Revolution: Congrats to all my co-Science Marchers and Especially Meghan Duffy (please check out her blog post on preparing her speech at the march)!

So much love to the Meghan and the other scientists who take a moment out of their busy lives to help others understand how all of our work is part of the big picture required for wise application of data to medicine and technology. Dare we think that the march influenced the decisions this week to forego the planned cut in the NIH budget?

I spoke on the main stage of the March for Science in DC on April 22. Last week, I gave the text of my talk. This post talks about how I prepared for the talk. Tomorrow, I’ll have a post with more on the day of the march. tl;dr for this post: it takes a […]

via How I prepared for my March for Science talk — Dynamic Ecology

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You Don’t Know What You’ve Got

Every day my mind is blown by live broadcasts of astounding, weird creatures from our deepest oceans. I’ve posted a taste of this live stream video and photography extravaganza.

In the past, it’s been almost impossible to study life in the deepest oceans. Why? Because it’s freakin’ freezing (sometimes just above zero degrees centigrade (C) or 32oF by your U.S. thermometer), or boiling hot (60 to 464 °C), and the hydrostatic pressure is enormous, almost beyond comprehension. A fish, worm, or crab living down at the bottom of the sea is experiencing literally tons of pressure per square inch, like the weight of an elephant or an SUV compared to the 14.5 pounds per square inch you are probably experiencing right now. And yet, as we speak, heroic explorers are sending live stream video directly to you. And WOW! What they are seeing is beautiful and bizarre!

My colleague from the Lehigh University Department of Biological Sciences, Santiago Herrera, is the lead biologist on an expedition to the American Samoas to some of the deepest parts of the ocean, 3,000-5,000 meters, that is, about 2 miles under the sea. He’s now aboard the Okeanos Explorer, an impressive vessel equipped with high-tech lights, cameras, robot arms and scoops, and lasers that are sent to the sea floor and manipulated by the crew with precision. They broadcast live every day from their American Samoa Expedition.

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NOAA Ship Okeanos Explorer docked at the pier at the Port of Pago Pago in American Samoa. Significant outreach was conducted prior to commencing the expedition. Interviews were conducted with media, and ship tours were held for local elementary through college students, local partners, and government and agency representatives. Image courtesy of the NOAA Office of Ocean Exploration and Research, 2017 American Samoa.

Alien life on Our Own Plant

Just this week, the Okeanos Explorer crew sent these videos of Dr. Seuss-like creatures that you might think were discovered in outer space. What’s incredible is that these creatures’ habitat is actually the most common habitat on our planet. Santiago tells us that most of our planet consists of deep oceans (about 72%), and yet we know very little about what lives there.

Sex and Food Under the Sea

The other day, as I watched the Okeanos team zoom in on some rare sponges, sea anemones, and a type of deep water clam never-before-seen alive, Santiago explained that another extreme feature of the deep sea environment is very low fuel and nutrient availability. Most animals down there depend on a small, slow trickle of organic matter that floats down from shallow parts of the ocean. The link between food and sex holds up in these alien environments. Deep sea creatures must conserve energy and nutrients by maturing very slowly. In comparison to the willy nilly reproduction that’s going on up here, deep sea creatures engage in the energetically-expensive process of reproduction only rarely.

There are many other fascinating adaptations to the extreme deep sea environment. Cell walls and nuclear membranes of deep sea creatures are made to withstand enormous hydrostatic pressure, and therefore, if they are brought up from their deep sea habitat into lower pressures, they literally fall to bits. Many of these creatures are a deep red color, owing to high levels of hemoglobin. Hemoglobin is the thing in your red blood cells that makes them red, and the thing that transports oxygen to your various organs. Extra hemoglobin helps deep sea organisms survive in their low-oxygen environment. So, in the Okeanos Explorer videos, you will often see bright red shrimp, psychedelic ctenophores (comb jellies), and fiery-colored fish in the deepest waters. Here are some screen shots from their gorgeous website.

Kiss it Goodbye

Now that you’re amazed by and bonded to these fascinating friends, let me crush your soul. Climate change will have a devastating impact on our deep sea organisms, and this is related to the food-sex connection and the reality of trickle-down economics. The slow trickle of energy-yielding food to the lower depths has led to the evolution of animals that are now adapted to living on very little food and oxygen. They have survived and spread their traits to each generation because they have an innate tendency to grow and mature very slowly, and reproduce infrequently. Their habitat has been very stable for long periods of time, and once disturbed, they don’t appear to have innate mechanisms to make a comeback. Their rates of reproduction are too slow, and when they experience changes in the acidity, levels of oxygen, or temperature, their populations might not  recover. Climate change, global warming, whatever you want to call it, will cause these devastating changes that disturb the deep sea conditions. Scientists from Scripps Institute of Oceanography have published a study indicating that the food supply to some areas of the earth’s deep oceans will decline by up to one half by the year 2100.

It doesn’t appear that we can count on the United States to delay the onset of climate change. Think about it. Why do we need the governments to make us install solar, purchase electric vehicles, and recycle? When you are planning your own survival and that of your children and grandchildren, think of these deep sea organisms, and our native American friends at Standing Rock, and let them inspire you.

Please let me leave you with something better than a sad Joni Mitchell lyric (“You don’t know what you’ve got til it’s gone”). Keep learning, dig, dig, dig deeper than your initial shallow understanding. Acquiring knowledge is not elitist; it’s freedom and it’s fun. In the words of the B52s, There Goes a Sea Robin!

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Idioteque (this is really happening)

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I Would Die 4 U (and my genetic contribution to future generations)

We knew that praying mantis females often cannibalize their mates after sex, and we suspected that there was some benefit to the male that would outweigh the cost, but why not just take the female out for an expensive dinner? Now we have some evidence. These  clever experiments show that cannibalized males make a greater somatic investment in their offspring leading to higher fecundity in the female. Check out their hot experimental methods for determining male investment in offspring bodies.

Males that are cannibalized after mating make a larger somatic investment in the offspring with a resulting increase in egg production.

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This post is dedicated to our beloved formerly alive One 

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best, me: Remembering Tim Bartness

Timothy J. Bartness died on September 24, this year (2015), and the progress of research on obesity will halt in its tracks, or so I feared until I started reading what his students are posting.

Screen Shot 2015-09-26 at 1.10.06 PMIf you didn’t have the good fortune to know him, Tim Bartness was brilliant, hilarious, and intense. He did innovative work on many frontiers. He elucidated how day length controls body fat loss and gain. He showed how chemical messengers in the brain affect hunger. When he studied food intake, he didn’t limit his observations to eating. He also studied food hoarding, or as he called it, “shopping for food.” Tim was on the verge of understanding how adipose tissue talks and listens to the brain.

If you didn’t know that your fat sends and receives neural input and output, then you weren’t up-to-date on the frontiers of obesity research. Tim had recently been appointed to head an obesity institute at Georgia State University. In his short life, he published more than 200 papers that received almost 10,000 citations, and almost 4,000 of these citations occurred since 2010. He had an important impact on his field of research, and had he chosen to study rats or mice instead of hamsters, more of my fellow neuroendocrinologists would recognize and make use of his foundational, inspired research. He would have loved that I said that.

Moreover, Tim Bartness was my science big brother– not the Orwellian big brother-is-watching-you kind, but the “I’ve-always-got-your-back-but-you’ll-never-be-as-great-as-I-am” kind of older sibling. Tim and I shared two of the same academic parents and grandparents (George Wade and Irv Zucker) (Tim’s full academic lineage appears on Neurotree), and so Tim and I learned, lived by, and then handed down the same set of advice, tricks, and scientific standards. Our loyalty to each other was not nepotistic, but based on our shared ideas about what constitutes hard evidence. We were writing a “how-to” manual for survival in our crazy academic science jobs.

I’ve lost a big brother, and the weight of this emptiness has left me weirdly paralyzed with confusion, heart-broken, and deeply sad. It feels almost wrong to think there might be something to be gained.

Of course we have gained from his life, and thanks to the internet, much of what we have gained is all around me and right in my face…in my Facebook to be more exact. On Facebook, I see not only his picture but hear Tim’s voice.

Tim’s voice is clearly living and breathing in the minds of his students and colleagues. What’s more, these voices are versions of George’s and Irv’s teachings, living on, even in these ridiculously young students.

Here are just a small sampling of quotes from Tim’s students and colleagues:Screen Shot 2015-09-26 at 1.10.37 PM

Laura Been: … We are all better scientists (and better people) for having Tim as a mentor and a friend. I can’t write anything without hearing his voice in my head (While vs. Whereas; Since vs. Because; never starting a sentence with an adverb). He will be very missed!!

Nicole Victoria: I refer to a Tim Bartness teaching almost on a daily basis and have passed them on to grad students, post-docs, my post-doc advisor and other colleagues (e.g. Presentations: Question, picture, answer. Only use ‘Since’ when referring to time. Hypotheses are present tense statements that answer your experimental question, whereas predictions are future tense statements using ‘if, then’. Use ‘In addition’ and never ‘Additionally’ to start a sentence…). I started talking about Strong Inference and alternative hypothesis testing at a job interview with the FDA the other day. They loved it; I thought of Tim and sent him a mental thank you. He had a dramatic impact on the GSU biology, psychology and neuroscience groups. Clearly he is going to live on in us all and our interactions with others. So sad to hear that Tim has passed. He was an amazing scientist, mentor and teacher.

Joe Normandin: His door was always open to all of us grad students. I remember stopping by his office many times to run experiments by him (and find out what I was doing wrong).

Pam Patterson: Just heard the incredibly sad news that one of my dissertation committee members, Timothy Bartness, has passed away. I am heartbroken by the news. He has influenced, and will continue to influence, every experiment I design (strong inference!!), every paper/grant I write (the art of if/then statements), and every presentation I give (EVERY line on a graph should have a purpose). I would not be the same scientist I am today without his mentorship, and I know I am not alone. Rest in peace, TJB. I know all of my fellow GSU neuro-peeps would agree: he will be missed.

The high standards to which he held himself had an amazing motivational effect on so many of us. Turned us all into little Bartnessites.

Amy Ross: So very true. I still ask myself quite often, “What would TJB do?”

Kyle Frantz: 1. Funnel from broad to narrow focus in the introduction; from narrow to broad in the discussion. So simple. 2. When colleagues acted up in faculty meetings, he’d comment “no GABA today, eh?”. Just two nuggets from Tim.

Screen Shot 2015-09-26 at 1.11.44 PMAres Patrulis: Tim was truly one-of-a-kind scientist. He prized thinking outside of the box but in a supremely rigorous way. He believed in the question and not scientific fads and went after all of it with passion and verve. Absolutely fearless. He always had, and will continue to have, my full respect. I miss his voice terribly. This is true loss for neuroscience. I could say much more, but this will suffice.

Stephanie Josephine: My heart is heavy over this news. Tim played a huge role in my decision to attend GSU. I owe him a massive amount of gratitude for his willingness to serve on my committees, for giving constant feedback, and his overall incredible scientific inspiration. I have a lot of days where I question some of my career decisions or feel a semblance of bitterness for being overworked and underpaid (“the students don’t care,” I say! Yes, I know, “these kids today….” I say, as more and more of my hairs turn gray). At my dissertation defense, Tim asked me what I wanted to be when I grew up. I answered that I wanted to have a positive influence on undergraduate education, but I didn’t quite know how I was going to do that (I felt, at the time, like that was a terrible answer since I didn’t have a clear trajectory at the time.). I have to say looking at the beautiful memories people are sharing tonight about Tim as an educator and a person reminds me of why we do what we do. Students do care. We’ve all been positively influenced as scientists and people by Tim and it’s quite clear we’re all continuing to share his legacy. RIP TJB.

Dayne Loyd Averett: This is devastating news. I’ve read all of your comments and they are all so touching and funny, and anyone who worked will Tim can relate to each of your wonderful comments. I have never written a grant without hearing Tims voice critiquing the organization and writing. All my grants have the Bartness stamp, bolding, underlining and italicizing, all of it lol. It is obvious he has left a legacy in his alum.

From me (Jill Schneider): This is so bitter sweet to see the hard evidence of your goodness and how you have honored your teachers and blessed your students. They will surely carry on your legacy to places we can’t even imagine. Love you, my brother.

Best, me

(Tim also played the sax, and I think he would have liked you to hear this!)

tim's email 2 Tim's email 1

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Mystery Achievement (So Real)

There’s something strange about the world’s brightest women in science, technology, engineering, and mathematics (STEM) connecting around one common theme: their own personal insecurity. It’s even more remarkable when this unlikely point of connection propels them toward their career goals.

Assoc. V.P. Research and Professor at UCLA

Nancy Wayne, Assoc. V. C. of Research and Professor at UCLA

I experienced this first-hand in a workshop, “Women Advancing Together” sponsored by the Lehigh University’s Department of Biological Sciences and their National Science Foundation Advance Program. It was not unlike hearing women with anorexia nervosa lament their obesity. These women were the cream of their respective crops. They were top-tier university administrators and full professors with long lists of publications and grant proposals rated in the top 9% of those submitted. They were bright, young  assistant professors ranked above hundreds of applicants for the same job, and they were students ranked in the top of their graduating classes. Despite these credentials, they all shared similar stories of serious and even crippling crises of confidence, i.e., self-confidence. More important, I learned that if I stop writing here, or if you stop reading here, we might be part of the evil forces creating the problem. So, please, read on!

Something short of a miracle occurred when the women joined together in this workshop to confront their fears, embrace their true talents, and promote their own future success. This remarkable transformation was accomplished with the encouragement and guidance of the Associate Vice Chancellor for Research and Professor of Neuroscience at the University of California, Nancy Wayne. Thanks, Nancy!

The workshop started with the well-known, dismal statistics, but ended with a transformative twist. First, we were reminded that there is a substantial gender gap in STEM employment, a gap that grows from a crevice to a grand canyon at the ranks of full professor/senior scientist. Only 5% of full professors in engineering are women. Furthermore, there is a persistent wage gap; women who have landed STEM jobs are paid significantly lower salaries than men in the same position. Not encouraging news, but Nancy countered with evidence that low self-esteem is reversible.

Confidence in Women EngineersTo support this idea, Nancy showed that women who enter engineering fields have credentials and performance levels equal to those of their male counterparts, but the same women have lower levels of self-esteem and self-confidence correlated with stalled advancement. Another graph showed that, after taking an exam but before receiving their grade, those who underestimate their grade tend to be women, whereas those who overestimate their grade tend to be men. Still another graph showed that women negotiate their salaries far less than do men, and as a result, each individual woman stands to lose more than $500,000.00 in salary by the time they are 60 years of age. Nancy is in a good position to know that the wage gap is reversible because she has successfully corrected her salary and recovered her own lost wages. If this were the end of the workshop, however, the dismal statistics would persist far into the future.

Identity-Safe Environments Work for Women

The important twist in Nancy’s version of the story came when she showed her own published data that she collected while she was training women in medical school. She found that women trainees were less likely than their male counterparts to volunteer for leadership positions. More important, she showed that the trend is reversed by subtle suggestions to the contrary. Nancy documented a fact well-known to psychologists: crises of confidence are either averted by “identity safety” or exaggerated by “stereotype threat” (Davies et al., 2005).

Stereotype threat is the fear that an individual‘s performance will justify a negative stereotype of the group with which the individual identifies. This fear affects performance in a direction that supports the stereotype. A well-known example is that poor math performance occurs when girls are told that “girls are bad at math.” The good news is that the vortex of stereotype threat is not inevitable. The opposite occurs when girls perform math in an identity-safe environment, that is, they are told that girls and boys don’t differ in math ability. Is it a lie to say that girls and boys don’t differ in math? Not if the difference is ameliorated and girls math scores improve by telling that “lie.” The bottom line is, when the stereotype involves women’s identity, stereotype threat can be mitigated by the suggestion that women and men do not differ in their ability.

Women Advancing Together

After the data presentation, Nancy instructed the participants to break into groups of 5-8 for some guided discussion. She first instructed the groups to share a time when they might have experienced self-doubt or a case of “imposter syndrome” (wherein we fail to acknowledge our achievements and therefore fear that we might be exposed as frauds at any given moment). There was no hesitation here, and most women struggled to limit their story to one example. At my table, all of the women spilled out feelings of debilitating anxiety and loneliness as they faced career transitions. The intensity was magnified when women moved up and out, from different countries, cultures, socioeconomic backgrounds, or geographic regions within the same country. During this outpouring of emotion, the discomfort melted away. A reciprocal flow of intimacy, empathy, and support seemed to clear the way for strength and confidence.

After this critical step, the stage was set for the realization that we had all survived and made it through our personal trials. Nancy finessed the group onward to acknowledge and share our talents and skills. We were invited to answer the question “What are your strengths?” There was a moment of silence, and then another outpouring. The skill set at our table was formidable. These women were expert computer programmers, software engineers, chemical engineers, biomedical imaging experts, microscopists, architects, civil and mechanical engineers, teachers, writers, scholars, and facilitators of change. As each woman shared her journey, we all learned different ways of coping with self-doubt.

One fascinating comment came from the women who had grown up in China, where teamwork and humility are valued over individual achievement and self promotion. They said that, after living in the U.S. for a while, they decided to assume the very American idea of the “self made man.” It was funny to realize that this cartoon stereotype actually might be useful. Some prominent American males grow up with this “boot-strap” notion and tend to take it to mythological extremes, but in this case, it works as a tangible point of cross cultural exchange. Picking up on this theme, another woman shared her spin on the boot-strap idea from a classic book entitled “Composing A Life.composing a life Our relaxed, meandering conversation sparked a transformation. Whereas social forces had been conspiring to limit our individuality and advancement, our group forged a bond based on the idea that we can be the authors of our lives, lives that truly exists independent of persistent stereotypes, perceptions, and projections.

If we feel stupid, so what? In STEM, one useful strategy is to face the necessity of feeling stupid while we work at the frontiers of knowledge. By definition, a frontier exists beyond the limits of what is known. Scientists therefore must enjoy and seek out the opportunity to feel stupid because that feeling is the signal that you have found the end of what is known and have courageously leapt off the cliff into the unknown. Authoring new knowledge requires that you first recognize your authentic ignorance about the answer to an important scientific question. Your hypothesis may or may not be true, but there is no guarantee that it will be supported by your data. My own mentor used to say that “Your hypothesis was no less brilliant just because it turned out to be wrong.” There is no point in doing research on a documented fact. Engaging in the scientific process requires the strength to feel stupid until you collect enough data to support (or refute) your hypothesis.

At another table, it was noted that experience in athletics or gaming had provided a foundation for persistence and fortitude. Those of us who played softball know that if you strike out, you don’t quit, you simply step up to the plate in the next inning. There are always new innings, and even if you lose, there are more games, and even if you lose the championships, there will be more seasons. For other women, it helped in times of self doubt to remind themselves of the people who first believed in them, those who opened doors, and provided opportunities. They were buoyed by their fear of disappointing those people and propelled by their desire to prove those people right. Other strategies included sharing fears with supportive friends and reminding each other that stereotype threat can be averted when we establish an identity-safe environment.

A related problem is that traits valued in men are often less valued in women, and these traits are devalued in women by both men and women. In men, leadership qualities are seen as positive, whereas in women they are seen as bossy. Women who are direct, logical, clear, concise, and bold, are labeled “ice queens” or “bitches.” Some women at our table have come to accept that they are not well liked. Women who excel in their field will lose their high status in social circles built on gossip and shared failures, but in the end, this is a good thing. When women seek other women across the disciplines, they find their tribe. We got a taste of this in Nancy’s workshop. We saw that when women persist in their goals while feeling lost or stupid, and when they band together to support each other, the fears and anxiety dissipate, and talent and creativity take over. The best way to combat fears about losing friends and allies is to join forces with women who find themselves in the same dilemma. One of the most gratifying parts of the day came when the participants started trading contact information and making plans for future meetings and collaborations. We learned why Nancy Wayne names her workshops “Women Advancing Together.”

nancy wayne and jms

The best part of it all was knowing that Nancy Wayne and I have been advancing along with another workshop participant and Full Professor and Associate Dean, Jennifer Swann since the 1980’s. Jennifer and I both agree, our friendship with Nancy has been fantastic. Here are the three amigas at happy hour, listening to our science colleague, Assistant Professor Julie Miwa, jamming on the saxaphone and drinking to our mystery achievements.three amigas

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Bad Birds Make Good Birds Feel So Good: It’s In the Genes

Donna Maney's lab found that the more aggressive white-striped morph has a change in the gene for estrogen receptor-alpha that makes expression of this gene more efficient in brain areas important for monogamy, aggression, and parental care.

Donna Maney’s lab found that the more aggressive white-striped morph has a change in the gene for estrogen receptor-alpha that makes expression of this gene more efficient in brain areas important for aggression and parental care.

Donna Maney and colleagues report that

the evolution of complex mating strategies are linked to changes in the gene for the estrogen receptor. Changes in one gene can predispose birds toward a “parental investment strategy” (low levels of competition, high levels of parental care) or a “mating strategy” (high levels of competition, low levels of parental care and exta-pair matings).

That in itself is remarkable, but there is another twist. The birds with the genetic change linked to more aggression and less parental behavior almost invariably mate with birds carrying the other genetic arrangement! We knew that both strategies have their advantages, but now it appears that

the two strategies might be complementary when they occur together in the same couple. One member of the pair is more aggressive and territorial, while the other tends to the nest. In pairs where the male takes on more parental duty, the female is likely to be the one who is more aggressive.

Genes and Behavior

Most people agree that our genes affect some behaviors. Think of Huntington’s disease, in which the devastating loss of motor function, memory, and impulse control are linked to a single gene, HTT. Think about the behavior of different dog breeds. The border collie’s intensity differs from the laid-back demeanor of the Labrador, and both of these tendencies differ from those of the happy yappy terrier. There is no doubt that these behavioral differences came about by selective breeding for specific traits, and that the basis for selective breeding is the heritability of those traits. Heritable traits, those that can be inherited, are affected by genes. No problem, but what about complex social behaviors?

Genes, Hormones, Monogamy, and Parental Care

We know that species differ in their mating strategies. Some species tend toward monogamy in that they show a strong preference for mating with a familiar partner, the parent of their own offspring. In these species, fathers tend to share the parental care of their own offspring, and these behaviors are often incompatible with high levels of aggressive competition. Other species tend toward promiscuity (multiple mating partners and no pair-bonds) and in these species, females tend to bear the burden of offspring care. We know quite a bit about hormonal control of these behaviors in certain species. Hormones are secreted from endocrine glands, and they act by binding to receptors. Hormone-receptor binding stimulates or inhibits the neural circuits that control behavior. In male prairie voles and marmoset monkeys, monogamy is linked to a number of hormones, two of which are oxytocin and vasopressin. Promiscuous species differ from monogamous species in the distribution of these receptors in the brain. One specific gene encodes the vasopressin V1A receptor, and monogamy in male voles is linked to the distribution of brain V1A receptors, which in turn is a consequence of the gene for this receptor. One form of the gene (a polymorphism) is linked with monogamy. How strong is the link between hormone receptor distribution and monogamy? In terms of their vasopressin and oxytocin receptors, monogamous marmoset monkeys look more like monogamous prairie voles than they look like promiscuous species of monkeys! Hormonal influences on monogamy and parental behaviors in birds and mammals are well accepted, and this line of research has provided insights into child neglect and abuse, postpartum depression, and autism.

 

Donna Maney and her students study song birds that are monogamous, but can be divided into two types, “dads or cads.” They study hormonally-mediated aggressive song and parental behavior in wild birds that form pair bonds with different levels of exclusivity. In biology, we say these species are “monogamous,” but this does not mean they don’t have sex with more than one partner.  In these song birds, they all form pair bonds, but high levels of aggression and territoriality and low levels of offspring care are correlated with more “philandering,” that is, mating with multiple partners. In male birds, sex and aggressive behaviors are linked to hormones like testosterone from the testes and estradiol made from testosterone in the brain. As you will see, this model system affords unique advantages.

Two Morphs of White-throated Sparrow (Dads or Cads)

To link the evolution of behavior to specific genes, we need a snapshot of evolution in action, that is, we need two groups emerging within one population. Maney chose to study two different wild morphs within one population of white-throated sparrows (Zonotrichia albicollis). The morphs differ in their degree of aggressive song and parental care, as well as their propensity for multiple mating partners. As pictured at the top of this post, the tan-striped morph shows more parental behavior, more exclusive pair bonds, and less aggressive song, whereas the white-striped morph forms pair bonds, but also copulates freely with other birds. The white-striped males are less parental. Aggression can be easily measured by recording the species-typical song in response to that of an intruding male. Videos of the aggressive songs and display can be seen in the video here.

The two morphs also differ at chromosome 2, or ZAL2. Sparrows of the white-striped, aggressive morph all have at least one copy of a rearranged chromosome 2, ZAL2m, whereas the tan-striped sparrows never have this inverted chromosome. Donna Maney set out to study gene differences on this inverted chromosome that might explain differences in complex social behavior.

What’s Estrogen Got To Do With It?

In both morphs, the onset of aggressive, territorial song is correlated with increases in testosterone secreted from the testes during the breeding season (spring). Thus, you might suspect that the white-striped morph is more aggressive due to higher levels of testosterone. You would be wrong. When testosterone levels are equalized, the behavioral differences persist. There is something else going on. In the brains of sparrows and many song bird species, testosterone is converted to estradiol. Aggressive song is blocked by treatments that prevent conversion of testosterone to estradiol or by treatments that block estradiol binding to the estrogen receptor-alpha (ER-alpha) (reviewed by Kiran Soma). Receptors for estradiol, in particular ER-alpha, are located in brain areas involved in aggression, including the medial amygdala. Parental behavior is related to ER-alpha in other brain areas, including the medial preoptic area. The differences between the morphs might be related to differences in ER-alpha in the amygdala and preoptic area.

Just to remind you, Maney and colleagues knew that wild males of the more aggressive, white-striped morphs all have at least one copy of a rearranged copy of chromosome 2 (the rearranged chromosome is called ZAL2m). It turns out, the gene for ER-alpha, called ESR1, is located on this chromosome. Yes. Maney and her colleagues hypothesized that the rearrangement in the chromosome led to a change in ESR1 that led to elevated sensitivity to estradiol, and hence, higher levels of aggression and less parental behavior.

Indeed, Horton et al. found that the white-striped sparrows’ aggression was associated with a more efficient transcription of the gene, ESR1. That is, when the DNA is transcribed to messenger RNA, it occurred at a greater rate in the more aggressive, less parental, white-striped birds. More transcription might led to more translation, and hence more ER-alpha.  This would be expected to render the white-striped birds more sensitive to estradiol’s effects on behavior.

Furthermore, Horton et al., found that in the white-throated morphs, territorial singing and ESR1 expression were higher in a region of the medial amygdala associated with aggression.  Similarly, levels of nest provisioning were predicted by the level of ESR1 expression in the medial preoptic area. Thus, Maney’s group 1) linked a genetic change to a change in behavior, 2) linked a genetic change to a change in efficiency of gene transcription, 3) linked a change in gene expression in a particular brain area to a change in a particular behavior.

Together, these results are consistent with the idea that a genetic change in the gene for the estrogen receptor-alpha has led to the evolution of two different morphs of sparrow that differ in complex social behaviors. These experiments were done using wild birds from natural environments, not just laboratory animals. This and other work on this species was blogged by the awesome, Grrlscientist, at the Guardian. To the best of my knowledge, the Horton et al. article is the first such report in any vertebrate species.

It Takes All Kinds of Birds

Depending on your personal bias, you probably jump to the conclusion that one morph is better than the other, and one morph will win out. Exclusive pair bonds and low levels of aggression might result in more offspring if the offspring receive more parental care. The investment in parental care leads to a pay off in terms of number of reproductively successful offspring.  On the other hand, aggressive, less parental birds can win larger territories and a greater abundance of resources (food and shelter). As this blog documents, the more energy, the greater the reproductive success. Read our latest review for more info on energy and reproduction. I wonder whether the frequency of the different morphs would change depending on the availability of energy in the environment. In any case, this means that in the white-stripe, “Don Draper-like” morph, greater investment in competition for resources might lead to more matings, greater fertility, and higher levels of long-term reproductive success. Maney tells us that these two morphs are not in competition, and probably not about to evolve into two separate species.

In reality, almost all white-throated sparrow breeding pairs consist of one individual with and one without the inverted ZAL2m chromosome. The females also differ in their level of parental investment. In other words, the tan-striped morph invariably mates with the white-striped morph, and the tan-striped male or tan-striped female takes up the slack at the nest. This increases the frequency of heterozygous individuals, and maintains the inverted chromosome ZAL2m in the population. Presumably, there is an evolutionary advantage to both the original version of chromosome 2 and the inverted chromosome ZAL2m, perhaps related to differential parental investment. It’s fascinating that the tan-striped males tend to mate with the more aggressive and territorial females and pick up the slack in the parenting department.

Maney and colleagues and their elegant experiments have shown that in white-throated sparrows, rearrangement of a specific gene, ESR1, is one of the genetic changes that underlies the emergence of two different, complementary life-history strategies.

Human Beings

In birds, voles, and monkeys, the behaviors are measured with precision, and these animals can’t deny, lie about, or exaggerate their sex behaviors. A number of studies have associated human monogamous/promiscuous and parental/nonparental tendencies with genetic polymorphisms, but it’s reasonable to wonder whether monogamy can be studied with any precision in people with such complicated sexuality. When it comes to sex, people are inhibited, shy, disingenuous, priggish, or boastful, rather than factual. Questions about human sexuality might have to wait until sex researchers get a hold of the data compiled by the NSA (that is, data compiled when the agents aren’t spying on their own love interests). Ah, yes. Therein lies a clue.

Well, if humans share anything in common with white-throated sparrows, it would surely be reflected in our musical archives…

 

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