Refuting Creationism - How an Ancient Gene Shaped Spider Evolution

Texas brown tarantula, Aphonopelma hentzi,
showing cephalothorax and abdomen

By Mothore - Own work, CC BY-SA 3.0, Link

Texas brown tarantula, Aphonopelma hentzi.

Ancient gene gives spiders their narrow waist | ScienceDaily

Although both have evolved from a segmented ancestor, as can still be seen in the larvae of insects, spiders and mites differ from insects in the number of major body-parts. While insects have well-defines head, thorax (to which wings and legs are attached) and an abdomen, where the reproductive organs or normally located, spiders, scorpions, tics and mites (arachnids or chelicerates) have just two - a cephalothorax, combining the head and thorax, and an abdomen.

Now scientists have discovered a gene in the chelicerates that controls the development of the 'waist' between the cephalothorax and the abdomen, which is missing in insects. The loss of this gene could be the reason the two groups of arthropods evolved in different directions.

The team of scientists, led by Emily V. W. Shetton, of the Department of Integrative Biology, University of Wisconsin-Madison, Madison, Wisconsin, USA, have just published their findings, open access, in PLOS Biology and explained it in a press release reprinted in Science Daily:

The research team also included: Jesús A. Ballesteros of the Department of Biology, Kean University, Union, New Jersey, USA and Pola O. Blaszczyk, Benjamin C. Klementz, and Prashant P. Sharma all of Department of Integrative Biology, University of Wisconsin-Madison.

Creationism in Crisis - Common Origins of Horns, Antlers and Ossicone In Hooved Mammals

Genetics show the common origins of horned, hooved mammals

A diverse array of mammal headgear is on display in the Museum’s Richard Gilder Center for Science, Education, and Innovation as part of the Louis V. Gerstner, Jr. Collections Core.

Alvaro Keding/ ©AMNH

Diverse Mammal Headgear Evolved from Common Ancestor | AMNH

Although the horns of cattle, gazelles and goats look very different to the antlers of deer and the ossicones on the head of a giraffe, and indeed, they are constructed differently, the cells they develop from in the embryo are the cells of the 'neural crest' that also develop into the face rather than the rest of the cranium. That and the fact that the underlying genetic control of their growth is sufficiently similar, provides compelling evidence that they share a common origin from which they, and the orders of which they are typical, have diverged.

This is the conclusion of two researchers at the American Museum of Natural History and Baruch College and the CUNY Graduate Center, who have just published their findings, open access in the journal, Communications Biology. It is also explained in an American Museum of Natural History press release: