Well begun is half done

After 5 weeks spent in South Africa it is time to draw the first conclusions regarding our new-born project on dispersal in meerkats. I do not want to sound presumptuous but I feel confident saying that this trip has been a great success. And as you know…well begun is half done. But let’s start with some facts from the field.

After few days spent testing the new collars and equipment, getting familiar with the terrain and the road system on the reserve, and getting to know all researchers and volunteers working at the Kalahari Meerkat Project, things got suddenly hectic when one morning we received a radio call from Teja (one of the volunteers) saying that she sighted a female evicted by her natal group a few weeks before being chased by some members of the neighboring group. We could not miss that chance, our first evicted female!

A breathing mask is applied over the head of the meerkat while it is still in the pillow case
A breathing mask is applied over the head of the meerkat while it is still in the pillow case

In few minutes and with the much-appreciated help of Lewis and Sky (the project field managers) we prepared the equipment to capture and anesthetize what turned out to be VLF143 (or spelled out: Female 143 of the Lazuli group). It took only a split second for Sky to close his fingers around the base of the tail of VLF143 that, without even noticing, found herself rowing with the four legs in the air before being gently put in a pillow case to be immobilized. Sky and Lewis applied a breathing mask with a mixture of Isoflurane and Oxygen over her head and in few seconds VLF143 was fast asleep. Few minutes later she was up and running again and, as if nothing happened, she resumed her activities. But this time with a collar around her neck.  In the following 13 days, thanks to the precious calls of the volunteers – our eyes on the reserve – we successfully collared additional 3 females (VEKF010, VJXF035 and VAZF027) from 3 different groups. Hopefully, by the end of this first field season, we will have collared a total of 10 females.

We are closely monitoring each collared individual to make sure that the collars do not negatively influence the animals and to collect important behavioral and ecological data. Daily observations already allowed collecting important information that will allow fine-tuning our research questions. GPS movement data automatically recorded by the collars at one-hour interval during daytime will be analyzed as a function of environmental factors (e.g. rainfall, temperature), social circumstances (e.g. number of individuals in the dispersing coalition but also their location in relation to unrelated territorial groups) and the animal’s individual state (e.g. body condition, stress level). In the long run, we aim to use information on dispersing individuals such as survival rate and reproductive success to improve already existing population dynamic models.

Close follows up are essential to record important behavioural and ecological information and to keep the animals habituated to researchers
Close follows up are essential to record important behavioural and ecological information and to keep the animals habituated to researchers

The first days of our monitoring already provided us with some very useful information. Female VJXF035 lost her sister (VJXF039) with whom she was travelling with after a car run her over. VJXF035 is now back with her group after the dominant female allowed her to rejoin. The collar that we fitted on female VAZF027 (who was dispersing alone) got found lying on the ground…without VAZF027. The collar was covered in blood and fur indicating that VAZF027 got predated, most likely by a raptor. Female VLF143 seems to have found a clever strategy to avoid spending too much time alone (the more eyes scanning around the lower the chance to be taken by a raptor of course); she has already associated, and mated, with 8 different males… I spare you the details. We hope that sooner or later she will build a somehow more stable bond with one or more males and that they will soon set off to find their own territory. Female VEKF010 seems to be the more enterprising and has already crossed the territory of two foreign groups. She has occasionally associated with a couple of males but she seems to be prioritizing a disperser’s business (the actually dispersing) to  a disperser’s pleasure (I believe it is clear what I am referring to…).

Movements of four collared females in and around Kuruman River Reserve, home to the Kalahari Meerkat Project
Movements of four collared females in and around Kuruman River Reserve, home to the Kalahari Meerkat Project

While I had to return to the foggy and miserable Zurich weather, Nino will remain in the sunny Kalahari until the end of March and will continue monitoring dispersing individuals. More info will follow soon.

Tied to two females and more will follow… – Preparations for rotifer resurrection ecology

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My science: all about bags of mud

Today I felt like going on a first (blind) date: being nervous and excited at the same time. Or perhaps this is more what marriage feels like: eager to be tied to your partner(s) for the coming years while knowing it has a high change of being a love-hate relationship. Today, my diapausing females arrived.

They were brought to our lab by Diego Fontaneto and Stefano Gerli of the Istituto per lo Studio degli Ecosistemi. Just like a first date I didn’t know what to expect, and I couldn’t trust that the outside would be a representation of the inside (which of course is the most important part): I was given bags of mud.

The mud comes from different layers of the sediment cores obtained from Lake Orta in Italy. This mud harbours the resting eggs (diapausing females) of the rotifers I will be using to investigate the relative contribution of ecological and evolutionary processes involved in the populations’ responses to changing environments. More information on how I will use resurrection ecology to address this topic will follow hopefully relatively soon.

Resting egg of Brachionus calyciflorus
Resting egg of Brachionus calyciflorus

Diego and Stefano taught us the necessary knowledge and skills on how to extract the eggs from the sediment. As I expected to find a lot of eggs in the mud, I had already designed a small experiment to be able to put the females directly to scientific use. However, in the small sample we investigated, we could only find 2 resting eggs of the rotifer species I will be using (Brachionus calyciflorus). As this is by far not enough for a proper experiment, we decided to put the females on hold: we stored them in the fridge.

To make up for the non-exciting mud picture, hereby a picture of what everyone thinks Science is about: green bubbly liquid. This is how we culture our algae, which we use as a food source for the rotifers.

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What Science is presumed to be all about: green bubbly liquid

Arpat’s Antrittsvorlesung

Our Lab is proud to announce Arpat’s “Antrittsvorlesung” (inaugural lecture), which will be held Monday, 11 November 2013 at 5 pm at the University of Zurich.

I thought I post it on our blog to put some extra pressure on Arpat… 😉

inaugural lecture Ozgul

Do not miss that out… apparently the apèro afterwards is really nice! Oh, yeah and of course the lecture will be absolutely amazing

Mollie Attended an ADMB Developers’ Workshop in Iceland

After the ADMB Developers' Meeting, I investigated the thermal activity in Iceland.

This photo has nothing to do with the workshop. I did some hiking after the workshop and found this huge boiling cauldron of water in the land of fire and ice. The landscapes were amazing with so much geothermal activity, old lava fields, and water falls.

The main purpose of my trip to Iceland was to work September 18-22 with eleven other developers on the statistical software Automatic Differentiation Model Builder (ADMB) at the University of Iceland and the Marine Research Institute in Reykjavik, Iceland. ADMB is useful for fitting nonlinear models and has the flexibility to fit random effects. It’s nearly as flexible as MCMC methods like WinBUGS, but much faster and without the need for specifying prior information (it’s really cool!).

It’s so much easier to get everyone engaged in a discussion and making decisions when we’re all working in the same room, rather than over email when we’re spread out over the corners of the earth. Since we had developers coming from North America and Europe, Iceland was a good midway point, and we had an excellent Icelandic host.

We discussed many important decisions for how to move forward with the software including documentation, parallelization, the most efficient linear algebra libraries, optimizers, links to R, and potentially moving to Github. We’re working to make the documentation easier for new users and writing an introduction aimed especially at R users. We discussed teaching workshops in the near future. We have one scheduled at the International Statistical Ecology Conference and we’re interested in teaching to other groups as well. Let me know if you’re interested.

Moving forward – Animal Movement Ecology Summer School

The last week of August could not have been more hectic and inspiring for some of the people of our lab. The first Animal Movement Ecology Summer School held at the University of Zurich as part of the PhD Program in Ecology of the Life Science Zurich Graduate School has been a great success. We managed to bring together 30 highly dedicated and motivated participants from UZH/ETHZ and from overseas as well as seven top lecturers for what has been an intense and dynamic week.

Participants had the opportunity to alternate high-quality lectures – covering a wide range of topics, such as remote sensing, home-range and movement analysis, patch occupancy models, population dynamics – with some social activities, such has bbq and the long-sought-after jump in the Limmat, the local river. The scope of such activities was to quickly create a cohesive group and promote interactions among the participants and with the lecturers to establish future collaborations. A great success has been the day organised at the Tierpark Goldau, where we had the possibility to follow lectures in a natural and inspiring environment.

 

Participants interacting during one exercise in the suggestive class room at the Tierpark Goldau
Participants interacting during one exercise in the suggestive class room at the Tierpark Goldau

We, organizers, received very positive feedbacks from all participants, which is very encouraging, and we are therefore keen to offer a similar, and even more exciting, course during the summer 2014! Stay tuned on this blog if you do not want to miss-out and want to…keep moving forward!

Necklaces for the girls, cars for the boys – Preparations for the first meerkat field season

Cable tie and epoxy instead of diamonds

My name is MaagNino Maag, and I am about to start my PhD in the Population Ecology lab. During my study, I will investigate dispersal strategies in a wild population of the Kalahari meerkat (Suricata suricatta) in South Africa. I will use high-resolution GPS telemetry data collected from GPS radio collared dispersing female subordinates to investigate the influence of individual traits, environmental factors and social context on transition and settlement strategies. Furthermore, I will assess the survival rates of dispersing females during the stages of transition and settlement. The results of my study shall provide the complementary information on dispersal for more comprehensive spatially explicit population dynamics models and the investigation of alternative life history strategies.

Alex is applying the epoxy.
Alex is applying the epoxy.

In order to acquire movement data of the dispersing individuals, we had to prepare GPS collars. However, two days before leaving for South Africa, the GPS collars yet had to be built. For this reason we set up a workshop in our office in Zurich. On Monday afternoon, 23 September, Gabriele and I were supposed to take a plane to Johannesburg and on Saturday morning we started the workshop. Alex, engineer at CDD Ltd in Athens, followed in for the weekend to build the collars with us.

GPS collar.
GPS collar.

Since meerkats are small animals and we plan to collect detailed dispersal data in an extended area over a time period of six months, GPS collars have to meet a set of specific requirements: The weight has to be below 25 grams, the coating must be robust but should not interfere with the GPS signal, the belting can not be too edgy, and both the GPS data collection schedule and the bidirectional remote communication regime (ZigBee) should be as frequent but in the same time as economic as possible. The GPS device, VHF sender, ZigBee component, and battery were coated with epoxy. We applied cable tie as belting, which will later get covered with heat shrink to make the edges smooth. The epoxy may not be as shiny as diamonds, but the girls will still be fitted with decent solid necklaces.

After a hard weekend’s work, which lasted until Monday noon, Gabriele and I just managed to catch the plane in the afternoon.

Big cars for big boys

In the early Tuesday morning, Gabriele and I arrived in Johannesburg. I bought some airtime and data for my iPhone, Gabriele a new cell phone. After that we picked up the rental car and headed out to buy a field vehicle. Equipped with a Kia picanto and a Tomtom, everything was prepared for the day becoming a successful journey. I have to tell you though, Johannesburg is quite a big city and it took time to visit the different car dealers in the different neighborhoods, especially without a street map. Fortunately, our hosts Nancy and Greg at the Strathavon bed and breakfast were very nice and, besides offering an extra bedroom for free, provided us with a street map, which enabled us to plan next day’s car search a lot more efficient.

Two experts do the technical examination of our Toyota Hilux.
Two experts do the technical examination of our Toyota Hilux.

On Wednesday afternoon we tried our luck in Pretoria. That was a smart move as we found two nice vehicles on that day. Two good-looking Toyota Hilux 3.0 4×4, both were diesel and in good condition. Just the type of car we need! On Thursday we even found a third one. All three dealers agreed to bring their vehicle to a mechanic for full mechanical examination. Well, I had to learn that you should not trust these people too much. One changed his mind and did not bring the car at all, and the second one sold the car to someone else while we were making the technical examination. First comes, first serves! That left us with only one car, a Toyota Hilux 3.0 Diesel 4×4 KZ-TE 2004. To be honest, that was the best one anyway. What a nice car!

Our new hosts Jenny and Pat, the owners of the Sengwe Place bed and breakfast, provided us with an entire apartment. They are such friendly and welcoming people, and, besides a lot of other things, they helped us to buy insurance for the car. On Friday we will hit the road and eventually drive to the field site near Van Zylsrus, Northern Cape. Lets chase some meerkats.

Meet the Rotifer Family

IMG_1387As from Thursday onwards, we are now part of the Family of Rotiferologists. This will be the most important family to deal with in my coming PhD years. Arpat, Stefan and I were welcomed by Diego Fontaneto (Uncle Rotifer) at the ‘Istituto per lo Studio degli Ecosistemi’ in Verbania (Italy). This Institute resides in a big manor house near an idyllic lake: the perfect place to retreat to when one has to write up an article as there is no distraction besides some thorough scientific discussion (which is always welcome) and the sound of calling gulls.

The scientists at this Institute have great knowledge on aquatic ecosystems and the invertebrates that are part of such an ecosystem (for example rotifers). During the two days we visited them, they have shared their knowledge on how to resurrect resting eggs from sediment cores obtained from Lake Orta (a great place to eat an ice cream). So now we are able to bring the past back to life in our lab in Zürich.

More information on the details of my PhD project and the bizarre world of rotifers will follow relatively soon. So keep an eye on this blog if you want to know why even the NASA thinks that rotifers are rather exciting animals…

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First field season accomplished at the Alpine Marmot Project

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If this picture makes you think that it is a holiday place, it is not… This is the nature reserve of La Grande Sassière (45 ° 29′N, 6 ° 58′E), located in the Alps where I spent the last two months starting our project on alpine marmots. The field season started the 15th of May in the snow and ended on the 13th of July under the sun. Weather conditions were especially harsh this year as we worked under the snow until mid-June. I developed an experimental design to understand the physiological mechanisms that drive life history processes and, consequently, population dynamics.

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A marmot looking for some food under the snow

Hibernation plays a central role in the life history of the marmot. Overwinter survival, available fat reserves at emergence, and reproductive success the following spring are mediated by energetic expenditure during the hibernation period.  To understand the link between winter conditions and subsequent changes in demographic rates I will determine hibernation pattern changes in juveniles, yearlings and dominants.To answer this question, I worked on 45 individuals belonging to 8 different families (territories S to Z on the territory map).

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A marmot not really convinced to go into the trap

Once captured, individuals are tagged, sexed and weighed. Several biometric variables are also measured such as the total length of the marmot, the width of the front and back paws, the width of the jaw, the size of the head at the cheek bone, and the width of the pelvis. DNA samples are also taken to determine family structure. In order to recognize the socio-spatial structure of each of the family groups studied, the territory and the composition of family groups was determined by behavioral observations.

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Measurement of the tibia

To determine hibernation patterns, 33 individuals (9 juveniles, 9 yearlings, 15 dominants) have been equipped with a small logger to record their body temperature. I was really stressed until the end as pups emerged later this year than the previous years. The first one emerged the 26th of June instead of the 15th. Juveniles of two of my families emerged on the 11th of July so 2 days before the departure ;-/. Ambient temperature of the main burrow of each family is also currently recorded by loggers.

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A juvenile newly emerged

I am now back in Zürich, and I can’t wait to go back next year to retrieve the loggers and obtain exciting data from the hibernation period._IGP3188

Evrimle matematiğin ne alakası var?

“What’s evolution got to do with math?” This is an article I wrote (in Turkish) on the mathematical analysis of microevolutionary process, focusing on demography, variation and selection components of the current eco-evolutionary models. It is published in Cumhuriyet Bilim Teknik (1373: 10-11), a popular science magazine in Turkey, and reproduced here with their permission.

matematikselevrim

Bu soruyu sormadan önce matematiğin doğa bilimleriyle ne alakası olduğunu bir kez daha hatırlayalım. Bilim insanları olarak, doğanın nasıl işlediğine dair gözleme dayalı öngörülerimizi hipotezler halinde paketleyip geçerliliklerini gözlem ve deneyler yoluyla sorguluyoruz. Bu uzun (ve kimine göre sıkıcı) sorgulamanın sonunda tutarlılığını koruyabilen hipotezler, bizim doğa tanımımızın son versiyonunu oluşturuyor. Her ne kadar bazı bilim dallarında bu sorgulamayı nitel (sözel) olarak yapabilsek de, nicel (sayısal) verilerin toplanabildiği ve problemlerin gittikçe karmaşıklaştığı alanlarda, hipotezleri matematiksel ifade edebilmek bu sorgulama sürecini çok daha verimli kılıyor. Yani, kullanılabildiği yerde, matematik etkili bir bilimsel sorgulama diline dönüşüyor. İki kere iki dört…

“Bir gram cebir bir ton sözlü argümana bedeldir” J.B.S. Haldane

Temel bilimlerin her alanında olduğu gibi, evrimsel biyolojide de hipotezlerimizin birçoğunu nicel olarak formüle ediyor, bu sayede bilimsel sorgulama işlemini daha titiz ve objektif hale getirebiliyoruz. Bunu görmek için evrimsel sürecin küçük adımlarının, yani mikroevrimin tanımına bakalım: bir popülasyon içerisindeki genotip ve buna bağlı fenotip dağılımlarındaki değişim. Bu değişim sürecini inceleyebilmek ve altında yatan mekanizmaları anlayabilmek için bu süreci nicel olarak formüle edip sorgulanabilir hipotezlere indirgiyoruz. Her ne kadar araştırmalarımızı bu sürecin belirli aşamalarında detaylı sorulara odaklanarak yapsak da, evrimsel sürecin tamamını matematiksel bir dille ifade edebilir ve bir sistem modeli olarak ele alabiliriz.

Doğal seçilim; mutasyon, göç ve genetik sürüklenmeyle birlikte, evrimin temel mekanizmalarından biridir. İlk kez Darwin’in nitel olarak tanımladığı “doğal seçilim yoluyla evrim” modelini üç ana bileşende inceleyebiliriz: demografi, farklılık ve seçilim modelleri. Sistemin ilk bileşeni, popülasyonu oluşturan bireylerin sayılarındaki değişimi tanımlayan bir demografi modelidir. Bu tür modeller insan ve yaban hayat popülasyonlarını konu edinen araştırmalarda sıklıkla kullanılır. Darwin’in evrim kuramını oluşturmasında da dönemin ekonomistlerinden Malthus’un popülasyon modeli önemli rol oynamıştır. Malthus’un kuramına göre popülasyonlar, aynı banka hesapları gibi anaparanın üzerine faiz* ekleyerek büyür ve bu özellik her popülasyona üssel artış potansiyeli sağlar. Popülasyon büyüklüğü N ve t süredeki büyüme oranı r ise dN/dt = rN. Ancak, kaynakların sınırlı olduğu bir çevrede, popülasyon hızla çevrenin taşıma kapasitesine ulaşır; hem tür içi hem de türler arası rekabet sonucu sağkalım ve üreme oranları azalır, popülasyon büyüme hızı yavaşlar ve durur. Taşıma kapasitesi K ise dN/dt = rN(K-N)/K. Peki, büyüklüğü çevrenin taşıma kapasitesiyle sınırlı bir popülasyondaki şanslı bireyler kimler? Ne tür fenotip özellikleri sayesinde bazı bireyler sağ kalıp üreyebiliyorken, bu özelliklere sahip olmayan şanssız bireyler üremeden yok oluyor?

Bu aşamada, popülasyonu oluşturan bireyler arasındaki fenotip farklılıkları ve bu farklılıkların üreyen bireylerin yavrularına aktarımlarını tanımlayacak bir farklılık modeli kullanıyoruz. Bu model hem fenotipik esneklik gibi ekolojik tepkimeleri, hem de kalıtım ve mutasyon gibi genetik etkileri içerir; belli çevresel koşullar altında belirli genotipteki bireylerin ne tür fenotip özellikleri olacağını tanımlar. Çoğu zaman incelediğimiz fenotip özellikleri, Mendel’in fasulyelerinin aksine, boy gibi nicel özelliklerdir ve belirlenmesinde rol oynayan genlerin sayısı çok olduğundan matematiksel takibi nispeten zordur. Bu durumlarda nesiller arasındaki fenotip dağılım farklılıklarını tanımlamak için nicel genetik (quantitative genetics) yöntemler olarak bilinen, fenotip değerleri ve aile soyağaçlarının istatistiksel analizi üzerine kurulu, biyometrik modeller kullanılır.

Sistem modelimizin üçüncü ve son parçası ise farklı fenotip özelliklerine sahip bireylerin göreceli sağkalım ve üreme becerilerini belirleyen, yani her bireye veya genotipe bir seçilim değeri (fitness) verebildiğimiz seçilim modelidir. Bu seçilim değeri sabit değil, aksine değişen çevre koşullarıyla ve popülasyondaki diğer bireylerle rekabetle sürekli güncellenen dinamik bir değerdir. Seçilim değerlerindeki bu dinamizmi tanımlamak için seçilim gradyanları ve diferansiyelleri kullanılır. Bu denklemler sistem modelimizin kritik parçalarından biridir ve doğru tanımlayabilmek için farklı fenotip özellikleri olan bireylerin farklı çevresel koşullarda sağkalım ve üreme performanslarını ölçebilmek veya öngörebilmek gerekir.

Bu üç ana parçayı – demografi, farklılık ve seçilim modellerini – birleştirdiğimizde oluşan sistem modeliyle sadece popülasyondaki birey sayısının değil aynı zamanda genotip / fenotip dağılımının da zamanla nasıl değiştiğini inceleyebiliriz. Demografi modeli popülasyonun büyüme potansiyelini ve sınırlarını belirlerken, farklılık modeli bireylerin fenotip özelliklerini ve yavrulara aktarımını tanımlar; seçilim modeli ise hangi bireylerin veya fenotip farklılıklarının bu rekabetten kazançlı çıkacağını belirler, yani bir sonraki nesilde popülasyonu oluşturacak yeni bireyleri seçer. Bu “geridönüşümlü” dinamik mikroevrim modelini kullanarak hangi özelliklerin zaman içerisinde rekabeti kazanıp popülasyonda sabitleneceğini öngörebiliriz. Bu tür “evrimsel sabit stratejileri” (ESS) belirlemek içinse ilk olarak John von Neumann tarafından geliştirilen ve evrimsel uygulamalarını John Maynard Smith’in başlattığı Oyun Kuramı metodları kullanılır. Bu matematiksel yöntemler sayesinde, ilk bakışta evrime aykırı gibi görünen fedakarlık (altruizm) gibi davranışların aslında nasıl evrimsel açıdan kalıcı stratejiler olabileceğini anlıyoruz.

Özetle, matematiksel evrimi şöyle tanımlayabiliriz: bir popülasyon içerisindeki genotip ve fenotip dağılımlarında zaman içerisinde görülen değişimin matematiksel ve istatistiksel yöntemler kullanarak nicel incelemesi. Tabii ki, evrimsel biyolojide kullanılan matematiksel ve istatistiksel yöntemler yukarıda belirtilen mikroevrim sürecini incelemekle sınırlı değildir. Bu yöntemler makroevrim analizlerinde kullanılan türleşme modelleri, farklı türlerin DNA dizilerinin kıyaslanması, filogenetik ağaç oluşturma yöntemleri, genotip-fenotip haritalaması ve nicel biyolojik verilerin toplanabildiği daha bir çok farklı alanda sıkça kullanılmaktadır. Eylül ayında Şirince’de düzenlediğimiz yaz okulunda evrimsel biyolojinin farklı alanlarında uzmanlaşmış bilim insanları olarak, araştırmalarımızda kullandığımız matematiksel ve istatistiksel yöntemleri lisansüstü öğrencilere ve akademisyenlere tanıtmayı, bu sayede Türkiye’de evrimsel biyoloji alanında bilimsel potansiyeli geliştirmeyi hedefliyoruz. Matematiksel Evrim Yaz Okulu’yla ilgili daha fazla bilgi için: matematikselevrim.org

* Aynı zamanda “çıkar” anlamına da gelen İngilizce “interest” kelimesinin doğru çevirisidir!

Burak Avcı ve Tüzer Kalkan’a titiz redaksiyonları için teşekkürler.