Patterns in Nature: The Analysis of Species Co-Occurrences

by James G. Sanderson, Stuart L. Pimm

What species occur where, and why, and why some places harbor more species than others are basic questions for ecologists. Some species simply live in different fish live underwater; birds do not. Adaptations most fish have gills; birds have lungs. But as Patterns in Nature reveals, not all patterns are so trivial.

Travel from island to island and the species change. Travel along any gradient—up a mountain, from forest into desert, from low tide to high tide on a shoreline —and again the species change, sometimes abruptly. What explains the patterns of these distributions? Some patterns might be as random as a coin toss. But as with a coin toss, can ecologists differentiate associations caused by a multiplicity of complex, idiosyncratic factors from those structured by some unidentified but simple mechanisms? Can simple mechanisms that structure communities be inferred from observations of which species associations naturally occur? For decades, community ecologists have debated about whether the patterns are random or show the geographically pervasive effect of competition between species. Bringing this vigorous debate up to date, this book undertakes the identification and interpretation of nature’s large-scale patterns of species co-occurrence to offer insight into how nature truly works.

Patterns in Nature explains the computing and conceptual advances that allow us to explore these issues. It forces us to reexamine assumptions about species distribution patterns and will be of vital importance to ecologists and conservationists alike.

Genres: Science

184 pages, Hardcover

First published November 2, 2015

Reviews

[Gavin · Rating 2 out of 5]

While it was interesting (and disheartening) to learn how ecologists are grabbing at straws to apply math and egos to understand the living world around us, the book can perhaps best be summed up by the following two quotes, plus some linear algebra.

1. "Why is it that the full richness of nature embodied in more than a billion years of evolution, the wondrous complexity and interactions of living organisms, must always be boiled, distilled, spun, and precipitated into a single number? That ecologists would place great value in such a number is in itself wondrous in its ofn mysterious simplicity." -Chapter 6, page 202 (ebook)

2. "The major outcome of the analyses is the dominance of nonsignificant results." -Hofer et al. 1999, Chapter 9, page 345 (ebook)

The main question raised in the book is: Does competition among two similar species cause them to form mutually exclusive communities? The answer anyone could probably give from their experience living on Earth might be something like: Competition is only one factor in where animals choose to live, but in general animals tend to form fluid communities with those most like them as well as with the species they rely on.

A few things to keep in mind with Jared Diamond's original study:
- The original two species studied lived on islands. It's entirely possible that competition is only one factor.
- Populations are fluid, so data collected at any one time is simply a snapshot of that moment.
- The original species studied were two kinds of pigeon that looked so similar bird watchers rely on guidebooks for an ID, based on the general agreement that "this kind lives on this island, and the other kind lives on the other island". This alone makes observational data pretty questionable.
- Islands it is where the species under study live. Don't repeat your points.

[Heather Browning · Rating 3 out of 5]

Sanderson & Pimm offer a convincing account of the appropriate methods of analysis for species distributions. As someone who has a casual interest in ecology and its philosophy, I found the book was often far too detailed and technical for me, but I can see that would have been important for anyone wanting to use the methods themselves.