Seal evolution: Sexual dimorphism in pinnipeds arose around 27 million years ago as climate changed

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In the world of science, one of the most exciting things a researcher can do is pin down an answer to a widely asked question. This experience came early for Carleton University graduate Thomas Cullen, who made a discovery about pinnipeds — the suborder that makes up seals, sea lions and walruses — while doing research for his Master’s degree under the supervision of Canadian Museum of Nature palaeontologist Dr. Natalia Rybczynski.His discovery, published today in the journal Evolution, relates to sexual dimorphism (a large variance in size between males and females), in a variety of pinniped species. Males in many species of pinnipeds are often much larger than their female counterparts, in some cases more than twice as large, and this has implications for how they mate and behave.Dimorphic pinnipeds such as the Steller’s Sea Lion and Northern Fur Seal typically mate in a harem, with one male pinniped presiding over a larger community of female mates. This behavior is not typically seen in non-dimorphic pinnipeds such as the Ringed Seal, and so sexual dimorphism is intimately linked with mating style.Researchers have long puzzled over both why sexual dimorphism exists in many pinniped species and when this trait evolved. When Cullen examined fossils of an extinct pinniped with Rybczynski, he discovered an incontrovertible answer to the question of when. He was able to examine it there before analyzing the data at Carleton in a lab headed by his other thesis supervisor, Prof. Claudia Schrder-Adams.Skull of Enaliarctos emlongi, an early pinniped ancestor. Cullen examined and analyzed the characteristics of this fossil for his study on the evolution of sexual dimorphism in pinnipeds.”We were examining a fossil of a pinniped that was previously thought to be a juvenile, but we looked at it again and found that, based on its skull structure, it was likely an adult,” says Cullen. This discovery, coupled with analyses comparing this fossil to others of the same species as well as modern dimorphic species, proved that the fossil belonged to a sexually dimorphic species.The fossil in question, the skull of an early pinniped ancestor called Enaliarctos emlongi, was discovered in the late 1980s off the coast of Oregon. …


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Making biodiverse agriculture part of a food-secure future

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Is biodiverse agriculture an anachronism? Or is it a vital part of a food-secure future?Given the need to feed an estimated 2.4 billion more people by the year 2050, the drive toward large-scale, single-crop farming around the world may seem inexorable.But there’s an important downside to this trend, argues Timothy Johns, Professor of Human Nutrition at McGill University in Montreal, in a paper to be presented Feb. 15, at the annual meeting of the American Association for the Advancement of Science in Chicago.Diets for most people around the world are becoming increasingly limited in biological and nutritional diversity. “Large-scale agriculture is characteristically simplified and less diverse than small-holder agriculture,” Prof. Johns cautions. “This is true in genetic, ecological and nutritional terms.”Small farmers, by contrast, in many places continue to grow a range of species and multiple varieties that form the basis of their diet and nutrition. Use of a range of wild species of fruit, vegetables, condiments and medicines, as well as wild animal-sourced foods, increase the likelihood that subsistence farmers with access to natural ecosystems meet their nutrition and health needs.The problem is that smallholder farmers in developing countries often have low productivity and little likelihood of generating the profits needed to rise above poverty level, says Prof. Johns, who directs the McGill Canadian Field Studies in Africa program. In particular, the smallholder farms in sub-Saharan Africa, which account for more than 90 percent of agricultural production and the primary livelihood of 65 percent of the population, need to be more productive.When they have access to improved technology, however, smallholder farmers can be both more productive and more sustainable than large-scale, intensive agriculture. Using family members in farming reduces labor and supervision costs, while a more intimate knowledge of the local soil, plants and animals enables smallholders to maximize output. …


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Environmental impact of Ontario corn production assessed

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Researchers at the University of Guelph examined the energy use and greenhouse gas (GHG) emissions associated with corn production in Ontario. Their findings are published today in the Agricultural Institute of Canada’s (AIC) Canadian Journal of Soil Science.The study reports estimated county-level energy and GHG intensity of grain corn, stover and cob production in Ontario from 2006-2011. According to the paper’s authors, most of the energy used during corn production comes from the use of natural gas and electricity during grain drying; the production and application of nitrogen fertilizers (which are also associated with GHG emissions); and the use of diesel fuel during field work.”Corn is a major economic crop in North America, and the renewable fuels developed from corn production are frequently used to mitigate the GHG emissions from fossil fuel use,” explained Susantha Jayasundara, lead author of the paper.”Assessing the GHG and energy intensity of corn production helps identify opportunities for efficiency and aids in improving the GHG mitigation potential of corn-derived renewable fuels,” continued Jayasundara. The authors note that reducing GHG intensity and improving energy efficiency during corn production can be achieved through the use of field-drying corn hybrids, reduced tillage and diminished nitrogen inputs.The article, “Energy and Greenhouse Gas Intensity of Corn (Zea Mays L.) in Ontario: A regional assessment,” by Susantha Jayasundara, Claudia Wagner-Riddle, Goretty Dias and Kumudinie Kariyapperuma, is available Open Access in the Canadian Journal of Soil Science.”Given the environmental and economic benefits of renewable fuels and the proliferation of their use in Canada, it is important to more fully understand the environmental impacts of their associated agricultural production,” added Serge Buy, CEO of AIC. “Essential studies such as this are of national significance and are certainly evidence of the need for targeted federal investments in agricultural science.”Story Source:The above story is based on materials provided by Canadian Science Publishing (NRC Research Press). Note: Materials may be edited for content and length.


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