Thanks Dad!

Daddy's girl. Photo from freedigitalphotos.net.

Let’s take a moment to appreciate just how special dads are. Across the animal kingdom, fathers caring for their young is the exception, not the rule. Paternal care is most often seen in species in which males can be pretty sure that they are indeed the father (for example, in species that fertilize eggs outside of the mothers’ bodies or in socially monogamous species). Mammals rarely act fatherly - Only 10% of mammalian species show paternal care at all. But among mammals, primates (including ourselves) are more likely to do so.

Dads do a number of things to care for their young: Depending on the species (and the individual), they may incubate them, provide them with food, groom them, keep them close to home, guard and protect them, and help them gain survival and mate-attraction skills. These behaviors are costly to a male, who could often be reproductively more successful by spending his time and resources courting more females. But they do it nonetheless.

Regardless of whether a dad is behaviorally involved with his offspring, he contributes a fair amount to the individuals we grow up to be. Dads provide nearly half of our genes, which are the instructions for the production of all of our bodies’ tissues and chemicals. These tissues and chemicals don’t just make up our physical bodies, they underlie much of our physical abilities, susceptibilities to disease, and behavior patterns (including personalities).

Just because about half of your genes are from dad and about half of your genes are from mom, doesn’t mean that you are strictly half-your-dad and half-your-mom. Imagine you are given two books of Thanksgiving Day recipes: Both books have the same recipe for turkey, so that is the one you are going to follow. But one book has a recipe for garlic mashed potatoes and the other has a recipe for plain mashed potatoes. If no one in your family likes garlic, you will likely follow the recipe for plain potatoes. In addition to choosing between recipes, you can also combine them: If one book has a recipe for stuffing with lots of garlic and onions and the other has a recipe for stuffing without garlic or onions, you could make stuffing with onions and no garlic. Your pairs of genes work in similar ways: if the two copies of a gene are different, you may get the trait of one of them or they could combine to give you an intermediate trait. If the versions of the gene are the same, you will likely just get that trait.

When something is made by following the instructions in a gene, this process is called gene expression. Not all genes are expressed equally everywhere: All of the cells of our body have the same genes, but the way they express in a particular cell determines whether that cell is part of a lung, a heart, a brain or something else. If for a particular gene the instructions in the gene from one parent are followed and the gene from the other parent is ignored, this is called parent-specific gene expression. We have several traits that occur as a result of dad-specific gene expression.

Your genes are lined up on doubled-stranded DNA, which is tightly coiled around proteins called histones. The DNA is then wrapped even more and packed into chromosomes. You have 23 different pairs of chromosomes in each cell, where one of each pair came from mom and the other came from dad.  Figure adapted from an image by KES47 at Wikimedia.

More variation is caused by the fact that two individuals with identical genes may not have identical traits. Our genes are encoded in strings of DNA, which are coiled around proteins called histones and then packed into chromosomes. Biological factors can cause the string of DNA to coil tightly around these histones, hindering access to any genes in that section of DNA. This reduces or even prevents gene expression from happening (Imagine what would happen if two pages of your Thanksgiving Day recipe book stuck together). Alternatively, other biological factors can relax the DNA string, increasing gene expression. Gene expression is often decreased or increased as a result of life experiences (such as social experiences, nutrition, or exposure to drugs and toxins). If a particular gene is decreased or increased this way in a sperm or egg cell, this effect can be passed on to the children (and often grandchildren and great-grandchildren and so on). This process of inheritance that is not a strict passing on of genes is called epigenetics. Epigenetics is a new and emerging field, but we have already learned that mothers that provide more parental care create lasting changes in their offspring that are passed down for multiple generations. It is likely that fatherly care has a similar effect. We also know that a father’s nutrition and exposure to drugs and toxins can pass several traits down the generational line through epigenetics.

Dads play a special role in the individuals we become. Their behavior with us, genetic makeup, and even personal experiences shape our physical appearances, health, abilities and personalities. If you haven’t yet, take a minute to say “Thanks, Dad!”

Happy (late) Father’s Day, Dad!


Want to know more? Check these out:

1. Curley, J., Mashoodh, R., & Champagne, F. (2011). Epigenetics and the origins of paternal effects Hormones and Behavior, 59 (3), 306-314 DOI: 10.1016/j.yhbeh.2010.06.018

2. Wilkins, J., & Haig, D. (2003). What good is genomic imprinting: the function of parent-specific gene expression Nature Reviews Genetics, 4 (5), 359-368 DOI: 10.1038/nrg1062


And a special thanks to Tony Auger, Cathy Auger, Stacey Kigar, and Robin Forbes-Lorman for their feedback.

Science Song Playlist

Are you looking for songs to add to your summer playlist? Try some of my favorite geeky life-science songs. Even bona-fide and popular bands (and apparently Daniel Radcliffe) can’t help getting into the science song scene!

Meet the Elements by They Might be Giants:

Pancreas by Weird Al:

The Bad Touch by The Bloodhound Gang:

And then there’s this…

Vote for your favorite in the comments section below and check out sciency song battles by actual scientists at The Science Life, Science Beat, Scientist Swagger and Battle of The Grad Programs! And if you feel so inspired, make a video of your own, upload it on YouTube and send me a link to include in a future battle!

Cicadian Rhythms: Why Does The 17-Year Cicada Emerge Like Clockwork?

Does your back yard look like this?
This swarm of periodical cicadas was photographed by Greg Hume at Wikimedia.

The 2013 Swarmageddon is here! After years of their absence, cicadas are overrunning parks, forests and communities all across the central-eastern United States. Periodical cicadas (from the genus Magicicada) are known for their synchronized emergence at 13- and 17-year intervals. Simply the fact that they can live this long is extraordinary: periodical cicadas have the longest life span of all insect species! But their precise 13- and 17-year emergence cycles have long been an evolutionary enigma.

Today I am over at Accumulating Glitches talking about periodical cicadas! I ponder questions like: How do periodical cicadas know when to emerge (and where are they before that)? How did different species living in the same regions get synchronized to the same cycle? And what evolutionary pressures led to life cycles that are precisely 13- and 17-years long?

Check it out here!

And to find out more, check these out:

1. Koenig, W., & Liebhold, A. (2013). Avian Predation Pressure as a Potential Driver of Periodical Cicada Cycle Length The American Naturalist, 181 (1), 145-149 DOI: 10.1086/668596

2. Koenig WD, Ries L, Olsen VB, & Liebhold AM (2011). Avian predators are less abundant during periodical cicada emergences, but why? Ecology, 92 (3), 784-90 PMID: 21608486

What Has No Legs And The Most Amazing Feet Ever?

 

This starfish photo is by Mike Murphy at Wikimedia.

We often think of echinoderms, like starfish, sand dollars, and sea urchins, as static ocean decorations. But if you watch them for long enough (or on fast-forward if you lack the patience) you will find that they have exciting motile lives. They hunt, they flee predators, and they mate. But how do they get around without any legs to stand on? Their secret is tube feet.

If you look at the underbelly of these critters, you will see lots and lots of little tubes with suction cups on the ends. These are the tube feet. Tube feet work through hydraulic pressure, the pressure created when incompressible fluids are pushed around. Tube feet extend when a muscular bulb at the top of the foot (called an ampulla) contracts, forcing water down the length of the tube. As the tube foot extends, it swings like a pendulum and then lands and plants itself on the surface. If the surface is smooth, muscles can contract causing the cup-shaped tip to form a vacuum, sticking the foot to the surface. When the ampulla relaxes, the tube foot retracts. To get around, the animal contracts and releases these ampullae in waves, causing the tube feet to extend and retract in a coordinated way that moves the animal in a particular direction (albeit very slowly). They can also use their tube feet in a coordinated way to manipulate objects, like food items.


If you take a close look at this Pycnopodia helianthoides, you can
see the structure of its tube feet. Photo by Stickpen at Wikimedia.

But tube feet aren’t just for movement! They can also be used for breathing, smelling, tasting, and even seeing! These abilities relate to the structure of the membrane in the tube feet. Echinoderms are slow moving and have a low metabolism, so they can get away with taking in oxygen and expelling carbon dioxide at low rates. The membranes in the tube feet are permeable to both of these gasses, and thus play an important role in respiration in these species. Additionally, tube feet often have chemoreceptors (receptors sensitive to smell and taste chemicals) and photoreceptors (receptors sensitive to light). It is largely through their tube feet that echinoderms perceive their world.

Echinoderm tube feet are far simpler than our own feet, with fewer muscles, no bones, and no toenails to trim. Yet their feet can look out for predator shadows, grab and taste prey and walk up walls. Sometimes, simplicity is just cooler than complexity.

Want to know more? Check these out:

1. Lesser, M., Carleton, K., Bottger, S., Barry, T., & Walker, C. (2011). Sea urchin tube feet are photosensory organs that express a rhabdomeric-like opsin and PAX6 Proceedings of the Royal Society B: Biological Sciences, 278 (1723), 3371-3379 DOI: 10.1098/rspb.2011.0336

2. Santos, R. (2005). Adhesion of echinoderm tube feet to rough surfaces Journal of Experimental Biology, 208 (13), 2555-2567 DOI: 10.1242/jeb.01683

Check Out My New Team-Blog, Accumulating Glitches!

I have some exciting news to share: Today is the launch day for Accumulating Glitches, a blog I am co-authoring with Sedeer el-Showk! Accumulating Glitches is one of many new science blogs launching this week at Scitable (by Nature Education), and I encourage you to check them out. (A summary of them can be found here).

In celebration of today's launch, I am sharing part of Sedeer's debut post, Do Species Really Exist?

Although these two may look like different species,
science says they are both Eclectus parrots...
But how do we determine which animals are the
same species and which are different species?
Photo by Doug Janson at Wikimedia Commons.

Faced with the rich diversity of living beings around us, humans have proven unable to resist the temptation to try to organize and categorize them. We have a natural tendency to classify things, a habit that's deeply rooted in our cognition and use of language. Our brain excels at recognizing patterns (and thus finding meaning where it doesn't exist), an ability that allows us to interact with the world using names — like "chair" — that we might be hard-pressed to properly explain. In fact, it's surprisingly difficult to define even a seemingly straightforward word like "chair" in a way that would let us recognize everything that should be included (from office chairs and recliners to stools and wheelchairs) but nothing that shouldn't (like tables, tree stumps, or other things we might decide to sit on).

Despite these difficulties, we've been classifying organisms throughout the history of human thought, from Aristotle's division between plants and animals to modern scientific nomenclature. The modern classification system is based on grouping organisms into units called 'species'; species, in turn, group together into a larger units called genus, family, order, and so on through the nested hierarchy of life. What make a species, though? Why should a particular group of organisms be thought of as a unit and given a distinct name? How do we decide which organisms make up a species?


To ponder these questions, read the rest of Sedeer's article!

Male Black Widows Sniff Out Femme Fatales

I am thrilled to announce that this month I am joining a new top-notch science blogging team at Scitable, Nature Education’s award-winning science education website! (But don’t worry, friends. I will continue to post here about animal physiology and behavior every Wednesday). Next week, Scitable will be launching eleven new blogs covering topics like neuroscience, genetics, oceanography, physics and more. I will be co-authoring an evolution blog called Accumulating Glitches together with Sedeer el-Showk (the author of the fantastic nature blog Inspiring Science). To celebrate the launch of these new science blogs, many of us are writing guest posts at Student Voices, another Scitable blog. What follows is the start of my guest post:

__

A female western black widow contemplates the tastiness
of her suitor. Photo by Davefoc at Wikimedia Commons.

Sexual reproduction is a costly affair, but the costs are not usually equal for males and females. Among animals, females generally produce larger gametes (eggs are way bigger than sperm), spend more energy gestating or incubating the young before they are born, and spend more effort caring for the young after they are born. It’s no wonder then that across animal species, females are typically more choosy of who they mate with than males are.

But what if the tables are turned and sex is more costly for males than it is for females? Such is often the case for black widow spiders, named for the females’ infamous reputation for making a post-coital snack of their mates. In such a situation where every sexual encounter is potentially the last, who would blame males for being more choosy of their mating partners? But are they?

To find out, read the rest of the post here!

And to find out more, check this out:

Johnson, J., Trubl, P., Blackmore, V., & Miles, L. (2011). Male black widows court well-fed females more than starved females: silken cues indicate sexual cannibalism risk Animal Behaviour, 82 (2), 383-390 DOI: 10.1016/j.anbehav.2011.05.018

Thanks Mom!

Like Mother, like baby!
Photo from freedigitalphotos.net.

Moms give us so much more than we ever give them credit for. Biologically speaking, we all have a mom and a dad (unless you’re a flatworm or some other species that can reproduce without sex) that provide us with one of each chromosome type (our chromosomes contain our genes, commonly thought of as our “biological blueprints”). So it makes sense that we tend to think of ourselves as being half-our-mom and half-our-dad. But not so! All of us are slightly more-our-mom and slightly less-our dad.

Our genes are encoded in our DNA, which is coiled and tightly packed into dense little chromosomes. Most of our cells contain 23 different pairs of chromosomes (for a total of 46), and one from each pair comes from each parent. One of those pairs is the sex chromosomes. Individuals with two X sex chromosomes are genetically females and individuals with an X and a Y sex chromosome are genetically male. Because genetic males are the only ones with Y chromosomes, all Y chromosomes are inherited from dad. But compared to X chromosomes, Y chromosomes are piddly little things that don’t contain as many genes. So if you’re a guy, you already have more genes from mom than from dad.

In addition to our 46 chromosomes that we keep in the nucleus of each cell, we also have a tiny set of genes in another cell structure, the mitochondria. This mitochondrial DNA is only inherited from the mother, so regardless of whether you are XX or XY, you have a few more genes from mom than from dad.

Wait! My genes are where??
Your genes are lined up on the doubled-stranded DNA, which is tightly coiled and packed into
chromosomes. You have 23 different pairs of chromosomes, where one of each pair came from
mom and the other came from dad. A copy of each of these 23 pairs of chromosomes
(46 chromosomes in total) is in the nucleus of every cell you have (except for sperm or egg cells,
which only have one of each pair, or 23 chromosomes in total). Get it?
Figure adapted from an image by KES47 at Wikimedia.

But we are not simply a product of our genes. If we were, identical twins would be, well… identical. But they’re not. The slight differences between twins results from differences in how our environment interacts with our genes. (By environment, I’m not just talking about temperature and air quality, but rather all external influences). Our environment plays a big role in shaping the individuals we become, and our mothers have more effect on our environment than our fathers do. When we are developing in the womb, our moms’ bodies single-handedly provide us with nutrients, hormones, and antibodies (and sometimes pathogens). During this time, her circumstances and decisions will determine what kind of setting we are born into. After we’re born, the social interaction, nutrition, and antibodies (through breast feeding and/or vaccines) she provides will all influence our gene activity and thus how we develop. Collectively, the traits that we develop due to these factors and all mom’s other nongenetic influences are called maternal effects.

Mom gives us more genes, and has more input in determining how active each gene is. In the end, we are who we are in large part because of our moms.

So Mom, this is for you:

Happy (early) Mother’s Day!


Want to know more? Check these out:

1. BERNARDO, J. (1996). Maternal Effects in Animal Ecology Integrative and Comparative Biology, 36 (2), 83-105 DOI: 10.1093/icb/36.2.83

2. Wolf, J., & Wade, M.J. (2009). What are maternal effects (and what are they not)? Phil. Trans. R. Soc. B, 364, 1107-1115

The Craptastic Conversations of the Black Rhinoceros

What are you saying with your smells? Image by freedigitalphotos.net.

Animals communicate in all kinds of ways: with vocalizations, body language, vibrations, and even odors. In fact, compared to most species, we are pathetic in our abilities to communicate with body odor. With just a whiff of eau de crotch, many animals can decipher that individual’s species, sex, age, health status, reproductive status, emotional state, and dietary history. Some species can go so far as to make out that individual’s exact identity (*Sniff Sniff* Oh! Hi Mike!).

There are a lot of advantages to using odors to communicate. For one thing, messages sent by smell are more likely to be honest than messages sent by other means. (You might be able to do a pretty good Shakira impersonation, but you can’t hide the fact that you had a tuna sandwich for lunch and haven’t brushed your teeth since). Another advantage is that unlike other signal types, an odor signal can be left behind, kind of like those sticky-notes you leave on your food in the fridge.

How do scientists know which species use odors to communicate and what information these signals contain? This investigatory process involves a lot of reasoning.

A solitary black rhino. Photo by John and Karen Hollingsworth
at the US Fish and Wildlife Service.

Wayne Linklater, Katha Mayer and Ron Swaisgood, an international team of researchers associated with Victoria University of Wellington in New Zealand, Nelson Mandela Metropolitan University in South Africa, University of Potsdam in Germany, and the San Diego Zoo Institute for Conservation Research in California, set out to test whether black rhinoceros use odor to communicate. Although rhinos lack the specialized scent glands that many smell-communicating species have, there are many reasons to suggest that they are a likely species to communicate this way.

A photo of field assistant Brayden
Crocker with rhino dung scrape mark.
Photo by Wayne Linklater.

Black rhinos are solitary. Females often have overlapping ranges, but males’ territories only overlap at their boundaries. This means that they would rarely encounter one another and would benefit from a means to leave “sticky-notes” behind to indicate where their territories are. Furthermore, despite their poor eyesight, male black rhinos have a poop-ritual in which they scrape at the ground and spread their dung. Although female rhinos don’t spread their poo, they do spray their pee when they are ready to mate.

Between 2004 and 2006, the Ezemvelo KwaZulu-Natal Wildlife Veterinary and Game-Capture Team captured a number of black rhinoceros from the Ezemvelo KwaZulu-Natal Wildlife Reserves in South Africa in order to relocate them to other reserves for conservation purposes. At this time, Wayne, Katha, and Ron collected dung from rhinos with known sexes and ages. They stored the dung in labeled plastic bags and froze them to preserve the odor freshness for a series of experiments to explore the extent of the black rhinos’ abilities to communicate with their bodily waste.

In one experiment, the researchers asked whether black rhinos could differentiate between the dung of males and females and between the dung of adults and immature subadults. They presented rhinos with the dung of young males, young females, adult males and adult females, and then measured how many times they sniffed each and how long they spent sniffing. The rhinos spent more time sniffing male dung than female dung. This means that rhino poop likely communicates the sex of the pooper. Rhinos also responded differently to adult and subadult poop, suggesting that they can tell whether the pooper is an adult or not.

In order to test whether rhinos may be able to tell the individual identity of the pooper, they did a habituation-dishabituation test. Habituation is when an animal gets used to something that happens repeatedly and stops responding to it. For example, the first time you heard Gangnam Style, you probably stopped what you were doing and maybe even learned the dance. But now it has been so ridiculously over-played that when you hear it, you just ignore it. Dishabituation happens when an animal is exposed to something slightly different and has a heightened response again. Kind of like the excitement over Psy’s new song, Gentleman, even though it sucks.

A photo of rhino performing flehmen, a behavior that helps
waft odors for better odor detection. Photo by Wayne Linklater.

Wayne, Katha, and Ron exposed rhinos to the same individual’s dung three times to see if their interest in it waned. With each presentation, the rhinos spent a little less time sniffing it. When the researchers put poop from a different rhino (that was the same sex and age as the first pooper) in front of them, their interest returned. This suggests that rhinos can tell the individual identity of the pooper from his/her poop.

But can rhinos use their poop like “sticky-notes”? The researchers aged dung for 1, 4, 16 and 32 days and put them in front of rhinos to smell. Their response was the same, no matter how old the dung was. This indicates that rhinos can spread their poop to leave an “I was here” message for at least a month.

As fun as it may be to spend years studying rhinoceros poop, there are some important uses for research like this. Black rhinos are critically endangered, largely due to hunting, poaching and habitat loss. In fact, Mozambique's Limpopo National Park declared the last of their rhino population killed as recently as last month. Conservation efforts such as captive breeding programs and reintroductions have helped in several areas, but have not been enough to sustain the populations. Conservationists could apply this knowledge of how rhinoceros use dung odors to communicate to these breeding and reintroduction efforts in order to make them considerably more successful.


Want to know more? Check this out:

Linklater, W., Mayer, K., & Swaisgood, R. (2013). Chemical signals of age, sex and identity in black rhinoceros Animal Behaviour, 85 (3), 671-677 DOI: 10.1016/j.anbehav.2012.12.034

The Science Life

Grad school is not like anything else you will ever experience. But don’t take my word for it:

"I’m a Grad Student" by Adam Ruben:

"Grad School, I Love You, But You're Bringing Me Down" (LCD Soundsystem Parody) by Nathaniel Krefman at UC-Berkeley:

"The Lab Song" (Bruno Mars Parody) by the Cohenford Lab at Marshall University:

Vote for your favorite in the comments section below. And if you feel so inspired, make a video of your own, upload it on YouTube and send me a link to include in a future post!

Check out other sciency song battles at Science Beat, Scientist Swagger and Battle of The Grad Programs!

How To Get Into An Animal Behavior Graduate Program: Getting Research Experience

You grew up watching nature documentary scientists travelling the world, covertly following and filming wild animals, learning all the secrets of the animal world first-hand with bewildering technology, and you have thought that should be me.


This could be you! Photo by Genny Kozak.

Conducting animal behavior research is incredibly satisfying and exciting, but it is also tedious and frustrating. It’s not for everyone… So how do you know if it’s for you unless you’ve tried it? And how do you try it if you’ve never done it before?

There are plenty of ways to get involved in research, even if you have no experience. And a good place to start is wherever you are.

If you are a college student or have a university in your area, chances are pretty good that there are people on your campus doing research that you would find interesting. Those people may be professors, research scientists, postdocs or graduate students. They may be in a biology, psychology or anthropology department. And their research interests are often listed either on their individual webpages or on departmental webpages. Poke around: They’re out there.

Another good place to look is your local zoo or aquarium. Many large and renowned zoos and aquariums have official research internship programs. But even smaller zoos that don’t advertise will accept volunteers if you make them the right pitch.

If you are interested in wildlife studies, your state DNR (the Department of Natural Resources) may have an internship program as well. Even if they don’t have an official program, there is a chance that they have researchers that can be persuaded to take on a dedicated mentee.

Once you have identified people that you would potentially like to work with, you need to contact them to assess whether they have something productive for you to do and to convince them that you are the one for the job. This first contact may seem intimidating, but the reality is that any researcher would love some help from an enthusiastic, dedicated, and intelligent volunteer (especially if you are willing to work for free or for college credit). However, the reality is also that researchers may not be in a place at the moment to have something productive for you to do. Furthermore, many researchers (particularly professors at large universities) are bombarded by e-mails from students interested in gaining research experience, and your interest can get lost in the chorus of applications. This is why your timing and your pitch are key.

This could be you too! Photo by Charity Juang.

As for timing, research tends to happen in fits and spurts that depend on the availability of research funding. Research can be slow when there’s no money to buy supplies and equipment, pay travel expenses, pay for animal care, and pay salaries. But when a grant does come through, the researcher is suddenly under intense pressure to collect and publish data as quickly as possible before the grant runs out. It’s hard to tell when a particular researcher may have funding, so one good strategy is to keep your eyes and ears open. Sometimes researchers post announcements around their departmental buildings when they're recruiting undergraduate research assistants. Positions and internships may be announced online. But more commonly, positions are filled before they're even announced. So how do you get a coveted position that isn’t even announced?

The best strategy is to contact researchers you are interested in working with as soon as you discover them and conveying your background and interests. They may not have an opening at the moment, but if you remind them of your availability and interest periodically (at the start of each semester, for example), you will likely be among the first to be informed when a position does open up.

What should you say when you contact a researcher you would like to work with? Generally, researchers want to know a few things when being approached by a prospective research assistant:

1. If you are a student, what year are you? Training an assistant is usually a sizable time commitment. During an assistant’s first year, researchers spend as much or more time training the assistant than the assistant contributes to the project. For that reason, researchers usually prefer to hire someone who is likely to stay in the lab beyond a year. The more time you have before you graduate, the more desirable you are as an applicant.



2. What are your research interests and how do they relate to the lab you are applying to? Researchers want assistants that are self-motivated. If you are genuinely interested in the project you will be working on, you are more likely to do a good job and get more out of the experience.



3. What do you hope to gain out of such a research experience? Do you want experience with a particular technique or species? Are you hoping to work for pay or are you willing to work for college credit or just for the experience of it? Be honest here (especially if you need this to pay rent), but keep in mind that most labs don’t have money to pay assistants.



4. What do you have to offer? If you are interested in field research, mention if you are an experienced outdoors enthusiast. If you are interested in learning wetlab techniques, mention your attention to detail. If you are willing to do menial tasks such as dishwashing and maintaining equipment, that could be a major selling point.

Your initial e-mail should be brief (a short paragraph is most effective). But you may want to attach a résumé as well. At the very least, your résumé should list any previous research experiences, classes you have you taken (biology, statistics, chemistry) that may be relevant to a project in this lab, and leadership/work positions you have held.

If you start early in your search and are persistent (but not pushy), you should be able to find a research position within a year. Good luck!

For more advice on applying to graduate programs, go here.