ESA Ecology – Field Talk

Considering canopy cover in Ecuador

liza — Wed, 30 Jun 2010 17:26:28 +0000

Jason Tylianakis

Loss of canopy cover in rainforests—compared to the other fragmented habitats in Manabi in southwest Ecuador—leads to a region-wide loss of diversity in species interactions, said researchers from the University of Canterbury in New Zealand. As Jason Tilianakis and Etienne Laliberté reported in the June issue of Ecology, the food webs and interactions between parasitoids and their bee and wasp hosts were simplified and homogenized across habitats. As it turns out, land use was not the major contributor to this loss of interaction diversity: The researchers proposed that the lack of canopy cover in the managed and abandoned coffee agroforests and pasture and rice fields allowed for easier access as parasitoids searched for their bee and wasp hosts. In this edition of Field Talk, Jason Tylianakis discusses his findings, the fragmented habitats of Ecuador and the Homogecene era.

Fruitful Savannahs: Termites enrich the soil in East Africa

liza — Thu, 15 Apr 2010 17:56:11 +0000

Vertebrate fertilizer is not the only source of nutrients in the soils of East African savannahs, at least according to a study recently published in the journal Ecology. Alison Brody from the University of Vermont and colleagues found that termites actually had more of an effect on the fruiting success of Acacia trees in Kenya than did dung and urine deposition from ungulate herbivores, such as zebras and gazelles. The underground termite mounds, covered in vegetation and ranging from 5-10 meters in size, increased nitrogen and other nutrients in the soil—significantly more so than ungulates typically provided. In this edition of Field Talk, Brody talks about the symbiotic relationships these Acacia trees have with vertebrates and invertebrates, her plans for future research on the effects of cattle grazing on this land and her experiences in the field with the Kenya Long-term Exclosure Experiment.

Stepping stones of diversity: the Santa Barbara landscape and giant kelp genetics

liza — Mon, 01 Mar 2010 22:06:00 +0000

What is it about the rocky habitat in California that makes giant kelp so prevalent? And how do they spread from one section of the Santa Barbara Channel to another? According to Filipe Alberto, a marine population geneticist at the Centre for Marine Sciences in Portugal, giant kelp spread from one area to another in a stepping stone fashion, changing their genetic make-up as they go along. In his study, published in the January issue of Ecology, Filipe and colleagues analyzed the effects of isolation on genetic diversity between kelp forests. Diving with researchers from the University of California, Santa Barbara, Filipe collected all the samples he needed to study their genetic diversity—and he did it in just two weeks at the coastal Long Term Ecological Research (LTER) site in Conception, California. The samples, which were then shipped back to Portugal, showed that habitat continuity plays an important role in genetic connectivity.

Arctic shrubs looming large: Climate change and tundra productivity

liza — Fri, 09 Oct 2009 19:37:38 +0000

All around the world, the subtle—and not-so-subtle—impacts of climate change are becoming apparent. In the Arctic, where temperatures are warming at about twice the rate of lower latitudes, researchers are discovering marked changes in the landscape. In this month’s Field Talk, we take a trip to the High Arctic with James Hudson, whose paper in the October issue of Ecology looks at a tundra community on Canada’s Ellesmere Island. Hudson and his colleagues found that changes in temperature and seasonality are causing the normally low-lying shrubs in this area to grow to nearly twice their usual weight. Given the importance of the Arctic to global nutrient cycling, these types of studies can provide a road map to identifying areas of likely change.

The abandoned mutualist: When ants take their business elsewhere

liza — Fri, 11 Sep 2009 21:07:47 +0000

Ant-plant mutualisms are ubiquitous in tropical areas. In these examples of cooperation in nature, plants provide nutrition and shelter for ants that live on their leaves and branches. In return, the ants provide defense, kicking out (or even killing) any herbivores that try to eat the plant. The evolution of this relationship suggests that both species now need each other for survival. But Heraldo Vasconcelos of the University of Uberlandia in Brazil noticed something strange: in some populations of an ant-plant in the genus Tococa, plants lacked ant mutualists. Join us as he tells us about his paper in the September issue of Ecology, taking us on a trip into the Brazilian cerrado, where the plight of the antless ant-plants might not be so bad after all.

It’s only skin deep: Melanism and thermoregulation in lizards

liza — Mon, 31 Aug 2009 21:22:06 +0000

Like all ectotherms, lizards gain energy to go about their business by absorbing heat from their surrounding environment. Often lizards bask in the sun to maximize their heat absorption. But there are other, subtler things that can also affect how much heat ectotherms take up, like the color of their skin. In the August issue of Ecology, Susana Clusella-Trullas of Stellenbosch University in South Africa (pictured at left) compared similar species of rock-dwelling South African lizards with one significant difference: the color of their scales. She found that darker-colored melanistic lizards reap thermal benefits from having darker skin, which can translate into more time spent being active in their environments.

Battles of the sexes: Competition and evolution in tropical hummingbirds

liza — Thu, 28 May 2009 21:07:59 +0000

In this edition of Field Talk, we catch up with Ethan Temeles, a biologist at Amherst College, who tells us a tale of competition among the sexes in Caribbean hummingbirds – competition so severe that it drives their evolution. The short, straight bills of male purple-throated caribs and the long, curved bills of female caribs correspond to the shape of heliconia flowers on which they feed. The story got more complicated, though, when Dr. Temeles and his students discovered that despite their curved bills, females prefer straight flowers to curved ones. Join us as Dr. Temeles explains how this species’ sexual dimorphism evolved, and read more in his paper in the May issue of Ecology.

Seasonality and climate change

liza — Tue, 31 Mar 2009 21:29:22 +0000

Rising temperatures as a result of climate change promise to alter the behaviors of temperature-sensitive organisms. But climate change is also affecting the timing of seasons, which can throw off the alarm clock for critical behaviors, such as breeding. In this edition of Field Talk, we speak with Shaye Wolf, a biologist at the Center for Biological Diversity in San Francisco. Her research, published in the March issue of Ecology, tracks the reproductive behaviors of a small seabird, Cassin’s Auklet, on islands from Alaska to Mexico. She explains that climate change affects different populations in different ways, but could have dire consequences for those that rely heavily on consistent seasonality.

The Sacrificial Sibling Hypothesis

liza — Tue, 03 Mar 2009 16:00:13 +0000

The success of an animal or plant is determined by how many offspring it produces. But in some cases, not all offspring are created equal. In the February edition of Field Talk, Jaboury Ghazoul of the Swiss Federal Institute of Technology in Zurich, Switzerland, describes how some species of trees invest resources in seeds that cannot produce viable offspring. His paper in the February issue of Ecology shows that when seed predators are abundant, investment in decoy seeds – or “sacrificial siblings” – can increase a plant’s chances of producing successful progeny.

Nonviable seed set enhances plant fitness: the sacrificial sibling hypothesis

Jaboury Ghazoul and Akiko Satake

Ecology 2009 90:2, 369-377

Lizard Evolution and the Ants In Your Pants Dance

liza — Mon, 26 Jan 2009 22:29:52 +0000

Invasive red fire ants from South America have become a major pest in southwestern U.S., bringing their stinging venom and crop-destroying ways. In this edition of Field Talk, we catch up with Tracy Langkilde, assistant professor of biology at Penn State University, who studies one of the ants’ seemingly unlikely targets: eastern fence lizards. The lizards have evolved a novel twitching response that flicks attacking ants off their bodies. But in her paper in the January issue of Ecology, Dr. Langkilde explains that since native ants don’t normally attack lizards, this behavior must have evolved in a very short time.

Invasive fire ants alter behavior and morphology of native lizards

Tracy Langkilde

Ecology 2009 90:1, 208-217