How do the tropics work?

If you ever visit the Neotropics, then A Neotropical Companion is a must-read. If you go to African or Asian tropics it is also worth your while although there are differences – no lions in Brazil and no leafcutter ants outside the Neotropics. After reading the just under 400 pages of text you will have an idea about the tropical ecosystem(s) that you are visiting. You will on the one side have learned a ton of stuff and on the other side have learned how little that is compared to what more is written about the tropics (thanks to a rain of references) and how little that in turn is compared to what still needs to be investigated.

Here is a disclaimer: I am not a biologist so I can not judge this book on scientific correctness. However, I think I can give you some insights into the book that may be worth your while if you are considering reading it. After I wrote most of this review, I discovered that there is a newer version from 2017. If you are considering that one, perhaps it is still worth your while to read this review, in particular because of the last paragraphs on deforestation and the possibilities of fighting that.

Our copy of the book in its current state

The book has 14 unequal-sized chapters, which I will list here because it gives a good idea of the width of the book’s scope and about the stress that the author puts on the different topics : 1 Tropical climates and ecosystems (18 pages), 2 Rainforest structure and diversity (23 pages), 3 How a rainforest functions (31 pages), 4 Evolutionary patterns in the tropics (51 pages), 5 Complexities of coevolution and ecology of fruit (38 pages), 6 The neotropical pharmacy (25 pages), 7 Living off the land in the tropics (20 pages), 8 Rivers through rainforest (29 pages), 9 Introduction to the Andes and Tepuis (10 pages), 10 Savannas and dry forests (11 pages), 11 Coastal ecosystems: mangroves, seagrass, and coral reefs (12 pages), 12 Neotropical birds (44 pages), 13 A rainforest bestiary (39 pages), 14 Deforestation and Conservation of biodiversity (43 pages).

As becomes plain from this list, and one of the first eyeopeners for me was that the tropics are really not just about tropical rainforests. Savannas, mangroves, dry forests, cloud forests, coral reefs, are included as well and differ wildly from rainforests and from each other. And indeed, here in Costa Rica, they have almost all of these in a country not much bigger than the Netherlands.

Another thing that jumps to me from this list is the stress on evolution and diversity. They are not just discussed in dedicated chapters, they pop up basically everywhere in the book. For example in the seemingly endless lists of species that Kricher en passant sums up when talking about, oh let’s say, fruits. A random pick from chapter 5: the following families of birds depend heavily on fruits: manakins, cotingas, toucans, parrots and tanagers (p. 135). A few pages later he reports having seen 17 species of birds on a single fruiting fig-tree and lists them all. I doubt I would see 17 species of birds during a day-hike in the the National Park the Hoge Veluwe in the Netherlands. An important question that is not entirely answered is why there are so many species in the tropics.

Complexity is yet another topic that is both explicitly addressed and woven into the fabric of the book. Virtually nothing is simple and clear cut. Yes, for starters some patterns or general insights exists, but then there are the numerous exceptions and additional loops and hooks added to those patterns, and to the exceptions. There is for example this whole issue of chemical warfare between plants and plant-eating bugs and mammals. There are insane amounts of insects and insect species in the Neotropics, but most of the plants are not eaten by them. Enter the chemicals. But then, some bugs do know how to deal with these. One of those are the leaf-cutter ants. As their name claims, they cut little pieces from the leaves of trees and what have you. But instead of eating them – which they can’t because of the chemicals – they bring them to their nest and feed them to a fungus. Well, first they chew them, pooh on them “defecates a fecal droplet of liquid” (p. 134, and then put a bit on fungus on top of the mass. The fungus grows and the ants eat the fungus, while keeping enough of it alive to continue producing. Duh. Doesn’t sound simple at all. But then, can the fungus eat all plant material? No way. The ant needs to be careful in fact. And on it goes, two and a half pages including ten references.

The book, like the tropics, is a bit overwhelming. There is a huge amount of facts, many illustrations of diversity and complexity and on top of that (or underneath if you want) a discussion on evolution. Kricher does not shy away from a beginners’ introduction into Darwinian evolutionary theory, but then goes deeper and deeper into the dynamics: selection pressures in the tropics, diversity gradients (diversity is not the same every in the tropics, but how come?) , adaptive radiation (diversity of species radiating out from one or a few), how does the splitting up of species actually happen, are the tropics in equilibrium (i.e. is the number of species stable?). The really good part about it: he manages to explain it all, also to the non-biologist. It is a lot to take in, but it is doable and wildly interesting. I ended up comparing evolutionary research to social science in the back of my head. In both disciplines one can never be absolutely certain about what can be taken as the independent variables. There is always this possibility that it – whatever one studies – could be more complex and more dynamic than assumed and that there are feedback loops of causes and effects that might make what one takes as the independent variables somewhat dependent on the assumed dependent variables.

The next point that I would like to make: the book is an introduction both for the educated biologist, or perhaps the students of biology, and for the lay audience. Well, you do need to know how to read a book and occasionally stop trying to absorb and follow everything in detail – because, as I mentioned, there is a lot of detail. Also, whereas Kricher takes you by the hand through evolutionary thinking, he does not do so with many other things. For example, the whole ordering of species in families, groups, things called taxa and genus, is used as if everybody knows this. I have read the book and I still need to look it up some time. Also, the text is speckled with technical terms that one would need to know or look up to fully understand what it means. Or, you can think, mwah,… In the end, I think, Kricher choose wisely in what to explain and what not.

The book honors its title in the sense that it is so dense with information and references that one would have to read it a couple of times. Or at least review the chapter about the part of the tropics that you are going to visit or otherwise has your current interest. So, it indeed is a companion. Take it with you. I have read the second edition, which apparently is an extended edition and a much bigger and heavier book then the first edition. Not the least because of the added pages with color photos. But bringing the weight is worth your while.

Is there no real downside to the book? Yes and no. Yes, this edition is from 1997, which is over twenty years ago. The academic frontier must have moved on since then. On the other hand, evolution does not go that fast, so virtually everything that existed twenty years ago, still exists today. Insights in evolutionary dynamics however may have progressed. I would be interested in that.
On the other hand, the fact that it is 20 years old also makes the last chapter on ‘Deforestation and Conservation of biodiversity’ a very interesting read. Deforestation has progressed since then and climate change – which he definitely links to deforestation – as well. Kricher is very concerned with the topics seems not too pessimistic. I wonder what he now thinks about it?
He notes that “As carbon dioxide accumulates, many climatologists predict that global heat patterns and climate will change.” (p. 355) He proceeds with a reference to the Intergovernmental Panel on Climate Change from, and here it comes boys and girls, 1990. As far as I know, they have stopped predicting this and started observing it. We all clearly remember tehe bloody hot summers of the past ten to fifteen years right? Well, Kricher remarks that it is “sobering to realize that the six warmest years on record (up to 1988) we 1988, 1987, 1983, 1981, 1980 and 1986”. I find it sobering to know that that was 30 years ago.
Kricher is ‘cautiously optimistic’ (p. 376) about what can be done about deforestation. In the face of economic pressure and population growth, conservation goals must not and need not be threatened, according to Kricher. He then discusses extractive reserves, reclamation of degraded ecosystems, ecotourism and national parks and preserves. More indirectly, he argues for more basic research, more conservation research and ends with education. Just like it takes some level of education to appreciate art, it might take education to appreciate nature, Kricher argues. So, he proposes that scientists – mostly from North America and Europe, but also from the Neotropics – should take it upon them to teach children both inside and outside the tropics about the natural history and the value of nature.

I am curious how Kricher discusses deforestation 20 years later in the 2017 edition.

Kricher, J. ( 1997 ) A Neotropical Companion. Princeton : Princeton University Press. Book review


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