Sexual selection and dinosaur fossils


Sexual dimorphism in the pterosaur Darwinopterus. (Credit: Image by Mark Witton)

From the University of Southampton in England:

Survival of the prettiest: Sexual selection can be inferred from the fossil record

Detecting sexual selection in the fossil record is not impossible, according to scientists writing in Trends in Ecology and Evolution this month, co-authored by Dr Darren Naish of the University of Southampton.

The term “sexual selection” refers to the evolutionary pressures that relate to a species’ ability to repel rivals, meet mates and pass on genes. We can observe these processes happening in living animals but how do palaeontologists know that sexual selection operated in fossil ones?

Historically, palaeontologists have thought it challenging, even impossible, to recognise sexual selection in extinct animals. Many fossil animals have elaborate crests, horns, frills and other structures that look like they were used in sexual display but it can be difficult to distinguish these structures from those that might play a role in feeding behaviour, escaping predators, controlling body temperature and so on.

However in their review, the scientists argue that clues in the fossil record can indeed be used to infer sexual selection.

“We see much evidence from the fossil record suggesting that sexual selection played a major role in the evolution of many extinct groups,” says Dr Naish, of the University’s Vertebrate Palaeontology Research Group.

“Using observations of modern animal behaviour we can draw analogies with extinct animals and infer how certain features improve success during courtship and breeding.”

Modern examples of sexual selection, where species have evolved certain behaviours or ornamentation that repel rivals and attract members of the opposite sex, include the male peacock‘s display of feathers, and the male moose’s antlers for use in clashes during mating season.

Dr Naish and co-authors state that the fossil record holds many clues that point to the existence of sexual selection in extinct species, for example weaponry for fighting, bone fractures from duels, and ornamentation for display, such as fan-shaped crests on dinosaurs. Distinct differences between males and females of a species, called ‘sexual dimorphism’, can also suggest the presence of sexual selection, and features observed in sexually mature adults, where absent from the young, indicate that their purpose might be linked to reproduction.

We can also make inferences from features that are ‘costly’ in terms of how much energy they take to maintain, if we assume that the reproductive advantages outweighed the costs.

Whilst these features might have had multiple uses, the authors conclude that sexual selection should not be ruled out.

“Some scientists argue that many of the elaborate features on dinosaurs were not sexually selected at all,” adds Dr Naish, who is based at the National Oceanography Centre, Southampton.

“But as observations show that sexual selection is the most common process shaping evolutionary traits in modern animals, there is every reason to assume that things were exactly the same in the distant geological past.”

November 2013: Dinosaur fossils can be recreated by CT and 3-D printers, according to new research published online in the journal Radiology: here.

Antarctic blue whale new research


This video says about itself:

Mar 23, 2010

Me (Caitlyn/Genora100) and My BFF (Rachel/ilovesilverherocks, http://www.youtube.com/user/ilovesilverherocks) have to do a project on an Antarctic animal! we chose the blue whale!

From Wildlife Extra:

Researchers leave port to search for and tag Blue whales in Antarctica

Voyage in search of the world’s largest creature

January 2013. A team of international whale researchers have sailed from Hobart in search of the biggest creature on Earth, the Antarctic blue whale. The scientists from Australia, United States, United Kingdom, Chile and New Zealand, will use newly-developed passive acoustic sonobuoy methods to track and locate the elusive animals across hundreds of kilometres in the Southern Ocean.

Antarctic Blue Whale Project

Australian Environment Minister Tony Burke said this is the inaugural voyage of the Antarctic Blue Whale Project which aims to estimate the abundance, distribution and behaviour of the species.

Mr Burke said “The Antarctic blue whale can grow to over 30 metres in length and weigh up to 180 tonnes, its tongue alone is heavier than an elephant and its heart is as big as a small car. Even the largest dinosaur was smaller than the blue whale. Despite their colossal size we know very little about the animals, including where they breed and feed, and how many remain in our oceans today after industrial whaling slaughtered more than 340,000 of them in the early 1900s.”

The researchers will target areas thought to be frequented by the blue whales along the ice edge west of the Ross Sea. If survey methods are successful in locating the whales, photographs of the animals’ flanks and biopsy samples will be taken to build individual sighting histories that will assist in estimating population size.

Satellite tags

The 18-strong team will also work from small boats in freezing Antarctic conditions to deploy satellite tags on the animals.

Not necessary to kill whales for research – Unlike Japan

Burke added “We then aim to be able to track their movements within their Antarctic feeding grounds and potentially further north to their breeding areas. This research shows, in contrast to Japan’s so called “scientific whaling” program, that you don’t have to kill these majestic creatures to get valuable information about them.”

The project is a flagship program of the international Southern Ocean Research Partnership (SORP) involving ten countries – Argentina, Australia, Brazil, Chile, France, Germany, New Zealand, Norway, South Africa and the United States. SORP was initiated by Australia through the International Whaling Commission (IWC) to promote non-lethal research in the Southern Ocean.

“Today the Antarctic blue whale is classified as critically endangered by the International Union for Conservation of Nature and is of global interest as one of the most at risk baleen whale species in the Southern Ocean,” Mr Burke said.

“The information gathered in this research will be supplied to the IWC to assist in the conservation and recovery of this iconic species.”

Florida wood stork, other birds decline


This video from the USA is called Endangered Florida Wood Storks.

From Wildlife Extra:

USA wading bird nesting in key area plummets 39 percent below 10-year average

Endangered Wood stork breeding failure

January 2013. One of the USA’s largest and most important wading bird breeding areas – south Florida, which includes the Everglades National Park – has seen wading bird nesting plummet to levels 39 percent below ten-year averages, according to a new report by the South Florida Water Management District. This weather-induced decline bucks a trend dating to 1985 of growing bird populations in South Florida as a result of restoration of water flows in the Everglades, and reaffirms the need for speeding completion of the project.

3rd consecutive year of poor nesting

The report says that an estimated 26,395 wading bird nests were initiated throughout south Florida during the 2012 nesting season which constitutes a 39% decline relative to the decadal average, and a 66% decline relative to the 77,505 nests for 2009, which was the best nesting year on record in south Florida since the 1940s. While the 2012 number is comparable to that of 2011 (26,452) and 2010 (21,885), it is the third consecutive year of relatively poor nesting effort in south Florida.

“These numbers are alarming because we are talking about extremely important bird breeding grounds on a national level and we’re looking at three years of poor breeding success,” said Kacy Ray, Beach Nesting Bird Conservation Officer for American Bird Conservancy, one of the nation’s leading bird conservation organizations. “Restoring water flows in the Everglades will re-establish prey production and availability across the landscape that, in turn, will support the return of large successful wading bird colonies to the traditional rookeries downstream.”

Wood stork, white ibis and snowy egrets worst affected

All species of wading birds suffered reduced nest numbers relative to the past ten years, but the extent of the decrease varied among species. Of particular concern are nesting failures of the endangered Wood Stork which declined 44%; White Ibises (39%) and Snowy Egrets (56%) also suffered significant declines. There was also limited nesting by Little Blue Herons and Tricolored Herons (only 89 and 412 nests, respectively), which continues a steep and steady decline in nesting activity for these two species during the past eight years.

Wood stork – 100% nest failure

The federally Endangered Wood Stork fared particularly poorly and it is thought that all 820 nests failed or were abandoned. By contrast, anecdotal observations suggested that Great Egrets, Snowy Egrets and White ibises in ENP were relatively successful. Another region that experienced poor nesting success was Lake Okeechobee where most colonies experienced complete or extensive nest failure.

This contrasts with long-term trends showing population increases for Wood Storks, Snowy Egrets, Great Egrets, White Ibis, Small White Heron, Great Blue Heron, and Roseate Spoonbill. Wading bird breeding patterns in south Florida are driven largely by hydrology through its influence on the production of prey and their vulnerability to predation. The 2012 breeding season was preceded by several drought years followed by a relatively wet season. Such conditions generally limit the production of small fishes that the birds feed upon.

“To restore and manage for wading bird populations in the Everglades, the right amount of water at the right time and the right place is needed to optimize the availability of aquatic prey species (small fishes and crayfish). The long-term monitoring programs in this report (both avian and prey related) are critical to this end,” said Mark Cook of the South Florida Water Management District. “We need to know what’s happening, why it’s happening and what’s working if restoration efforts are to be targeted effectively. These programs have made considerable advancements in our knowledge of wading bird ecology in recent years, although much still remains to be learnt about getting the water right for the birds.”