Title:
URL Source: blob://pdf/706683c3-a2dd-4592-b1e8-b7014df72d40
Markdown Content:
Today, March 27 th
CH 14 Predation/Herbivory
CH 15 Parasitism
Due Fri, March 28 th 11:59PM
Quiz 14, 15
Reminder
Phenolgy 1 st draft due April 11
> 1
Chapter 14 Learning Objectives
Predation and Herbivory
Predators and herbivores can limit the abundance of
species.
Populations of consumers and consumed populations
fluctuate in regular cycles.
Predation and herbivory favor the evolution of defenses.
# 1
# 2
# 3
> 2
2
# How to not get eaten
> 3
Structural Aposematism/Chemical
Crypsis Behavioral 2
Crypsis : camouflage that either allows
an individual to match its environment
or breaks up the outline of an individual
to blend in better with the background
(e.g., katydids, horned lizards).
Structural defenses reduce a predators
ability to capture, attack, or handle prey.
Some prey have defenses that are
phenotypically plastic ; when the crucian
carp detects a predatory fish, it grows
muscle mass that allows it to swim
faster.
# Crypsis and structural defenses
> 4
2
# Chemical defenses
> 5
Warning coloration (aposematism): a strategy where distastefulness
evolves in association with very conspicuous colors and patterns. Mimicry
> 6
## Mimics exploit coevolutionary
## interactions
> 2
## Mimics exploit coevolutionary
## interactions
> 7
Mullerian mimicry: several unpalatable species evolve a similar
pattern of warning coloration; similarity in warning confers
protection
2Batesian mimicry: when palatable species evolve warning
coloration that resembles unpalatable species (e.g., hover flies
and hornet clearwings resemble the common wasp).
> 8
2 Mimics exploit coevolutionary
## interactions
> Common wasp
> (aposematism )
> Hover fly (mimic)
> Hornet clearwing
> (mimic)
2
Defense costs can reduce growth, development, and reproduction.
Many species of ladybugs are red with
black spots, which informs predators
that they contain foul -tasting alkaloids
(aposematism) .
Alkaloids are energetically expensive to
produce.
Only ladybugs that consumed high
amounts of food were able to produce
the aposematic coloration and high
amounts of alkaloids.
# Costs of defenses
> 9
# Evolution of Herbivory
10
Labandeira , C. C., 1997. Insect Mouthparts: Ascertaining the paleobiology of insect feeding
strategies. Annual Review of Ecology and Systematics 28: 153 -193
400+ MYA 300MYA 200MYA 100MYA
2Plant chemical defenses
## (secondary metabolites)
> 11
nitrogen compounds
(e.g., alkaloids >3000)
terpenoids (>10,000)
(e.g., citronella, menthol)
phenolics
(e.g., tannins, flavinoids , lignin)
Tradeoff in investing in growth and
reproduction versus defense.
22
Many plants produce defensive chemicals
at the cost of reduced fitness .
Tobacco plants respond to herbivores by
producing chemicals including nicotine.
Researchers damaged two groups of
tobacco plants but treated one group with
a hormone that blocked nicotine
production.
The group without hormones produced
more nicotine and fewer seeds.
# Defenses against herbivores
> 12
## Coevolution of secondary defense:
## tradeoffs
> 13
> 100 plant families
31 plant families
8 plant families
2 genera!
Dr. May Berenbaum , UIUC
National Academy Fellow
2U.S. President Barack Obama prepares to present Professor May Berenbaum
of the University of Illinois at Urbana -Champaign with the National Medal of
Science in the East Room of the White House November 20, 2014 in
Washington, DC. According to the White House, Brenbaum was awarded the
medal for pioneering studies on chemical coevolution and the genetic basis of
insect -plant interactions, and for enthusiastic commitment to public
engagement that inspires others about the wonders of science." The medals
are the highest honors bestowed by the United States Government for
achievements in science, technology, and innovation.
> 14
2X Files
> 15
2Many different types of parasites affect the abundance of
host species.
Parasite and host dynamics are determined by the
parasites ability to infect the host.
Parasite and host populations commonly fluctuate in
regular cycles.
Parasites have evolved offensive strategies while hosts
have evolved defensive strategies.
# 1
# 2
# 3
# 4
Chapter 15 Learning Objectives
Parasitism and Infectious Diseases
> 16
# Consumer -resource interactions
> 17
> Ectoparasites
> Endoparasites
1 does not kill host directly, consumes part of prey (host)
increases host probability of death, lowers fitness
complex life cycles generally involving 2 hosts
e.g., bot fly (Family Oestridae ) obligate parasite of mammals
> 18
1 What is a parasite? Ectoparasites
Live on outside of host.
Mostly arthropods
(e.g., ticks, mites, lice,
fleas)
Includes some leeches,
lampreys
Nematodes
~4000 plants
(e.g., mistletoe)
1
> 19
## Endoparasites
Intracellular : live inside the cells of a host
Intercellular : live in spaces between cells of a host
Viruses
Helminths
Prions
Protozoans
Bacteria
Fungi
Types of endoparasites :
1
> 20
Tobacco mosaic virus H5N1 ( etc )
Bovine spongiform encephalopathy
Chronic wasting disease Fungus that lives in the outer layer
of amphibian skin; causes ion
imbalance.
It rapidly spread across Central
America.
It is now the suspected cause of
dozens of amphibian extinctions.
1
> 21
## Batrachochytrium dendrobatidis (Bd)
## Chytridiomycosis
Panamanian golden frog
(Atelopus zeteki ) aquatic fungus (ancient lineage) has
always been in ecosystems
evidence for emergence as novel
pathogen due to climate and stress
factors (low haplotype divergence
across continents)
>6,500 amphibian species
>1,300 susceptible
Atelopus (71 of 113 species extinct) 22
> Panamanian golden frog
> (Atelopus zeteki )
1 Batrachochytrium dendrobatidis (Bd) 23
1Janthinobacterium lividum
(potential bacteria biocontrol )
Anaxyrus boreas boreas
(boreal toad)
Dr. Valerie McKenzie,
U Colorado -Boulder
## Operation Purple Rain to combat
## Chytridiomycosis
> 24
1Chapter 15 concepts
Parasitism and Infectious Diseases
Many different types of parasites affect the abundance of
host species.
Parasite and host dynamics are determined by the
parasites ability to infect the host.
Parasite and host populations commonly fluctuate in
regular cycles.
Parasites have evolved offensive strategies while hosts
have evolved defensive strategies.
# 1
# 2
# 3
# 4
> 25
## Parasite and host dynamics
Dynamics are similar to predator -prey, but parasites often have
a higher reproductive rate than their hosts and do not often kill
their hosts.
2
> 26
## Mechanisms of parasite transmission
Vertical transmission : parasite transmitted from parent to offspring.
2
> 27
Horizontal transmission : parasite moves between individuals other
than parents and offspring. Factors influencing probability of infection
Mode of entering the host:
Piercing tissue (e.g., leeches)
Reliance on a vector (e.g., malaria)
2
> 28
Ability of parasite to jump between species:
A lethal parasite that specializes on one host may face
extinction; solution is to infect multiple species (e.g.,
bird flu, HIV)
Reservoir species: (e.g., mice in Lyme disease example)
Species that carry a parasite but do not succumb to disease.
They can be a continuous source of parasites as other hosts become rare.
Counterattacks to hosts immune system:
Avoiding detection by incorporating into chromosomes (e.g., HIV)
Form protective outer layer (e.g., schistosomes )Chapter 15 concepts
Parasitism and Infectious Diseases
Many different types of parasites affect the abundance of
host species.
Parasite and host dynamics are determined by the
parasites ability to infect the host.
Parasite and host populations commonly fluctuate in
regular cycles.
Parasites have evolved offensive strategies, whereas hosts
have evolved defensive strategies.
# 1
# 2
# 3
# 4
> 29
Parasite adaptations:
Offense
4
> 30
> Cordyceps : attack of the killer fungi
> Planet Earth Attenborough BBC wildlife
Fungi manipulate insect host behavior to increase
their own reproductive fitness. Host adaptations:
Defense
Hosts have developed a range of defense responses to combat
parasites.
4
> 31
Behavioral minimize exposure
Anti -viral, anti -bacterial, anti -fungal
compounds
Sexual reproduction recombination
Co -evolution arms race Red Queen Hypothesis arms race
> 32
sexual selection allows hosts to evolve at a rate that counters the
rapid evolution of parasites
hosts and predators/parasites are constantly engaged in an
evolutionary arms race --- evolving defenses (host) and
overcoming defenses (parasites/predators) just to maintain fitness
This results in
dynamic steady
state, where neither
hosts nor parasites
permanently gain
the upper hand.
CH 7: LO1 CH 7: LO1
Recombination: the reshuffling of genes that can occur as DNA is
copied during meiosis and chromosomes exchange genetic material.
During meiosis, pairs of homologous chromosomes (one from each
parent) can exchange DNA in a process called crossing over .
# Genetic Recombination
> 33
Recombination helps the immune system rapidly evolve. Hosts have developed a range of responses to combat parasites.
4
> 34
Host adaptations
Defense Example: Self -medication
When infected with nematode
parasites, chimpanzees will consume
Aspilia leaves, which are covered with
tiny hooks that pull nematodes out of
the digestive tract.
They also chew bitter twigs from the
Vernonia plant, which contain chemical
compounds that kill parasites.
Host adaptations
Defense
4
> 35
Chapter 15 concepts
Parasitism and Infectious Diseases
Many different types of parasites affect the abundance of
host species.
Parasite and host dynamics are determined by the
parasites ability to infect the host.
Parasite and host populations commonly fluctuate in
regular cycles.
Parasites have evolved offensive strategies while hosts
have evolved defensive strategies.
# 1
# 2
# 3
# 4
> 36
Modeling parasite and host populations
Infection resistance: ability of host to prevent infection from
occurring (e.g., through immune response or behavior).
Infection tolerance: ability of host to minimize harm from infection.
3
> 37
Vaccinations control infection resistance and tolerance .
> US measles vaccination
> program begins
> >200 cases/yr in
> 2024 and 2025
Modeling parasite and host populations
Susceptible -Infected -Resistant (S -I-R) model: the
simplest model of infectious disease transmission that
incorporates immunity.
S = Number of individuals susceptible to a pathogen
I = Number of individuals that become infected
R = Number of individuals that develop resistance
b = rate of transmission (via contact) between individuals
g = rate of recovery and development of immunity
3
> 38
> **S -I-E-R models are more accurate and account for Exposed individuals
S-I-R models ( Susceptible Infected Recovered)
> 39
b = rate of transmission (via contact) between individuals
g = rate of recovery and development of immunity
Ratio of new infections to recoveries is the reproductive
ratio ( R0):
S I b
I g
If R0 > 1, the infection will spread (each individual produces
>1 new infected individual)
If R0 < 1, the infection fails to spread (each individual
produces <1 new infected individual)
R0 =
3
Rate of infection
Rate of recovery Typical dynamics of an infection over time
3
> 40
Typical dynamics of an infection over time
assuming no evolution
3
R0 > 1 R0 < 1 41
Infection will not spread Infection will spread How to reduce R0?
> 42
b = rate of transmission (via contact) between individuals
g = rate of recovery and development of immunity
Ratio of new infections to recoveries is the reproductive
ratio ( R0):
S I b
I g
If R0 > 1, the infection will spread (each individual produces
>1 new infected individual)
If R0 < 1, the infection fails to spread (each individual
produces <1 new infected individual)
R0 =
3
Rate of infection
Rate of recovery 43 Wikipedia
S-I-R models: importance of vaccines
and COVID -19
SARS -CoV -2 Airborne
droplet 6-7