Week 30 Flashcards
Name two impacts of humans in the Anthropocene
Impact 1: Urbanization causes fragmentation, isolating populations and reducing genetic diversity within habitat patches
Impact 2: Human activities like hunting, farming, and habitat destruction contribute to the spread of zoonotic diseases and the extinction of larger, slow-reproducing organisms.
Define the term zoonotic disease and explain its importance
A zoonotic disease is an infectious disease caused by pathogens (such as viruses or bacteria) that jump from animals to humans. These diseases are important because they can lead to pandemics (e.g., HIV, COVID-19) and pose significant threats to global health.
Name at least 3 zoonotic diseases
HIV, H5N1, Covid 19
Explain how habitat destruction, hunting, farming, and other intensive human disturbances have increased the number of zoonotic diseases
Habitat destruction forces wildlife into closer contact with humans, increasing transmission opportunities.
Hunting and wildlife farming (e.g., bushmeat, live markets) expose humans to animal pathogens.
Intensive farming and urbanization create stressful, unhygienic conditions that facilitate pathogen mutation and spread.
Describe which types of organisms are threathened by human impacts, and which types of organisms typically beneift
Threatened: Large species, specialists (e.g., koalas), and those requiring large habitats (e.g., bobcats).
Benefit: Generalists (e.g., raccoons, white-footed mice) and species adaptable to urban environments (e.g., cliff swallows with rounded wings).
What’s the difference between genetic diversity WITHIN patches and ACROSS patches?
Within patches: Genetic variety in a single isolated population
Example: White-footed mice in one urban park have low diversity due to inbreeding
Across patches: Differences between separate populations
Example: Bobcats in different forest fragments develop unique immune genes
Summairze some of the impacts of our own actions on ourselevs, as humans in these ecosytems
Human activities (e.g., wildlife markets, deforestation) increase zoonotic disease risks (e.g., COVID-19, HIV).
Urbanization and pollution alter ecosystems, leading to pest adaptations (e.g., DDT-resistant bed bugs).
Loss of biodiversity threatens ecosystem services and increases human vulnerability to environmental changes.
Background extinction rate
The number of species that would be expected to
go extinct over a period of time based on nonhuman factors.
Zoonoses
A phenomenon where infections caused by bcateria, viruses or other parasites, are passed on from animals to humans. Most often, the animals are not affected by the pathogen and are merely acting as a host
What do human disturbances reduce
They reduce the buffering effect of natural ecosystems
What are the 3 main factors increasing disease spread in ecological epidemiology?
High host density (cities, farms, zoos)
Habitat destruction (forces animals together + human contact)
Artificial animal mixing (travel, wildlife markets, zoos)
What is ideal for transmission & mutation
Wildlife markets
Evolution vs adaptation vs adapting
-
Evolution = change in frequencies of genes in a
population over time - Can be positive, negative, or neutral for the
population. -
Adaptation = a trait that is heritable, benefits an
organism and increases reproductive success in a
particular environment. - Positive by definition, occurring as a result of evolution
-
Adapting = a general term for an organism or
population changing in response to their
environment. - Positive, but not necessarily heritable.
Name the five ways urbanization can affect evolution
- Mutation – changes to DNA
- Loss of genetic diversity within patches
- More isolation of populations across
patches → greater differences between
patches. - Shift in the types of species that are
favoured by natural (human) selection. - Adaptation!
Urban pollution and mutation
Urban pollution can elevate mutation rates in birds and mammals
Loss of genetic diversity
- Urbanization causes fragmentation: breaking up habitat into smaller pieces.
- Smaller patches = smaller populations
- Patches become isolated, little dispersal between
patches. - Genetic variation within patches drops.
Why are live wildlife markets so likely to produce new diseases?
. Pathogens mutate in response to the close
presence of unknown species, because they
represent a new infection opportunity.
B. As pathogens spread within a species, they have
more opportunity to mutate.
C. Pathogens spread easily among species because of
the close quarters and stressed immune systems.
D. Both A and B
E. Both B and C
E. Both B and C
What can urbanization cause?
decreased dispersal of organisms
Which organisms are expericnng the highest rates of extinction
Large organisms that are slow to reproduce
Background extinction rate
Number of species that would be expected to go extinct over a period of time based on non human factors
Name the species most at risk for extinction
- Those that are large, and/or have require large
territories of habitat. - Those that are specialized to a very specific resource or
a very specific natural habitat. - Those that are naturally rare to begin with (have always
had small populations) - Those that are sensitive to changes in the environment
or climate.
Generalists vs specialists
- Generalists: a species that is able to thrive in a wide variety of environmental conditions and can make use of a variety of different resources
- Example: generalists have a varied diet.
- Specialists: can only thrive in a narrow range of environmental conditions, or has a limited ability to use resources
Towards which species do human activites strongly shift selection towards ?
Generalists and smaller species
- Remove top predators such as wolves and big cats.
- Favours species that have a broad range of habitat
and resource use.
Bobcats and adapatation
- Bobcats in Thousand Oaks had been exposed to rat poison,
which weakened their immune systems. - Mange then killed so many bobcats, the annual survival rate
dropped from 80% to 20%! - The remaining bobcats had different MHC and TLDR genes,
which help the immune system recognize disease.
How does habitat destruction increase disease risk?
Packs animals into smaller areas → higher density
Forces wildlife near humans → more spillover chances
Stress weakens immunity → easier infections
Give 2 examples of “artificial animal mixing” causing outbreaks.
COVID-19: Wildlife market (bats + pangolins + humans)
Bird flu: Crowded poultry farms
Define “spillover event” with an example.
When a pathogen jumps from animals to humans.
Example: HIV (chimps → humans via bushmeat hunting).
How do humans increase mutation rates in organisms?
Urban pollution causes DNA damage
Example: Herring gulls near factories show more mutations
Example: Lab mice exposed to chemicals develop more genetic errors
How do humans reduce genetic diversity WITHIN patches?
Habitat fragmentation creates small, isolated populations
Leads to inbreeding and genetic drift
Example: Urban mice populations lose rare alleles over time
How do humans increase genetic differences ACROSS patches?
Prevents gene flow between isolated populations
Each patch adapts differently to local conditions
Example: Bobcat populations develop distinct traits in separate forest fragments
What kinds of adaptations do human activities drive in organisms?
Immune resistance (urban bobcats fighting new diseases)
Dietary flexibility (mice evolving to neutralize aflatoxins in human food waste)
Behavioral changes (birds adapting to city noise)
Define: Genetic drift, Gene flow, Adaptive evolution
Genetic drift: Random changes in gene frequencies (common in small populations)
Gene flow: Movement of genes between populations (blocked by fragmentation)
Adaptive evolution: Beneficial traits becoming more common
