Navigation Links
News tips from the May/June issue of Physiological and Biochemical Zoology
Date:5/2/2011

MAY/JUNE PBZ TIPSHEET

  • Giant Hummingbirds: Running a little hot, but not on empty
  • What keeps an asexual fish species from taking over?
  • Small sea birds: Holding heat, rather than cranking up the furnace

For the complete table of contents for the May/June issue, go to journals.uchicago.edu/pbz.


Giant Hummingbirds: Running a little hot, but not on empty

Scientists have long thought that the giant hummingbird (Patagona gigas) was just about as big as a hummingbird could get. They're nearly twice the size of the next largest species, and it was assumed that the energy needed for hovering flight would take the giants close to the upper metabolic limits for an animal that size. Not so, according to a study led by Mara Jos Fernndez of the University of California, Berkeley, and the Pontificia Universidad Catlica de Chile. Fernndez and her colleagues measured the amount of energy burned by giant hummingbirds when hovering and at rest. They also assessed the total amount of energy that the birds use in a day. The research found that giant hummingbirds do use more energy for their body size than smaller hummingbirds do, but they were still well below what is thought to be the upper metabolic limit. The finding suggests that metabolism is not necessarily the constraining factor in the evolution of hummingbird body size.

Mara Jos Fernndez, Robert Dudley, and Francisco Bozinovic, "Comparative Energetics of the Giant Hummingbird (Patagona gigas).


What keeps an asexual fish species from taking over?

When a red-bellied dace and a finescale dace (freshwater fish in the carp and minnow family) mate with each other, they produce a hybrid with a very special ability: it can reproduce asexually. This asexual hybrid should have a tremendous evolutionary advantage over its sexually reproducing forefathers. In sexual populations, two individuals need to get together to reproduce, but in asexual populations every individual can reproduce on its own, giving asexuals twice the reproductive potential. Theoretically, the asexual advantage should enable the hybrids to outcompete sexual dace living in the same pond. But in reality that doesn't happen. Sexual and asexual dace are known to live side-by-side. So why doesn't the hybrid dace take over? According to a study by researchers from the University of British Columbia, it's because the hybrids aren't as healthy. Using swimming speed as a proxy for overall health, the researchers found that hybrids performed worse than at least one of the parent species in a series of speed tests. The results suggest that at minimum, the hybrid has no physiological performance advantage over the sexual species, and is probably at something of a disadvantage. The lower physiological performance may counteract the hybrids' reproductive advantage, preventing them from taking over. The results offer one possible explanation for why sexual reproduction has stayed dominant in vertebrates.

Jonathan A. Mee, Colin J. Brauner, and Eric B. Taylor, "Repeat Swimming Performance and Its Implications for Inferring the Relative Fitness of Asexual Hybrid Dace (Pisces: Phoxinus) and Their Sexually Reproducing Parental Species."


Small sea birds hold heat rather than cranking up the furnace

A new study offers some clues about how small aquatic birds survive in extremely cold climates. Staying warm is hard work for aquatic birds. Heat loss is around twenty times greater in water than in air, so aquatic birds have to increase their resting metabolism to generate heat on the water. Heat loss is an even greater issue for small birds, so it was assumed that small birds would have to increase their metabolism in water even more than large birds do. But according to a study by researchers at the University of Wyoming, that's not always the case. The researchers studied the metabolism of Cassin's auklets, a small sea bird found throughout the Northern Pacific Ocean. They found that auklets do increase their metabolism on the water, but not as much proportionately as some larger birds do. In fact, ducks, auks, cormorants, and small penguins responded quite differently to air and water temperatures, perhaps reflecting very different demands during evolutionary history.

Samantha E. Richman and James R. Lovvorn, "Effects of Air and Water Temperatures on Resting Metabolism of Auklets and Other Diving Birds."


'/>"/>

Contact: Kevin Stacey
kstacey@press.uchicago.edu
773-834-0386
University of Chicago Press Journals
Source:Eurekalert

Related medicine news :

1. The Hastings Center Report table of contents for May/June 2010
2. Tissue spacers reduce risk of rectal injury for prostate cancer patients
3. Rice wins $1.2 million for heart-valve tissue research
4. Researchers inject nanofiber spheres carrying cells into wounds to grow tissue
5. Study shows how discrimination hurts: lack of fair treatment leads to obesity issues
6. Brachytherapy, the official journal of ABS, expands to 6 issues in 2011
7. Sleep issues contribute to cognitive problems in childhood cancer survivors
8. Insights gained from growing cold-causing virus on sinus tissue
9. Experts issue recommendations for evaluating and treating pituitary incidentalomas
10. Quality health care delivery key election issue, says CMAJ
11. Newsbriefs from the April issue of the journal Chest
Post Your Comments:
*Name:
*Comment:
*Email:
(Date:6/27/2016)... ... 2016 , ... TopConsumerReviews.com recently awarded their highest five-star rating to Best Buy ... in the United States and Canada wear eyeglasses. Once considered to be a purely ... make a fashion statement. Even celebrities use glasses as a way of creating an ...
(Date:6/26/2016)... ... ... Brent Kasmer, a legally blind and certified personal trainer is helping to develop a weight ... app plans to fix the two major problems leading the fitness industry today:, ... program , They don’t eliminate all the reasons people quit their exercise program ...
(Date:6/25/2016)... ... June 25, 2016 , ... "With 30 hand-drawn hand gesture animations, ... Christina Austin - CEO of Pixel Film Studios. , ProHand Cartoon’s package transforms ... Final Cut Pro X . Simply select a ProHand generator and drag it above ...
(Date:6/25/2016)... Canada (PRWEB) , ... June 25, 2016 , ... Conventional ... pursuit of success. In terms of the latter, setting the bar too high can ... risk more than just slow progress toward their goal. , Research from ...
(Date:6/24/2016)... ... June 24, 2016 , ... ... Scientific Sessions in Dallas that it will receive two significant new grants to ... came as PHA marked its 25th anniversary by recognizing patients, medical professionals and ...
Breaking Medicine News(10 mins):
(Date:6/23/2016)... June 23, 2016 Capricor ... ), a biotechnology company focused on the discovery, ... that patient enrollment in its ongoing randomized HOPE-Duchenne ... exceeded 50% of its 24-patient target. Capricor expects ... third quarter of 2016, and to report top ...
(Date:6/23/2016)... BOGOTA, Colombia , June 23, 2016  Astellas today announced the establishment of Astellas Farma Colombia ... the company,s second affiliate in Latin America . ... ... Farma Colombia ... ...
(Date:6/23/2016)... Tenn. , June 23, 2016 /PRNewswire/ ... automating, integrating and transforming the patient payment ... of several innovative new products and services ... of its revenue cycle offerings. These award-winning ... more efficient workflows, remain compliant in an ...
Breaking Medicine Technology: