Ecology & Zoology

By Oliver Griffith, University of Sydney

Have you ever wondered why we give birth to live young rather than lay eggs? Scientists have pondered this for a long time and answers have come from an unlikely source: some of Australia’s lizards and snakes!

In research published this month in the American Naturalist, my colleagues and I at the University of Sydney studied reptile pregnancy to identify the factors necessary for a placenta to evolve.

Although most reptiles lay eggs, live birth has evolved many times in the group of reptiles that includes lizards and snakes.

In European culture, it is widely accepted that magpies (Pica pica) are the thieves of the bird kingdom, attracted to sparkly things and prone to stealing them for their nests.

But psychologists at the Centre for Research in Animal Behaviour (CRAB) at the University of Exeter have analyzed magpies and found that the species is actually frightened of new and unfamiliar objects rather than attracted to them. 

The researchers carried out a series of experiments with both a group of magpies which had come from a rescue center, and wild magpies in the grounds of the University. The birds were exposed to both shiny and non-shiny items and their reactions recorded. 

A new paper delineating spiders’ roles within their colonies is intriguing because the spiders’ specialization (like caregiver or hunter-warrior) isn’t determined by size or physical structure, like with ants, but by personalities.

Aren't spiders loners? Most are, but a few species such as Anelosimus studiosus live in groups.

Colin Wright, a second-year PhD student in the University of Pittsburgh’s Department of Biological Sciences, along with Jonathan Pruitt, assistant professor of behavioral ecology at Pitt and Tate Holbrook of the College of Coastal Georgia, separated docile spiders from the aggressive by observing how much space they demanded from fellow colony members. Aggressive females demand more space than docile ones.

A scientist has discovered a potentially new form of plant communication, one that allows them to share an extraordinary amount of genetic information with one another.

Professor Jim Westwood examined the relationship between a parasitic plant, dodder, and two host plants, Arabidopsis and tomatoes. In order to suck the moisture and nutrients out the host plants, dodder uses an appendage called a haustorium to penetrate the plant. Westwood previously broke new ground when he found that during this parasitic interaction, there is a transport of RNA between the two species. RNA translates information passed down from DNA, which is an organism’s blueprint.

Trees have been a part of the human existence for as long as humans have existed but that doesn't mean we know everything about them, like why they are the size they are. What limits the height of trees? Is it the fraction of their photosynthetic energy they devote to productive new leaves? Or is it their ability to hoist water hundreds of feet into the air, supplying the green, solar-powered sugar factories in those leaves?

The easy and therefore not vary satisfying answer is that both resource allocation and hydraulic limitation might play a role, but the question still becomes which factor (or what combination) actually sets maximum tree height, and how their relative importance varies in different parts of the world.  

 Humans train animals by rewarding them with tasty treats and trainers couple the reward with a sound, such as a buzz or a whistle. Once the animal has mastered the task, the trainer stops dispensing food, relying instead on the whistle or buzzer to inform the animal that it has performed successfully and that it will be rewarded - with food, but later.

Even though there may be no food reward at the time, whales and dolphins still squeal in response to the sound substituted for the food reward. And Sam Ridgway found that when he trained dolphins and beluga whales to switch off a sound after diving hundreds of meters, the animals produced the same squeals of victory when the sound stopped.  

Conservation wants to preserve nature as it is while wildlife management seeks to maintain responsible levels for animal populations. There is a reasonable balance. In Pennsylvania, for example, there are plenty of state and national park acres but hunting is big business and the fees pay for biologists and state nature management.

Slippery as an eel may be a popular phrase but it turns out they are a lot easier to catch when marine vessels make noise nearby.

In a Global Change Biology paper, researchers from the Universities of Exeter and Bristol found that fish exposed to playback of ship noise lose crucial responses to predator threats - European eels (anguilla anguilla)were 50% less likely to respond to an ambush from a predator, while those that did had 25% slower reaction times.

Those that were pursued by a predator were caught more than twice as quickly when exposed to the noise.  

Juvenile loggerhead turtles don't just passively drift through life, they swim into oncoming ocean currents, according to a new study.

Lanternsharks produce and perceive bioluminescent light in order to communicate, find prey, and camouflage themselves against predators in the mesopelagic twilight zone.

The mesopelagic twilight zone is 200-1000 meters deep in the sea - a vast, dim habitat, where, with increasing depth, sunlight is progressively replaced by point-like bioluminescent emissions. To better understand strategies used by bioluminescent predators inhabiting this region that help optimize photon capture, the authors of a new study analyzed the eye shape, structure, and retinal cell mapping in the visual systems of five deep-sea bioluminescent sharks, including four Lanternsharks (Etmopteridae) and one kitefin shark (Dalatiidae).