You guys are gonna kill me, but...

I can't resist posting another cool abstract, this time from Behavioral Ecology. But wait, it's about an anti-predator adaptation I'd never thought about before! And for all you hunters out there, it'll be something fun to test next time you've got to clean your birds. (I'm totally paying attention to this next time I dove hunt with my family!)

Losing the last feather: feather loss as an antipredator adaptation in birds

Anders Pape Møller ^{1 *}, Jan Tøttrup Nielsen ², and Johannes Erritzøe ³

Birds often lose feathers during predation attempts, and this ability has evolved as a means of escape. Because predators are more likely to grab feathers on the rump and the back than on the ventral side of an escaping bird, we predicted that the former feathers would have evolved to be relatively loosely attached as an antipredator strategy in species that frequently die from predation. We estimated the force required to remove feathers from the rump, back, and breast by pulling feathers with a spring balance from a range of European bird species in an attempt to investigate ecological factors associated with ease of feather loss during predation attempts. The force required to loosen a feather from the rump was less than that required to loosen a feather from back, which in turn was less than that required to loosen a feather from the breast. The relative force needed to loosen rump feathers compared with feathers from the back and the breast was smaller for prey species preferred by the most common predator of small passerine birds, the sparrowhawk Accipiter nisus. Likewise, the relative force was also smaller in species with a high frequency of complete tail loss among free-living birds, which we used as an index of the frequency of failed predation attempts. The relative force required to remove feathers from the rump was smaller in species with a high frequency of fear screams, another measure of the relative importance of predation as a cause of death. Feather loss required particularly little force among solitarily breeding bird species that suffer the highest degree of predation. Antipredator defense in terms of force required to remove feathers from the rump was larger in species with a strong antiparasite defense in terms of T-cell-mediated immune response. These findings are consistent with the hypothesis that different defenses are antagonistic and that they are traded off against each other.

Ewes young guys ain't got nothin' to worry about

Hi there, EP peeps,

I just thought I'd post an abstract of a study I found kind of amusing. I subscribe to eTOCs from the journal "applied animal behavior science" (which is generally not that useful, but whatever, I checked it off when I was signing up for a bunch of eTOCs). Anyway, I think it was the "sexual performance" bit in the title that piqued my curiosity. So see below for an abstract I found kind of amusing.

(To any self-conscious rams out there: apparently your "sexual performance"--how was that measured, I wonder? (I'm not curious enough to actually read the paper, however)--doesn't matter, just your age. )

A note on ram preference by oestrous ewes: Influence of rams' age and sexual performance

Ewes in oestrus, besides being receptive to rams, develop an active search for them. We performed two experiments to determine if oestrous ewes prefer: (1) high or low sexual-performance rams, and (2) 2-year-old or aged (>8-years-old) rams. In the first experiment, the preference of ewes for rams with high or low sexual performances was compared in 16 tests. In the second experiment, 17 tests were performed comparing ewes'’ preference for aged rams (>8-years-old) or young rams (2-years-old). In each test, two rams were tied at equal distances from the point of entrance of the ewe, with a maximum mobility for each ram of 2 m. The first approach to a ram, the quantity of approaches toward each ram (less than one body length), and the total time that the ewe remained near each ram were registered during 5 min. Oestrous ewes did not display any preference according to sexual performance of rams, but spent significantly more time (P = 0.02), and did it in more tests (P = 0.025), with young than with aged rams. Ewes also tended to approach first (P = 0.07), and more times in more tests (P = 0.06), to young than to aged rams. We conclude that ram's sexual performance seems not to influence oestrous ewes preference, and that ewesÂ’ prefer young (2-years-old) rather than aged rams (>8-years-old).


P. S. By "did it", in there, on first read, I thought, "They're using the euphemism "did it" in a (semi-) academic journal?!?!" (Is that what they mean?)

Conceptual Foundations of EP?

Ok for our Evolutionary Social Psych class, David assigned a 6 page paper on what we consider to be the conceptual foundations of evolutionary psychology. It's been interesting to me to see what my fellow lab mates chose...while there was some overlap, we all had some things different. What would you guys pick?

Here was the exact assignment: "I am looking for YOUR take--what you perceive to be the most fundamental conceptual foundations of the field. Perhaps 5 - 8 fundamentals, with a paragraph devoted to each, justifying it as a part of the conceptual foundation. Each foundational pillar must be justified, that is, precisely why do you view it as part of the conceptual foundation?"

I already made my choices (the paper is due tomorrow) so I'll reveal them after everyone else posts theirs (that way...mine aren't prompters...). (Please feel free to skip the paragraph but perhaps a sentence for why important would be good for discussion purposes...)

Have fun!!

Psychological mechanisms vs. behavior: which would win a boxing match?

Hi buddies,

I just thought I'd post a comment about a disappointing experience I had today in a discussion group. Basically, it was a frustrating (though brief--Elizabeth broke it up before it got too intense) discussion of psychological mechanisms vs. behavioral outcomes, and the value of each as products of evolution. Anyway, I probably should've expected as much, as I'm in anthropology here, but hopefully I can at some point get a few people to slow down and appreciate what is driving this behavior they so prize, and that mismatches between psychological preferences and behavior are not just something to be ignored in favor of pure emphasis on behavior. The mechanisms behind this behavior were selected, too. Anyway, arg, there's no need for comments in response to this, I just needed to vent to a sympathetic audience.

Self-deception

Hey guys,

This is a request asking you to keep your eyes out for any literature directly or indirectly related to self-deception. I'll probably have to wait until I leave FAU to start a self-deception project, but at least this gives me time to get my thoughts together.

I just found this study in Proceedings.
"Overconfidence has long been noted by historians and political scientists as a major cause of war. However, the origins of such overconfidence, and sources of variation, remain poorly understood. Mounting empirical studies now show that mentally healthy people tend to exhibit psychological biases that encourage optimism, collectively known as ‘positive illusions’. Positive illusions are thought to have been adaptive in our evolutionary past because they served to cope with adversity, harden resolve, or bluff opponents. Today, however, positive illusions may contribute to costly conflicts and wars. Testosterone has been proposed as a proximate mediator of positive illusions, given its role in promoting dominance and challenge behaviour, particularly in men. To date, no studies have attempted to link overconfidence, decisions about war, gender, and testosterone. Here we report that, in experimental wargames: (i) people are overconfident about their expectations of success; (ii) those who are more overconfident are more likely to attack; (iii) overconfidence and attacks are more pronounced among males than females; and (iv) testosterone is related to expectations of success, but not within gender, so its influence on overconfidence cannot be distinguished from any other gender specific factor. Overall, these results constitute the first empirical support of recent theoretical work linking overconfidence and war." [Overconfidence in wargames: experimental evidence on expectations, aggression, gender and testosterone]

I'm not particularly interested in overconfidence, but it is a form of self-deception.

Thanks.

Mate value experiment in birds

Hey guys,

Here's the abstract of a neat experiment in Animal Behaviour manipulating "mate value"/attractiveness in a bird species, and its effect on female choosiness. I haven't read it yet, but I thought you guys might find it interesting/relevant.

Variation in female choice of mates: condition influences selectivity

Nancy Tyler Burley^{, a,} and Valerie S. Foster^a

The occurrence and significance of variation in apparent mate choice within populations are poorly understood. While one possible explanation for variation is that individuals differ in their mate preferences, an alternative possibility is that individuals vary in their mate selectivity or ‘choosiness’: that is, some individuals may be willing to accept less attractive mating partners than are others. This latter possibility is likely to result from bidirectional mate choice and differential mating access of high- versus low-quality mating partners. Here we altered the physical condition of female zebra finches, Taeniopygia guttata castanotis, through modest trimming of their flight feathers to explore the possibility that individuals adjust selectivity in response to their own condition. We compared the selectivity of individuals with clipped versus intact wing feathers. Female finches spent less time associating with attractive males when their wings were clipped than when wings were intact. To ascertain whether their choices were influenced by the behaviour of stimulus males that perceived their altered status, we performed a companion experiment that measured male mate choice of females with clipped versus intact wings; no discrimination against clipped females was found. Collectively, these results indicate that a female's mate selectivity is dynamically adjusted based on her assessment of her own condition or mate-getting ability. Future studies that investigate the relationship between realized and ideal mate preferences are necessary to better understand preference functions and the genetic basis of mate preferences.

( Animal Behaviour
Volume 72, Issue 3 , September 2006, Pages 713-719)

NYTimes Article on Sexual Cannibalism

Hi all!

This is an article from today's NYTimes regarding sexual cannibalism in animals. Talks a little about sperm competition as well.

September 5, 2006
This Can’t Be Love
By CARL ZIMMER

http://www.nytimes.com/2006/09/05/science/05cann.html

I was going to post the actual article, but it comes out looking rather odd so you'll have to go to the site if you're interested.

Enjoy!