BIOL1030 U5

Know these two concepts - evolution and adaptation - both in terms of disease and in general

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Viruses are typically made up of…

Viral RNA enclosed in a protein coating that is sometimes stored in a lipid membrane

When two or more viruses infect the same cell…

Recombination can occur

Epidemiology

The study of the emergence, distribution, and control of disease, disability, and death among groups of people - while generally associated with outbreaks and epidemics, they can also study noninfectious health problems

The epidemiology triangle pillars - connections between the cause of the disease and the conditions that allow it to spread:

• Who: host or person/people who has the disease

• What: agent or cause of the disease

• Where: the environment the disease occurs in

Severing at least one of the links in the epidemiology triangle…

Stops the disease in its tracks

Endemic

A disease or condition present among a population at all times

Epidemic

Occurring in above average rates in the population, but not spreading to new populations

Pandemic

A disease moving between multiple populations that are often geographically isolated from each other; an epidemic that spreads across regions

Outbreak

A disease moves between populations, but not at a higher rate than normal

Law of Conservation of Energy

Energy cannot be created or destroyed

How does the law of conservation of energy apply to ecosystems?

In an ecosystem, energy is captured by primary producers and turned into chemical energy, which is in turn consumed by all organisms that the various trophic levels to support maintenance, growth, and reproduction

At each level, most of the energy used by organisms is for…

Maintenance - energy used this way is converted into heat energy, mechanical energy, etc. - only a small amount of energy is used for growth and reproduction

There is also a limit to how much energy an organism can acquire at any given time, depending on factors such as…

availability of food and light, the ability to store energy, the efficiency of physical structures, physiological processes, and chemical reactions

All species have an energy budget where they must…

balance the intake of energy with various demands for the use of energy

Dynamic Energy Budget Theory

A simple set of rules that specify how an individual organism acquires energy and building blocks from the environment to fuel its life cycle from embryo to death

When an organism is placed under stress, it requires…

Energy to cope with or overcome that stress

When an organism uses energy to cope with or overcome its stress, this means…

Less available energy for maintenance, growth, and reproduction, which may result in the decreased ability to survive and/or production of fewer offspring or poorer quality offspring

Emerging Diseases

Infections that appear or increase in a population for the first time

Infectious Disease

When a pathogen invades a host and causes harm to the host’s tissues and can be transmitted to other individuals

Pathogen

A microorganism that is capable of causing disease, but most microorganisms do not cause disease

Pathogens can alter the structure and function of…

Populations, species, and ecological communities - but many pathogens are also living organisms

New diseases come from:

Know your coronaviruses!

yippeeeee

Zoonosis/Zoonotic Diseases

An infectious disease caused by a pathogen that has jumped from animal to human (can be animal to animal) - 75% of emerging diseases are zoonotic and can be bacteria, fungi, or viruses

Most commonly zoonotics are…

viruses - because viruses mutate much faster than other organisms due to the way they reproduce

Viral copying errors leading to mutations are called…

Antigenic drift

With viruses, phylogenetics helps us…

Identify variants, predict changes in the biology of viruses, find super-spreader events, speed up contact tracing

Zoonoses are increasingly frequent, with one new disease every…

5 years in humans

Know about bats and why there are so many zoonotics from bats!

flappy flappy flap

Human induced drivers of zoonoses are:

• Population change

• Land-use change

• Human-wildlife interactions

Top drivers of zoonotic disease emergence:

• Biodiversity loss

• Chemical pollution

• Climate Change

• Invasive species

Disruption to ecosystems leads to…

The disruption of the interaction of pathogen, disease vectors, and hosts

Disease Vector

Any living agent that carries and transmits an infectious pathogen to another living organism

Ecological Network

A representation of the biotic interactions in an ecosystem in which species are connected by pairwise interactions, can be trophic or symbiotic - a change in one component of a network can affect many other components

Know about the connections between ecological networks and sharing viruses!

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A change in biodiversity can affect disease transmission by changing…

• The abundance of the host or vector

• The behaviour of the host, vector, or parasite

• The condition of the host or vector

The influence of biodiversity loss on emerging disease has more to do with __________________ than with ___________________.

How organisms respond to disturbance, the dilution of biodiversity

Pathogens evolve rapidly due to…

Short generation times

Adaptations during generations + natural selection =

Evolution in viruses

Pathogens entering new host species cause havoc because…

The new host species have not evolved resistance

Pathogens evolve to adapt to their environment - for pathogens, the “environment” is…

The immune response of an infected host

There is a dynamic interplay between…

The pathogen causing a disease and host immune systems developing resistance

Know about rabbits in Australia!

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Species and disease can evolve to…

Tolerate each other

AMR (antimicrobial resistance) is the process of…

Natural selection in action

Superbugs

Infections caused by bacteria that have resistance to common antibiotics

Solutions to AMR include…

Decreasing antibiotic use, creating new antibiotics, supporting the development and maintenance of clean water and sanitization, bolster natural immunity

Know about the energy budget of organisms and how it relates to disease!

im siiiiiiiiiick in the heeeeeeeaaaad

im mennnnnnntaaaaaallllllllly illllllllllllllllllllll

More energy needed for maintenance (including fighting off disease) means…

Less available energy for growth, maturation, and/or reproduction

The total amount of energy an organism can have is limited by…

Food intake, efficiency of digestion, and metabolism

Organisms also have an energy reserve, but when stressed…

Trade-offs take place

The extent of a disease’s impact on an individual depends on:

• The amount of energy reserve available

• The severity of the disease

• The environmental conditions an organism experiences

Disease almost always reduces fitness in individuals, especially in…

Sub-optimal environmental conditions

Know a disease’s consequences for populations, communities, ecosystems

Sometimes i think about dropping out of uni but then i remember my coworkers at my old internship and i get scared into continuing my degree (no hate to them id just hate to live the life they do)

Factors that contribute to sub-optimal conditions for an organism are often referred to as…

“stressors”

Not all _______________ are stressors!

Environmental changes

Impacts of stressors can be:

• Additive: the sum equivalent to the impact of each stressor

• Synergystic: the combined effect is more than the sum of separate effects

• Antagonistic: the combined effect is less than the sum of separate effects

• Neutralizing: results in no effect at all

Disease is a particular concern when…

It is new (no resistance), it occurs in small populations, there is low genetic variation in the population, and there are multiple stressors - this is because all of these factors reduce the resilience of these populations and increase their vulnerability to extinction