Chapter 4: Adaptation
Chapter 4.1 Climate Change Factors
The definition of adaptation is a trait with a current functional role in the life history of an organism that
is maintained and evolved by means of natural selection. Natural selection is a process that involves
dominate species surviving and the weaker species dying, as coined in the term “Survival of the Fittest”.
The evolution of a species is characterized by adaptation, which can be caused by many things, but what
we are going to discuss is the effect made by climate change.
Under certain conditions, climate change can induce adaptation in organisms. For example, the coral
reefs, which are very sensitive to temperature, are predicted to decrease by a third of their size within
the next forty years. More specifically, the zooxanthellae, which provide food and color to the corals, are
leaving the corals when the temperature rises, causing corals to turn white and die and invoking a
process collectively known as coral bleaching. More examples include Canadian squirrels breeding
earlier in the spring, feral sheep in Scotland are getting smaller, species that live upon mountains are
moving uphill, and other species are shifting away from the equator and toward the poles. All of these
adaptations have at least one thing common: climate change.
One reasoning for climate change invoking adaptation is that climate change provides unfamiliar
environments to the species, forcing them to either adapt or die off. For example, let’s say a group of
bald eagles live in the Appalachian Mountains. Storms have been passing over the past few days, and
now the lakes are muddy and high. The fish, bald eagles’ primary prey, have decided to lay low and not
rise to the surface as often. Unfortunately for the eagles, this means in order to survive, they have to
find prey on the ground. This is an example of adaptation induced by climate change. Since the fish are
unapproachable, the eagles must adapt and search for food on the ground, or else they will starve.
As humans, we alter the natural systems of our planet, as you have read by now. Because of this, and
the fact that climate change directly affects species adaptations, humans indirectly induce adaptation.
Unfortunately for the animals that are unable to adapt in time, this means they are most likely die.
Therefore humans also indirectly increase species death rate.
Case Study
During the Paelocene-Eocene Thermal Maximum era, a 175,000-year interval around 56 million years
ago, the average global temperatures rose by about 10 degrees Fahrenheit. Around one-third of the
mammals in this time period significantly reduced in size. Sifrhippus, the first horse 56 million years ago,
was one of these mammals. Once 12 lbs., Sifrhippus shrank by about 30% to the size of a domestic cat
(8.5 lbs.).
Chapter 4.2: Genetics
Now that you know the reasoning behind the adaptation of a species, it’s time to find out the cause, and
that’s where genetics steps in, genetics being the study of genes, heredity, and variation in living
organisms. Adaptation occurs when a new gene combination, known as an allele, is formed in the gene pool
of a species, changing the way some of the organisms in that particular population develop, for better or for
worse. I say for worse, because the change could have just as much of a chance of being beneficial as it could
detrimental to the particular organism. That’s how evolution works, constant amount of changes brining up
new traits, the bad ones being weeded out and the good ones being passed down to advance future
generations for the betterment of survival.
So, how do these traits form? To understand that, you must know the relationship
between genotypes and phenotypes and the concept of punnet squares. A genotype is the genetic makeup
of a cell, and a phenotype is the physical, observational trait that is produced by said genotype. Each genotype
is made up of the combination of two alleles, which could consist of a dominant allele and recessive allele,
or simply a pair of either. Depending on the pair, you can have one of a few different types of traits develop
in an organism, depending on the species. The most basic ones are the trait that appears whenever there is at
least one dominant allele in the mix and the one that only appears if the genotype consists of only recessive
alleles. For some types of organisms there is a third trait that could be developed if you have two dominant
alleles paired together. For example, let’s say you have two birds who both carry the genotype for blue
coloring, Bb. When the two mate and pass down their genes, their offspring has a chance of inheriting one of
three possible combinations, BB (dominant dominant), Bb (dominant recessive), and bb (recessive recessive).
As you can see, their offspring inherits only one allele from each parent for the trait, with a 50% chance that
it will be blue just like its parents. But, I’m sure you’re wondering what exactly that picture is actually
showing, and the answer is that is one example of a punnet square. Punnet squares are used in order to
determine the percent chance that a certain trait would be passed down, as well as show all the different
possible combinations that could arise.