Abaco, Bahamas lost songbirds by climate change


This video from the USA says about itself:

Eastern Bluebird Song

23 April 2015

Male Bluebird on the Ball listening to other birds call, sing, and a woodpecker pounding, chased by doves, sliding off the ball and finally singing as a female sits in her new front yard nest nearby.

From the University of California – Riverside in the USA:

Bahamian songbirds disappeared during last glacial-interglacial transition

Warming event 12,000 years highlights the impact of climate change on ecosystems

August 29, 2017

Two species of songbirds that once made a home in the Bahamas likely became extinct on the islands because of rising sea levels and a warmer, wetter climate, according to a new study by researchers at the University of California, Riverside and the University of Florida, Gainesville. The study, which was published in the Proceedings of the National Academy of Sciences, presents a historical view of how climate change and the resulting habitat loss can affect Earth’s biodiversity.

Titled “Origin, Paleoecology and Extirpation of Bluebirds and Crossbills in the Bahamas Across the Last Glacial-Interglacial Transition,” the authors are Janet Franklin, distinguished professor of biogeography in UCR’s College of Natural and Agricultural Sciences, and David Steadman, curator of ornithology at the Florida Museum of Natural History at the University of Florida.

The Eastern Bluebird (Sialia sialis) and Hispaniolan Crossbill (Loxia megaplaga) were among 17 species of birds that were found on the Bahamian Island of Abaco during the last Ice Age, but that no longer live there today. Both species are still alive elsewhere, with the former found in continental North America and the latter in Hispaniola. Fossil records from Abaco suggest that these birds resided on the island year-round, as opposed to migrating there in winter.

This is a Hispaniolan Crossbill video in Spanish from the Dominican Republic.

“The abundance of fossils, the presence of young birds among the fossils, and the evolution of a shorter wingspan in the Eastern Bluebird all suggest that these birds did not migrate to the island but were a resident population. But then they disappeared,” Franklin said.

Unlike many bird species that are now extinct on the Earth’s small islands, the Eastern Bluebird and the Hispaniolan Crossbill disappeared long before the first people arrived, uncoupling their extinction from human actions, such as the introduction of new predators and habitat loss for agricultural use. Instead, the fossil record indicates they vanished during the Earth’s glacial-interglacial transition, which occurred about 12,000 years ago and led to much warmer conditions and the start of the current Holocene period.

Using topographic data and sea level models, Franklin modelled the effect of this transition, showing how of a 400-foot rise in sea level affected the Bahamas, reducing their land area by more than ten-fold. Climate models showed that the cooler, drier Bahamian weather would have provided suitable habitat for these species.

“We know from studying these birds today that their habitats are pine grasslands that are found in cooler, dryer regions. These habitats were lost when the Bahamian Islands became more tropical,” Franklin said.

Franklin said the research underscores what might happen to threatened species in the future, with rapid climate change happening on a scale of decades rather than millennia.

“In the coming decades both modern day climate change and other human activities will have a profound impact on our ecosystem. Anthropogenic climate change and resulting sea level rise are now happening much more rapidly than at the transition from the last ice age to the modern global climate. Species and ecosystems do not have time to adjust, especially when climate change is happening in a world where people have transformed the face of the planet in other ways, through deforestation and so forth.”

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Bahamas pupfish, new study


Bahamas pupfish

This picture about Bahamas pupfish shows San Salvador Island generalists (red), molluscivores (green), large-jawed scale-eaters (dark blue), small-jawed scale-eaters (light blue), and outgroup species (black) in the Caribbean, California, and Mexico. Credit: Emilie Richards and Christopher Martin; CC-BY.

From PLOS:

San Salvador pupfish acquired genetic variation from island fish to eat new foods

Study finds that ecological and genetic factors both contributed to rise of new pupfish species

August 10, 2017

Pupfish living in salty lakes on San Salvador Island were able to diversify into multiple species with different eating habits, in part, by interbreeding with pupfish from other islands in the Caribbean, report Emilie Richards and Christopher Martin, of the University of North Carolina at Chapel Hill, August 10, 2017 in PLOS Genetics.

Pupfish are small, brightly colored fish that commonly live in coastal areas and salty lakes and feed off of algae. But on San Salvador Island in the Bahamas, a group of pupfish has undergone adaptive radiation, a process where existing species rapidly evolve and differentiate into new species, to take advantage of a new environment. Where most pupfish species eat algae, one San Salvador species has a protruding nasal region that allows it to eat snails, while another has enlarged jaws that enable it to bite the scales off of other fish. To understand why these specialized species evolved only on San Salvador Island, despite the availability of scales and snails across the Caribbean, the researchers used whole genomes to identify regions of the San Salvador pupfish genome that came from outside sources.

They examined 42 pupfish genomes collected from populations on San Salvador Island, two distant Caribbean islands, Laguna Chichancanab in Mexico, and Devil’s Hole in California, to identify regions of the genome that have been exchanged between San Salvador Island and outside pupfish populations. They identified 11 gene variants in the San Salvador fish that came from other Caribbean pupfish populations, with four of these regions known to affect jaw size and shape, traits important in the evolution of their specialized diets.

The study suggests that multiple outside sources of genetic variation contributed to the adaptations found in pupfishes on San Salvador Island. These findings indicate that a complex suite of factors, including breeding with related species, in addition to new ecological opportunities, may be necessary for adaptive radiations to occur.

“The really intriguing thing here is that new species are assembled from different pots of genetic variation over a very large range. Our own species is likely no different,” says study corresponding author Dr. Martin.

Bahamas wild spotted dolphins


This video says about itself:

27 January 2017

In the Bahamas, a group of wild Spotted Dolphins play “keep away” with a bandana–a game they invented with seaweed and people started playing with them. Jonathan travels to the Bahamas with dolphin expert Wayne Scott Smith to meet these playful animals and try playing the Bandana Game with them.

How a dolphin eats an octopus without dying, by Sarah Zielinski. 1:00pm, April 25, 2017: here.

Shark senses research


This video says about itself:

7 October 2016

In the Bahamas, Jonathan joins shark biologist Dr. Stephen Kajiura from Florida Atlantic University to perform an experiment which demonstrates how the electrosensory system of sharks works.

JONATHAN BIRD‘S BLUE WORLD is an Emmy Award-winning underwater science/adventure program that airs on public television in the United States.