The Life of an Island

     Biological evolution fascinates me.  I find it truly wondrous that life began where there was no life and evolved over millions and millions of years into the astonishingly complex web of life that exists today.

     Because I love learning about evolution, I am reading THE SONG OF THE DODO:  ISLAND BIOGEOGRAPHY IN AN AGE OF EXTINCTION by David Quammen.  In an effort to understand the implications of the ‘islands’ that human activity is creating on our continents, Quammen explores the ways in which life evolves differently on islands than it does on large mainlands.  We humans are turning once vast stretches of wilderness into small, isolated chunks, with our roads, pipelines, shopping centers, and subdivisions.  By better understanding the ways of evolution on islands, Quammen believes we can better understand why diversity declines on isolated ’islands’ of wilderness.  

     Despite the book’s sobering premise, it reads like a novel.  Quammen, an award-winning science writer, tells us so interestingly why some kinds of creatures abound on islands, while others are rare or non-existent there.  He writes with humor and a great sense of ‘Wow!’  And you don’t have to be a scientist–or even particularly science-oriented–to love this book.

     I would like to share here a short passage from THE SONG OF THE DODO that explains why mammals are found only in small numbers, if at all, on islands.–April Moore

     “If I haven’t said much about mammals in this discussion of island colonization, it’s because there is not much to say.  Mammals don’t travel as well as most other vertebrates.  Their dispersal ability across salt water is generally low.  They are burdened with urgent physiological needs and blessed with only modest endurance.  Starvation and drought can kill them quickly.  So can drowning.  If they do manage to make a crossing, their prospects of establishment are still poor.  Since they reproduce sexually, give birth to live young, and suckle those young, they don’t enjoy the same adaptive advantages as many plants, insects, and reptiles.  An adult mammal needs a mate;  an infant mammal needs a mother.  All these factors reduce their chances of colonization.  Rarely a species of mammal does reach an island and establish itself, but more commonly an island remains empty of mammalian fauna despite the passage of eons.  As reptiles and ferns and pigeons tend to be disproportionately present on islands, mammals tend to be disproportionately absent.”–David Quammen, THE SONG OF THE DODO


3 Responses to “The Life of an Island”

  1. Diane Says:

    Interesting…so this means we should see increasingly distinct sub-species of mammals as artificial islands make it less likely for mammals to breed over larger areas with more diverse partners?

  2. Gila Says:

    Thanks for sharing this.

    This sin’t about islands but it is about birds, who famously evolve quickly on islands: I just read this morning that cuckoos, who place their eggs in other birds’ nest for fostering, are placing their eggs in different species’ nests as the subtle shift in temperature caused by global warming makes birds migrate earlier. It is upsetting the balance and making some species vulnerable to extinction.

    Also, male tits who live near light posts are more likely to get the opportunity to mate than those who live further from artificial light because they start singing 3.5 minutes earlier in the morning!!! Early birds get the mate! It makes these mostly monogamous females stray, even.

  3. Steven Earl Salmony Says:

    Petition Presentation, Town of Chapel Hill, NC, November 21, 2011.

    Opening remarks…….

    In Chapel Hill and around the world, it is all the same: many too many people can be found in too many places destroying the natural world for personal economic gain. Many human-induced pressures on Earth’s finite resources and its frangible ecology, that directly result from the unbridled global growth of overconsumption, overproduction and overpopulation activities by the human species, put demands on the natural world that can overwhelm any efforts to achieve a sustainable future for children, not only in Chapel Hill but elsewhere on the surface of our planetary home. If we are to halt the reckless destruction of Earth as a viable resource base as well as the irreversible degradation of an already polluted environment and a warming climate, we must accept limits to growth.

    We must start somewhere soon to chart a sustainable course. Endless economic and population growth appear to be unsustainable. Let us consider now and here ways we can humanely, fairly, equitably and realistically define limits to economic and population growth in Chapel Hill, while there is still time to do so. Once the comfortable and friendly size of Chapel Hill is lost due to economic and population growth pressures, Chapel Hill’s quality of life and special characteristics will be impossible to regain.

    Perhaps we can “think globally” about the predicament seven billion human beings present to the viability of Earth as a fit place for human habitation. Then we choose to”act locally” in ways that move us in the direction of a sustainable future for children everywhere and for life as we know it. Thank you.


    A Petition to Define Limits to Economic and Population Growth in the Town of Chapel Hill, NC

    Whereas the Town of Chapel Hill appears to be outgrowing the comfortable and friendly size that has made it a wonderful place to live, raise children, work and retire; and
    Whereas increasing traffic congestion, crime and other social ills are presenting worrisome trends that result from human population growth which will eventually degrade Chapel Hill’s eco-friendly environs, deplete its limited natural resources and conceivably ruin what makes our town beautiful and special; and
    Whereas the Town of Chapel Hill has established limits and the Great State of North Carolina has boundary lines that separate it from adjacent states; and
    Whereas the USA has borders that confirm the limits of authorized human activity under its regulations and laws as well as distinguish itself as a separate nation; and
    Whereas Earth is round, bounded and finite with frangible environs not flat, unbounded and unperturbed by human production, consumption and population activities of the human species worldwide; and
    Whereas there are well-known biological and physical “rules of the house” in our planetary home that are categorically different from the manmade laws which regulate day to day production, consumption and population activities of human species, but are no less important to citizens of Chapel Hill, the State of NC and the USA as well as to the global citizenry of the human family, precisely because the biophysical reality of God’s Creation places immutable limits on the unbridled global growth of human overproduction, overconsumption and overpopulation activities; and
    Whereas a billion human beings were added to family of humanity worldwide in the last dozen years (1999 to 2011); and
    Whereas in the month of October 2011 the seven billionth human being joined the human community; and
    Whereas there are more human beings in November 2011 existing on resources valued at less than two dollars per day globally than were alive on Earth in the year of my birth (2.3+ billion in March 1945); and
    Whereas we have heard many times, understood well enough, and can reasonably be expected to at least consider acting in a morally responsible way upon a shibboleth of humanity that goes like this, “Think globally, act locally,”

    Now, Therefore, It appears appropriate to Propose and Present this brief Summary of a Program for Action.

    As a part of the town-wide envisioning process to consciously and deliberately manage economic and population growth in the Town of Chapel Hill between now and 2020, leaders, planners and stakeholders will assure that the maintenance of the unique character and the quality of life in Chapel Hill, as we enjoy it now, is protected and preserved for the children and future generations. To accomplish this goal, various scenarios or different elements of a single scenario will be developed with the hope that the following steps will be examined for their efficacy.

    Because overpopulation is ultimately a local issue, set an optimum/maximum population size for the Town of Chapel Hill in 2020. This goal can be fulfilled by adopting growth-management policies related to limits on the number of new residential dwelling units and to additional eco-friendly curbs on commercial developments per year between now and 2020. Zoning regulations can be promulgated to further restrict the size of residential, commercial and industrial buildings within the town limits. The reality-oriented adoption of “soft caps” on economic and population growth will make it possible for the Town of Chapel Hill to sensibly acknowledge and adequately address the considerable and potentially unsustainable growth pressures that are readily visible on our watch.

    Steven Earl Salmony

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