Ecological Interactions
Introduction
Ecological interactions are the effects in a climate that certain affect species. They can be divided up
into interactions between biotic creatures, interactions between an abiotic factor and a biotic
creature, and the interaction between two abiotic factors. No organisms exists in absolute isolation,
and thus every organism must interact with the environment and other organisms. An organism's
interactions with its environment are fundamental to the survival of that organism and the
functioning of the ecosystem as a whole. In this chapter we will be using some crucial ideas and it is
important to define them to understand the relevance of the text.
Definitions
Biotic Interactions:
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Species may interact once in a generation in cases like pollination or can coexist (such as types of
symbiosis). Effects can range from predation to mutualism. Interactions are not always direct, in fact
often individuals may affect each other indirectly through intermediaries such as shared resources or
common enemies. Symbiosis is used to describe various degrees relationships between organisms of
different species. There are many types of symbiosis, some where both organisms benefit and
sometimes it is used to describe really close relations that are not so beneficially such as parasitism.
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Biotic interactions even predation. Thus biotic interactions determine all living behavior and how
each organism affects its organic surroundings.
Abiotic Interactions:
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Biotic components include components such as ants, horses and people among others. They refer to
living things in the ecosystem. Abiotic refers to nonliving components of an ecosystem. In biology,
abiotic factors include soil conditions, light, radiation, temperature, humidity, and the state of the
atmosphere. Pressure can also be considered as an abiotic factor in marine and sub-terrestrial
environments. All of these factors affect the organisms that are part of that ecosystem to different
extents. For example when there is no sunlight plants will wither and die from not being able to get
enough sunlight to sustain the process of photosynthesis. Thus abiotic interactions are the basic
processes that keep organisms alive. One basic example would be an oak tree an interaction between
abiotic and biotic components in the ecosystem is of an orange tree using light and air to make its
food.
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Trophic Level:
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Trophic level is the level that an organism occupies on the food chain in its ecosystem. A food chain
is a "chain" or succession of organisms that eat each other until they are eaten themselves. The
number of steps an organism is from the start of the chain is a measure of its trophic level. Food
chains start at trophic level 1 with primary producers, which are always plants. Trophic level two
includes herbivores, and predators that eat these herbivores are at level three. These food chains end
with apex predators who are at the 4th or 5th trophic level. From these food chains arise webs of
trophic interactions which involve eating or being eaten.
Key Themes
Range Shifts
Ranges are is the land distribution that a species can live on. Some species exist under very fragile
conditions and due to the current rate of climate change they are forced to move habitats. With
general warming trends climate envelopes, also known as ranges, have become increasingly more
shifted towards the poles and higher altitudes. Such dispersal and resource availability allow species
to move several degrees in latitude. In some cases, range shifts in response to changing temperature
may not occur if the geographical distributions are also limited by other abiotic factors such as light.
The biological impacts of climate change are always focused on species abundances in the predicted
shifts areas. This shift does not affect all species equally however. There are many species with wider
ranges than others. For example migratory species are well documented for their large fluctuations
in year to year breeding sites. This makes it harder to really judge whether they are truly affected by
climate change. On the contrast range changes in more sedentary species are much more noticeable
and follow the slow processes of population extinctions and renewal. This has made it easier to
detect true geographic shifts in the latter group because change is more methodical and missing data
have a smaller impact. Most importantly there are very scenarios where these shifts in sedentary
species will cause problems. For example in tropical latitudes, while most migratory organisms like
fish and birds are expected to be able to tolerate climate warming, the fate of sedentary species are
dependent very local conditions. Corals are sensitive to changes in temperature and when they are
out of their temperature range coral bleaching will occur. Coral has a number of special relationships
with these fish and birds that are much more mobile than they are. Coral depends on these fish to
clear out seaweed and phytoplankton. Without these fish there is a high probability that a majority of
the coral will no longer be able to access the sunlight necessary to sustain the population. There are
also many species that will be shifted that into the coral's habitat which will prove detrimental to
their survival. There are also other examples of warm-water species in the Mediterranean and the
North seas such as thermophilous plants that spread from gardens into surrounding countryside.
Effects on Land Based Competition
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Range shifts that are detrimental to the current native species are not just limited to the ocean, they
also occur in terrestrial environments. With climate change, invasive species from adjacent areas may
cross frontiers and become integrated into their new habitats. Previously these long distances
migrations have been mediated by human activity however now that species are moving on their
own out of the need to survive they will choose habitats more suitable their previous one. This
permanent establishment in the new local environment may not be possible without changes in local
conditions and availability of resources. Climate change has occurred in the past and extrapolating
from those results we can expect huge amounts of extinctions due to land based competition. We
can use the late quaternary period (around 2.6 million years ago to present) range shifts as proof of
this. In the Northern Hemisphere many species roam free because they can adapt to the warming by
simply migrating and they continued to grow in population at the same latitude. However in the
Southern Hemisphere, species were forced to adopt elevation shifts and refuges in response to
warming. In the arid southwest for example there were large changes in population size of several
tree species. There were also elevation range shifts when trees could not adapt and travel quickly
enough. This type of forced hyper adaption could often lead to extinction. The limits to adaptation
are indicated by the extinction of some pine tree species in southeastern United States.
Effects on Flowering Times of Plants (Trophic effects)
Historically climate change has had a profound effect on current geography of life, so we can expect
our current trend of rapid climate change to have as great an effect. Climate change has important
implications for nearly every aspect of life on Earth, and effects are already being felt. Climate
change most importantly affects the base of our entire ecosystem: plants. Here are a number of ways
that the trophic level of plants are affected.
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Temperature is greatly affected. Average minimum and maximum temperatures of areas are
changing which changes plants distribution. This is exemplified in tropical trees such as Arecaceae
(family of palm trees) which are cold intolerant as their single vascular system is susceptible to frost.
When temperatures change this means that they can move more northbound. Boundaries between
vegetation types are generally determined by summer warmth and also greatly changed.
The atmosphere's water-holding capacity increases by about 4 percent for every 0.6 degree Celsius
rise in temperature. This is a "steamroom" effect which is the difference between a warm bathroom
and a cold bathroom: the mirror fogs up more when the air is warmer.
Extreme precipitation is likely when a storm passes through a warmer atmosphere holding more
water. This means that in a warmer climate there will be more extreme and wetter weather. In the
future we should expect torrential rainstorms in the warmer months and in winter blizzards are
more likely.
Wet places also get wetter. Atmospheric circulation over oceans, plains, and mountains is part of the
water cycle and helps determine where rainforests thrive and semi-arid regions develop. Due to this
recirculation, wet places tend to get wetter and dry places dryer in a warming world. Since rain
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determines types of vegetation this means that wet places will have only certain types of vegetation
and arid places likewise.
Other factors such as soil type or the types of herbivores nearby may also be affected by climate
change
All of these factors that are predicted to come into play as the climate warms up will very likely
change the flowering time of species. Climate change will change soil conditions as well as
availability to the necessary resources for life of plants. It is expected that flowers will flower earlier.
This will force the secondary consumers to change their patterns of consuming the plants, migrate
to a location where the plant flowers regularly for them, or change food sources.
Effects on Plant Diversity
Plants changing flowering times is just the beginning. Plants are not like animals, they are a lot less
mobile and do not adapt to change well. As plants will not be able to keep up with the rapidly
changing climate there is a good chance that plant diversity will go down. However, in some areas
where rainfall increases there is a large probability that plant diversity will skyrocket due to these
areas essentially being "super rainforests." Here are some reasons that plant diversity will be
influenced.
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Plants will often be ‘left behind’ as they are unable to change their range and elevation distribution
fast enough
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Plants have longer life cycles and are typically slower in dispersing with their seeds and will not adapt
well.
Several plants species are isolated and when climate change occurs they may have nowhere to
migrate to. These types of plants include arctic and alpine species, and many endemic island species
Coastal plant species which will be divided by human settlements and rising sea levels.
Increased invasions by invasive alien species may occur, as conditions become more suitable for
exotic species whilst native species become less well suited to their environment.
Due to these factors some plant communities may be lost as species adapt at different rates. We can
see examples of this already. Many species are much more invasive during wet years and typically kill
off all the native species. Not to mention that human interventions which has deliberately and
accidentally facilitated this spread of species into nonnative habitats.
Effects of Decreased Oxygen on Fish
Global warming consequently causes ocean warming which leads to a decline in dissolved oxygen in
the ocean. This is because the solubility of oxygen decreases as ocean waters get warmer. Zones of
low oxygen in the ocean were found to be shrink in cold periods and expand in warm periods based
on geological records. Warm ocean waters also destroys the oceans natural flower. Normally the
ocean has a thermohaline conveyor belt circulation current that cycles surface layers of the water
into the deep and vice versa. Without this natural cycling there is less oxygen carried from the
surface layers of the water into the deeper layers. In addition, the slowing down of the ocean’s
circulation cycle also brings fewer nutrients from the deep layers into the ocean surface. With fewer
nutrients available at the surface layers, the plant like oxygen-producing phytoplankton that drift in
the ocean surface will greatly decrease in number. The declining numbers of phytoplankton species
will affect all fish since phytoplankton are the backbone of the oceans. Phytoplankton organisms
produce half of the world’s oxygen output and are the 1st level of the food chain. Hence, with
decreasing numbers of these oxygen producers, the level of oxygen in the ocean and fish is bound to
decline further. Decreased oxygen also has a direct impact on the fish leading many fish to simply
suffocate due to lack of oxygen.
Effects of Decreased Oxygen on Marine Plants
To continue the previous topic the decreased phytoplankton means that there are fewer plants to
absorb the greenhouse gas carbon dioxide humans are pumping into the atmosphere which restarts
the cycle of warming and lack of oxygen. Phytoplankton, the tiny basis of the ocean food chain grow
even more slowly in the warmer oceans of the future. Whenever climate temperatures cooled,
marine plant life became more vigorous or productive. Another effect of global warming on the
carbon cycle is the acidification of the ocean. The ocean and the atmosphere constantly are regulated
with processes to maintain a state of equilibrium, so a rise in atmospheric carbon naturally leads to a
rise in oceanic carbon. When carbon is dissolved in water it forms hydrogen and carbonate ions.
Hydrogen ions are what acidity is measured by so all these extra hydrogen ions obviously increase
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the acidity of the ocean and make survival harder for plant organisms and those that depend on
calcium carbonate to form their body. A decrease in the 1st level of the food chain will be extremely
destructive to the ecosystems to which they belong.
Data
Simulation
Instructions
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Go to https://www2.cesm.ucar.edu/ modeling website
Go to Legacy Releases
Go to CCSM 3.0
Follow it, and then click on Source Code
After this you need to log into the Earth System Grid website
The OpenID is https://www.earthsystemgrid.org/myopenid/ZielkeNCSSM and the password is
NCSSM14
7. Then go to http://www.cesm.ucar.edu/models/ccsm3.0/ and download Community Land Model
and Community Atmosphere Model
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Case Studies:
Pinyon Pine Case Study:
The climate change in the Southwest appears to be having a negative effect on pinyon pine
reproduction. Findings have shown that wildlife sharing the same woodland ecosystem have had
implications because of the pinyon pine decline. New studies have shown that pinyon pine seed
cone production has declined by an average of about 40% at study sites in New Mexico and
northwestern Oklahoma over the past four decades. The highest declines were found in places with
greater increases in temperatures over the past several decades. Pinyon pines are mast-seeding
species, which basically means that pinyon pine populations, every few years, produce high amounts
of seeds and then other years, produce very few seeds. As the percent, change in growing
temperature increases the cone production during mast years decrease. The full case study on pinyon
pines can be found at this site:
http://sciencecases.lib.buffalo.edu/cs/files/pinyon_pine.pdf
Coral Reef Bleaching
Climate affects both terrestrial, as seen in the Pinion pine case, and there are effects on aquatic
ecosystems. One of the biggest impacts that climate change has is on coral reefs. Coral reefs have
narrow temperature range, which is usually between 25º and 29º Celsius, but it differs depending on
where they are located. Higher water temperatures caused by global warming have already cause
major coral bleaching events. Coral bleaching occurs when corals respond to the stress of warmer
temperature. Coral reefs rely on Zooxanthanllae for some of their food and are the source of the
color for the corals, but because of the warmer waters, the Zooxanthellae leave the coral tissues and
the corals turns white. White, unhealthy coral are called bleached and bleached corals are weak and
less able to combat diseases. Some coral are able to recover from it, but too often, the coral dies.
Because of this the entire ecosystem for which it forms the base, virtually disappears. Long lasting
and more extensive bleaching are already on the rise and further increase is expected in the next few
decades as ocean temperatures continue to rise. Further, on the coral reef bleaching case study can
be found here: http://sitemaker.umich.edu/section6group1/data_and_analysis
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Lab:
Purpose
The purpose of this activity is for students to see how variations in temperature and pH caused by
global climate change can affect the success of enzymes within organisms.
Overview
This lab is a way for students to gain an understanding of how environmental conditions impede or
facilitate the activity of enzymes, while also being involved in the process of developing and testing
hypotheses. It also is intended to emphasize the importance of enzymes in different aspects of
organisms’ growth and survival. Finally, the lab will do this in the context of the effects that climate
change has on environmental conditions and how they can affect life.
The full lab can we found here:
http://osep.northwestern.edu/sites/default/files/Yeast%20Enzyme%20Activity_ALL.pdf
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