It's hard not to see the world through the lens of our own preconceptions and biases. We tend to be more interested in other large mammals. We're drawn to human-like qualities in pets. But even the most benign insect is disturbingly alien when seen up close. We also tend to use the familiar as a metaphor for understanding the unfamiliar. Sometimes this gives us additional insight. Other times, it leads us down the wrong path.
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About Ian
A Trinidadian in Oklahoma, I am a biology post-doc interested in tropical dry forests and island ecology. I also have a blog called (full bio)
I saw the coolest thing ever on the Rachel Maddow Show tonight. Ever. Thomas Gillespie of the Geography Department at UCLA was on the show discussing his attempt to predict bin Laden's location using satellite imagery and biogeographic theory! It was so amazingly cool to hear him discussing distance-decay models and island biogeography theory to predict bin Laden's location. It's all the cooler because Gillespie is, at least in part, a tropical forest ecologist, did his Ph.D. on tropical dry forests in Nicaragua, and has published on dry forest fragments in south Florida.
In my last article, I ended with the observation that:
While we cannot reject Cook's scientific contribution simply on the
basis of his embrace of racist pseudoscience, we also can't simply
ignore it either. Sloppy thinking, after all, is sloppy thinking.
Roystonea, the royal palms, are the most striking palms in the Caribbean, and arguably, in the world (though, granted, a talipot palm in flower comes a close second). The name of the genus was coined by Orator F. Cook, an American botanist, in 1900, in honour of Roy Stone, an American general involved in the capture of Puerto Rico during the Spanish-American war.
The 12th edition of Berry Go Round, the botanical blog carnival, is now online at Foothills Fancies. Lots of good reading to be had.
There's a discussion going on over at Wikipedia regarding the naming convention for articles about plants. In general, article titles are supposed to be the "most common" name for the thing in English. But when you're trying to compile "the sum total of human knowledge", that simple rule can be problematic. Do you really want to use "the most common" name, or do you want to use the most accurate name? After all, Wikipedia seeks to be an encyclopaedia.
Things get far worse when you try to write articles about plant species. There are about a quarter million species of flowering plants. Most of them lack common names in English. But where they exist, common nam
In a closed system (and the biosphere as a whole is a closed system) the only way to generate additional species is through evolution.
While the evolution of new species is a necessary condition for the generation of diversity, it isn't good enough on its own. If a species splits into two daughter lineages that are unable to interbreed, you should have two species. But in order for them to coexist in a given area, some sort of ecological difference needs to have evolved. If two species occupy the same area, they are in a position to compete for resources. The more similar their needs, the more intense the competition is likely to be.
While the evolution of new species is a necessary condition for the generation of diversity, it isn't good enough on its own. If a species splits into two daughter lineages that are unable to interbreed, you should have two species. But in order for them to coexist in a given area, some sort of ecological difference needs to have evolved. If two species occupy the same area, they are in a position to compete for resources. The more similar their needs, the more intense the competition is likely to be.
If you set out to answer questions about species diversity, there are two questions you need to consider - how is diversity generated, and how is diversity maintained?
In my recent post on Mexican dry forest, I mentioned the fact that about 80% of the species in the genus Bursera were endemic to Mexico. Things like that tend to jump out at you. Why are there so many species in one area, relative to the rest of its range?
Bursera simaruba has always been one of my favourite tree species. It’s a dry-season deciduous tree with compound leaves and a coppery peeling outer bark and a green (presumably photosynthetic) inner bark. It’s a conspicuous element of tropical dry forests in Trinidad and Tobago, Puerto Rico and parts of southern Florida (where they call it the ‘gumbo limbo’ tree). In all these places it’s the only representative of its genus. In my experience, Bursera was Bursera simaruba, so I was surprised when I came across a Bursera that was grown from seed collected in Costa Rica that was obviously not B. simaruba.
This is the first in a series of posts in which I plan to examine one of the fundamental concepts in ecology - the species-area relationship
Species conservation has always been intimately linked with the idea of habitat conservation. While habitat quality determines the amount of habitat required to protect a viable population of a given species, it’s only a modifier - the determining factor is area. Habitat quality can determine whether you need more or less area, but area is still the critical factor. While protected areas can be set aside for specific species, more commonly protected areas seek to protect as many species as possible. More land is likely to protect more species, but there are other factors that influence conservation decisions like the cost of land acquisition and the competing interests such as agriculture, mining or housing development.
One way to maximise the number of species in a protected area is to include as many habitat types as possible. If you include a forest, a meadow, a marsh and a lake in your protected area, you are likely to get a lot more species than you would if you only had forest habitat. The heterogeneity of the area increases the number of species. (After all, you don’t find a lot of fish in a pine forest, or field mice in a lake.) But again, this overlays a simple factor of area. A larger tract of forest will probably have more species than a smaller tract of forest. A larger section of a marsh will probably have more species than a smaller section of marsh. This fact, known as the species-area relationship is fundamental in both ecology and conservation biology. The existence of a relationship between species richness and area is obvious to anyone who has taken the time to think about it, but it is still interesting enough that it has attracted the attention of generations of ecologists.
Succession is one of the first things that students learn about in ecology. Each intervening stage modifies the environment in such a way that lays the groundwork for the next stage, while making the environment less hospitable to its own offspring. Only the final stage is self-perpetuating and stable.
Frederic Clements, one of the pioneers of community ecology, saw ecological succession as an ontogenic process in which the community - a superorganism - developed into its final, mature form. The orderly progression from bare ground to mature forest is orderly, progressive…and very Victorian.
I'm hosting the 102nd edition of The Tangled Bank, a blog carnival dedicated to science medicine and natural history over at Further Thoughts.
When people think about the destruction and degradation of tropical forests, they tend to focus on rainforests. Tropical dry forests tend to get overlooked. They aren’t as striking - no cathedral-like understorey, no mind-boggling biodiversity. But more importantly, they often just aren’t there. Over much of their potential range they have simply been erased from the landscape. They may have covered as much as 42% of the land area in the tropics1, but have been reduced to less than 27% of their former range in Mexico2, and as little as 2% in Central America3 and New Caledonia4.
Despite this fact, tropical dry forests are often seen as being quite well-adapted to human disturbance.
Plant leaves are photosynthetic organs. Their main job is to harvest energy from sunlight, and use that energy to convert carbon dioxide and water into carbohydrates. In addition to capturing sunlight, leaves need to be good at doing two other things - taking up carbon dioxide and conserving water. These requirements conflict - anything that lets carbon dioxide in also lets water out. To deal with these conflicting requirements, plants produce a waterproof cuticle and regulate carbon dioxide uptake by opening and closing their stomata.
Over the last decade, genetically modified crops have become widespread in agriculture. One of the more successful of these are Bt crops - transgenic plants that express genes derived from Bacillus thuringensis. These genes allow the plants to produce toxins which specifically affect certain groups of insects. Since these plants do not need to be sprayed, and since the toxins are relatively specific, the environmental effects appear to be lower than conventional agriculture.
When European naturalists first visited the New World Tropics they saw vast forests that seemed untouched by humans. While indigenous people often lived in these forests, their populations were small. This led to a perception of tropical forests as primeval, “virgin” forests. In the last few decades, this perception has changed - large areas now covered by mature forests have a history of cultivation. In many cases, “primeval” forests are less than 500 years old.
In response to Wright and Muller-Landau’s paper on the future of tropical forests (which suggests that declining rural populations can allow forest recovery; see my previous post), Sloan pointed out reduced rural population often leads to increased deforestation. Really that’s not a huge surprise - peasant farmers tend to have limited labour to clean and plant land, and being capital-limited they tend not to be able to switch to mechanised agriculture.
In a fairly optimistic paper published in Biotropica in 2006 Joseph Wright and Helene Muller-Landau suggested that declining rates of population growth in tropical countries, coupled with increased urbanisation "give reason to hope that deforestation will slow, natural forest regeneration through secondary succession will accelerate, and the widely anticipated mass extinction of tropical forest species will be avoided." Their assertions have been controversial, and have attracted a fair bit of criticism.
