Lecture 14-16 Flashcards

Question

How does immigration impact pop. numbers?

Answer 1

Increases --> allows for gene flow between isolated populations Moves genetic history around and increases variability

Answer 2

The movement of alleles between two geographically separated populations A single individual moving between populations can cause gene flow

Answer 3

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

Answer 4

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

Answer 5

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

Answer 6

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

Answer 7

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

Answer 8

last slides i did not include finish this review recording

Answer 9

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

Answer 10

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

Answer 11

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.

Answer 12

Shallow seas Other habitats are less represented in the fossil record

Answer 13

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.

Answer 14

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

Answer 15

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

Answer 16

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

Answer 17

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

Answer 18

Mass extinctions

Answer 19

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

Answer 20

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

Answer 21

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

Answer 22

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

Answer 23

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)

Answer 24

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

Answer 25

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

Answer 26

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

Answer 27

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

Answer 28

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

Answer 29

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.

Answer 30

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

Answer 31

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)

Answer 32

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

Answer 33

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

Answer 34

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"

Answer 35

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

Answer 36

Generally unintended consequences of human activity Most common reasons for extinction - habitat loss - invasive species - overhunting

Answer 37

Directed human effort to drive a species to extinction

Answer 38

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

Answer 39

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

Answer 40

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

Answer 41

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

Answer 42

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)

Answer 43

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

Answer 44

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

Answer 45

Does not necessarily spread through everyday contact (e.g. ringworm) Spread from individual to individual

Answer 46

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

Answer 47

Organism that causes diseases within their host

Answer 48

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

Answer 49

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)

Answer 50

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

Answer 51

Worldwide immunization program eradicated smallpox through vaccination First and only successful attempt to eradicate a human disease

Answer 52

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

Answer 53

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

Answer 54

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

Answer 55

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

Answer 56

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

Answer 57

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

Answer 58

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

Answer 59

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

Answer 60

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

Answer 61

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.

Answer 62

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

Answer 63

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

Answer 64

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

Answer 65

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

Answer 66

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

Answer 67

A pathogen's ability to infect or damage a host Higher virulence means higher ability

Answer 68

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

Answer 69

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

Answer 70

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

Answer 71

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

Answer 72

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

Answer 73

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

Answer 74

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

Answer 75

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

Answer 76

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

Answer 77

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

Answer 78

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

Answer 79

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

Answer 80

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

Answer 81

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

Lecture 14-16 Flashcards

(105 cards)