and reduce soil nutrients
predictions about exotic species
- which exotic species will become common and invasive: focus on traits to predict if it will attain high abundance and then become a problem
- which communities are more prone to invasions by exotic species: observe communities to understand how/if it can be affected
how to predict invasive species
compare traits of closely related invasive and non invasive exotic species
example of invasive species prediction
- 24 west pine studied
invasive species had: - shorter juvenille period (faster reproduction)
- shorter interval between large seeds (high repro rate)
- smallest seeds (greater dispersal)
exotic species have
- high repro rates
- high dispersal rates
- ability to live in many habitat types
biotic resistance hypothesis
native species / native diversity regulated exotic invasion successfully
- Direct (consumption): native eat invasive (blue crab eat green crab, kangaroo rats eat exotic plant)
- Indirect (competition): native compete invasive (local species richness, because diverse species are more resistant)
why are diverse communities more resistant to invasion
- as diversity increases, fewer resources are available, so more intense competition
in graph: high density have many clustered curves, low density is more spaced out, allowing for invasive curves to come in
exotic vs native diversity relationship
higher the native diversity, fewer the exotics
sustainable model graphically
be above P* and approaching k, but not all the way
far from P* is sustainable– true or false
true
