New designs in well-studied species

Photo credit: David Coppedge.

While it’s fascinating to discover new species in exotic environments, sometimes common organisms that scientists thought they knew about turn out to possess equally amazing traits. These examples, one representing a giant plant and the other a small animal, suggest that biologists will never run out of functional designs to discover any time soon. Sometimes they just need to take a closer look.

redwood leaves

The Coastal Redwoods of Northern California (Sequoia sempervirens) are well known for their superlatives: the tallest trees in the world, among the most massive living things, and perfectly suited for survival against pests and fires. Tourists by the millions love to walk the trails through these magnificent specimens. For decades, scientists have studied them from the base to the crown. Is there anything else to learn? Ask the scientists at the University of California, Davis: “Redwoods are among the most studied trees on the planet, yet their mysteries continue to surprise and delight scientists and nature lovers alike.”

The new surprise is that these trees have two types of leaves – not one, as previously thought – and there is a “division of labor” between them. There is a good functional reason for this:

Scientists from the University of California, Davis have found that redwoods have two types of leaves, and these leaves have completely different jobs, according to a study in the American Journal of Botany. Together, these functionally distinct sheets allow the tallest trees in the world to thrive in both wet and dry parts of their range in California, without sacrificing water or food. [Emphasis added]

Two types of leaves

Check out the photo of the two leaf types below, by Alana Chin at UC Davis, via EurekAlert!

The “peripheral leaf” extends its leaflets outward to capture light for photosynthesis. The “axial leaf” type wraps its leaflets around the stem to absorb water. Additionally, it has been found that trees can shift populations of these leaf types up or down the tree depending on the environment, as if rearranging their “office space” for a better productivity.

The peripheral leaf spends its working hours making food for the tree – converting sunlight into sugar through photosynthesis. Its colleague, the axial leaf, does almost nothing to help with photosynthesis. In place its specialty is to absorb water. In fact, the study found that a large redwood can absorb up to 14 gallons of water in just the first hour its leaves are wet.

In the wetter northern parts of the redwood range, the crowns produce more peripheral leaves to gather as much light as possible during inclement weather. These leaves have a waxy coating that slows water absorption without hindering photosynthesis. In the southern parts of the range, the axial leaves sit higher in the tree “to take better advantage of fog and rain, which occur less often in a drier environment”. Leaf types are therefore distributed throughout the tree for better overall productivity.

De facto Design reasoning

Whether or not biologists accept the theory of intelligent design, the discoveries were made by de facto design reasoning:

“I would be surprised if there weren’t a lot of conifers doing this,” said lead author Alana Chin, who holds a Ph.D. an ecology student in the Department of Plant Sciences at UC Davis at the time of the study. “Having leaves that are not meant for photosynthesis is in itself surprising. If you’re a tree, you don’t want to have a leaf that isn’t. photosynthesis unless there is a very good reason for it.

Plants cannot move for cover. Instead, they internally adjust their cells, tissues, and structures to make the best of their situation. These majestic trees, which rise high in the sky against the force of gravity, present multiple strategies to obtain the best performance, no matter where their seeds land. From cells that use strong building blocks to form woody tissue and bark that can support the weight of 100 million leaves and branches, to vessels that can carry water over 300 feet high, to the protective bark that can protect them from pests and forest fires. , these giants rightly inspire our admiration. Here is another surprising functional design that was discovered on closer inspection.

grasshopper teeth

If redwoods are synonymous with tallness, grasshoppers represent the opposite. And what insect could be more common or familiar? You would think that there is nothing more to learn about them. However, biologists from the University of Leicester have just discovered something “surprising”: “What do grasshoppers eat? It’s not just grass! New research from Leicester shows similarities to mammalian teeth like never before. Like mammalian teeth? No kidding.

New research by paleobiologists at the University of Leicester has identified surprising similarities between the mouths of grasshoppers and the teeth of mammals.

Perhaps the Old Testament prophet Joel was prescient when he described locusts as having “teeth [like] lion’s teeth.

There are approximately 11,000 known species of grasshoppers. It’s probably surprising that not all grasshoppers eat grass. In fact they play a range of important roles in grasslands and other ecosystems – some are even carnivorous.

Luckily, there are no man-eating grasshoppers roaming our lawns like lions on the prowl. The team explains their reason for taking a closer look at grasshopper teeth:

Understand the relationship between form, function and nutrition in foraging structures is essential to limit the roles of organisms in their ecosystem and the adaptive responses to food resources. However, analysis of this relationship in invertebrates has been hampered by a reliance on descriptive and qualitative characterization of forms feeding structures. This led to a lack of sound statistical analyzes and overreliance on analogy and plausibility, especially for extinct taxa and hard-to-see feeding animals.

Using non-destructive imaging methods, the team obtained more precise and precise measurements of the shape of the teeth of 45 extant species of grasshoppers found in museum display cases. To their surprise, the same models biologists use to infer the diet of extinct mammals from their teeth can be used to infer the diet of Orthoptera, the order of insects that includes grasshoppers, locusts, and locusts. crickets. Stockey’s open access article et al. in Methods in ecology and evolution States:

We find that topographic measurements applied to Orthoptera successfully recover the same relationship between food indocility and morphology of dental tools as they do in mammals, and this combination of individual metrics in the multivariate analysis most strongly captures this relationship. Furthermore, multivariate topographic metrics calibrated on food consumed by mammals accurately predict dietary differences among Orthoptera (82% taxa correctly assigned).

A look at the shape of grasshopper teeth confirms a variety of contours suited to the diet of each species: whether jagged with “complex undulating landscapes” for cutting plant material or sculpted with “steeper slopes and edges sharper cliffs” to eat worms and other insects.

Form and function

But how can the relationship between form and function be so similar between mammals and grasshoppers when they have no evolutionary relationship? They don’t say it, even if they find it “pretty incredible”.

Surprisinglycomparing grasshopper mandible landscapes with mammalian teeth predicts grasshopper diet with 82% accuracy — quite amazing considering that the mouthparts of mammals and grasshoppers evolved independently over 400 million years and were not present in their common ancestor.

In effect. Given the evolutionary premises, similar forms should not be expected to “span large phylogenetic distances”.

Our analyzes confirm that the love relationship between topographic metric values ​​and Orthoptera diet is primarily a measure of ecological similarity rather than a reflection of the closeness of evolutionary relationships. The similarity of multivariate metrics between the Orthoptera and mammals with similar diets discussed below further demonstrate this.

Multivariate analysis provides powerful confirmation that the the relationship between form and function in feeding structures holds true across phylogenetic distance: non-homologous feeding structures distant taxa are comparable.

Not much help from Darwinism

Darwinism doesn’t seem to have provided much help in understanding this lesson that form follows function. The team hasn’t even begun to speculate on how these functional designs might have appeared independently. Their last paragraph states:

Our results indicate a high degree of comparability of dental tools and food indocility in animals separated by vast phylogenetic distances. Further validation of the relationship between dental topographic parameters and diet would be useful, adding dietary specificities for non-gnathostoma groups in particular. But it is clear that multivariate dental topographic analysis can be confidently applied to a wide range of feeding structures with functions similar to those of teeth, allowing quantitative analysis and statistical hypothesis testing of the relationships between form, function, and diet across much of bilateral phylogeny and through half a billion years of evolution.

This narrative gloss says more about the gullibility underlying a blind commitment to Darwinism than it does about the actual utility of Darwin’s theory in bringing understanding. Intelligent design theory has a ready-made assumption that form follows function: any successful organism will have the toolkit necessary for its success. ID encourages scientists to take a closer look and learn. When they do, as these two examples illustrate, wonderful new functional designs are likely to appear.


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