EEB255 Quiz 4 Notes

pdf

School

University of Toronto *

*We aren’t endorsed by this school

Course

255

Subject

Geography

Date

Oct 30, 2023

Type

pdf

Pages

Uploaded by DrCrane3711

Lecture 8.5 Globalization: Economic Teleconnections - Drivers for globalization in soya bean crops → tropical deforestation can be driven by many different factors and threads What Happened in 2019? - Brazil had beautiful environmental laws but the issue was enforcing them - Enforcement loosened starting in 2019 and deforestation is slightly increasing What Are the Ecosystems Impacts? - Wetter = more humid (most important role of a factor is its role in the water cycle) - Hotter = no shade, sun beating down Evapotranspiration

- The process by which water is transferred from the land to the atmosphere by evaporation from the soil and other surfaces and by transpiration from plants The Effect of Deforestation on the Water Cycle - Precipitation is the same - Amount of water of evapotranspiration being evaporated decreases - The amount of water run off under soil and over land increases Climate Regulation in the Amazon - H2O comes off ocean, lots are recycled and will move downwards as precipitation - Lack of trees this cannot occur as strongly Tanguro (rewatch lecture) Edge Effects - What happens at an edge of a forest? ● Noise ● Changes in vegetation ● Interrupting water flow ● Increased human-animal interactions (e.g., road mortality) ● Pollution ● Biotic homegenizations ● Wind can go much farther ● Increases in dust fluxes Habitat Fragmentation - SLOSS debate = single large or single small ● Single large is better but there are reasons for why one single large park and a bunch of smaller parks is the best strategy 1. Fragments have larger edge area 2. The more fragments you have = the closer to an edge you’re in 3. Each fragment supports a smaller population - Fragments have a greater amount of edge per unit area - The center of the habitat fragment is closer to an edge - When a formerly continuous habitat hosting a large population is divided into fragments, each fragment hosts a smaller population Week 9 Emerging Infectious Diseases - Are those that have recently: ● Expanded in geographic range ● Moved from one host species to another ● Increased in impact or severity

● Undergone a change in pathogenesis ● Or are caused by recently evolved pathogens - In many cases, humans have caused and facilitated the EIDs affecting wildlife populations - And animals are the cause of 75% of the EIDs in the human population, diseases that are spread among species are described as zoonotic Amphibians and Chytridiomycosis - Chytridiomycosis is a disease caused by a pathogenic fungus, Batrachochytrium dendrobatidis (Bd) - There are ~6600 identified species of amphibians worldwide, 30% are threatened - > 700 species have been shown to be infected with chytrid fungus - It has caused population declines in at least 200 - It has been implicated in the extinction of at least 3 species (maybe many more) What is Bd Fungus? - Identified as an agent of disease in late 1990s - Found on all continents except Antarctica - Cold-loving fungus (<25 degrees celsius) - Host-generalist, can survive without a host, can decompose (aka eat) dead organic matter - Has flagellated zoospores What is Chytridiomycosis - Fungus infects the permeable skin, blocks electrolytes, and causes an imbalance in electrolytes = heart attack Amphibians and Chytridiomycosis Cycle - Cap lost, zoospores escape through the skin → swims in water, penetrate skins and form zoosporangium → motile zoospores: → growth in diameter and complexity → discharge papilla forms → mortality ~2 weeks Where Did it Come From? - Global trade in amphibians for pets and other uses believed to have caused its spread - African clawed frog ● Often used in pregnancy tests ● Common laboratory animal (fetal development) ● Samples with Bd infection from 1938 Life History Traits Increase Infection - Amphibians spend part of their lifecycle in high-density groups - During metamorphosis their immune system is suppressed Is There a Cure? - For individual amphibians = able to cure fungus but no solution in the wildlife

Your preview ends here

Eager to read complete document? Join bartleby learn and gain access to the full version

Access to all documents
Unlimited textbook solutions
24/7 expert homework help

What Can We Do? - Stopping international trade of amphibians Bats in NA - 47 bat species in NA - Ecosystem services - keystone species, → Pest suppression, seed dispersal, pollination Bat and White-Nose Syndrome - Infects many bat species in NA - Has killed nearly six million bats - Little brown bat is now endangered in Canada - Can kill 90-100% of bats in a cave - Caused by infection from a pathogenic fungus What is P. destructans - Identified as a pathogen in 2006 in 3 caves outside Albany, NY - Native to Europe, where it is not pathogeni - Cold-loving fungus (4-15, not >20 degrees celsius) - Host-generalist, can survive without a host, can decompose (aka eat) dead organic matter even if not present in bat species, can persist in caves off organic matter Little Brown Bat - Hypothesis: infection awakes bats during hibernation but if a bat wakes up too often during hibernation they get super hungry during the winter in search of food and starve to death Life History Traits Increase Infection - Immune suppression - High-density group What Can We Do? - Control the movement of people between caves - Heat up their caves ● Make localized refugia within caves that are 26 degrees celsius to allow the bats to survive and kill the fungus ● Hasn’t yet been implemented in actual caves Biological Control - 75 bats were successfully treated for WNS - Treated with a common bacterium that releases volatile organic compounds that have anti-fungal properties → delays ripening and preventative of fungi - The bacterium was first investigated as a way to delay fruit-ripening in bananas - Bats were kept in coolers with the bacteria for 24-48 hours Biodiversity Loss and Disease Transmission

- Biodiversity loss can increase disease transmission if: ● Lost species are not hosts or are suboptimal hosts ● Loss of diversity increases host diversity ● Change to behaviour in host, vector, or parasite ● Change in condition of the host - It appears that more than 1 of these conditions are often met and biodiversity loss appears to most often increase disease transmission How Biodiversity + Human Encroachment = a larger source of novel pathogens - Recent analysis showed probability of emergence of pathogen between wildlife and humans positively correlated with species richness - Increased contact between humans and wildlife also contributes Climate Change If you have been alive for fewer than 33 years, have never experienced a cooler than average month climate-wise - >450 consecutive months hotter than average Newest Climate Consensus Report (AR6) - Summary for policymakers: ● The figure shows the relative changes in global surface temperatures from 1850 to 1900 ● On the left figure, the change in surface temperature reconstructed and observed over the past 2000 years ● See climate variation, had ups and down in average temperature in Earth ● Orbital changes have driven ups and downs of the climate cycle over time ● But in 1850 and 2020 is unobserved in the last 2000 years (unprecedented rapid warming) - In blue band = looking at models that only use natural forces between 1850 and 2020, climate is relatively stable, no huge anomalies - In black = line is the actual observed warming, so simulated natural only is a bad model - The best model is one that uses human and natural drivers of climate Drivers of Climate Conditions - Incoming energy cap (amount of energy that all ecosystems are working with) all come from the sun - Incoming radiation (high-intensity, short, wavelength of light) - As light hits, Earth’s surfaces, about a third is reflected back to space - The rest comes down to the Earth’s surface - Some energy that is present at the Earth’s surface is re-radiated and emitted back into the atmosphere - Some greenhouse gas concentration is good but the more active gases are there, the more random heat is being scattered across the Earth’s surface - Greenhouse effect = trapping of gases and re-emitting them back to the Earth’s surface

What Are Greenhouse Gases (GHGs)? - CO2, N2O, CH4, fluorinated gases (HFCs, PFCs, SF6) - GHGs keep heat in the atmosphere by reradiating heat that is reflected off of the surface of the Earth - The Presence of GHGs in the atmosphere are why the Earth is not frozen solid - GHGs keep heat in the atmosphere by re-radiating heat that is reflected off of the surface of the Earth that is being sent back out to space - The presence of these is why the Earth is not frozen solid The Atmosphere - 78% = Nitrogen (N2), a super stable form of nitrogen gas - 21% = O2 - 0.9% = Argon - 0.1% = various trace gases ● Within this 0.1%: 93% is CO2 ● 0.44% = methane ● 0.078% = nitrous oxide ● 0.010% = ozone Atmospheric CO2 Is Increasing - Daily observations of CO2 concentrations are consistently increasing over time - Humans have increased radiative forcing at the Earth’s surface ~2.3 watts/m squared - Each year has an increase and decrease in CO2 concentrations = driven by primary productivity Annual Cycle of Primary Productivity - Summer months = pulse in primary productivity in the Northern hemisphere as there is so much more land and more drawdown and fixing of CO2 occurs Albedo - A measure of the reflectivity of the Earth’s surface and it affects how much light energy from the sun is absorbed - 2 ways humans are impacting albedo: 1. Extent of ice cover (increases light energy absorbed) ● As ice sheets and glacial cover shrinks forming warming the amount of light energy reflected also decreases ● Positive feedback loop: as ice sheet shrinks, more light absorbed by the Earth’s surface, more warming of water bodies and more shrinking of ice covers 2. Bare soil patches (decreases light energy absorbed) ● Some are more lighter coloured which will reflect more light energy - Humans are altering albedo but less predictably (altering albedo in both directions) 60% of Culumalitve Emissions are not in the Atmosphere, Where Did They Go? - 40% will stay in the atmosphere - 30% is taken up by the oceans (which causes ocean acidification)

Your preview ends here

Eager to read complete document? Join bartleby learn and gain access to the full version

Access to all documents
Unlimited textbook solutions
24/7 expert homework help

- 30% goes to unknown places, it’s taken up by plants and soils but don’t know where ● Why it’s so important to keep forest and land cover in our ecosystems ● We depend on the terrestrial biosphere to fix and absorb CO2 How Can Climate Change Affect Biodiversity What Can a Species do When Faced with Environmental Change? 1. Move 2. Acclimate 3. Adapt 4. Die Moving: Range Shifts - As climate warms, species are moving poleward towards colder temperatures - E.g., populations of butterflies are moving more North where the percentage of extinctions in northern latitudinal bands are much lower - Distributions of species are changing in response to global warming: - A meta-analysis showed 84% of species have moved in a poleward direction ● To higher elevations an average of 11.0 m/decade ● To higher latitudes an average of 16.9 km/decade Acclimation/Adaptation: Phenology - Phenology: The timing of seasonal life history events - Environmental cues often trigger the events, however, some don;t change with climate change this means that some species are shifting in response to climate change but some are not - With climate change, the cues are shifting: ● Spring comes earlier

● Fall comes later ● Maximum and minimum temperatures increased Phenological Mismatch - All organisms interact across trophic levels but if the timing changes, entire interactions can be interrupted - E.g., the time of hatchling food needs for birds align with the peak mass of caterpillars, however, the caterpillars are responding to the increase in climate and will hatch earlier - This means that when birds are at their hatchling food needs it may be misaligned with the peak mass of caterpillars since the caterpillars hatched earlier - Inducing selective pressure for earlier bird migrations Adaptation - If isolation in time and space with high generation time, adaptation can be quite fast a) Phenological isolation: - 2 populations phenologically isolated will rapidly diversify and evolve = adaptive evolution b) Phenological connectivity: - 2 isolated populations come together and have rapid evolution c) Evolutionary implications of isolation: - Local adaptation - Inbreeding depression - Speciation - Extinction d) Evolutionary implications of connectivity: - Heterosis - Outbreeding depression - Population stability - Extinction Week 10 Small Populations - Are susceptible because: 1. More susceptible to random demographic fluctuations 2. More susceptible to random environmental fluctuations 3. The loss of genetic diversity limits their ability to adapt and affects survival rates Demographic Stochasticity - Stochasticity: or random variation, in reproduction can further shrink small populations - Can be from random decreases in reproductive rates of increases in mortality - Once a population is affected by a driver of population decrease (habitat loss, etc) it is more susceptible to impact from demographic stochasticity A Simplistic Illustration: Coin Flipping!

- The average probability of a given individual surviving from one year to the next is 50% Allee Effect - A population response in which the fitness of individuals is positively correlated with population size or density Environmental Stochasticity - Random variation in the biological or physical environment can also change population size - Generally more important than demographic stochasticity in increasing the risk of extinction - Can be driven by biotic or abiotic factors Biotic Environmental Stochasticity - Lynx and hare dynamic - One affecting the other, population of one goes up population of another goes down, continues in an oscillating relationship Abiotic Environmental Stochasticity - Number of Przewatski’s Horse was steadily rising until a stochastic event (severe winter) caused starvation and deaths of horses to extremely decline - One environmental event is intense enough can wipe out an entire small population - When introducing another species = widespread Why does Genetic Diversity Matter? - Low genetic diversity lowers survival of populations or species, so maximizing genetic diversity affects conservation success - Allows populations to respond to environmental variability (evolutionary flexibility) Genetic Drift - The random process of allele frequency changes simply because of chance - based on which individuals happen to survive to sexual maturity, mate, and leave offspring - It happens in all populations that are not infinitely large, it does not lead to adaptations - Allele frequencies in the new populations are always different than in the source population - Genetic drift increases variation AMONG populations - By chance, a small population may have a high frequency of a rare allele - Alleles with lower frequencies have a lower chance of getting fixed than alleles with higher frequencies - Genetic drift decreases genetic diversity WITHIN populations - Genetic drift has a larger effect in smaller populations than in larger ones - Genetic drift affects alleles at all loci simultaneously → always decreasing in genetic diversity → inbreeding more common Genetic Drift: Special Cases with Big Impact - The founder effect: a subset of a population establishes in a new geographic area

Your preview ends here

Eager to read complete document? Join bartleby learn and gain access to the full version

Access to all documents
Unlimited textbook solutions
24/7 expert homework help

- Population bottlenecks: a population is substantially reduced in size by a chance event, and the remaining population contains certain individuals by chance to re-establish Genetic Drift: How Is It Counteracted? - Mutations: the rate of mutation is quite low and will likely not be sufficient to counteract genetic drift in small populations - Migration: even a low frequency of movement of individuals between populations minimizes the loss of genetic variation associated with small population size Consequences of Reduced Genetic Diversity - Loss of evolutionary flexibility - Inbreeding Depression - Outbreeding depression Loss of Evolutionary Flexibility - If rare alleles became advantageous they will quickly increase in frequency through natural selection - Can move, acclimate, adapt, or die Inbreeding Depression - A condition that occurs when an individual receives two identical copies of a defective allele from each of its parents - Inbreeding depression leads to: ● Higher mortality of offspring ● Fewer offspring ● Offspring that are weak, sterile, or have low mating success Outbreeding Depression - Occurs when individuals mate with individuals of related species - Outbreeding depression leads to: ● Weakness or sterility ● Lack of adaptability to the environment ● But, outbreeding depression is rare ● And, the opposite also occurs Hybrid Vigor - Sometimes when more distantly related species mate and increases fitness Effective Population Size (Ne) - An estimate of a population based on how many individuals are breeding, in general the effective population is smaller than the total population What Can Decrease Ne? - Unequal sex ratio

- Variation in reproductive output - Population fluctuations and bottlenecks Temperature-Dependent Sex Determination - The sex of the baby in the egg is determined by the external temperature - Cooler temps = male, warmer temps = all female Hunting Only Males E.g., 1166 elephants: 709 adults, 704 females, 5 males in a park where males were hunted - Ne = (4 x 704 x 5 )/ (5 + 704) = 20 (round to the nearest whole number) - Sex ratio = Ne/N = 20 / 1166 = 2% Unequal Sex Ratio Variation in Reproductive Output - In highly fecund species, most individuals will reproduce but some may produce more offspring, leading to an over-representation of those individuals in the next generation The Extinction Vortex

- Just getting worse and worse and leading to eventual extinction MVPs and PVAs: Applied Population Biology - MVP: minimum viable population - PVA: population viability analysis MVP (minimum viable population) - Refers to a population, not an entire species - First defined by Shaffer in 1981: - “A minimum viable population for any given species in any given habitat is the smallest isolated population having a 99% chance of remaining extant for 1000 years despite the foreseeable effects of demographic, environmental, and genetic stochasticity, and natural catastrophes .” - 99% survival for 1000 years is not always applicable to us today

Your preview ends here

Eager to read complete document? Join bartleby learn and gain access to the full version

Access to all documents
Unlimited textbook solutions
24/7 expert homework help

- If you want high probability for survival for 50 years you will need >50 sheep in the population but >100 sheep is better for the sae side - When the population of sheep are <50 sheep all populations plunge to zero at 50 years Is There a One-Size-Fits-All Solution? - Scientists have tried to look at averages: - Analysis of >200 species showed MVP values between 3000-5000 individuals with a medium of 4000 - Species with more viable populations (invertebrates or annual plants) MVP might be closer to 10,000 Minimum Dyanmic Area (MDA) - How big a habitat available must be for an MVP - Different animals need different amounts of space available to support the MVP of different animals - E.g., a lion (large carnivore) needs much more park area than a rabbit (small herbivore) because it is higher in trophic level Why Might MVP Not Be Enough? - If there is a chronic stressor, it doesn’t matter if we know the MVP because it still can’t be supported if that stressor still exists - “Conservation biology is a crisis discipline akin to cancer biology, where one must act in a timely manner on the best information available. Decision-makers cannot afford the luxury of adhering to a ‘null’ philosophy that says everything is unique; rules of thumb are desperately needed, including quantitative goals such as MVP.” PVA (population viability analysis) - A process in which researchers construct a mathematical model that estimates the ability of a species to persist into the future - Models are used to define MVP

- Models are used to predict the effect of different conservation activity and the effect of human activity - It takes many years of monitoring data (>10) What Do We Need to Know? 1. An estimate of current population sizes 2. A model for estimating how a population will change over time - Want the birth and death rates - Lifespan - Reproductive + gestation rates - Biotic interactions, abiotic resources Estimating Current Population Size - Censusing: going out and counting them - E.g., scientists went out and monitored and counted seal populations - Found that as the station coast guard closed, the population of seals on Tern Island rapidly increased → seals were super impacted by human activity Tracking - Conservation action in response to data - E.g., put a radio transmitter on penguins to track where parents were moving to incubate chicks Making a Model to Estimate Population Change - What four parameters do you need to calculate the change in population?

Geometric Growth Model - Birth rate = births/total population - Death rate = deaths/total population Planning a PVA: - As long as Nt is there, lambda can be randomly drawn and multiplied by Nt for each year - All population simulations start at year 0 and at 1000 individuals - Did this for 10 trials for 100 years - PVA: 6 went extinct, 40% change for survival and 60% for extinction Why are PVAs so Tricky? - Data short falls - Wallacean shortfall: studied why organisms exist across the globe and the shortfall is that we can’t know where each species is found - Linnean shortfall: not knowing where something is at a given time

Your preview ends here

Eager to read complete document? Join bartleby learn and gain access to the full version

Access to all documents
Unlimited textbook solutions
24/7 expert homework help

- Without appropriate data PVAs are difficult to estimate Week 11 In-situ vs Ex-situ Conservation - In-situ conservation: conserving an animal in the wildlife itself - Ex-situ conservation: taking an organism out of its wild habitat and conserve it in captivity Ex-Situ Conservation Benefits Costs - Easy to monitor - Very expensive - Educational/research benefit - Some species respond poorly in captivity - Full environmental control - Labour intensive - Protection from humans - Species can lost their ability to survive in the wild - Can monitor genetic diversity, good for small populations - Doesn’t solve the problem of their decline In-Situ Conservation Benefits Costs - Preserve species interactions (inter and intra) - Finding land to set aside is very difficult - No captivity stress - No full environmental control - Less expensive - Without additional intervention, a species may not survive - Maintains ability to survive in the wild - Habitat may be unsuitable - Preserves many species and ecosystem services - Difficultt to interact with individuals Re-Establishing Populations - Re-introduction programs: re-introducing an organism to its natural habitat