She has cracked a long-standing conundrum about insect eggs.
Whereas most researchers work with only a handful of well-studied animals, such as fruit flies and mice, Extavour’s success comes from her penchant for less-ubiquitous lab critters, such as sand fleas and crickets. Typical model organisms harbour just a fraction of the diversity found in nature, so alongside the usual suspects, she examines a wide range of animals that help to reveal which genetic tools evolution most commonly uses.…
The researchers looked for connections between egg shapes and sizes and many insect features, including where the insects lay their eggs and the time it takes for a fertilized egg to turn into a larva. The analysis revealed a surprise: the evolution of egg shape and size depends largely on where the eggs are laid. Eggs laid in water are often small and spherical; those deposited into the body of another animal are also small, but tend to be oddly shaped.
The findings challenge old assumptions that relate egg size to adult body size, says Laura Lavine, an insect physiologist and evolutionary biologist at Washington State University in Pullman. Many scientists assumed that those size relations were the “end of the story”, Lavine says. “Now the story starts from this study,” she says. Understanding how eggs change depending on the environment could reveal some of the major constraints on how animals grow and evolve, Lavine says.Giorgia Guglielmi, “The biologist using insect eggs to overturn evolutionary doctrine” at Nature
Studies of eggs from nearly 7000 insect species, showed that no traditional theory about what governs egg size held water:
“The eggs reflect the local ecological conditions that the eggs themselves are living in, much more than anything about the other life stages,” Woods says.
Thus, earlier ideas explaining egg size and shape based on their correlations to traits like developmental time and adult size appear to be incorrect. Big adults don’t always come from big eggs; nor does egg size correlate with development time. Insects have life cycles with four life stages (egg, larva, pupa, adult), each with its own ecology, and each is subject to different selective pressures, Woods explains. “Their data support the idea that the stages may be less connected to one another than we thought, and that shows up in the data as the evolution of the egg stage in relation to its own proximate environments rather than in relation to other stuff happening in other parts of the life cycle. That’s just super cool,” Woods says.Viviane Callier, “Ecology, Not Physics, Explains Diversity of Insect Eggs” at The Scientist
The new findings almost put the egg in charge of its own shape, not what anyone expected to hear. But also note this:
One of the key things Extavour says was critical in their analysis was to take the phylogenetic relationships of the insects into account using sophisticated statistical methods, because otherwise one could be led to incorrect conclusions. For instance, many beetles tend to have round eggs, so similarities between beetle species are explained by their evolutionary relatedness, not ecology. Only because the researchers chose features such as endoparasitism and aquatic egg laying, which have evolved independently many times, and because they had complete information about the insect evolutionary tree that allowed them to control for the relatedness, were they able to find the pattern that the egg’s environment predicted its size and shape.Viviane Callier, “Ecology, Not Physics, Explains Diversity of Insect Eggs” at The Scientist
Darwinians don’t like ecology much but they had better get used to it.
Is Extavour the new Lynn Margulis?
See also: Darwinism is taking a beating in the Anthropocene It gets really interesting when the anti-Darwinists are not creationists but fronting various neglected ideas like epigenetics. Will they be more vicious?