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(Bio) Crustacean: Evolution Doesn't Always Favor Bigger Size

 
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PostPosted: Thu Jan 19, 2006 8:41 am    Post subject: (Bio) Crustacean: Evolution Doesn't Always Favor Bigger Size Reply with quote






Source: University of California - San Diego
Date: 2006-01-18
URL: http://www.sciencedaily.com/re.....091713.htm

--------------------------------------------------------------------------------

Study Finds Evolution Doesn't Always Favor Bigger Animals

Biologists have long believed that bigger is better when it comes to body size, since many lineages of animals, from horses to dinosaurs, have evolved into larger species over time.

But a study published this week by two biologists at the University of California, San Diego in an early online edition of the Proceedings of the National Academy of Sciences suggests that maxim, known as “Cope’s Rule,” may be only partly true.

The scientists found that populations of tiny crustaceans retrieved from deep-sea sediments over the past 40 million years grew bigger and evolved into larger species, as might be predicted from Cope’s Rule. However, the changes in the sizes of these clam-like crustaceans commonly known as ostracodes —from the genus Poseidonamicus — increased only when the global ocean temperature cooled. When temperatures remained stable, not much happened to body size.

“These data show a very nice correlation between temperature and body size,” said Kaustuv Roy, a professor of biology at UCSD and a coauthor of the paper.

“Although not the most glamorous of fossils, deep-sea ostracodes are very useful for this question because they have a rich fossil record, which allows us to reconstruct the evolution of body size in great detail,” said Gene Hunt, who designed and conducted the study while postdoctoral fellow at UCSD.

“Scientists have been interested in how body size evolves for a long time, but there is a lot of uncertainty about what factors are most important in determining whether animals get bigger or smaller over time,” added Hunt, now a curator at the National Museum of Natural History in Washington, DC.

The two scientists said their data suggest that Cope’s Rule—named for Edward Cope, a 19 th century American paleontologist who claimed the fossil record showed that lineages became larger over time—may simply be an evolutionary manifestation of Bergmann’s Rule, which holds that animals increase in mass in colder environments.

Biologists had long assumed that Bergmann’s Rule—named after the 19 th century German biologist Christian Bergmann—reflected the adaptation of warm-blooded animals to become larger when they move in colder environments. The reason: Bigger animals have smaller surface to volume ratios and can more effectively conserve heat in cold environments. Similarly, smaller animals with larger surface to volume ratios are better adapted to warmer environments where they can more effectively dissipate heat.

However, this simple relationship doesn’t explain why ostracodes and other cold-blooded creatures that do not regulate their internal body temperatures, such as mollusks to turtles, also follow this rule.

“It is a bit of a puzzle why Bergmann's Rule holds in cold-blooded animals like ostracodes,” said Hunt.

Hunt and Roy found that as ocean temperatures declined by some 10 degrees centigrade, from 40 million years ago to the present day, the overall size of the deep-sea ostracode Poseidonamicus dramatically increased.

“It’s not just that the small species got replaced by a larger species,” said Roy. “The same species, the same lineage got bigger over time.”

In addition, the biologists discovered that the body size increases in nine species of ostracodes that evolved over that 40 million year span were commensurate with the change expected given how much the ocean temperatures decreased over this time and how body sizes of living ostracodes vary with temperature. On average, for every degree centigrade of climatic cooling, each of the species of Poseidonamicus increased in length by about 29 micrometers.

Hunt and Roy said biologists are uncertain what may be triggering this biological response to larger size from cool environments. Nevertheless, the UCSD study is important because it establishes a firm link between climatic change and the body size of organisms, paving the way for a better understanding of the evolution of body size in fossil organisms as well as in environments that are now being impacted by global warming.

“There’s still a huge debate over what drives Cope’s Rule, but our study shows that climate change can undoubtedly play an important role” said Roy.

For much of the past 40 million years, global climate has been exhibiting a steady cooling trend. But within the last century, as greenhouse emissions have accumulated in our atmosphere, temperatures have rapidly warmed.

“If you look at most of life today, they’ve all been adapted to a world getting gradually cooler,” said Roy. “But our future is destined to be significantly warmer. What are animals going to look like when everything must adapt to a warmer world? Size correlates with many aspects of the biology of an animal so changes in size are likely to translate into substantial ecological changes. A better prediction of the biological effects of future global change requires that, among other things, we understand how climate change shapes body size evolution.”

The study was supported by a grant from the National Science Foundation.

*************************************************************

Questions to explore further this topic:

What are crustaceans?

http://www.seasky.org/reeflife/sea2e.html
http://www.kidport.com/RefLib/.....aceans.htm
http://www.enchantedlearning.c.....ndex.shtml
http://www.amonline.net.au/invertebrates/cru/
http://mbgnet.mobot.org/salt/o.....aceans.htm
http://www.mesa.edu.au/friends.....ceans.html
http://tolweb.org/tree?group=C.....Arthropoda

What are arthropods (the bigger group to which crustaceans belong)?

http://www.ucmp.berkeley.edu/a.....opoda.html
http://www.imagequest3d.com/ca.....ropods.htm

Crustaceans: A Detaled Lesson

http://www-biol.paisley.ac.uk/...../crus1.htm

Images of crustaceans

http://www.seafriends.org.nz/images/crust.htm
http://www.yale.edu/inverts/caribs/caribpods.html
http://biog-101-104.bio.cornel.....yfish.html
http://www.marinethemes.com/aa.....ustaceans/

Crustaceans in the Philippines

http://www.panda.org/news_fact.....;uLangID=1
http://rmbr.nus.edu.sg/biodive....._crab.html
http://www.pan-uk.org/pestnews/pn59/pn59p4.htm

What are ostracodes?

http://www.ucl.ac.uk/GeolSci/m.....racod.html
http://www.isgs.uiuc.edu/fossils/ostracodes.htm
http://www.priweb.org/mastodon.....earch.html

What is Cope's rule?

http://www.blackwellpublishing.....s_rule.asp
http://biomed.brown.edu/Course.....amp;S.HTML

What is Bergmann's rule?

http://anthro.palomar.edu/adapt/adapt_2.htm

A useful exercise for learning surface-volume relationships

http://www.learner.org/channel.....index.html

Kids, did you know that you have a higher surface-volume ratio than adults do? (This has very important consequences)

http://www.peterboroughmoves.c.....Kids.pmove

GAMES

http://www.bbc.co.uk/nature/bl.....ster.shtml
http://magma.nationalgeographi.....index.html
http://www.seasky.org/sea_games.html


Last edited by adedios on Sat Jan 27, 2007 3:46 pm; edited 3 times in total
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PostPosted: Wed Mar 08, 2006 3:41 pm    Post subject: New Furry Crustacean Found Reply with quote

New Furry Crustacean Found

Associated Press
posted: 08 March 2006
10:00 am ET

PARIS (AP) -- A team of American-led divers has discovered a new crustacean in the South Pacific that resembles a lobster and is covered with what looks like silky, blond fur, French researchers said Tuesday.

Scientists said the animal, which they named Kiwa hirsuta, was so distinct from other species that they created a new family and genus for it.

The divers found the animal in waters 7,540 feet deep at a site 900 miles south of Easter Island last year, according to Michel Segonzac of the French Institute for Sea Exploration.

The new crustacean is described in the journal of the National Museum of Natural History in Paris.

The animal is white and just shy of 6 inches long -- about the size of a salad plate.

In what Segonzac described as a “surprising characteristic,'' the animal's pincers are covered with sinuous, hair-like strands.

It is also blind. The researchers found it had only “the vestige of a membrane'' in place of eyes, Segonzac said.

The researchers said that while legions of new ocean species are discovered each year, it is quite rare to find one that merits a new family.

The family was named Kiwaida, from Kiwa, the goddess of crustaceans in Polynesian mythology.

The diving expedition was organized by Robert Vrijenhoek of the Monterey Bay Aquarium Research Institute in California.
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PostPosted: Tue Jul 18, 2006 2:47 pm    Post subject: The Perils of Being Huge: Why Large Creatures Go Extinct Reply with quote

The Perils of Being Huge: Why Large Creatures Go Extinct

By Bjorn Carey
LiveScience Staff Writer
posted: 18 July 2006
08:34 am ET



Once upon a time, a 2-ton wombat lumbered across the Australian Outback. Around the same time, mammoths and saber-toothed tigers had the California coastline all to themselves.

Millions of years before any of these animals existed, Tyrannosaurus rex and other colossal dinosaurs ruled the world.

These and some of the other largest and most fantastic creatures ever to walk the planet are long gone, victims of mass extinctions of large beasts. And for reasons poorly understood, often the animals to fill the voids were tiny by comparison.


For the full article with illustrations and additional links:

http://www.livescience.com/ani.....imals.html
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PostPosted: Mon Oct 02, 2006 1:36 pm    Post subject: A plan for reintroducing megafauna to North America Reply with quote

University of Chicago Press Journals
2 October 2006

A plan for reintroducing megafauna to North America


Dozens of megafauna (large animals over 100 pounds) – such as giant tortoises, horses, elephants, and cheetah – went extinct in North America13,000 years ago during the end of the Pleistocene. As is the case today in Africa and Asia, these megafauna likely played keystone ecological roles via predation, herbivory, and other processes. What are the consequences of losing such important components of America's natural heritage?

In the November issue of The American Naturalist, a group of 12 ecologists and conservationists provide a detailed proposal for the restoration of North America's lost megafauna. Using the same species from different locales or closely related species as analogs, their project "Pleistocene Rewilding" is conceived as carefully managed experiments in an attempt to learn about and partially restore important natural processes to North American ecosystems that were present for millennia until humans played a significant role in their demise 13,000 years ago.

"Over the past 30 years, more and more evidence suggests that if we lose large animals from ecosystems, they often collapse and biodiversity, along with society, are the ultimate losers," says Josh Donlan (Cornell University). "For millions of years, large animals were the norm all over the world … we should start thinking about reintroducing these large animals and restoring these important processes back to ecosystems."

Starting with giant tortoises and wild horses, then moving toward lions and elephants, the authors provide a number of case studies for "Pleistocene Rewilding" and argue such introductions would contribute biological, economic, and cultural benefits to North America. The authors acknowledge that there are substantial risks and challenges; the risks of inaction may be even greater, however, including the continued global loss of megafauna.
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PostPosted: Mon Oct 02, 2006 1:49 pm    Post subject: Why do cold animals make bigger babies? Reply with quote

University of Chicago Press Journals
2 October 2006

Why do cold animals make bigger babies?

Reproduction involves a critical decision: Should an organism invest energy in a few large offspring or many small ones? In a new study from The American Naturalist, Michael Angilletta (Indiana State University), Chris Oufiero (University of California, Riverside), and Adam Leaché (University of California, Berkeley) used a new statistical approach that can test multiple theories at the same time, an approach they hope will shed light on many evolutionary problems. They used data from many populations of Eastern Fence Lizards (Sceloporus undulatus), which revealed that the lizards in colder environments produce larger offspring than lizards in warmer environments.

So why do animals in colder climates produce larger offspring? One theory suggests the larger size of offspring counteracts their slow growth in the cold. Yet another theory suggests large offspring are not directly linked to temperature at all. Instead, large offspring just happen to be produced by large mothers, who grow large because they require more energy to reproduce in the cold.

When they tested the theories simultaneously with their new approach, the team concluded that temperature's effect on reproduction is a byproduct of its effect on adult size. "This result could have widespread significance," says Angilletta. "Temperature determines the adult size of virtually all organisms. For many of these organisms, we expect temperature to also leave an imprint on reproduction."

###
Founded in 1867, The American Naturalist is one of the world's most renowned, peer-reviewed publications in ecology, evolution, and population and integrative biology research. AN emphasizes sophisticated methodologies and innovative theoretical syntheses--all in an effort to advance the knowledge of organic evolution and other broad biological principles.

Michael J. Angilletta Jr., Christopher E. Oufiero, and Adam D. Leaché, "Direct and indirect effects of environmental temperature on the evolution of reproductive strategies: an information-theoretic approach." The American Naturalist 167:10.
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PostPosted: Tue Oct 24, 2006 8:05 am    Post subject: Tiny 'housekeeper' crabs help prevent coral death in South P Reply with quote

University of California - Santa Barbara
23 October 2006

Tiny 'housekeeper' crabs help prevent coral death in South Pacific

(Santa Barbara, Calif.) –– Tiny crabs that live in South Pacific coral help to prevent the coral from dying by providing regular cleaning "services" that may be critical to the life of coral reefs around the world, according to scientists from the University of California, Santa Barbara.

The story of the relationship between the crab and the coral is described in the November 2006 issue of the journal Coral Reefs and is now available on-line. The coral provides a home and protection for the crabs. The crabs provide "housekeeping" duties for the coral, routinely "sweeping" out sediment that falls onto the coral, according to the study.

Thus the relationship between the corals and the trapeziid crabs is mutually beneficial, or symbiotic. The little crabs, measuring only a centimeter wide, make their home in branching corals like Acropora or Pocillopora. The research was done on coral reefs near the shore of the French Polynesian island of Moorea, in the South Pacific.

"Although we don't know much about these crabs, we do know that they are 'picky,' and are always tasting and exploring," said Hannah L. Stewart, first author of the paper and a postdoctoral researcher at UCSB's Marine Science Institute (MSI). "They use their front appendages to manipulate and shovel out the sediment."

Stewart said that this family of crabs is common around the world. "This relationship probably occurs all over the Pacific and is likely more ubiquitous than we know," she said. "Crabs are in corals everywhere. There are major ecological implications to this research; species of crabs that associate with corals may be more important than we realized."

She explained that coral reefs are one of the most productive and diverse ecosystems in the world. They support more than nine million species and provide a livelihood for millions of people around the globe.

The accumulation of sediment on coral tissue is known to reduce metabolic and tissue growth rates of coral, increasing the probability of bleaching and coral death. Many corals can remove some sediment from their surfaces but high sediment loads can be deadly. Predicted increases in sedimentation threaten coral reefs in many near shore areas around the world.

Coral reefs are threatened by a variety of environmental changes. For example, higher water temperatures and increased ultraviolet radiation, which are associated with climate change, are sources of widespread coral bleaching.

Changing land use patterns, caused by population increase on the coasts, are another threat because population growth increases the sediment load on coral. This is due to the higher amount of water run-off from development, deforestation with erosion, and expansion of agriculture.

The studies were conducted as part of The Moorea Coral Reef Long Term Ecological Research Site (MCR LTER), located in the complex of coral reefs and lagoons that surround the island of Moorea. Stewart performed the research with Sally Holbrook, professor and vice chair of UCSB's Department of Ecology, Evolution and Marine Biology; Russell Schmitt, a professor in the same department and the director of the MSI's Coastal Research Center; and Andrew Brooks, assistant research biologist at the MSI and deputy director of the MCR LTER. Experiments were carried out in the coral reef as well as in the laboratory.

The scientists showed the importance of trapeziid crabs by gently removing crabs from sections of the two species of branching corals on a coastal reef. This resulted in 50 to 80 percent of those corals dying in less than a month. By contrast, all corals with crabs survived. The nature of this common symbiotic relationship had not been recognized until this study. For surviving corals that lacked crabs, growth was slower, tissue bleaching was greater, and sediment load was higher. Laboratory experiments revealed that corals with crabs not only shed substantially more of the sediments deposited on coral surfaces, but also that crabs were most effective at removing grain sizes that were most damaging to coral tissues. These were the largest grains studied, those measuring two to four millimeters in width.


###
The MCR LTER, funded by the National Science Foundation (NSF), is a research partnership between UCSB and California State University, Northridge. Additional researchers on the project are affiliated with UC Davis, UC Santa Cruz, UC San Diego, and the University of Hawaii. Field operations are conducted from the UC Berkeley Richard B. Gump South Pacific Research Station in Moorea. The MCR LTER is part of the NSF's LTER network established in 1980 to support research on long-term ecological phenomena. The MCR LTER became the 26th site in the NSF LTER network in 2004 and is one of two LTERs operated by UCSB.

Note to editors:
Hannah Stewart can be reached at 805-450-0094, or at stewart@msi.ucsb.edu
Sally Holbrook can be reached at 805-893-3956, or at holbrook@lifesci.ucsb.edu
Andrew Brooks can be reached at 805-893-7670, or at brooks@msi.ucsb.edu
Web page for Moorea Coral Reef LTER: http://mcr.lternet.edu/
Web page with PDF of article: http://springerlink.metapress......lltext.pdf
Web page for Hannah Stewart: http://sbc.lternet.edu/~stewart/
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PostPosted: Wed May 09, 2007 7:45 am    Post subject: Crabs Shack Up in Safe Sandcastles Reply with quote

Crabs Shack Up in Safe Sandcastles
By Charles Q. Choi, Special to LiveScience

posted: 08 May 2007 10:05 pm ET

Female fiddler crabs find male suitors more attractive if the chaps can arrange safe sand castles for booty calls, new findings suggest.

In the animal kingdom, females are often attracted to outrageously showy displays such as a peacock's plumage. If gaudy males can escape from predators despite their flamboyant ornaments and behavior, such daredevil living helps prove their worth as a mate.

For the full article:

http://www.livescience.com/ani.....ycall.html
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PostPosted: Mon Jun 04, 2007 11:15 am    Post subject: Furry-clawed Asian crabs found in Delaware and Chesapeake Ba Reply with quote

Smithsonian
4 June 2007

Furry-clawed Asian crabs found in Delaware and Chesapeake Bays

Chinese mitten crabs, first reported in the Chesapeake Bay, are more widespread than initially thought. Four crabs have now been caught in Delaware Bay during the last week of May 2007, and may occur in other waters of the U.S. east coast.

In total, seven adult male mitten crabs have been documented from the two bays since 2005. Prior to this, the potentially invasive species had never been recorded from coastal waters of the eastern United States.

The mitten crab is native to eastern Asia and has already invaded Europe and the western United States, where it has established reproductive populations. The crab occurs in both freshwater and saltwater. Young crabs spend their lives in freshwater and migrate to saltwater estuaries for reproduction.

Named for the unusual thick fur-like coating on its claws, the mitten crab looks very different than native crabs and is easily recognized. It is listed as injurious wildlife under the Federal Lacey Act, due to its potential to cause ecological and economic damage.

“We don’t know the present status of this crab along the eastern U.S. coast” said Gregory Ruiz, senior scientist at the Smithsonian Environmental Research Center. “At the moment, it is not clear whether these crabs are reproducing or established in the Mid-Atlantic region, or whether the captured crabs are just a few individuals that originated elsewhere.” These crabs may have arrived in the ballast water of ships or through live trade.

###
A Mitten Crab Network has been established to examine the abundance, distribution, and reproductive status of crabs in Chesapeake Bay, Delaware Bay and other estuaries along the eastern United States. The initial partnership between the Smithsonian lab, Maryland Department of Natural Resources, U.S. Fish and Wildlife Service, National Oceanic and Atmospheric Administration and Delaware Division of Fish and Wildlife, is now being expanded to include resource managers, commercial fishermen, research organizations and citizens along the east coast.

Anyone seeing a mitten crab is asked to take a close-up photograph if possible, and please report it directly to the Mitten Crab Network (443-482-2222; SERCMittenCrab@si.edu) or a state resource manager.
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