Easton 1

Not Your Average Penguin

How Evolution Has Shaped the Galapagos Penguin Andrew Easton Sophomore College Stanford University ©2008

Easton 2

The view from Bartoleme

There is something so breathtaking about the thought that, as an environment

changes, living organisms actually adapt, generation by generation, to accommodate the

new features that may arise. And yet, this is a reality. The concept of evolution accounts

for these slight changes in species over time as they adjust to their surroundings.

However, many people are misled by this notion. For example, in many discussions with

educated individuals about the dangers of global warming, I have heard the response,

“but the species will just adapt to the new conditions.” Many people are under the

impression that evolution can adapt any species to any environment. Sadly, this is simply

not the case. The Galapagos Penguins are a perfect example of a species that is

endangered by environmental change in such a way that it will not be able to adjust if the

trend continues in the future. These penguins have significantly adapted to the warmer

climate of the Galapagos in such a way that they are unable to conform to new

environmental pressures while still remaining successfully reproductive in the warmer

temperatures.

Known to the Spanish

sailors as Las Islas Encantadas (or

the Enchanted Islands), the

Galapagos Archipelago is

comprised of several volcanic

landmasses. These islands,

located directly on the equator,

have an incredibly unique ecosystem. There are several important reasons for this. First,

Easton 3

the Galapagos is located at a confluence of currents. One of the currents, the Panama,

brings warm water down from Mexico while a second, the Humboldt, carries cold water

as it streams up the coast of South America.

Meanwhile, the South Equatorial Current,

caused by the rotation of the Earth, forces all

the surface water to cycle across the Pacific

Ocean from east to west. These waters then

cycle back as an undercurrent, known as the

Cromwell Current, which surfaces as it hits the

western shores of the islands. Because the

Humboldt Current brings Antarctic waters to the eastern islands and the Cromwell

Current delivers water from the depths of the ocean, the water surrounding the Galapagos

is, surprising, quite cold. The Cromwell Current, however, also brings with it a bountiful

and nutrient rich marine life, which acts as food for many of the birds in the area

(Galapagos Ocean Currents).

The unique marine environment is not the only interesting factor controlling life

in the Galapagos however. The air above the Pacific Ocean is cycled as well, caused by

the same forces as the Equatorial Current. The air is lower traveling from east to west,

and then rises before circling back over the vast expanse of water. As a result, the air

becomes very moist in the west as it absorbs water from the surface of the ocean. As it

rises, it becomes less dense and dumps rain onto the South Pacific. It then cycles back

towards the Galapagos and sinks, absorbing all the water that exists in the air and moving

it away, back towards the east (TAO Project). Because of this, and also partially because

*1 The currents of the Galapagos

Easton 4

much of the volcanic soil of the Galapagos is infertile, the land is often dry and barren.

As a result, very few land species have successfully adapted to the harsh conditions of the

islands (Kricher 2002: ). The penguin is one of the lucky few.

But the process wasn’t easy, and the penguin varies significantly from its

Antarctic counterparts. The Galapagos Penguin (Spheniscus mendiculus) is the only

penguin that can be found in the northern hemisphere, for example. Of the seventeen

different species of penguin, sixteen are confined entirely south of the equator. Fifteen of

these species breed only south of the Tropic of Capricorn, located more than 23° south. It

is quite clear that penguins typically live in very cold climates. As a result, they are

normally fairly large, and coated with both fat and feathers to trap in all the heat it can

possibly retain. Also, species of penguins that breed further south are larger than their

more northerly counterparts. The average height of penguins breeding in Antarctica is

about 100cm. In the sub-arctic islands and the tip of Africa, they grow to an average of

80cm. Those on the coast of South America general measure around 70cm, and those

found on Australia or New Zealand are, on average, 65cm. Essentially, the warmer the

climate, the smaller the penguin. This trend applies not only to height, but to girth and

insulation as well. Two more trends of penguins worth noting are that sixteen of the

seventeen species moult once a year, directly preceding their breeding season. Also, on

average, a penguin is known to swim as far as thirty-five kilometers from its breeding

ground when it hunts for food (Penguins).

While all seventeen species of penguin evolved from a common ancestor, it is

quite clear that the Galapagos Penguin most recently diverged from the Humboldt

Penguin. This species roams the western shores of South America, mostly in northern

Easton 5

Chile. The Humboldt Penguin is most similar to the

Galapagos both physically and genetically. The

divergence probably occurred as a result of the Humboldt

Current. Recall that this current runs up the coast of

South America and funnels straight to the islands. All that

the ancestor penguin had to do was swim off shore and

catch a ride directly to the Galapagos Islands. At this

point, the separate penguin populations continued

speciating slightly differently until, three million years

later, they are the separate species as we now see them (Vargas 1997: 30).

In many ways, the Galapagos Penguin continued

following the same evolutionary trend as all penguins that

venture further north. On average, the Humboldt Penguin is

seventy centimeters tall. The Galapagos Penguin is only

fifty. The Humboldt Penguin also has more insulating fat

than the Galapagos variety (Penguins). Because of the

warmer climate of the islands, the smaller size was selected

for, and the Galapagos Penguin adjusted by adopting a

smaller body size in order to help regulate heat and stay cool (Boersma 2008). However,

because this trend is not found only in the Galapagos and, instead, is true of all penguins

that venture north, it is an exaptation rather than an adaptation.

But there were Galapagos specific adaptations as well. These came mostly in the

form of changes in breeding and feeding behavior. Because the penguin’s food source

*3 Comparing the Galapagos Penguin

*2 Comparing the Humboldt Penguin

Easton 6

depends almost entirely on the Cromwell Current, and because this current is not entirely

regular (there are sometimes fluctuations in the South Equatorial Current), they became

opportunistic breeders. This means that instead of having one breeding season like every

other species, they breed whenever there is

sufficient food to feed their young. As a result,

the penguins moult twice a year, instead of once

directly preceding their breeding behavior. Also,

in order to be able to return to their nests quickly,

the penguins began hunting closer and closer to

shore. In fact, they never search for food more

than two kilometers from their nests (Boersma

1978: 1481-83). However, part of this limited feeding range is hypothesized to also be

influenced by a ridge approximately two kilometers of shore, after which hammerheads

and other predators become much more prevalent. The penguin’s abnormally small size

makes it easy prey for these animals, and thus it avoids their territory (Boersma 2008).

For thousands of years these adaptations continued to benefit the penguins of the

Galapagos Islands.

However, there is one environmental situation in which the Galapagos Penguins

do not fair well. El Nino events are very harmful to the population, and almost every time

one occurs, hundreds of penguins die (Boersma 1998: 245). El Nino’s occur when the

trade winds causing the South Equatorial Current to move from east to west change

directions. It is still unknown exactly why this phenomenon occurs, however the effects

are tremendous. All of the warm surface water on the equator is directed towards the

*4 Feeding range of the Galapagos Penguin

Easton 7

Galapagos instead, drastically increasing the

temperature surrounding the islands. At the same

time, the Cromwell Current is completely cut off, and

a significant amount of the marine life simply

disappears. In addition, the dense moist air that once

hung above the south pacific now accumulates

directly above the archipelago and pours rain onto the

islands, transforming the land conditions from dry to

almost tropical (TAO Project). While many land

species thrive in these conditions, the penguins, which

rely on the delicate balance of currents for food, are

decimated (Vargas 2005: 3-5). It is the adapted traits tailored to the usual environment

that harm the penguins during these times. Because of both their new opportunistic

breeding habits and their smaller size, which makes them more vulnerable to predators,

the penguins are not able to swim the distances required to find food.

Unfortunately for the Galapagos Penguin, El Ninos are becoming more and more

frequent in recent times, giving the population less time to recover between events. Many

people are speculating that humans are causing this change, however regardless of the

accuracy of these claims, these alterations pose a major problem for the penguins. In the

past, there has been enough time between El Ninos for the penguin population to

convalesce, and over extended periods of time the population has remained fairly

constant. However, this is slowly changing and is no longer the case. With the events

*5 Diagram of how El Nino works

Easton 8

occurring more frequently, the penguin population is beginning a steady decline (Vargas

2005: 371-73).

In the El Nino of 1982-1983, 77% of the penguin population died. During another

El Nino, from 1997-1998, 66% of the penguin population died. What is even more

unnerving, however, is that from 1980 until 2006, the population decreased by more than

50%. This includes eight years of recovery time since the last major El Nino (Boersma

1998: 248). If this trend continues, penguins will not reside on the Galapagos Islands for

long.

But El Ninos are not the only cause of this decline. Introduced predators are also

playing their part. Because life on the islands is so arduous, and because it was incredibly

difficult for land animals to reach the archipelago, there have been no real land predators

of the adult penguin (rice rats and snakes, among others, attack the eggs) (Bingham). This

is one reason that the major decrease in body size was not detrimental. However, with

feral cats and dogs being introduced to the islands, the penguin’s small size makes them

perfect prey (Vargas 2005: 6).

With an increasing number of predators, and an increasing need to swim further

from shore, one may postulate that the penguin would begin to adapt for a larger size and

swimming range. However, these are

the exact traits that were selected

against when the penguin first came

to the islands and this poses a major

problem. A large penguin would

overheat in the warm climate, but a

Swimming of the coast of Floreana

Easton 9

small penguin would be easy prey for the new predators. Essentially, if these new

phenomena subsist, the penguin will not be able to successfully adapt to the new

environment. Most specialists believe the Galapagos Penguin will be extinct in less than

two hundred years and my research fully supports these claims.

The only way to stop the current decimation of the penguin population is to

address these two major issues. El Nino is tricky because it is hard to say if, or how much

of, the increase in frequency is caused by

humans. As such, we should continue

studying these events in order to ascertain the

cause of the increase in frequency. However,

eliminating the introduced species will

certainly immediately help the penguin, as

well as many other species on the islands, so this should be the major conservation focus

at this time.

If we do not address the problem, or do not succeed in fixing it, the Galapagos

Penguin will become extinct. In the increasingly prevalent ecosystem, the penguin will

survive neither as small nor large, and neither as a long-range nor short-range swimmer.

It simply cannot adapt to these new conditions. This relationship demonstrates how

evolution is not a theory in which any species can successfully change to fit and thrive in

any environment. Evolution is the process in which organisms adapt to their changing

surroundings, however the process is not perfect. Using the theory of evolution as an

excuse for humans to change the world is simply unacceptable considering that the

majority of current species, like the penguins, would not survive.

A penguin resting on Isabela Island

Easton 10

WORKS CITED *1 underlying image from commons.wikimedia.org *2 underlying image from www.theanimalfiles.com *3 underlying image from www.spallek.net *4 underlying image from wallpapers.jerko.net *5 from TAO Project Bingham, Mike. “Galapagos Penguin.” International Penguin Conservation Work Group.

5 Sept. 2008. < http://www.penguins.cl/galapagos-penguins.htm>. Boersma, Dee. 1977. “An Ecological and Behavioral Study of the Galapagos Penguin.”

Living Bird 15: 43–93. Boersma, Dee. 1978. “Breeding Patterns of Galapagos Penguins as an Indicator of

Oceanographic Conditions.” Science200: 1481–1483. Boersma, Dee. 1979. “Penguins in the Galapagos.” Noticias de Galapagos 29: 15 – 16. Boersma, P. D. 1998. “Population Trends of the Galapagos Penguin: Impacts of El Niño

and La Niña.” The Condor 100: 245-253. Boersma, P. Dee. Personal Emails. 5 September, 2008. 7 September, 2008. Fitter, Daniel and Julian and David Hosking. Wildlife of the Galapagos. Princeton, NJ:

HarperCollinsPublishers Ltd., 2007. “Galapagos Ocean Currents.” Galapagos Online. 4 Sept. 2008.

<http://www.galapagosonline.com/Galapagos_Natural_History/Oceanography/Currents.html>

Kricher, John. Galapagos. Washington D.C.: Smithsonian Institution, 2002. Muller-Schwarze, Dietland. The Behavior of Penguins: Adapted to Ice and Tropics.

Albany, NY: State University of New York Press, 1984. "Penguins." Wildlife of Antarctica. Antarctic Connection. 4 Sept. 2008

<http://www.antarcticconnection.com/antarctic/wildlife/penguins.shtml>. TAO Project. "What is an El Nino?" NOAA. US Department of Commerce. 4 Sept. 2008

<http://www.pmel.noaa.gov/tao/elnino/el-nino-story.html>. Vargas, Hernán, et al. 1997. “First Report of Penguins Nesting on Isla Floreana.”

Noticias de Galapagos. 58: 30 – 32. Vargas, Hernán F., et al. 2005. “Biological Effects of El Niño on the Galapagos

Penguin.” Biological Conservation: 1-6. Vargas, Hernán, et al. 2005. “Population size and trends of the Galapagos Penguin

Spheniscus mendiculus.” Ibis. 147 (2): 367 – 374.