The Big Answer: There isn’t one. There are many.
Every
situation involving an ecological change is unique; a single generalized answer
is hence inadequate. The characteristics- the variables- of the situation must
be considered before determining the answer. These variables can be broadly
classified into space, time, magnitude and nature of the organism.
For the sake
of clarity, a few definitions first: Ecological changes are shifts from the
current eco-system in terms of abiotic or biotic elements. Abiotic changes are
changes that occur in the environment, such as climatic changes, increase in
soil fertility or increased acidification of the sea. Biotic changes are
variations in the living organisms in an eco-system. They can be further
divided into changes in individual organisms, such as genetic mutations;
changes in populations, such as alteration in species distribution; and changes
in interactions between organisms, such as predator-prey dynamics.
Now to the
real business: Variables.
A change may be good or bad depending
on the place we see it occurring in. The migration of a species into a new
environment benefits its ecological diversity; however, due to the very migration
the ecological balance in its original habitat might be upended. Conversely, the
introduction of a new species may be detrimental to the abiotic and biotic
factors in the eco-system. Zebra mussels, for example, were brought to the
Great Lake region through ballast tanks of ships coming from Western Europe.
Owing to high reproductive rates and lack of predators, the mollusks quickly established
a substantial presence in the ecosystem. They (literally) ate into food
supplies of other organisms and propagated algal blooms as their water
filtering habits improved water clarity. They also attached themselves to
insides of water supply pipes thus clogging them (NOAA). The presence of Zebra
mussels was evidently disadvantageous to the new habitat. However, as they did not cause new competition or
disrupt the norm in their old habitat,
they were not damaging there. This is how the Space variable comes to fore.
It was pretty much an open-and-shut
case. The Change was accused of being adverse and all evidences were against
it. But someone overturned the verdict. Cue: Time variable. A change might be
deemed bad at one point in time, but not quite so at another. The Chicxulub
asteroid impact that occurred at the Cretaceous-Paleogene boundary, roughly 65.5 million years
ago, is widely believed to have wiped out several species of plants and
animals, most notably the dinosaurs (Science, 2010).
It was undoubtedly a bad change for the entire biosphere.
Correction: It was undoubtedly a bad change for the entire biosphere then. This very asteroid that led to the
mass extinction of dinosaurs, allowed the mammals to flourish. They gradually
occupied the ecological niches previously occupied by the dinosaurs and spread
to nearly every corner of the globe (Bascom, 2010). They eventually evolved
into the species we know today, including Homo
sapiens. Therefore you and I would
not exist had it not been for the asteroid. I bet that change doesn’t look so
bad now?
When it comes to change: Size matters.
The magnitude of a change could become a deciding factor in answering the Big Question.
For example, planktonic algae presence in a pond is a good change- it increases
food production for fish thereby increasing the number of pounds of fish. But
every silver lining has a cloud; if nutrient levels increase exponentially, the
algae will explode and cover the whole pond in green scum. This could lead to
low water clarity and fatally low oxygen levels in the early morning (Lynch, 2006).
Changes
almost always affect more than one organism. Thus it matters from which
organism’s perspective we are looking at the change for it might benefit one
organism but damage another. Look at the sequoias of California that survive
wildfires while other plants do not. Interestingly enough, they not only brave
the life-threatening flames but also profit from it. The fire forces the
sequoias to let go of its cones en bloc leading to massive dispersal. The other
plants (lacking the two feet thick, fire resistant bark of the sequoia) char
away and the sequoias have their competition removed. As an added bonus, the
ash from the fire serves as a useful fertilizer for the newly shed cones. So
while the fire is a terrible change for most of the eco-system, it is of huge
reproductive advantage to these big trees. (Howard, 2015)
As we are
talking variables, here is the X-factor. Thus the last variable that helps us
answer that million-dollar question is (drum roll please) - the reaction of the
organism to the change. Imagine a culture of E. coli bacteria, thriving in their little test tube world.
Suddenly, the absent-minded scientist accidentally spills some penicillin into
the test tube putting the entire culture under the threat of a wipe-out! But
just as all prospects seemed bleak, a mutated bacterium with a
penicillin-resistant gene comes to the rescue. It multiplies and creates
generations of penicillin-resistant bacteria thus saving the culture from total
annihilation. Despite the dramatics, this is a wonderful example of how
organisms’ can convert a potentially lethal change into a beneficial one. After
all, the culture as a whole became stronger and survived (and lived happily
ever after).
These variables are important
characters in a larger story such as evolution. The formation of chlorophyll
changed the reducing atmosphere of primitive earth to an oxidizing one. The
change was bad then as it stopped the
abiogenesis of life but good now as
the primitive autotrophs that evolved due to that change led to the formation
of life as it is today (Blankenship, 2002). Sometime then mutation struck
primitive earthlings, mainly asexually-reproducing unicellular organisms. They
found out that beneficial variations increased survival. To increase the
frequency or magnitude of these
mutations, they came up with sexual reproduction.
Fast-forward to speciation. Prehistoric
short-necked giraffes encountered change in the form of depleting food
resources. The slightly longer-necked giraffes managed to survive by eating
leaves on higher branches while its short-necked kin died out due to
competition for lower leaves (Latter, 2006). This change was bad for some organisms- the short necks- but the
population as a whole survived by evolving into a longer-necked species.
Evolved behavior is another chapter in this story. Winter temperature changes
create adverse living conditions for birds. But they make it a good change by developing
a migratory behavior where they fly to the Tropics, a space where the change is good (Winger, Barker, Ree, 2014).
So the Big Question can be answered
after considering all variables. However, our work is not done.
There is a Bigger Question: What do we
do once we find our answer?
The Bigger (and simpler) Answer: We
react.
Thus, the reaction to the change is the
perhaps the most important variable of the change because it can direct a
change to being good, even if it is potentially bad. Evolution is the biggest
evidence of this. It has taken many changes for the species of today to reach
where they are. Some of the changes have been bad, some even fatal, yet certain
organisms survive and through them, their populations. This kind of thinking is
important for our species to understand for we face an era of colossal changes
ahead of us, such as climate change and population changes, which have the potential
to be a ‘Bad change’. However, it is our reaction to these changes that will decide
whether that will be so or not.
References:
1. Zebra Mussels: The Invasion of
Zebra Mussels; National Oceanic and Atmospheric Administration; http://www.noaa.gov/features/earthobs_0508/zebra.html
2.
Dinosaurs: The Chicxulub Asteroid Impact
and Mass Extinction at the Cretaceous-Paleogene Boundary; Science; Schulte et
al; http://www.sciencemag.org/content/327/5970/1214.short;
3. Probing
Question: Why did mammals survive the 'K/T extinction'?; Penn State News; Nick
Bascom; January 19, 2010; http://news.psu.edu/story/141227/2010/01/19/research/probing-question-why-did-mammals-survive-kt-extinction
4. Planktonic Algae: Benefits and Disadvantages of Aquatic Plants in Ponds; Ohio State University Extension Fact sheet; William E. Lynch Jr; April 17, 2006; http://ohioline.osu.edu/a-fact/0017.html
5. Sequoias: Sequoias and Historic
Stump in Path of California Wildfire; National Geographic; Brian
Clark Howard; September 14, 2015; http://news.nationalgeographic.com/2015/09/150914-california-rough-fire-sequoias-chicago-stump-wildfires/
6. Primitive Autotrophs: Early
Evolution of Photosynthesis; Plant Physiology; Robert E. Blankenship; October
2010; http://www.plantphysiol.org/content/154/2/434.full
7.
The Evolution of Sexual
reproduction: http://www.evolutionary-philosophy.net/sex.html
