Abstracts: Is it only humans that count from left to right?

An interesting bias experiment. Directional biases are well known in various critters, but not numerically! What they're talking about is how humans tend to put small values on the left, and large values on the right without thinking much about it. And apparently so do nutcrackers.
Link is here.

We report that adult nutcrackers (Nucifraga columbiana) and newborn domestic chicks (Gallus gallus) show a leftward bias when required to locate an object in a series of identical ones on the basis of its ordinal position. Birds were trained to peck at either the fourth or sixth element in a series of 16 identical and aligned positions. These were placed in front of the bird, sagittally with respect to its starting position. When, at test, the series was rotated by 90° lying frontoparallel to the bird's starting position, both species showed a bias for identifying selectively the correct position from the left but not from the right end. The similarity with the well-known phenomenon of the left-to-right spatially oriented number line in humans is considered.

Abstracts: Effects of a Snowshoe Hare decline on Survival of Dall's Sheep in Alaska

I can't believe I didn't post this. Steve Arthur is a good biologist, and a good person, and the study is wonderfully clever. In his talk he dissected the relation between hare abundance and predation on Dall's sheep lambs. Coyotes increase in abundance after hare highs, and when hares subsequently plummet, predation shifts to the lambs. But that didn't become apparent until the data was analyzed as a function of survival, and not census, as abundance was generally positively correlated with hare abundance.

Very clever.

EFFECTS OF A SNOWSHOE HARE DECLINE ON SURVIVAL OF DALL’S SHEEP IN ALASKA
Arthur, Stephen M., and Laura R. Prugh

We estimated survival of Dall's sheep (Ovis dalli) in the central Alaska Range during years of differing snowshoe hare (Lepus americanus) abundance to test whether indirect interactions with a cyclic hare population affect Dall's sheep either negatively, by subsidizing predators (apparent competition), or positively, by diverting predation (apparent commensalism). Annual survival of adult ewes was consistently high ( = 0.85); whereas, lamb survival was low and ranged from 0.15-0.63. The main predators of lambs were coyotes (Canis latrans) and golden eagles (Aquila chrysaetos), which rely on hares as their primary food and prey on lambs secondarily. Coyotes and eagles killed 78% of 65 radiocollared lambs for which cause of death was known. Lamb survival was negatively related to hare abundance during the previous year, and lamb survival rates more than doubled when hare abundance declined, supporting the hypothesis of predator-mediated apparent competition between hares and sheep. However, stage-specific predation and delays in predator responses to changes in hare numbers led to a positive relationship between abundance indices of adult Dall's sheep and hares. Lacking reliable estimates of survival, a manager might erroneously conclude that the relationship was apparent commensalism. Thus, support for different indirect effects can be obtained from differing types of data, demonstrating the need to determine the mechanisms that create indirect interactions. Long-term survey data suggest that predation by coyotes is limiting this sheep population below levels typical when coyotes were rare or absent. Understanding the nature of indirect interactions is necessary to effectively manage complex predator-prey communities.

Abstracts: Koala Birth Seasonality

Just because you can breed continuously throughout the year doesn't mean you can, or you should. Animals that breed throughout the year can have higher fitness, but only if there's enough resources available that the young aren't a major drag for future reproduction. Also, having accurate breeding information is important for establishing even basic demographic information, as it can push which demographic model you use.

Establishing accurate demographic information for free-ranging populations of animals is difficult without knowledge of individual chronological age. We estimated the birth dates of 743 koala (Phascolarctos cinereus) joeys at 3 sites in Queensland, Australia, using body mass obtained from a reference population with known birth dates. From these age estimates we compared the annual distribution of births across calendar months. At all 3 locations about 60% of births occurred between December and March. The annual pattern of births was identical for males and females within locations, but overall annual patterns of births differed between the southern and northern sites. We conclude that koalas can bear offspring in every month of the year, but breed seasonally across Australia, and that a sex bias in the timing of births is absent from most regions.

The reason they include the bit about the sex bias is because previous authors (McLean and Handasyde 2006) found one in an island population of Victoria Koalas.

doi: 10.1644/08-MAMM-A-358R.1.

Abstracts: Body Size Variation in Caribou Ecotypes and Relationships with Demography

One of the bigger arguments amongst Caribou biologists is what is the relationship between the different forms we see, and how important they are. For example, on one hand you have the big migratory herds like Western Arctic, but then you have more woodland herds like the Mentasta. Finally, there are sedentary montane herds. All three look like they have different things going on morphologically too, according to these authors. I'm fairly willing to believe that, and I'm willing to believe their mechanism - that it's habitat induced variation, and not anything genetic. That is to say, they're like that because they live there, and if they didn't live there, they wouldn't be like that.


Here's the abstract

ABSTRACT In many vertebrates size is one of the most influential and variable individual characteristics and a strong determinant of reproductive success. Body size is generally density dependent and decreases when intraspecific competition increases. Frequent and long- distance movements increase energy expenditures and, therefore, may also influence body size, particularly in highly mobile species. Caribou (Rangifer tarandus, also known as reindeer) exhibit tremendous variation in size and movements and thus represent an excellent candidate species to test the relationships between body size, population size, and movements. We analyzed body measurements of adult female caribou from 7 herds of the Que ́ bec-Labrador Peninsula, Canada, and we related their morphology to population size, movements, and annual ranges. The herds represented 3 ecotypes (migratory, montane, and sedentary). Ecotypes and herds differed in size (length), shape (roundness), and movements. The sedentary ecotype was larger and moved 4 to 7 times less than the migratory ecotype in the 1990s. At the start of a demographic growth period in the early 1960s, migratory caribou from the Rivie` re-George (hereafter George) herd had longer mandibles than caribou of the sedentary ecotype. Mandible length in the George herd declined in the 1980s after rapid population growth, while individuals performed extensive movements and the herd’s annual range increased. Migratory caribou then became shorter than sedentary caribou. After the George herd decline in the 1990s, mandible length increased again near levels of the 1980s. Caribou from the migratory Rivie` re-aux- Feuilles herd later showed a similar decline in mandible length during a period of population growth, associated with longer movements and increasing annual range. We hypothesize that the density-dependent effect observed on body size might have been exerted through summer habitat degradation and movement variations during herd growth. Our study has 2 important implications for caribou management: the distinctiveness of different populations and ecotypes, and the correlations between population trajectories and changes in body condition and habitat.

Couturier, Otto, Côté, Luther and Mahoney. 2010. Body Size Variations in Caribou Ecotypes and Relationships With Demography. J. Wildlife Management, 74, pp. 395-404. DOI: 10.2193/2008-384

Totally unrelated, but I met Shane Mahoney last year - I think it as at the Wildlife Soc. 2009 meeting, but I'm fuzzy on that point. He's an entertaining guy, and as smart as it gets. Côté is also very clever, though I been able to meet him directly yet.

Abstracts: Two much?

I picked this up from Barking up the Wrong Tree:
 When two is too many: Collaborative encoding impairs memory

Humans routinely encode and retrieve experiences in interactive, collaborative contexts. Yet much of what we know about human memory comes from research on individuals working in isolation. Some recent research has examined collaboration during retrieval, but not much is known about how collaboration during encoding affects memory. We examined this issue. Participants created episodes by elaborating on study materials alone or collaboratively, and they later performed a cued-recall task alone, with the study partner, or with a different partner (Experiment 1). Collaborative encoding impaired recall. This counterintuitive outcome was found for both individual and group recall, even when the same partners collaborated across encoding and retrieval. This impairment was significantly reduced, but persisted, when the encoding instructions encouraged free-flowing collaboration (Experiment 2). Thus, the collaborative-encoding deficit is robust in nature and likely occurs because collaborative encoding produces less effective cues for later retrieval. 

This goes against my intuition, as I thought the process of teaching things to other people (being forced to explain it) actually improves information retention. 

In general, the best type of studying (in my experience) is a) having a nice lunch and b) learning the information before the night before.

Abstracts: Cross-cultural recognition of basic emotions through nonverbal emotional vocalizations

 Disa A. Sauter, Frank Eisner, Paul Ekman, and Sophie K. Scott. Cross-cultural recognition of basic emotions through nonverbal emotional vocalizations. PNAS 2010 107:2408-2412; published online before print January 25, 2010, doi:10.1073/pnas.0908239106

Emotional signals are crucial for sharing important information, with conspecifics, for example, to warn humans of danger. Humans use a range of different cues to communicate to others how they feel, including facial, vocal, and gestural signals. We examined the recognition of nonverbal emotional vocalizations, such as screams and laughs, across two dramatically different cultural groups. Western participants were compared to individuals from remote, culturally isolated Namibian villages. Vocalizations communicating the so-called “basic emotions” (anger, disgust, fear, joy, sadness, and surprise) were bidirectionally recognized. In contrast, a set of additional emotions was only recognized within, but not across, cultural boundaries. Our findings indicate that a number of primarily negative emotions have vocalizations that can be recognized across cultures, while most positive emotions are communicated with culture-specific signals.

---

Vaguely interesting! I'm not sure I'm 100% on board with their methods, but the idea is definitely intriguing.

Recently, I was talking to a friend, who told the story of how a new teacher from the states tried to correct an elder's pronunciation. I said to my friend that I would have gone "That's nice" if it were me; my friend replied that the elder went "Mmm" and walked away (It was described as "Very Yup'ik" ;) ). And since we all know annecdotes are the best data (I say, tongue in cheek), I'd use this to suggest that there are also culture specific disapproval signals.

Random papers.

Here's some stuff that's not from my normal journal reading list, but I none the less find interesting:

Danger! Science jargon ahead!

Chimpanzees adopting unrelated children. (Altruism in Forest Chimpanzees: The Case of Adoption. Boesch et al 2010) So, the question is, is this an evolutionarily adaptive trait, that is to say, in provisioning these young they gain a benefit to their own fitness, or is this a spandrel - a maladaptive piece of behaviour that is the result of a more adaptive behaviour. I can see how the adaptionalist case would work - after all, rearing offspring would be a strong signal as to mate quality - but the argument that it's a spandrel seems more appealing, given the evidence. What I'd put a whole nickel on happening is that chemically, the same brain changes are going on in bonding with these unrelated individuals as it is with their actual offspring. Question: Why the heck isn't this seen in captive situations?

Positive selection in armpit odour? (A Functional ABCC11 Allele Is Essential in the Biochemical Formation of Human Axillary Odor. Martin et al 2010) So, Europeans and Africans have some components to their armpit sweat, and people descended from East Asian populations (which would include the groups that peopled the Americas?) have individuals with subtly different compositions. The frequency of the derived allele can reach upwards of 95% in those populations. Researchers found a DNA substitution that seems to result in a change in odour composition. East Asian (does this follow into American groups?) have a subtly different odorant composition, which the authors argue is the result of positive mate choice. Genomically, the show that it has benefit from strong positive selection. The allele reaches 95% frequency in some populations. I'm totally onboard with the idea that odour drives matechoice in humans (or is a driving factor), but I'm not sold on their description that this is the primary driver of this gene. Problem is, this gene also is a factor in the dry ear wax. Which we strongly suspect is adaptive. So, the adaptive tale of that gene is probably very complex.

Abstracts: Evolution of a Novel Carotenoid-Binding Protein Responsible for Crustacean Shell Color

Why are cooked lobsters so bright and shiny. The answer? SCIENCE. Oh, wait, that's how we got the answer. :P

Evolution of a Novel Carotenoid-Binding Protein Responsible for Crustacean Shell Color. Molecular Biology and Evolution 2009 26(8):1851-1864; doi:10.1093/molbev/msp092 

Carotenoids are commonly used by disparate metazoans to produce external coloration, often in direct association with specific proteins. In one such example, crustacyanin (CRCN) and the carotenoid astaxanthin combine to form a multimeric protein complex that is critical for the array of external shell colors in clawed lobsters. Through a combined biochemical, molecular genetic, and bioinformatic survey of the distribution of CRCN across the animal kingdom, we have found that CRCNs are restricted to, but widespread among, malacostracan crustaceans. These crustacean-specific genes separate into two distinct clades within the lipocalin protein superfamily. We show that CRCN differentially localizes to colored shell territories and the underlying epithelium in panulirid lobsters. Given the paramount importance of CRCN in crustacean shell colors and patterns and the critical role these play in survival, reproduction, and communication, we submit that the origin of the CRCN gene family early in the evolution of malacostracan crustaceans significantly contributed to the success of this group of arthropods.

You can read the article for free. In short, there are a class of compounds produced by shelled stuff that is part of a complex signalling that the shells do. The darker bits are for hiding, the brighter bits for communicating with their conspecifics (e.g., other lobsters). When you cook them, you nuke their ability to regulate the signalling, and the original colour comes out.

Abstracts: The function of contrasting pelage markings in artiodactyls

The function of contrasting pelage markings in artiodactyls Behav. Ecol. Caro and Stankowich 21: 78  DOI:10.1093/beheco/arp165

Comparative studies of pelage coloration in mammals suggest that certain prominent markings on an otherwise uniform pelage background serve in communication. We matched the position and coloration of contrasting markings on the bodies of all even-toed ungulates to ecological and social variables in order to ask whether marks are used in communication generally, as a signal to predators, or as a signal to conspecifics. Controlling for phylogeny, we found that many marks are located in prominent visible positions on the body; that flank marks seem to amplify stotting and leaping, which are pursuit deterrent signals; and that front leg marks may amplify foot stamping, an antipredator signal. We found that upper leg markings, particularly markings on the podials, are associated with group living hinting at an intraspecific communicatory function. Surprisingly, we found that contrasting marks do not reliably indicate position of scent glands across this taxon and that many white marks may have a cryptic function. These results extend and contradict those of previous analyses and force us to conclude that contrasting pelage marks have a number of functions in this taxon including pursuit deterrence, intraspecific signaling, and possibly even crypsis

Generally, research has focused on conspicuous markings on artiodactyls (artiodactyls with an even number of toes) as being intraspecific signals - that is, between one Roe deer and another, or a Moose and more different Moose. The figure I posted came from Ecology and Management of North American Moose, where they repeat the line about within-species signalling.  The idea of interspecific signalling - say a signal from a moose to a wolf - is very interesting. It's pretty clear that that pelage markings in deer is more complex than purely sexual signalling.

Abstracts: Lower Predation Risk for Migratory Birds at High Latitudes

L. McKinnon, P. A. Smith, E. Nol, J. L. Martin, F. I. Doyle, K. F. Abraham, H. G. Gilchrist, R. I. G. Morrison, and J. Bêty (15 January 2010) Science 327 (5963), 326. [DOI: 10.1126/science.1183010]

Quantifying the costs and benefits of migration distance is critical to understanding the evolution of long-distance migration. In migratory birds, life history theory predicts that the potential survival costs of migrating longer distances should be balanced by benefits to lifetime reproductive success, yet quantification of these reproductive benefits in a controlled manner along a large geographical gradient is challenging. We measured a controlled effect of predation risk along a 3350-kilometer south-north gradient in the Arctic and found that nest predation risk declined more than twofold along the latitudinal gradient. These results provide evidence that birds migrating farther north may acquire reproductive benefits in the form of lower nest predation risk.

There's a long standing debate on why birds migrate north to the arctic for the summer. This paper gives evidence that birds are migrating further to avoid predators. I suspect they're partially wrong, in that the initial (primitive) cause was more tired to taking advantage to seasonally available resources. Part of the lower predation risk is due to dilution effects (this is my suspicion), something the initial birds would not have enjoyed - dillution only works if there's many of you, not one or two.

Abstracts: Long-Term Persistence of Spent Lead Shot in Tundra Wetlands

From JWM,  Flint PL, Schamber JL (2010) Long-Term Persistence of Spent Lead Shot in Tundra Wetlands. Journal of Wildlife Management: Vol. 74, No. 1 pp. 148–151 DOI: 10.2193/2008-494.

We seeded experimental plots with number 4 lead pellets and sampled these plots for 10 years to assess the settlement rate of pellets in tundra wetland types commonly used by foraging waterfowl. After 10 years, about 10% of pellets remained within 6 cm of the surface, but >50% remained within 10 cm. We predict that spent lead pellets will eventually become unavailable to waterfowl; however, it will likely require >25 years for all pellets to exceed depths at which waterfowl species may forage.

It'd suggest we're not being conservative enough in controlling lead shot in other areas. Despite recent efforts to step up lead shot control in the YK, it's still 25 years out before it ceases to be a human and wildlife hazard.