Texas Tech visit

Thanks to the generosity of Robert Baker, I was invited to visit with faculty and students at Texas Tech University and give 3 talks– a biology seminar, a family-friendly outreach talk, and a brief show-n-tell to a introductory biology class regarding my work with vampire bats.

Thank you to everyone who met with me and showed me around. I had some really interesting discussions with faculty and graduate students. It makes me realize I should put more time and effort into having these kinds of informal but stimulating conversations with people at my own school.

Texas Tech now probably has the largest collection of bat-focused faculty researchers of any school I’ve visited, with Tigga Kingston, Robert Baker, Richard Stevens, and now Liam McGuire. Liam (who I’ve known since 2007) studies links between physiology, ecology, and behavior in bats, with a focus on migration and hibernation. He has just set up his new lab and has a really, really cool research program planned. Although while looking for a link, I see that he needs to make a lab website though! I look forward to some amazing work coming out of his lab in the future! Also, his kids are adorable.

I had an interesting discussion about transposable elements and gene duplication with David Ray and Neal Platt.

Tigga Kingston is a conservation biologist who has conducted long-term ecological studies of bats in Southeast Asia. She has a terrific group of graduate students doing a remarkably wide variety of conservation-relevant projects around the world. I was particularly excited about Marina’s work on the SEABCRU online bat database. These kinds of scientific contributions (where are a huge amount of data is made available to many people) are not given the due academic credit that they deserve– they are way more important than a single paper. I’m glad many people in science are creating incentives for sharing data and not simply papers. I was also really impressed by the work of Kendra Phelps, Joe Huang, and Julie Senawi.

In the bat world, Texas Tech is synonymous with Robert Baker, who has been there for 46 years– more than half of the duration of the school’s existence. He has mentored about 100 graduate students in that time. Baker has spent much of his career studying the diversity and evolution of the phyllostomid bats, and as early as the 1960s he understood the importance of using genes and chromosomes (rather than just morphology) for constructing phylogenetic trees. In 2003, he published an influential phyllostomid phylogeny that assessed 48 of the 53 identified genera. I enjoyed talking systematics and phylogenetics with his graduate students Julie Parlos, Howie Huynh, and Cibele Caio. Julie was an extremely generous (and organized) host.

Julie and Kendra took me along for their acoustic survey spent listening for bats along a transect, driving around Lubbock at 20 mph. We heard no bats. But it made me realize that simply cruising around, hanging out, and chatting about science– could provide some useful data if you make it a recurring event and attach a bat detector to the roof of your car. Why didn’t I think of that? Also, I wish I lived someplace that had a “prairie dog town” as part of the local park.

It was the most enjoyable time I’ve had visiting a university.


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You can’t help me or you won’t? What kinds of “cheats” should a food-sharing bat care about?

In response to a talk I gave at the bat meetings, some people saw a problem in the experimental design of my partner choice tests, because I had a condition where a bat can’t reciprocate, but not a condition where a bat won’t reciprocate. I do know that hungry bats will beg other hungry bats, but the argument is that I don’t know if they will treat a simultaneously hungry bat that can’t reciprocate in the same way as a bat that won’t reciprocate. And perhaps bats would only “punish” or “abandon” partners that choose not to reciprocate, not those unfortunate bats who fail to reciprocate due to being repeatedly absent or starved themselves.

The first obvious logistical problem is that creating a situation where a bat can reciprocate but won’t is extremely difficult and maybe impossible in practice. But I don’t think this even matters that much because a bat should respond to both can’ts and won’ts, and here’s why.

Imagine you’re a female vampire bat maintaining cooperative social relationships with several other bats. Your time and energy are limited and you should therefore choose wisely with regards to which individuals you target with your social investments (i.e. food sharing and social grooming). Assume that you are equally related to Bat A and B, and that Bat A consistently feeds you when you are hungry. Under which of the following scenarios, should you begin to invest more in Bat A and less in Bat B?

1. Bat B never feeds you even when she has food to give you.

2. Bat B never feeds you because she is always hungry herself. 

3. Bat B is never around when you are hungry.

The answer, which seems obvious to me, is that you should prefer bat A over B in all 3 scenarios. That is, under all 3 scenarios, you should invest less time and energy feeding Bat B and instead use that time and energy feeding and grooming Bat A. Now there might be differences between the three scenarios in how long it takes you to start preferring A versus B. You might be far less forgiving of scenario 1 vs scenario 2 and 3, but the basic point is that you should reduce your investment in bat B in all 3 cases.

The problem here is that people sometimes think that you, as the female bat, should only care about scenario 1 because that matches people’s’ notions of “cheating” whereas the others are accidental. Bat B has an excuse so it’s not cheating. People think that it matters a lot whether a bat won’t reciprocate versus whether it can’t reciprocate. I agree there’s a difference, but the difference is quantitative not qualitative.

To the extent that you are a Darwinian agent, your only concern is the probability of an investment leading to a fitness return. If a bat won’t reciprocate, this information will certainly change your prediction of the likelihood of this bat reciprocating in the future. But if a bat can’t reciprocate and it has an excuse (I was not around; I did not feed either), then you would judge this as less informative as to whether that bat would reciprocate in the future. The kind of information you glean is the same, but the information is different. The partner that won’t reciprocate is probably bad social investment; whereas the can’t reciprocate partner *might* be a bad investment (or it might just be a fluke). But in either case, you should remember the event and it should damage (if only very slightly) your relationship with that partner.

If you simulated cheating in Bat B by consistently removing (or fasting) Bat B whenever the subject bat was hungry (i.e. bat B can’t reciprocate), then biological market theory suggests you should certainly see a response, because you have made that partner look worse relative to others. The partner switching response might be faster if the bat won’t reciprocate, but it should come eventually in any case.

What’s a cheat? In the evolution of cooperation literature, authors often talk about “cheats” (reviewed here) to describe an individual that exploits the cooperation of others by gaining the fitness benefits without paying the fitness costs. Talking about “cheats” is often very useful in explaining why evolutionarily stable cooperation often requires some form of conditional enforcement or discrimination. But the term can also create unnecessary confusion for at least two reasons. First, “cheat” sounds like a discrete type, behavior, or trait, whereas much of the time it’s used to describe a scenario with individuals that vary continuously. Imagine if we talked about human prosocial behavior using the terms “cooperators” for anyone who cooperates more than average and “cheats” for anyone who cooperates less than average. Most people (who cooperate to an average degree) would be ambiguous. You can’t model this in the same way you might model conflict between more discrete “types” like males and females or discrete reproductive strategies. This is a problem I see in the behavioral syndromes literature too.

Second, people think “cheating” refers to something cognitive or intentional, rather than just variation in a cooperative trait. This is not such a problem in bacteria or plants, but it can be a big problem in animal cooperation studies. For (hypothetical) example, in a group of vampire bats clustering for warmth, a “cheat” could simply describe an individual that maintains a slightly lower body temperature allowing itself to be warmed by an adjacent body. Two normal bats that cluster together are both paying some cost and receiving a benefit of the other’s warm body. But a normal bat that clusters with a cold cheat is not receiving that benefit, only the cold cheat benefits, and it might be paying a larger cost. In reality, “cold cheats” probably do not exist because of physiological constraints, but the logic still applies. Cheating in this scenario is not a strategic behavior; it’s just a physiological trait.

To be clear, I’m not saying that the distinction between can’t help versus won’t help doesn’t matter. Some authors writing on this topic have argued that  it would be very cognitively difficult to distinguish between partners that can’t and won’t reciprocate, and so this might be very rare distinction to make. But in fact precisely such a difference has been demonstrated in cooperatively mobbing birds.

Experimenters first used fake owls to induce cooperative mobbing among 3 mated pairs of pied flycatcher mated pairs. They created experimental triads of three equidistant nestboxes. One pair (the subject pair) was exposed to a fake owl near their nestbox to induce mobbing. The second pair (the defector pair) was held captive (either nearby in a blind or trapped inside their own nestbox) and hence prevented from mobbing. The third pair (the helper pair) was left untreated, such that the helper pair always helped the subjects with mobbing, but defector pair could not. The authors then simultaneously presented the helper and the defector pairs with owls, and tested at which nestbox the subject pair would choose to help. The subjects helped the helper pair more often. In a follow-up experiment, the defector pair was presented with an owl. In most trials, the helper pair, but not the subject pair, joined the defector pair in mobbing. This makes sense because the defectors only defected against the subjects, not the helpers.

Then using the same setup, the experimenters showed that the degree of reciprocity was also sensitive to whether the failure of partners to mob was caused by their absence (“the excuse principle“). To simulate voluntary defection, the experimenters removed the defection pair, but played their alarm calls to simulate their presence. To simulate involuntary absence, the experimenters completely removed the pair during the predator presentation to simulate their absence during the owl attack. There was no sign of their presence at all. When the captured birds appeared present but unwilling to help, the subjects later reciprocated help in only 2 of 20 cases, but when captured pair was completely absent, the subject pair reciprocated help in 20 of 21 cases.

This is a great experiment. But it does not suggest that the birds will forgive indefinitely. I think we can be fairly confident that if the absent birds were consistently and repeatedly absent whenever an owl showed up. The subjects would begin to reduce their help towards those partners as well, because repeated “voluntary defection” and “unintentional absence” are just two different ways of being a bad cooperative partner.

Alongside the partner’s capacity to help, there are many factors that should influence the degree of contingency in a cooperative exchange. One example is the cost-benefit ratio of the social investment. For example, mobbing birds only help past helpers at fairly distant nestboxes, but when mobbing birds are responding to an owl at a neighboring nestbox that is very close, they always help unconditionally (see here). This is because mobbing an owl that is very close to your own nestbox has a larger immediate selfish benefit (which immediately outweighs the cost of doing nothing), whereas mobbing a more distant owl poses large costs that have to compensated by the relationship you build with the neighboring pair.

Kinship is another factor that can influence the degree of experience-based contingency in helping decisions. Social bonds consisting of multiple cooperative services would decrease the contingency that can be easily measured, because asymmetries in one service can be balanced out with other services.

So now all these interactions begin to get very messy. Because we have multiple factors moving the degree of contingency in opposing directions. Vampire bats make larger social investments in highly bonded partners, which should make contingency very strong. But highly bonded partners might have multiple ways of helping each other (multiple currencies) which makes the measurable contingencies within each currency very weak. Moreover, social bonds tend to form between close relatives, and kinship could conceivably decrease contingency, because investors are compensated indirectly through indirect fitness, or increase contingency, because the larger investments in kin that are not reciprocated are worse than smaller losses. Hopefully, models that integrate kinship, partner choice, and exchange with multiple services will increasingly tackle such complexities to give us some clear predictions.

The one thing we can see for sure is that “tit-for-tat” (where a bat simply remembers only the last round with a single partner and makes a binary “yes” or “no” helping decision within a single service) is not a good model for predicting the pattern of cooperation in vampire bats or probably any long-lived social animal.






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Updates: a conference talk, an outreach talk, and an article (and soon… results)

Did you know that Oct 26–Nov 1 is National Bat Week?

October 23. Bat Meetings in Albany, NY. My 15-min talk is “Complex Cooperation: Food Sharing in Vampire Bats is Not Simply “Tit For  Tat”

October 30. Public outreach event at the Museum of Texas Tech University, Lubbock, Texas entitled Vampire Bats: The Secret Lives of Real Vampires. A kid-friendly talk with games and activities. 6-8 pm in the Helen DeVitt Jones Sculpture Court. With cookies apparently! https://www.depts.ttu.edu/museumttu/programscal14.html#oct13

Also, there’s an ongoing exhibit, “Vampire Bats – The Good, the Bad, and the Amazing” at this museum. I’ll be staying in Lubbock, Texas until Nov 1.

I also recently wrote this paper on why behavioral ecologists don’t agree on the importance of reciprocity in animal social behavior. In a nutshell, it’s because different authors use the term in contradicting ways (only some of which make sense). This paper was generously invited by my friend and collaborator Dr. Jennifer Vonk, who studies animal cognition. Here’s the abstract:

Reciprocity (or reciprocal altruism) was once considered an important and widespread evolutionary explanation for cooperation, yet many reviews now conclude that it is rare or absent outside of humans. Here, I show that nonhuman reciprocity seems rare mainly because its meaning has changed over time. The original broad concept of reciprocity is well supported by evidence, but subsequent divergent uses of the term have relied on
various translations of the strategy ‘tit-for-tat’ in the repeated Prisoner‘s Dilemma game. This model has resulted in four problematic approaches to defining and testing reciprocity. Authors that deny evidence of nonhuman reciprocity tend to (1) assume that it requires sophisticated cognition, (2) focus exclusively on short-term contingency with a single partner, (3) require paradoxical evidence for a temporary lifetime fitness cost, and (4) assume that responses to investments are fixed. While these restrictions basically define reciprocity out of existence, evidence shows that fungi, plants, fish, birds, rats, and primates enforce mutual benefit by contingently altering their cooperative investments based on the cooperative returns, just as predicted by the original reciprocity theory.

Today, after manually entering >3,000 rows of behavioral observations into excel from paper scoresheets, I’ve decided to record observations on computers whenever possible. Makes me wonder what kinds of apps are available for data scoring?

Finally, I should know by the end of the day whether my oxytocin treatments worked. The treatments seemed to slightly increase grooming and food sharing in the first pilot study with a small group of females, but they did not seem to work in a second small study with male bats and their moms. I’ll see very soon how it turned out.

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Group selection and adaptation in social spiders: an entangled web (y’see what I did there? clever wordplay)

Why biologists say group selection is wrong, but it’s not, but it is… kinda.

Whenever I talk about vampire bat food sharing to a public audience, someone will inevitably say something like, “Wow! It’s amazing that vampire bats will feed each other to perpetuate their species” or “It’s so interesting how vampire bats will act for the good of the group” (this despite the fact that a main point of my talk is that they don’t act for the good of the group). The idea is pervasive, “Animal X does Y to perpetuate the species/group/population/ecosystem.” It originates, I presume, from years of Disney animal documentaries on how lions eat zebras to keep the circle of life going. Little do people realize that if you make this simple innocent statement in the presence of a talkative biologist, it will induce a frustrated sigh followed by a boring and condescending monologue that begins something like:

Aaactually… that’s not really how evolution works… [bla bla bla]”.

Behavioral ecologists refer to this popular idea, which they love to hate, as “group selection” and many consider it to be an out-of-date theory, or biological myth, akin to Lamarck’s famously wrong idea that giraffe necks are big because they keep stretching them to reach stuff. Richard Dawkins is well-known among biologists not for being an outspoken atheist, but because he wrote a book, The Selfish Gene, that could have just well been called The Group Selection Delusion.

But Aaaactually

In modern evolutionary biology, there is nothing controversial about the existence of group selection. It occurs when individuals live in social groups and those groups go extinct or proliferate at different rates.  You can easily create group selection in the lab and show that it produces certain traits, and stable social groups in the wild can clearly have differing rates of extinction.

Yet, for many evolutionary biologists, talking about group selection is almost like talking about gender politics, gun control, or the Israeli-Palestine conflict. You better tread carefully. Group selection has been a controversial topic in evolution since this 1964 exchange in the journal Nature and biologists are still reading and writing exchanges on it. Researchers who invoke the theory of group selection in their work are always on the defensive, wary of being discriminated against as someone who doesn’t really understand social evolution.* Why all the controversy?

The real controversial question is: Under what conditions does group selection lead to group-level adaptation? That is, when should we expect individuals to act or possess traits “for the good of the group”?

The textbook answer is basically, never– adaptive behavior maximizes gene propagation not success of social groups. But a more correct answer is that individuals can be said to act for the good of the group under two specific conditions. First, when the groups are genetically identical (in this case, the group selection can be equivalently viewed as kin selection). Second, when all competition exists between groups rather than within groups (ie “altruism” within the group can be equivalently understood as cooperation with group members in collective competition with all others in the population). This is what happens when you perform group selection in the lab: you are effectively suppressing genetic competition within groups and creating genetic competition between groups.

If either of these two conditions are met, individuals can eventually possess traits that appear to exist for the good of the group even at the expense of their own reproduction (such as worker bees that sacrifice their lives for the bee colony). In many cases, both conditions are met. For example, all your (non-cancerous) cells act for the good of the group (i.e. your body) because the cells share the same genome (more or less); but in addition, competition between your cells is suppressed, because the best bet for each cell to compete with all the other living cells in the world is not to selfishly replicate as a rogue individual (like a cancer cell), but rather to collectively and cooperatively coordinate their actions with other cells in your body to make babies. As an animal, there’s a limit on how many cells your body can make through growth; but there’s essentially no limit on how many new bodies (and hence cells) your own body can make through reproduction.**

OK, now on to the spiders!

In summary, evolutionary theory tells us that group selection does not really lead to group-level adaptation, except under the strict conditions when the groups are clonal or devoid of any within-group competition. Theorists have shown this many times in many ways.***

But a recent (soon to be controversial) Nature paper claims to have done the impossible: demonstrated that group selection has lead to a group-level adaptation even in groups that are neither clonal nor devoid of competition. The paper entitled Site-specific group selection drives locally adapted group compositions is fascinating. I posted the PDF here (because the journal Nature charges you money to read an article that the author gives away for free).

Anelosimus studiosus (from http://www.texasento.net/Anelosimus.htm)





Social spider webs can get really big (from http://texasento.net)

Before you get lost on the internet and destroy an hour reading about how interesting social spiders are, here’s the basic group selection story in a nutshell. In these amazingly cool group-living spiders (Anelosimus studiosus), the individuals can have two distinct personalities: aggressive or docile. Each group of spiders has a stable ratio of aggressive to docile spiders, and the optimal ratio is different in different environments (just like the optimal phenotypic trait like skin color differs across different environments). This optimal ratio persists when a spider group is moved to a different environment (just like how your skin color largely remains the same when you move to a new environment). Each group has some evolved optimal ratio of aggressive: docile spiders, and the actions of the individual spiders somehow move the group towards that optimal ratio and maintain it there. In conclusion, this optimal ratio is a group-level adaptation that is driven by group selection.

In the authors’ own words:

Our observation that groups matched their compositions to the one optimal at their site of origin (regardless of their current habitat) is particularly important given that many respected researchers have argued that group selection cannot lead to group adaptation except in clonal groups and that group selection theory is inefficient and bankrupt.

Our study shows group selection acting in a natural setting, on a trait known to be heritable, and that has led to a colony-level adaptation.

Does this mean that all these evolutionary theorists were wrong? No. I think (and please someone correct me if I’m wrong) that the contradiction comes from two different meanings of group-level adaptation. When I think of a “group-level adaptation” I think of a phenotypic trait of an individual bee that maximizes the success of the bee colony. And I think this is how most theorists were using the term as well. When you think in terms of inclusive fitness (fitness is a property of individuals not groups), you also tend to think of “adaptive traits” as properties of individuals rather than groups (one level up) or cells (one level down).

A different meaning of a group-level adaptation–the one used by these authors in the spider study– is the “trait” of a colony that cannot be reduced down to the traits of the individuals. For example, this could be the size of the bee colony, the ratio of types in a spider colony, or the diversity of personalities in a human tribe.

So really, we have two different types of group-level adaptation. It seems that group selection is not a good explanation for the first kind (heritable traits of individuals that maximize group survival), but it can explain (and perhaps it’s the only explanation) for the other kind of group adaptation (heritable “traits” of entire groups). It’s important not to confuse these two different things that are often labeled by the same term. In the latter case, does it really make sense to ignore the individuals and talk about group-level fitness or group-level adaptations? I don’t know, maybe.

I used to be really annoyed by group selection, because it always seemed to just glaze over what I thought were the interesting aspects of behavior (the strategies and interactions of individuals within the groups). Just showing that cooperative groups outperform non-cooperative groups, does not explain what makes cooperation stable within each group. That seemed like the real difficult question. In my mind, groups don’t perform “behaviors”, individuals do. So talking about collective actions of groups, without understanding what the individuals are doing just seemed confusing to me.

But now after reading this spider paper and others like it, I am beginning to see more and more that being able to “zoom out” and see groups as having “traits” might be useful in some cases. This is not necessarily just taking the group mean and ignoring the variance (as you do when you talk about things like “bat roost 1 kinship vs bat roost 2 kinship” or “boy height vs girl height” or “white wealth vs black wealth” where you reduce populations to a single average value). Just like a t-test, we can simplify matters by talking about mean differences between groups without losing sight of variation within-groups.

But I still think it’s crucial to figure out what the individuals are actually doing to create this emergent behavior. In this case, we still don’t know. What exactly are the individual spiders doing to reach their optimal ratio? Are they monitoring and policing certain types? Are certain types leaving the group to start new groups? Are they switching groups? I don’t feel like I can understand what’s going on until I can answer these questions. The trick of using group selection theory is to figure out when it’s really solving a puzzle or when it’s just obscuring it.

Should we always try to reduce the properties of groups to the individuals and their interactions? Or should we allow ourselves to think of groups as “individuals”?

I think both. The semantics are confusing, but there’s no contradiction whatsoever between these perspectives. Even if one can’t keep both perspectives in focus at once (I can’t), one should be able to think in both ways and switch between them. If you can’t explain the behavior of the whole using the interactions between the parts, then you don’t really understand the whole. But if you can’t switch perspectives and zoom out to see the whole as an individual node in an even larger network, then you can’t see the bigger picture. (If you like that idea, you’ll love this.)



* At conferences, I’ve had conversation with graduate students working on group selection, who are obviously try to suss out where I stand on the issue to figure out “Is this safe place to discuss group selection?” and on the other side of the coin I’ve also heard one researcher say something like, “Did he just invoke group selection? Jesus Christ.”

**I guess there’s actually an interesting exception: the immortal Hela cancer cells, which are from one woman’s cervix and are now in labs all over the world and collectively weigh more than 20 tons. If these human cells were all in one place, there could be a giant human cervix tumor that weighs the equivalent of 250 humans. So this woman’s cancer cells were much more evolutionarily successful than her other cells, whose DNA has been diluted by 1/2 down every generation.

***By “demonstrate” I mean using models and theory laden with partial differential equations and other mathematical arguments that most biologists– like myself– don’t fully follow, but we will never admit that because we are too embarrassed of our mathematical incompetence and want to think we are real scientists too. We read the words in the introduction and discussion, and we get the gist. We know statistics. That’s math, ok?


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This weekend: Great Lakes Bat Festival

September 27, 2014, 10 am to 5 pm.

at the Ann Arbor Hands-On Museum

Washtenaw Community College
Morris Lawrence Center
4800 E. Huron River Drive
Ann Arbor, Michigan

I’ll have a booth with live vampire bats and give a talk on vampires 4:30-5pm.

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Field Course in Barro Colorado Island

AnComm Panama grp photo

I just spent 2 amazing weeks at the Smithsonian Tropical Research Institute at Barro Colorado Island, Panama as part of a graduate student course led by Hans-Ulrich Schnitzler, Annette Denzinger, Jerry Wilkinson, and Cindy Moss– all leading authorities on vocal behavior in bats. I worked with two German students, Diana Shoeppler and Marie Manthey, on the echolocation and social call behavior of the free-tailed bat Molossus molossus (below). Other teams studied bat species diversity in treefall gaps, temporal patterns in the avian dawn chorus,  and chorusing in frogs.

Photo by Courtney Platt (click for website)

Our team found that Molossus molossus has an extraordinary number of alternating frequencies in its search phase echolocation calls (up to 6 tones). We also found that the bats responded to distress call playbacks. More on that later…

Other highlights included learning about the local birds and frogs, two new bat species, a talk by Mirjam Knoernschild, and talking briefly with PhD student (and talented artist) Jacqueline Dillard about adjustments for Hamilton’s rule under monogamy.

If all goes well, I’ll be doing a postdoc here working with Rachel Page and Yossi Yovel immediately after I graduate next year (fingers crossed).

The absolute highlight of my trip was watching the very charismatic Trachops cirrhosus respond to rewarded playbacks with Inga Geipel.  See this video. Below is a picture of Rachel Page hand-feeding one with pieces of fish. Apparently, they can train the bats to do this within one night.

(photo by Carrie Webber; stolen without permission from Rachel’s website).

Such an extraordinary bat.

Here’s a photo of Trachops exiting a roost in Belize by Brock Fenton.

Trachops cirrhosus by Brock Fenton

And some pics I took of the bats inside the same roost:


Now back to the vampire bat food sharing project….


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Recent and relevant papers– July 23, 2014

Niche-specific cognitive strategies: object memory interferes with spatial memory in the predatory bat, Myotis nattereri (Journal of Experimental Biology)– Fruit and flower bats tend to use spatial memory over shape because those foods don’t move. But insect-eating bats tend to do the opposite, perhaps because insects have distinct shapes and don’t stay still.

Maternal lineages best explain the associations of a semisocial marsupial (Behavioral Ecology)–kin selection in brushtail possums

Frugivorous bats evaluate the quality of social information when choosing novel foods (Behavioral Ecology)– Tent-making bats copy the foods found on other bats’ breath rather than others’ fur

Tent-making bats (Uroderma bilobatum)

Roosting behavior and group decision making in 2 syntopic bat species with fission–fusion societies (Behavioral Ecology) — “In a field experiment where we created a conflict of interests among colony members where to roost, brown long-eared bats always achieved a colony-wide consensus about communal roosts. On the contrary, in Bechstein’s bats, individuals with conflicting interests often formed subgroups in different roosts according to their individual interests instead of reaching a consensus on a single communal roost. “

The dynamics of sperm cooperation in a competitive environment (Proceedings B)– sperm cooperation differs depending on sperm competition

Friendship and natural selection (PNAS) genetic similarity between unrelated friends versus unrelated strangers in large human samples

A functional role of the sky’s polarization pattern for orientation in the greater mouse-eared bat (Nature Communications)– bats use polarized light to set their compass

Partner switching can favour cooperation in a biological market (Journal of Evolutionary Biology)– partner switching in house sparrows and effects on fitness

Group augmentation and the evolution of cooperation (TREE) Do cooperative breeders try to increase the size of their own groups?

In August, I will be speaking at APA Convention in DC and the Animal Behavior Meetings in Princeton, NJ. Then off to Panama.

A vampire bat echolocates into my ear

A vampire bat echolocates into my ear

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