Caribbean lizards, victims and survivors of hurricanes

Posted on July 25, 2018 by petrel41

This 2014 video says about itself:

The Phylogenetic Tree of Anole Lizards

Biologist Jonathan Losos describes the traits that enable anole lizard species to live in their various habitats. In this educational video, join Dr. Losos on his quest to understand evolution by natural selection.

Explore the evolutionary path of the green anole lizards found in the Caribbean. Discover how the different species have evolved traits adapted to their environments and developed into distinct species.

From Nature magazine, 25 July 2018:

Hurricane-induced selection on the morphology of an island lizard

Hurricanes are catastrophically destructive. Beyond their toll on human life and livelihoods, hurricanes have tremendous and often long-lasting effects on ecological systems.

Despite many examples of mass mortality events following hurricanes, hurricane-induced natural selection has not previously been demonstrated. Immediately after we finished a survey of Anolis scriptus—a common, small-bodied lizard found throughout the Turks and Caicos archipelago—our study populations were battered by Hurricanes Irma and Maria.

Shortly thereafter, we revisited the populations to determine whether morphological traits related to clinging capacity had shifted in the intervening six weeks and found that populations of surviving lizards differed in body size, relative limb length and toepad size [which may help clinging to trees, thus surviving hurricanes] from those present before the storm.

Our serendipitous study, which to our knowledge is the first to use an immediately before and after comparison to investigate selection caused by hurricanes, demonstrates that hurricanes can induce phenotypic change in a population and strongly implicates natural selection as the cause.

In the decades ahead, as extreme climate events are predicted to become more intense and prevalent, our understanding of evolutionary dynamics needs to incorporate the effects of these potentially severe selective episodes.

Biologists have published a first-of-its-kind look at the physical characteristics of lizards that seem to make the difference between life and death in a hurricane: here.

Hogfish colours, new study

Posted on March 13, 2018 by petrel41

This 2015 video says about itself:

Hogfish at Cleaning Station – Turks and Caicos

A very rare sighting to capture on camera, a hogfish at a cleaning station. After approaching the Hogfish very slowly and passively we managed to capture some fantastic footage of the hogfish being cleaned by some small reef fish. Whilst the hogfish hangs motionless the other fish enter and clean inside of the mouth and gill area. Shot on a GoPro Hero 3 Silver Edition by Kieran Bown.

From Duke University in the USA:

Color-changing hogfish ‘sees’ with its skin

Fish’s skin senses light differently from eyes

March 12, 2018

Summary: The hogfish can go from white to reddish in milliseconds as it adjusts to shifting conditions in the ocean. Scientists have long suspected that animals with quick-changing colors don’t just rely on their eyes to tune their appearance to their surroundings — they also sense light with their skin. But exactly how remains a mystery. A study reveals that hogfish skin senses light differently from eyes.

Some animals are quick-change artists. Take the hogfish, a pointy-snouted reef fish that can go from pearly white to mottled brown to reddish in a matter of milliseconds as it adjusts to shifting conditions on the ocean floor.

Scientists have long suspected that animals with quick-changing colors don’t just rely on their eyes to tune their appearance to their surroundings — they also sense light with their skin. But exactly how “skin vision” works remains a mystery.

Now, genetic analysis of hogfish reveals new evidence to explain how they do it. In a new study, Duke University researchers show that hogfish skin senses light differently from eyes.

The results suggest that light-sensing evolved separately in the two tissues, said Lori Schweikert, a postdoctoral scholar with Sönke Johnsen, biology professor at Duke.

With “dermal photoreception”, as it is called, the skin doesn’t enable animals to perceive details like they do with their eyes, Schweikert said. But it may be sensitive to changes in brightness or wavelength, such as moving shadows cast by approaching predators, or light fluctuations associated with different times of day.

Schweikert, Johnsen and Duke postdoctoral associate Bob Fitak focused on the hogfish, or Lachnolaimus maximus, which spends its time in shallow waters and coral reefs in the western Atlantic Ocean, from Nova Scotia to northern South America. It can make its skin whitish to blend in with the sandy bottom of the ocean floor and hide from predators or ambush prey. Or it can take on a bright, contrasting pattern to look threatening or attract a mate.

The key to these makeovers are special pigment-containing cells called chromatophores, which, when activated by light, can spread their pigments out or bunch them up to change the skin’s overall color or pattern.

The researchers took pieces of skin and retina from a single female hogfish caught off the Florida Keys and analyzed all of its gene readouts, or RNA transcripts, to see which genes were switched on in each tissue.

Previous studies of other color-changing animals including cuttlefish and octopuses suggest the same molecular pathway that detects light in eyes may have been co-opted to sense light in the skin.

But Schweikert and colleagues found that hogfish skin works differently. Almost none of the genes involved in light detection in the hogfish’s eyes were activated in the skin. Instead, the data suggest that hogfish skin relies on an alternative molecular pathway to sense light, a chain reaction involving a molecule called cyclic AMP.

Just how the hogfish’s “skin vision” supplements input from the eyes to monitor light in their surroundings and bring about a color change remains unclear, Schweikert said. Light-sensing skin could provide information about conditions beyond the animal’s field of view, or outside the range of wavelengths that the eye can pick up.

Together with previous studies, “the results suggest that fish have found a new way to ‘see’ with their skin and change color quickly”, Schweikert said.

Caribbean fish citizen science

Posted on March 14, 2013 by petrel41

This video from Mexico is called Fish at the Coral Reef – Mayan Riviera.

From the University of East Anglia in Britain:

Marine Diversity Study Proves Value of Citizen Science

Mar. 12, 2013 — Citizen science surveys compare well with traditional scientific methods when it comes to monitoring species biodiversity — according to new research from the University of East Anglia.

Research published today in the journal Methods in Ecology and Evolution shows that methods to record marine diversity used by amateurs returned results consistent with techniques favoured by peer-reviewed science.

The findings give weight to the growing phenomenon of citizen science, which sees data crowd-sourced from an army of avid twitchers, divers, walkers and other wildlife enthusiasts.

The field study compared methods used by ‘citizen’ SCUBA divers with those used by professional scientists, to measure the variety of fish species in three Caribbean sites.

The divers surveyed the sites using two methods — the ‘belt transect’, used in peer reviewed fish diversity studies, and the ‘roving diver technique’, used by the Reef Environmental Education Foundation (REEF) volunteer fish survey project.

Two teams of 12 divers made 144 separate underwater surveys across the sites over four weeks.

While the traditional scientific survey revealed sightings of 106 different types of fish, the volunteer technique detected greater marine diversity with a total of 137 in the same waters.

Dr Ben Holt, from UEA’s school of Biological Sciences, led the research in partnership with the Centre for Marine Resource Studies in the Caribbean and the University of Copenhagen, Denmark.

He said: “The results of this study are important for the future of citizen science and the use of data collected by these programs. Allowing volunteers to use flexible and less standardised methods has important consequences for the long term success of citizen science programs. Amateur enthusiasts typically do not have the resources or training to use professional methodology. Our study demonstrates the quality of data collected using a volunteer method can match, and in some respects exceed, protocols used by professional scientists.

“Enlisting the help of a large pool of volunteers helps professional researchers collect valuable data across many ecosystems.

“The popularity of SCUBA diving has resulted in monitoring of the underwater environment on a scale that was previously impossible. For example, the REEF method has been used by volunteers in more than 160,000 underwater surveys across the world. It would have cost many millions of pounds for professionals to have undertaken the same work.

“Very few, if any, scientific groups can collect data on the scale that volunteer groups can, so our proof that both methods return consistent results is very encouraging for citizen science in general.

“I think we will really see the value of volunteer schemes increase in future. We’re living in a world that’s changing very significantly. Environmental changes are having a big impact on ecosystems around us so we need to harness new ways of measuring the effect.

“For example Lion fish is an invasive species which was not in the Caribbean until roughly 10 years ago. They have now become a real problem in many areas and this invasion has been tracked using volunteer data. Following our study, scientists can have more confidence when using these data to consider the impact of threats, such as invasive species, on the wider natural communities.

“It is important to note that our study does not consider the abilities of the individuals performing the surveys and this is also an important consideration for any large scale biodiversity program. By addressing these issues we can make important steps towards enabling the large pool of volunteer enthusiasts to help professional researchers by collecting valuable data across many ecosystems.”

The research was carried out in under water sites close to South Caicos in the Turks and Caicos Islands.