Turning pretty penstemon flowers from blue to red

While roses are red, and violets are blue, how exactly do flower colors change?

In the case of penstemons, with over 200 species to choose from, scientists Carolyn Wessinger and Mark Rausher have now shown that turning their flowers from blue to red involves knocking out the activity of just a single enzyme involved in the production of blue floral pigments.

A genetically conserved biochemical pathway produces the vivid blue pigments that they found to mutate over time to produce red. To shift into red pigment production, the enzyme flavonoid 3', 5' -hydroxylase (F3'5'h) is functionally inactivated in the 13 red-flowered species they examined by mutations that abolish enzyme activity. This occurred by independent evolutionary events, showing a relatively simple, predictable genetic change behind the evolution from blue to red penstemons.

While blue can change to red, in this case, evolution always drives down a one-way street, as reverse changes of red to blue are not observed.

"Evolutionary shifts from blue to red flowers in Penstemon predictably involves degeneration of the same particular flower pigment gene, suggesting there are limited genetic 'options' for evolving red flowers in this group," said Wessinger. "However, it is lot easier for evolution to break a gene than to fix one, so we suspect that reversals from red to blue flowers would be highly unlikely."

Source: Science daily

N.H.Kh

Vast carbon residue of ocean life

The oceans hold a vast reservoir -- 700 billion tons -- of carbon, dissolved in seawater as organic matter, often surviving for thousands of years after being produced by ocean life. Yet, little is known about how it is produced, or how it's being impacted by the many changes happening in the ocean.

Think of dissolved organic carbon, or DOC, in the ocean as tree leaves and other dead organic matter falling to the forest ground -- a portion of this natural carbon sustains life while the remainder remains hidden in the soils, being sequestered for many years. As is true in the forests, this vital, residual carbon reservoir is necessary to sustain life in the ocean, and to sequester vast amounts of carbon in its great depths.

Jumping spiders are masters of miniature color vision

Jumping spiders were already known to see in remarkably high resolution, especially considering that their bodies are less than a centimeter long. Now, researchers have figured out how spiders in the colorful genus Habronattus see in three color "channels," as most humans do.

"The eyes of jumping spiders could not be more different from those of butterflies or birds, and yet all three tune the color sensitivities using pigments that filter light," says Nathan Morehouse. "It's actually a pretty clever, simple solution with a big payoff."

The "spectral filtering" the researchers discovered had never before been described in any spider. That makes this visual strategy a remarkable example of evolutionary convergence.

Spiders have four pairs of eyes that pick up on different aspects of their surroundings. The new study shows that their "principal eyes" see in red, green, and UV. Their secret is a filter that converts some green-sensitive cells in their eyes to seeing red, much like a pair of sunglasses.

Birds who flock together become firm friends

It is often said that birds of a feather flock together.

In fact, birds who flock together become firm friends and even set up home near each other.

A study of great tits found that when the birds settle down to breed in the spring, they chose sites near the flockmates they spent the most time with over the winter.

Researcher Josh Firth said studied great tits that live in woods.

The birds wore ankle tags that provide information on which feeding boxes they visit.

Great white sharks and tuna share genetics that makes them super predators

Despite evolving separately for 400 million years, some sharks and tuna share genetic traits linked to higher metabolism and quick swimming behaviour.

Tuna fish and the lamnid group of sharks, which includes great white sharks, share some similar traits that help make them super predators, including their style of swimming and their ability to stay warm.