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ENVR 202 > Lecture 14-16 > Flashcards

Lecture 14-16 Flashcards

1
Q

Extinction def

A

Death of the last individual of the species
Likely lost forever –> if it comes back, it will likely not be the same species
Diffiucult to prove a negative in sciences

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2
Q

How do you demonstrate extinction?

A

Successive searches throughout the native range
- no individuals found where previously there had been individuals –> classified as extinct

Different agencies can disagree as to what constitutes a thorough search

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3
Q

What does extinct in the wild mean?

A

A species that is extinct in its habitat, but still found in captivity

Death of the last individual of the spcies in the wild. Individuals persists in captivity

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4
Q

What are some problems with the reintroduction of a species that was extinct in the wild?

A

Differences between environments
When they are gone, other things filled the niche –> hard to reintegrate

Pop. size is small which causues inbreeding –> low genetic diversity leads to alleles being shared

Most species cannot be kepy indefinitely in captivity
- often do not breed well
- prone to disease
- very low genetic diversity

Last stage before full extinction

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5
Q

What does funtionally extinct mean?

A

A species which still has members present in the environment, however pop. is greatly reduced compared to the ancestral pop.

Have decreased below their minimum viable pop.

Have obvious factors in the envr. preventing pop. from recovering

Are no longer performing their role in the ecosystem

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6
Q

When does a species fall below the minimum viable pop.? What are the issues?

A

Genetic diversity too low for healthy breeding over the long term

Greater likelihood that “chance events” could wipe out your entire pop. such as severe drought, hurricane, etc.

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7
Q

Extirpation definition

A

Local extinction of a population from a geographical range

Other populations of the species survive elsewhere

Extirpation (N=0) is about population dynamics

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8
Q

What is a population?

A

A group of individuals of the same species inhabiting the same area (implicit – breeding; genetic mixing)

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9
Q

What is population dynamics?

A

Changes in population size (N) and composition over time

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10
Q

What processes increase population size?

A

breeding, immigration, supplementation

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11
Q

What processes decrease population size?

A

Death, emigration, harvesting, carrying capacity truncation

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12
Q

What does a positive r represent? What does a negative r represent?

A

Positive: population will grow
Negative: population will decline

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13
Q

What do population numbers at a certain time t (Nt) depend on in the equation?

A

Numbers in the pop. in previous time N(t-1)

The intrinsic rate of pop. increase r
- add variations in rates of births and deaths

Introduce stochasticity (epsilon) –> fluctuation
- sampled from a normal distribution

Carrying capacity K
- the number of individuals an envr can support before resources run out or the envr begins to degrade
- add variations in resources

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14
Q

What is the equation for Nt?

A

Nt = N(t-1) * (1+(r+epsilon1,t) * (1-Nt-1/(K+epsilon2,t)))

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15
Q

What are other factors that impact population numbers?

A

Humans
- change of environmental conditions (changes in K)
- invasive species (competition)
- nonlinearity in pop. growth
- selective harvesting
- pollution
- land-use change

Extreme events
- spread and impact of disease
- natural catastrophes

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16
Q

How does pollution impact pop. numbers?

A

Releases chemicals into the environment
Acid rain

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17
Q

How does land-use change impact pop. numbers?

A

Changing environments
Loss of habitats

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18
Q

What is a stochastic simulation of pop. numbers?

A

Based on predictable pop. dynamics, but allowing for change variations (probability) from individual to individual and year to year, and allowing for the numbers of individuals in the population in the preceding year (history)

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19
Q

What are stochastic simulation models and what do they allow?

A

They are computer programs that quantitatively describe all processes known to influence pop. size, including both the intrinsic characteristics of the species and the extrinsic influences of biotic and abiotic conditions in the local envr

Allow random variability in the parameters of the model within bounds set by our knowledge of the mean and variance in each process and each factor in the envr

Run the model many times, each time reassigning new random values to each parameter, and use the frequency across many simulations to estimate the probability of extinction in the pop. or species

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20
Q

What are allee effects?

A

a density-dependent phenomenon in which population growth or individual components of fitness increase as population density increases

a correlation between population size or density and the mean individual fitness

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21
Q

What are some examples of allee effects?

A

Mate limitations
Loss of genetic diversity

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22
Q

What are some possible side effects of low genetic diversity?

A

Greater susceptibility to disease
Greater change of deleterious alleles (detrimental to survival) becoming prominent in the pop.

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23
Q

How does bottleneck events impact pop. size and genetic diversity?

A

Severely reduces it
All the genetic variation from these individuals is lost from the species forever

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24
Q

What are metapopulations?

A

Networks of spatially isolated populations connected by some exchange of individuals (or pollen, gametes) over time

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25
Q

How does immigration impact pop. numbers?

A

Increases –> allows for gene flow between isolated populations

Moves genetic history around and increases variability

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26
Q

What is gene flow?

A

The movement of alleles between two geographically separated populations

A single individual moving between populations can cause gene flow

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27
Q

What do population viability analyses (PVA) include?

A

Uses stochastic simulation models to integrate knowledge about:

1) demographic fluctuations due to random variations in demographic parameters

2) environmental fluctuations due to variation in predation, competition, disease, food supply, catastrophic events, etc.

3) loss of genetic variability, inbreeding depression, genetic drift (random change in allele frequency) in small populations; may be offset by migrations from other populations and mutations

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28
Q

What is the role of chance in pop. dynamics?

A

Chance plays in important role in the probability of natural catastrophes and pop. demography

Chance also plays an important role in metapopulation dynamics
- degree of movement among adjacent populations and environmental conditions that influence emigration/immigration

Chance plays a role in effects of small population size
- detrimental influence on interactions among individuals
–> inbreeding depression, genetic bottlenecks

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29
Q

What are the arguments for and against the overkill hypothesis?

A

For:
- extinctions fall clearly at 11,000 BP
- kill sites/evidence mammoth were hunted
- disproportionate effect on large mammals

Against:
- extinctions of species not hunted by humans
- no extinctions of some vulnerable species
- extinctions also in Alaska where no humans
- few kill sites, incomplete fossil record

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30
Q

What is the overkill hypothesis?

A

Human hunting was proposed to have caused the extinction of the megafauna that roamed North America during the Pleistocene

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31
Q

What is an alternate hypothesis to the overkill hypothesis? What are the arguments for and against?

A

Climate caused the extinctions.

For:
- last glaciation coincides with extinctions
- changing vegetation, food source, competition
- may explain impact on species not hunted

Against:
- no extinctions through dozens of past glacial advances and retreats
- extinctions may be too rapid

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32
Q

FINISH LECTURE 14!

A

last slides i did not include finish this
review recording

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33
Q

Is extinction a normal part of evolution/

A

Yes, of all species which have ever existed, 99.9% are now extinct

It is the most likely the fate of a species

There is a normal background rate of extinction, punctuated by mass extinctions
- rate of extinction is substantially higher than what the background rate of extinction usually is

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34
Q

How is background rate of extinction measured?

A

Calculated rate of extinction using the fossil record to first count how many distinct species existed in a given time and place, and then to identify which ones went extinct

This has limitations

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35
Q

What are limitations on estimating background rate of extinction?

A

Fossil record does not accurately represent past species diversity

Fossil formation is not possible (or likely) in all environments (habitats)

Soft-bodied organisms do not preserve well
- almost no fossil record for jellyfish and worms

Fossils of land animals are scarcer than those of plants

Not always possible to accurately classify species in the fossil record
- particularly from small fragments

Chronospecies

Pseudoextinction

Extinction rates generally measured at the taxonomic level of family, not species or genus. Therefore it is hard to tell distinctions between species in the fossil record.

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36
Q

What is the environment with the most conducive environment for fossil formation?

A

Shallow seas

Other habitats are less represented in the fossil record

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37
Q

What conditions are required for a fossil to form?

A

Fossils can form through freezing, drying, or encasement (in tar or resin) but these types of fossils are very rare

Most fossils are formed when a plant or animals dies in a watery envr and is buried in mud and silt
- after an organism’s soft tissues decay in sediment, the hard parts (bones) are left behind. Over time sediment builds over the top and hardens into rock.

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38
Q

What is a chronospecies?

A

A single species, changing morphologically, genetically, or ecologically over long time scale
- still the same species but might look different in the fossil record

Changes occur to such an extent that the original species, and its descendants, are identified as separate species

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39
Q

What is pseudoextinction?

A

When a species is presumed to have gone extinct, but has instead become a different species (or sub-species)

Incomplete fossil record can lead us to believe a species has gone extinct, when it simply evolved into a different species over time

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40
Q

What are some biotic mechanisms of extinction?

A

A species can be competitively excluded by a closely related species

The organisms that the species exploits (what is feeds on) may come up with an unbeatable defense

A new predator may expand its territory

A species can be wiped out by a disease

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41
Q

What are some abiotic mechanisms of extinction?

A

The niche or habitat the species occupied can no longer support the species

Temperature or climate fluctuations

Extreme sea level changes

Impact events (meteorites)

Volcanism

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42
Q

What happens when extinction rates rise above the expected background rate of extinction?

A

Mass extinctions

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43
Q

What is a mass extinction?

A

Extinction of a large number of unrelated species (biodiversity loss) over a short period of geological time

Extinctions are globally distributed

Happen over the course of millions of years

44
Q

How do mass extinctions affect the evolution of life?

A

There is a very rapid period of speciation among the few species that do survive
- species that remain have a lot more niches that can be filled

Mass extinctions drive the evolution and diversification of life

As populations separate and move away, they adapt over time to the new environmental conditions and eventually can be considered a brand new species and biodiversity expands rather quickly

45
Q

What characterizes the late-ordovician extinction?

A

At the time, most complex multi-cellular organisms lived in the sea

Almost all major taxonomic groups were affected during this extinction

Marine organisms suffered most

49-60% of marine genera and nearly 85% of marine species were eliminated

46
Q

What are the causes of the late-ordovician extinction?

A

The global temperatures cooled and the sea levels fell

Considering that much of the plant and animal diveristy of the time had adapted to shallow warm waters, this was devastating
- these species could not survive in colder, deeper oceans and many died out

Land moved to the south pole due to plate tectonics allowing for the formation of glaciers

Glacier formation removed water from oceans leading to rapid fall in sea levels
- many shallow seas were drained completely

47
Q

What characterized the Devonian age? 375 millions years ago

A

By the late devonian the land had been colonized by plants and insects. In the oceans were massive reefs built by corals

Known as the age of fishes: famous for thousants of species of fish that developed in Devonian seas –> know this because of fossils

During the Devonian, the Earth experienced super greenhouse climate conditions

It was very warm and there was a lot of CO2 in the atmosphere (4000 ppm)

48
Q

What characterized the late-devonian extinction?

A

The devonian period ends with a series of mass extinction events that occurred over a period of 20 million years (long)

Consisted of series of extinction pulses
- no single cuase has been identified, likely multiple causes

49
Q

What are the theories behind the devonian extinction?

A

Potentially had to do with a rapid reduction in atmospheric CO2 that led to the earth cooling and the extinction of many organisms
- could have been due to photosynthesis

As plants expanded onto land to form first forests, they depleted CO2 in the atmosphere
- their max height went from 30cm to 30m

Reduction in CO2 through either may have lead to the cooling of the Earth
- glacial deposits in northern Brazil suggests widespread glaciation at the end of the Devonian

50
Q

What characterizes the Late-Permian Extinction 250 million years ago?

A

Largest of all known mass extinctions

Termed the great dying
- 70% of terretrial vertebrates
- 96% of marine species went extinct

All life today is descended from the few survivros of the great dying

51
Q

What are the cuases of the Permian Extinction?

A

Series of great volcanic eruptions

Eruptions would have released CO2 into the atmosphere resulting in a greenhouse effect – heating up te atmosphere and acidifying the oceans

When CO2 dissolved in seawater it forms carbonic acid and as more CO2 is taken up by the oceans, the pH decreases, moving towards a more acidic state

Eruptions would have also released aerosols and lead to dust clouds, which would have blocked out sunlight and thus disrupted photosynthesis both on land and in the ocean, causing food chains to collapse

These eruptions may also have caused acid rain when the aerosols washed out of the atmosphere

Life bounced back fast after

Through uranium/lead dating –> determined that the siberian traps erupted at the right time, and for the right duration, to have been a likely trigger for the Permian extinction

52
Q

What characterizes the late-triassic extinction 200 million years ago?

A

76% of all species went extinct

Mass extinction on land

This event vacated ecological niches on land, allowing the dinosaurs to assume the dominant roles in the Jurassic period

53
Q

What are the cuases of the late-triassic extinction?

A

several explanations, still not clear what the exact cause was

Observed elevated mercury concentrations in extinction-aged rocks from around the world

Becuase volcanism is the main nonanthropogenic source of mercury in the envr, the findings suggest that volcanic activity was likely the main extinction trigger at the end of the Triassic.

54
Q

What characterized the late-cretaceous extinction 66 million years ago?

A

75% of plant and animal species went extinct
- no tetrapods (four-legged vertebrates) larger than 25kg survived (exceptions were leatherback turtles and crocodiles)

End of the dinosaurs

Followed by the rise of the mammals
- rapid adaptive radiation to fill niches left by extinct dinosaurs

55
Q

What are the causes of the late-cretaceous extinction?

A

Caused by the impact from a comet or asteroid (10-15 km wide)

Impact would have ejected enormous amount of dust, ash into the atmosphere, blocking the radiation from the sun
- zero sunlight reaching the surface of the Earth for a year or so
- caused a global winter
- this would have prevented photosynthesis by plants on land and plankton in the oceans. As plants and plankton died, extinctions expanded up the food chain

Dust and debris falling back to Earth was hot and may have triggered widespread wildfires

Increase in volcanic activity?
- deccan traps –> one of the largest volcanic features on Earth
- likely produced many of the same effects seen during the extreme volcanism of preceding mass extinctions (release of gases, particles in the atmosphere)

56
Q

Volcanism vs. impact?

A

One may have led to the other or volcanism may have been occuring already and impact followed

57
Q

What is the evidence for Impact Hypothesis?

A

150 km wide crater dated precisely to 66 million years ago

High concentrations of iridium in sedimentary layers deposited globally during End Cretaceous
- iridium extremely rare element on Earth surface but common source in asteroids and comets

Shocked quartz found in the sedimentary layer of late-cretaceous
- found in the vicinity of the impact crater
- shocked quartz only formed when intense blast (nuclear impact) causes intense pressuses, which deforms the internal structure of a typical quartz

58
Q

What is the press/pulse theory?

A

Where two events occur:
- the first event stresses an envr
- a second event then occurs, as a result of the environmental stress caused by the first event, and has a greater-than-expected impact on the environment

No single cause has satisfied all scientists for any extinction event
- combination of deadly sudden catastrophes “pulses” with longer, steadier pressures on species “presses”

59
Q

The sixth mass extinction - Anthropocene extinction

A

Historical rates of extinction is 0.1 species per million species per year
Current rate of extinction is 100 extinctions per million species per year
- 100 to 1000x the natural background rate of extinction

60
Q

What are the causes of the sixth mass extinction?

A

Generally unintended consequences of human activity

Most common reasons for extinction
- habitat loss
- invasive species
- overhunting

61
Q

What is a planned extinction?

A

Directed human effort to drive a species to extinction

62
Q

Describe the extinction of the passenger pigeon

A

At the beginning of the 19th century it was the most abundant bird in North America
- a flock could have so large is would take hours to pass over a single spot

Passenger pigeon has all the biotic traits of a species suited to avoiding extinction:
- extremely common
- generalist
- excellent disperser (flight)
- short lifecycle
- high reproductive rate (can have multiple nests a seasons)

Seen as agricultural pests –> blamed for eating crops

Many areas put a local bounty
- large concentrated flocks made it easy to hunt large numbers
- the species was gunned, netted, and clubbed into oblivion

63
Q

How is modern gene editing useful in terms of planned extinctions?

A

CRISPR/Cas9

New gene-editing technology is now extremely versatile and accurate and can remove targeted gene from a species

We can now guarantee any gene we insert into an individual can and will spread rapidly through the pop.

We can insert a deleterious mutation, an adaptive one, or one which has never been in a species before

64
Q

Was was previous gene-editing insufficient?

A

Largely based on trial and error (luck)
Could not remove genes
Inheritance of inserted gene was based on gentic recombination (meiosis)
- no guarantee the gene you inserted would be inherited

65
Q

How did scientists use CRISPR to plan a mosquito extinction? Should we make mosquitoes go extinct?

A

Generated a mutant gene that left female mosquitoes unable to reproduce but allowed males to continue to spread the female infertility mutation to offspring

By eigth gen. all mosquitoes carried infertility gene, meaning no eggs were laid and the entire pop. died

No, mosquitoes play a critical role in a few environments (Arctic, Tundra) where they hatch out by the billions over a short period and are a significant food resource for birds

66
Q

What is a disease?

A

An abnormal condition that negatively affects the structure or function of part or all of an organism, and that is not due to any external injury

Diseases are often described as medical conditions that are associated with specific symptoms

A disease may be caused by external factors (pathogens) or by internal factors (autoimmune disorders)

67
Q

What are the types of causes of diseases?

A

Airborne
- caused by pathogens transmitted through air

Foodborne
- consumption of food contaminated with pathogenic bacteria, viruses, or toxins

Lifestyle
- disease that appears to increase in countries that become more industrialized and where people live longer
- also in places that have diet that is high in unhealthy foods/and or sedentary lifestyles

Non-communicable
- disease that cannot be spread directly from one person to another (e.g. cancer, heart disease, etc.)

Infectious
- illness resulting from infection, presence and growth of pathogen in a host organism
- can be contagious or communicable

68
Q

What is contagious disease?

A

Infection that spreads commonly from one person to another (e.g. common cold)

69
Q

What is communicable diseases?

A

Does not necessarily spread through everyday contact (e.g. ringworm)

Spread from individual to individual

70
Q

What is a parasite?

A

An organism that lives on or in a host organism and gets its food from or at the expense of its host

Can cause a disease in the host therefore a parasite can be a pathogen
- the vast majority of the known parasites are not pathogenic for humans, although they can be pathogenic for other organisms

71
Q

What is a pathogen?

A

Organism that causes diseases within their host

72
Q

What is an epidemic?

A

A widespread occurence of an infectious disease in a community at a particular time

73
Q

What happened during the arrival of Europeans with diseases?

A

When europeans began arriving on the shores of the Americas, the diseases they brought with them set off one the largest depopulations in human history

Prior to their arrival, diseases such as measles and yellow fever did not exist in these regions of the world
- having never been exposed to these illnesses, Aboriginal peoples did not have the antiboies needed to ward off infection

Aboriginal populations were drastically reduced by epidemic disease over the course of the next 400 years as europeans continued to explore new territory and came into contact with different communities

Smallpox was often the worst disease (1535)

74
Q

Give general info about smallpox

A

Variola major and minor
- two viral species which caused the smallpox disease in human populations

Highly contagious and destructive human disease
- 30% mortality rate, highest mortality in children

Debilitating chronic conditions in some survivors (paralysis)

Last naturally occuring case in oct. 1977

Currently, there is no evidence of naturally occuring smallpox transmission anywhere in the world
- exist in two research labs

75
Q

How did smallpox go extinct?

A

Worldwide immunization program eradicated smallpox through vaccination

First and only successful attempt to eradicate a human disease

76
Q

General info about the Black Plague

A

1347-1350

One of the most devastating epidemics in human history resulting in the deaths of 75-200 million ppl in Europe and Asia

Estimated to have killed 30-60% of Europe’s pop.

It took 200 years for the world pop. to recover to its previous level

77
Q

What caused the black plague?

A

Caused by the bacterium Yersinia pestis that circulates among wild rodents (rats) where they live in great numbers and density

The bacterium is specifically associated with fleas that live and feed on the rate

The organism is transmitted to humans who are bitten by fleas that have fed on infected rodents or by humans handling infected animals

78
Q

Where did the black plague originate from? How did it spread to Europe and why?

A

Orginated in Asia

Due to climate fluctuations, rodents began to flee the dried out grasslands to more populated areas, spreading the disease

Disease may have travelled along the Silk Road with armies and traders or it could have come via ship

79
Q

What happened to life after the black plague?

A

A series of religious social and economic upheavals

Rising standards of living after the epidemic
- food prices dropped and labor wages increased (less available labour)
- survivors had more resources available to them (improved quality for everyone)
- people were eating more meat and fish, better quality ingredients and greater qties

Higher proportion of older adults, and mortality risks were generally lower

80
Q

What are the 4 types of influenza?

A

A: infects humans, other mammals, and birds, an causes all flu pandemics

B: infects humans and seals

C: infects humans pigs and dogs

D: infects pigs and cattle

81
Q

What is an influenza pandemic?

A

An epidemic of an influenza virus that spreads on a worldwide scale and infects a large proportion of the world pop.

There are been about 9 in the past 300 years

Historically, a new strain appears about every 30-40 years

82
Q

Describe the 1918 influenza pandemic

A

Spanish flu

Infected 500 million ppl around the world (1/3 of the world pop.)

50-100 millions deaths

Most influenza outbreaks disproportionately kill young and elderly, but the 1918 pandemic predominantly killed previously healthy young adults

83
Q

Why was the spanish flu so bad?

A

During the 1st world war –> close quarters and massive troop movements helped fuel the spread of the victims

Not more agressive, but that the special circumstances of the epidemic (malnourishment, ovecrowded medical camps and hospitals, poor hygiene) promoted bacterial superinfection that killed most of the victims

Preventation and treatment methods for flue were limited
- no vaccines, no antiviral drugs, no antibiotics to treat secondary bacterial infections like pneumonia

84
Q

Why was the 1918 called the spanish flu?

A

Because Spain had remained neutral during the war and freely reported the news of flu activity

For the U.S. and other countries involved in the war, communications about the severity and spread of disease was kept quiet as officials were concerned about keeping up public morale and not giving away info about illness among soliders during wartime

85
Q

What was the impact of the spanish flu?

A

Affected mostly young men, which created a labour shortage

Generally epidemics killed more men than women

Brought more women in the workforce and helped advance women’s rights
- women stepped into public roles that had not previously been open to them
- by 1920, women made up 21% of all gainfully employed individuals in the U.S.

86
Q

What is malaria?

A

Mosquito-borne infectious disease that affects humans and other animals
- not spread from person to person

Caused by eukaryote microorganism that is parasitic to insects
- caused by a microbe not a bacteria

The parasites travel to the liver where they mature and reproduce

Causes symptoms that typically include fever, tiredness, vomiting, and headaches

87
Q

Where is Malaria prevalent and why?

A

Tropical and subtropical regions due to consistant high temperatures and high humidity and high rainfall, along with stagnant waters where mosquito larvae readily mature, providing them with the environment they need for continuous breeding

88
Q

What happened with malaria in the Panama canal?

A

Ideal envr for mosquitoes
- high temp. that varies little during the year
- rainy season lasts for nine months and the interior of the Isthmus is tropical jungle, ideal for mosquito breeding

The control of malaria was vital for the construction of the Panama canal
- France first attempted
- Us.s received the rights to the canal zone in 1903

89
Q

Bad air theory

A

Diseases were caused in Panama by toxic vapors from swamps, sewage and urban filth

90
Q

How did the U.S. control the malaria problem?

A

Fumigated buildings and homes

Cut all grass to less than 12 inches

Drained swamps and open water

Filled or removed stagnant water sources

Custom poisons were spread in areas where larvae grew

Cleared away trash

91
Q

Virulence definition

A

A pathogen’s ability to infect or damage a host

Higher virulence means higher ability

92
Q

How is virulence related to transmission?

A

A highly virulent pathogen does a lot of damage to its host and produces a lot of offspring. However, if the hosts’s illness prevents the host from coming into contact with new hosts, the pathogen actually has relatively low evolutionary fitness

A pathogen that is less virulent could infect far more hosts because the hosts are well enough to come in contact with many other potential hosts

93
Q

How does virulence evolved?

A

Natural selection selects for pathogens virulent enough to produce many offspring that are likely to be able to infect a new host if the opportunity arises, but not so virulent that they prevent the current host from presenting them with opportunities for transmission

One important factor that influences how virulence evolved is based on the pathogen’s mode of transmission

94
Q

HIV/AIDS

A

Sexually transmitted
Very long latency period (average 10 years) with no symptoms

95
Q

Cholera

A

Caused by eating food or drinking water contamiated with bacterium called Vibrio cholerae

Leads to sever diarrhea which can lead to dehydratino and even death if untreated

Cholera has evolved a high level of virulence and may kill its host just a few hours after symptoms begin (even in previously healthy ppl)

Cholera victims are soon immobilized by the disease, but they are tended by others who carry away their waste, clean their soiled clothes and in the process transmit the pathogen to a water supply where it can be ingested by new hosts

Therefore, virulent cholera strains that strike down a host immediately can easily be transmitted to a new host

96
Q

What happened during the cholera outbreak in Haiti in 2010?

A

Source was suspected to be the Artibonite River
- most of the affected ppl had consumed water from this river
- many Haitians bathe, wash their clothes and dishes, obtain drinking water and recreated in this river

UN peacekeeper base was positioned on a stream that flowed into the river
- neighbouring farmers reported an undeniable stench of human feces coming from the base

The epidemic was due to waste from outhouses at the UN base that flowed into and contaminated the Artibonite River

97
Q

How is climate change impacting disease?

A

Because of rising temperatures and changing rainfall patterns, climate change is expected to have a substantial effect on the burden of infectious diseases

Humans and animals are forced to compete for dwindling habitat and resources

Insect vectors tend to be more active at higher temps.
- tropical mosquitoes that transmit malaria require temperatures above 16 degrees to complete their life cycles

98
Q

How is climate change affected malaria?

A

Mosquitoes that transmit malaria require temps above 16 degrees to complete their life cycles

Malaria has spread to highland regions of East Africa, where this disease previously did not exist

This spread occurred in areas where weather is much warmer and wetter than usual

Experiments show that parasites developed more quickly in warmer temperatures, however it is not a clear cut mechanism between temp. increase and malaria spread –> there is a not of nuance to take into consideration
- concluded that warmer temps seem to slow transmission of malaria-causing parasites by reducing their infectiousness

99
Q

Where is avian malaria an issue what why?

A

Hawaiian birds are extremely vulnerable to avian malaria (especially honeycreepers) since they evolved in isolation. They are susceptible to diseases that are mostly harmless to birds elsewhere

Rising temps have allowed mosquitoes to expand into the birds’ high-elevation ranges, which were once too cool for them to tolerate
- high altitude no longer guarantees safety for native birds from a disease that can kill them in a matter of days

In response, some birds have retreated to higher ground where it;s too cold for mosquitoes but there areas are now under threat

100
Q

What are ways to protect Hawaiian birds from avian malaria?

A

Using chemicals
- However, mosquitoes can breed in less than a teasproon of water and can do so nearly anywhere in Hawaii. Their eggs are often inaccessible, hidden in rocks, caves and the hollows of trees
- Also, poison that can kill mosquitoes frequently also kills the plants and animals that surround them

Genetically engineering mosquitoes to make females unable to reproduce bur allowing males to continue spreading the female infertility mutation to offspring using CRISPR

101
Q

Ebola

A

Caused by virus

Symptoms start 2-21 days after contracting virus
- people begin to bleed both internally and externally

High mortality rate: about 50% of people infected die typically 6-16 days after symptoms appear

Virus spreads through direct contact with bodily fluids, such as blood from infected humans or other animals

May also spread from contact with items recently contaminated with bodily fluids

102
Q

How does climate change affect ebola?

A

Fruit bats are believed to be the normal carrier in nature, able to spread the the virus without being affected by it

Increase in sudden and extreme weather events is thought to play a role in Ebola outbreaks
- Dry seasons followed by heavy rainfall produce an abundance of fruit and have coincided with ebola outbreaks

When fruit is plentiful, bats and apes may gather together to eat, providing opportunities for the disease to jump between species
- humans can contract the disease by eating or handling an infected animal

Almost 50% of ebola outbreaks have been directly linked to bushmeat consumption and handling (the origin of the 2014 outbreak, however, has still not be determined)

In agrarian West Africa, climate change may also be bringing humans into closer contact with virus-carrying bats, as increasing and more severe dry spells hit agricultural yields and drive humans into the forest for food

Deforestation

103
Q

How is deforestation impacting ebola?

A

Deforestation leads to habitat loss and more ppl entering the forest, thus, forcing animals like bats to find new habitats and hunt for food near humans

More and more wild animals, which may have carried diseases without effect for years, are coming into contact with humans

Almost 75% all new, emerging, or re-emerging diseases affecting humans at the beginning of the 21st century are zoonotic meaning they originate in animals

104
Q

What are the arguments for COVID-19 being a from a natural source?

A

Natural spillovers happen frequently

SARS2-like viruses have been found in nature

Early large cluster detected at wildlife market

Documented pipline of bringing in and selling potential intermediate hosts

105
Q

What are the arguments for COVID-19 being from a laboratory related source?

A

Lab accidents happen with increasing frequency

SARS2-like viruses have been studied in a Wuhan lab

1st outbreak detected in city with SARSr-CoV research lab

DOcumented pipeline of collecting and creating potential precursor virus

ENVR 202 (7 decks)

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