Arguments published, in order:
Complexity, ecosystem . . .
Design of vertebrate eye
Expanding forests . . .
Complexity, ecosystem and the art of the soluble
A pond, a meadow and a forest, in Poland. Photo credit Wikipedia
This photograph illustrates parts of a landscape that are often called ecosystems. A scientific definition of an ecosystem is more difficult. Boundaries of the forest are vague. How many species of the forest are included - all the trees, but what about all smaller plants and microbial life of the soil? System implies functional interconnections between most or all parts of the system but in the vast assemblage of species within a forest how can this be possible?
The alternative perspective for understanding of how a lake or meadow or forest works as a whole is to study its parts, as those species that are accessible to be counted, measured and weighed. How those species might interact with others close by is best understood by studying how they have evolved by natural selection to survive and reproduce well within the forest.
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Good or bad design of the eye of vertebrates?
Human eye. Credit: Petr Novák, Wikipedia
The eye is the most important sense organ for us humans. It has been important in the development of ideas about how life evolved. One is the proposition that the design is poor when compared to cameras. Seemingly the problem with our eyes is that the light sensor, the retina, is the wrong way round! The photoreceptor cells, face away from the incoming light. Bad design? An octopus has eyes with the photoreceptor layer facing towards the lens, and with the nerve cells going beneath this layer as they lead from the retina to the brain. Better design?
Our eyes work well because of the inverted retina, not despite it. Our retinas have the highest demand for oxygen of any tissue in our bodies. To supply the retina there are separate blood supplies to inner and outer layers of the retina. This adaptation for vision of high information content is physically possible only with the inverted retina that all vertebrate animals have.
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Are the world's forests really expanding?
Forest cover in part of North America mapped using satellite data; yellow to blue = least to most.
News reports of deforestation and forest fires in the context of the climate crisis are often depressing. But is this the whole story or is there more happening to forests that is cause for optimism? Yes is the short answer, but as often with ecology the story contains accounts of reliable research that seem contradictory. This argument presents the case for optimism when these studies are balanced against each other.
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