Lizard blizzard survivors tell story of natural selection

Date:  August 3, 2017

Source:  University of Illinois at Urbana-Champaign

Summary:

An unusually cold winter in the US in 2014 took a toll on the green anole lizard, a tree-dwelling creature common to the southeastern United States. A new study offers a rare view of natural selection in this species, showing how the lizard survivors at the southernmost part of their range in Texas came to be more like their cold-adapted counterparts further north.

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Outnumbered and on others' turf, misfits sometimes thrive

Date: May 31, 2017
Source: University of Texas at Austin

It's hard being a misfit: say, a Yankees fan in a room full of Red Sox fans or a vegetarian at a barbecue joint. Evolutionary biologists have long assumed that's pretty much how things work in nature too. Animals that wander into alien environments, surrounded by better-adapted locals, will struggle. But a team of researchers from The University of Texas at Austin was surprised to find that sometimes, misfits can thrive among their much more numerous native cousins.

"One hundred years of evolutionary theory is built around the idea that immigrants from one population dropped into another population of the same species don't do well," says Daniel Bolnick, a professor of integrative biology and the primary investigator on the study published today in the journal Nature. "Such immigrants are usually rare, and we have found that sometimes their rarity provides a competitive edge."

Bolnick and his team studied a small fish called a three-spined stickleback that lives in the lakes and streams of Vancouver, British Columbia. They studied two populations of the same species: one group that lives in a lake and another group in an adjacent stream.

Evolutionary theory suggests that taking the fish that are adapted to the lake environment and placing them into the stream would put them at a competitive disadvantage compared with the residents. In the dog-eat-dog world of natural selection, outsiders are often poorly adapted to a new environment and less likely to survive or pass on their genes. In the case of the sticklebacks, that's because the lake-adapted fish have different physical traits from their stream-adapted cousins -- such as their overall size, immune traits, body shape and defenses against predators -- that allow them to fare better back home but not necessarily in other environments.



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Stabilizing evolutionary forces keep ants strong

Date: December 20, 2016

Source: Hokkaido University

Hokkaido University researchers are finding evidence of natural selection that maintains the status quo among ant populations.

A type of natural selection, called "stabilizing selection," is thought to maintain functional characteristics in species. But it is difficult to find evidence of this type of selection through research.

"Random genetic drift," on the other hand, where genetic variations occur randomly over time, is an evolutionary process that affects characteristics under "weak selection," implying that maintaining these characteristics is generally unimportant.

Hokkaido University researchers studied two ant species in Japan and Korea that were molecular-phylogenetically indiscriminate -- thus they could be considered one species -- and found evidence that there were different selection forces at play on different body parts.

The researchers first observed how ants use a tiny spur that projects from their legs. They found the front spurs were frequently used to clean the antennae, a major sensory organ in ants. By contrast, the hind spurs were only seldom used to scratch the back surface of the abdomen where no important organs were found.

The team assumed that natural selection forces would strongly affect the front spur, due to its relative importance and its special brush-shape as a cleaning organ. They also assumed that the less functionally important hind spur would be relatively unaffected by natural selection forces.

The researchers found significant genetic differences between ten ant populations of the species, implying there is limited gene flow between them. They also found limited evidence of inbreeding within the populations. This means that any observed morphological differences within and between the populations would reflect how strongly natural selection acted on each character.

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A Snapshot of Pupfish Evolution

Jan. 8, 2013 — Chris Martin has bred more than 3,000 hybrid fish in his time as a graduate student in evolution and ecology at UC Davis, a pursuit that has helped him create one of the most comprehensive snapshots of natural selection in the wild and demonstrated a key prediction in evolutionary biology.

"We can see a surprisingly complex snapshot of natural selection driving the evolution of new specialized species," said Martin, who with Professor Peter Wainwright published a paper on the topic in the Jan. 11, 2013, issue of the journal Science.

The "adaptive landscape" is very important for evolutionary biology, but rarely measured, Martin said. He's been fascinated with the concept since high school.

An adaptive landscape takes variable traits in an animal or plant, such as jaw size and shape, spreads them over a surface, and reveals peaks of success (what evolutionary scientists call fitness) where those traits become most effective, or adaptive.

It is a common and powerful idea that influences thinking about evolution. But while the concept is straightforward, it is much harder to map out such a landscape in the wild.

Read on:  http://www.sciencedaily.com/releases/2013/01/130110142043.htm

Historic collection of naturalist Alfred Wallace goes online for the first time

Treasure-trove of writings and images by the co-discoverer of natural selection

October 2012. The complete works of the great naturalist Alfred Russel Wallace have been made freely available online on the Wallace Online website.

First announcement of the theory of evolution by natural selection
Amongst the thousands of pages of writings, it includes the first announcement of the theory of evolution by natural selection.

Wallace and Darwin
Since the scientist's death 99 years ago, Wallace's complete publications have never been gathered together. The new website is unveiled in time for the centenary celebrations in 2013 that mark the anniversary of Wallace's death in 1913.

Back in the 1850s, Wallace independently formulated the theory of evolution by natural selection during a fit of tropical fever. He later sent an outline of the theory - in one of the greatest ironies in history - to Charles Darwin. To avoid a priority dispute, papers by both men were read together at a London scientific meeting in July 1858. The event unleashed the Darwinian revolution whose shockwaves continue to this day.

Wallace has long been in the shadow of his more famous contemporary Charles Darwin. The compilation of this new website is timely and long overdue. It provides 28,000 pages of searchable historical documents and 22,000 images. They can now be seen free of charge by anyone around the globe at Wallace Online.

Continued:  http://www.wildlifeextra.com/go/news/alfred-wallace.html