Hellbenders Deserve Love Too

My #scicomm story is about the eastern hellbender (Cryptobranchus alleganiensis). Aptly nicknamed the ‘snot otter’ (I mean, just look at it), the hellbender is North America’s largest salamander species. Fun fact, it was recently named as Pennsylvania’s state amphibian.

Eastern hellbender (Photo: USFWS Midwest)

Side note: Before doing research for this post, I didn’t realize state amphibians were even a thing.

Thanks to anthropogenic effects, the hellbender is also in serious decline. One study held over the course of twenty years observed a 77% decline in hellbender populations (Wheeler et al, 2003).

So, what is causing such a sharp downturn for the lowly ‘lasagna lizard’? Unfortunately, like most of the declining populations that we see in ecosystems today, the ‘Allegheny alligator’ suffers from an acute case of humans. We’ve screwed up their habitats pretty badly.

The hellbender conducts gas exchange completely through their skin. As a result, they require oxygen-rich, shallow, fast-flowing streams for their habitats. Because of their strict habitat requirements, hellbenders are extremely sensitive to environmental changes. One of the biggest contributors to the ‘devil dog’s’ decline is siltation of their habitat via roadways, agriculture runoffs, pollution, and damming of waterways (Unger et al, 2017). All of these things muddy up their native stream systems. This reduces oxygen availability in the environment and can smother the animals.

Hellbenders aren’t prolific breeders, either. A relatively long-lived species, hellbenders have slow growth and developmental rates and an extremely low number of offspring live long enough to join the breeding population (only around 1% in the wild). With their recruitment rates practically crawling along and full-grown adults dying thanks to damaged habitat, things aren’t looking good for the lowly ‘ground puppy’. It isn’t hard to see how their population numbers dropped so drastically

But it isn’t all over yet. Hellbenders have been getting a helping hand recently thanks to joint efforts from state agencies, zoos, and university research. Captive breeding programs and scouting areas for appropriate habitats alongside PR campaigns for public support (Mullendore et al, 2014) have helped the hellbender slowly make a comeback.

Check out this video by the Toledo Zoo to learn more about conservation efforts for these guys:



  1. Mullendore N, Mase AS, Mulvaney K, Perry-Hill R, Reimer A, Behbehani L, Williams RN, Prokopy LS. Conserving the eastern hellbender salamander. Human Dimensions of Wildlife. 2014 Mar 4;19(2):166-78.
  2. Wheeler BA, Prosen E, Mathis A, Wilkinson RF. Population declines of a long-lived salamander: a 20+-year study of hellbenders, Cryptobranchus alleganiensis. Biological Conservation. 2003 Jan 1;109(1):151-6.
  3. Unger SD, Williams LA, Groves JD, Lawson CR, Humphries WJ. Anthropogenic Associated Mortality in the Eastern Hellbender (Cryptobranchus alleganiensis alleganiensis). Southeastern naturalist. 2017 Jun;16(2).
  4. Toledo Zoo (2014)

*Nicknames provided by the US Fish and Wildlife Service: https://www.fws.gov/southeast/wildlife/amphibians/eastern-hellbender/

Snake X-ing: Massasaugas and the dangers of sunbathing

I’ve decided to stick with herps for my second #scicomm post. This time we’ll be talking about rattlesnakes, specifically the Eastern Massasauga (Sistrurus catenatus) which is currently listed as threatened throughout its entire range.

 Figure 1: Range map for the Eastern Massasauga

The massasauga, like all other reptiles, is an ectotherm meaning that they need to use outside forces to regulate their internal temperature (thermoregulation). This strategy for thermoregulation becomes a problem when the environment they require for that action has been changed. Yes, we’re taking about habitat degradation again. Humans are really good at it.

Massasaugas primarily live in wetlands, lowlands, and riparian areas. These areas have perfect basking sites – regions where an individual can intentionally go out and warm up under the sun (Harvey and Weatherhead, 2010).  Unfortunately for the massasauga, a lot of these spaces have been taken by humans for urbanization and agriculture.

A lot of reptiles live in warm, typically sunny environments that provide plenty of basking sites regardless of human interference. However, the massasauga is a temperate species, ranging through the American Midwest region. Because of the area’s lower average temperature and natural geography – more forests and woodlands rather than open prairie and scrubland – the basking sites they do have are crucial. Loss of these important sites causes massasaugas to look for other alternatives, which in this case means roads. Where there are roads, there are cars and in the fight of snake vs F-150, the truck wins. Every time. Roadkill accounts for a very large proportion of human related deaths for massasaugas (Jones et al, 2012).

And that’s not the only human problem that massasaugas face.

Historically, public opinion has not been on the side of snakes. Rattlesnakes get a particularly bad rep. It’s understandably hard to be considered beneficial or cute when you’ve got a mouth full of venom. However, human fear leads to aggressive action when it comes to massasaugas. The first response of many people when confronted with a massasauga is to kill it and this practice along with habitat loss is what has severely depressed the massasauga’s population numbers. In order to combat this, local DNRs and the federal government have been attempting to educate the public on their importance. Massasaugas eat small mammals, birds, and other vertebrates, making them an important source of pest control in their ecosystems. They also serve as an important source of food for larger predators. This, along with making snake removal an option in more regions has helped cut down on direct human mortality. There has also been a recent management effort to create new basking sites in protected areas to reduce their roadkill mortality.

Learn more about massasauga research here: https://www.youtube.com/watch?v=xe2e1d38LyQ

  1. Jones PC, King RB, Bailey RL, Bieser ND, Bissell K, Campa III H, Crabill T, Cross MD, Degregorio BA, Dreslik MJ, Durbian FE. Range‐wide analysis of eastern massasauga survivorship. The Journal of Wildlife Management. 2012 Nov;76(8):1576-86.
  2. Weatherhead PJ, Prior KA. Preliminary observations of habitat use and movements of the eastern massasauga rattlesnake (Sistrurus c. catenatus). Journal of Herpetology. 1992 Dec 1:447-52.
  3. Harvey DS, Weatherhead PJ. Habitat selection as the mechanism for thermoregulation in a northern population of massasauga rattlesnakes (Sistrurus catenatus). Ecoscience. 2010 Dec 1;17(4):411-9.
  4. US Fish and Wildlife Service
  5. Photos: USFWS, Creative Commons, and New York State Conservation Site

Light Pollution and Grey Mouse Lemurs

Light Pollution

Light pollution alters the cycle of natural light and behavior of many organisms (Le Tallec et al., 2013). Nocturnal species rely on natural light for cues for physiological behaviors, causing them to be severely impacted by light pollution as they are attracted to artificial light (Le Tallec et al., 2013). Light pollution can cause changes in reproductive cycles, migration patterns, locomotion, and general orientation/direction (Le Tallec et al., 2013). To fully understand the extent of light pollution’s impact on natural environments, mammals facing its consequences must be studied, like the grey mouse lemur.

Grey Mouse Lemurs

Grey mouse lemurs (Microcebus murinus) are small, nocturnal primates living in various parts of Madagascar (Zimmermann et al., 1998). Grey mouse lemurs have a specialized biological rhythm that defines their reproduction and locomotion activity (Le Tallec et al., 2016). Mouse lemurs have two annual reproductive states, an active sexual state where the mouse lemur is exposed to more than 12 hours of light (photoperiod) for a certain long period of time, and an inactive sexual state where the mouse lemur is exposed to less than 12 hours of light for a certain short period of time (Le Tallec et al., 2013). There is also a daily  locomotion rhythm that entails euthermy (normal body temperature) at night and hypothermia (lower body temperature) during the day (Le Tallec et al., 2013).

Image result for male mouse lemur

A Grey Mouse Lemur (Image: Blanchard Randrianambinina)

A study conducted by (Le Tallec et al., 2016) examined how 12 adult male mouse lemurs react to light pollution in mid-winter (shorter, inactive sexual period), and if this possibly resembles normal reproduction in a long-day, active sexual state. Melatonin production, testis size, body temperature, and locomotion were monitored. Results showed that in the times where the mouse lemurs were exposed to light pollution, their body temperatures were higher, testis size was higher, sexual activity was induced, and hormones were higher (Le Tallec et al., 2016). Melatonin secretion was also inhibited with the exposure to artificial light, causing changes in nocturnal behavior.

Another study on light pollution’s impact on grey mouse lemurs rhythm and behavioral patterns showed that exposure to artificial light caused increased body temperatures and active/resting phase delays in locomotion activity (Le Tallec et al., 2013). The time when the mouse lemur emerged from the nest and returned to the nest was much later when exposed to artificial light, but the total time they were out of the nest was shorter than the normal light (Le Tallec et al., 2013). Timing of foraging and feeding was later in the day when exposed to artificial light pollution (Le Tallec et al., 2013).

File:Griffith Observatory 2012 Light pollution.jpg

An example of light pollution a grey mouse lemur may be exposed to (Image: Mike Peel)

Possible Solutions

These two case studies show how light pollution can impact a plethora of behaviors in grey mouse lemurs, including reproduction, body temperature, and locomotion. This is yet another example of an unfortunate consequence from anthropogenic expansion and urbanization on wildlife.  To alleviate some of the light pollution affects on wildlife species like the grey mouse lemur, solutions to limit the strength of artificial light should be implemented. There are small solutions that if applied on a large scale, could help this problem. Using energy efficient light sources and time controls to regulate the amount of light can help limit the strength of impact on wildlife (Crawford, 1998). It is very difficult to fix the problem of light pollution in large urban areas, so there must be a conversation between important officials and organizations to determine laws and regulations of the amount of light used. Organizations like the International Lighting Commission (CIE) have already started theses discussions to address this issue, and hopefully more individuals will understand the significance of addressing this issue to save species like the grey mouse lemur.



All images were obtained from CreativeCommon

Crawford, DL (1998) Light pollution: The problem, the solutions. Preserving the Astronomical Windows 139, 13-16.

Le Tallec, Perret M, Thery M (2013) Light pollution modifies the expression of daily rhythms and behavior patterns in a nocturnal primate. PLoS ONE 8(11), 1-8.

Le Tallec T, Thery M, Perret M (2016) Melatonin concentrations and timing of seasonal reproduction in male mouse lemurs (Microcebus murinus) exposed to light pollution. Journal of Mammalogy 97(3), 753-760.

Zimmerman E, Cepok S, Rakotoarison N, Zietemann V, Radespiel U (1998) Sympatric mouse lemurs in north-west Madagascar: A new rufous mouse lemur species (Microcebus ravelobensis). Folia Primatol 69, 106-114.

Ringed seals and Global Warming

As of March 2019, the global temperature has risen about 1.62 degrees Fahrenheit since the late 19th century (Global Climate Change, 2019). This number might not sound big but, when it comes to climate and all the organisms who inhabit this planet this number is huge. Changes in temperature can have influence over the seasons, specifically the winter season, and how much snow fall occurs. Researches have predicted there would be less snowfall in the arctic and with decreased ice coverage this could lead to a terrible time for the focus of this post, Ring seals.

Polar bears may come to mind first when thinking of animals affected by climate change, but ringed seals are negatively affected, too—directly impacting polar bears.

© Ian Stirling


Ringed seals are widely distributed in the Arctic and, call the Northern Hemisphere’s circumpolar oceans home. These seals have a lifespan of around 40 years and can grow up to 5 feet and weight up to 150 pounds. This species of seal relies heavily on sea ice and with global warming melting the ice in the arctic, this species will begin to show negative effects. These seals spend most of their time under the ice and self-maintain their breathing by scratching at re-freezing sea ice with their claws (Sterling, 2017).  In early April, females will give birth to their pups in small caves that are dug underneath snowdrifts. These caves are used to provide protection to their young from predators in the area. Rain is also possible in the area because of fluctuating temperatures and washes away birth lairs leaving the pups exposed to predation from polar bears, and arctic foxes (Sterling, 2017).

In 2005 a study was done using 639+ ringed seals focusing on their recruitment in the western Hudson Bay area. Data from previous years indicated trends of less snowfall for the area for the months April and may which be when pups are born and nursed (Ferguson, Stirling, & McLoughlin, 2005). The data from 1999-2001indicated decreased snow depth in April and may which resulted in shallower snow drifts and consequently less protection for pups (Ferguson, Stirling, & McLoughlin, 2005). With increasing temperatures, premature breakup of the ice also lead to significant impacts on growth, condition, and overall survival of nursing pups in the eastern Beaufort sea area (Ferguson, Stirling, & McLoughlin, 2005).  Ringed seals need approximately 20 to 30 centimeters or snow to create their lairs for their pups and with the increasing temperature that may not happen due to the decrease in snowfall around the area. As this trend of warming continues, the arctic will continue to increase in temperature and the many species of seal and other organisms that live in the area will be greatly impacted and increased conservation efforts will be needed.

Figure 1: Example of a perfect snowdrift for concealing a ringed seal birth lair and protecting the occupant. (© Ian Stirling)




Ferguson, S. H., Stirling, I., & McLoughlin, P. (2005). CLIMATE CHANGE AND RINGED SEAL ( PHOCA HISPIDA ) RECRUITMENT IN WESTERN HUDSON BAY. Marine Mammal Science, 121-135.

Global Climate Change. (2019, april 21). Retrieved from NASA: https://climate.nasa.gov/evidence/

Sterling, I. (2017, January 10). What About the Ringed Seals as the Arctic Climate Warms? Retrieved from Polar Bears international: https://polarbearsinternational.org/news/article-climate-change/what-about-the-ringed-seals-as-the-arctic-climate-warms/


Keeping up with the Caribou

Luke Hrubik and I discuss the effects of climate change on caribou populations in this podcast. Factors such as increasing temperatures, drying climates, forage abundance, and population and individual dynamics are covered. We consider how these effects change energy expenditure, metabolism, body condition, and other physiological aspects of the caribou. Enjoy!

Image from: The Caribou and its Species. https://majesticcaribou.weebly.com/description.html


Jandt R., Joly K., Meyers R., Racine C. (2007) Slow Recovery of Lichen on Burned Caribou Winter Range in Alaska Tundra: Potential Influences of Climate Warming and Other Disturbance Factors. Arctic, Antarctic, and Alpine Research. An Interdis. Journal. 40: 89-95.

Leblond M., St-Laurent M. H., Côté S. D.(2016) Caribou, water, and ice – fine-scale movements of a migratory arctic ungulate in the context of climate change. Movement Eco. 4: 14.

Mallory CD, Campbell MW, and Boyce MS. (2018). Climate influences body condition and synchrony of barren-ground caribou abundance in Northern Canada. Pol Bio 41(5):855–864.

Mallory CD, and Boyce MS. (2018). Observed and predicted effects of climate change on Arctic caribou and reindeer. Environ Rev 26:13–25.

Masood S., Van Zuiden T., Rodgers A., Sharma S.(2017) An uncertain future for woodland caribou (Rangifer tarandus caribou): The impact of climate change on winter distribution in Ontario. Rangifer. 1:11-30


Save the Turtles – Salvar a las Tortugas


Sea Turtle Conservation and Temperature-dependent Sex Determination

In 2018, a group of marine biologists reported on an alarming trend they discovered in one of the largest populations of sea turtles in the world. They found that the northern Great Barrier Reef population of Green sea turtles (Chelonia mydas) has produced primarily females (99%) over the past two decades. Whereas the southern Great Barrier Reef population is experiencing a moderate female bias (67%) in their population. When overlapped with temperature data from their respective nesting beaches, warmer temperatures due to global climate change was ascribed as the leading cause of this extreme feminization in the northern population.1

Figure 1 Temperature-dependent Sex Determination (TSD) curve

Why does temperature matter in determining the sex of sea turtles? The sex of most vertebrates is determined by the genetic information of the gametes that join at fertilization. This strategy is referred to as Genetic Sex Determination (GSD), however sea turtles and several other groups of reptiles utilize an alternative strategy known as Temperature-dependent Sex Determination (TSD).2 In this case, the differentiation of gonads into male or female parts occurs during the thermosensitive period which is the middle third of embryonic development. The transitional range of temperature (TRT) is a narrow range of temperatures that produces both male and female offspring and the pivotal temperature (PT) is the temperature at which the sex ratio is 50/50.3 Therefore, if the average nesting temperatures during the thermosensitive period is above the PT, then there will be a bias towards the development of more females. It is also to be expected that average temperatures above the TRT will produce 100% females (see Figure 1).

Around the world, sea turtle conservation projects have been using hatcheries as a management tool for protecting eggs against predation and producing a higher number of hatchlings.4,5,6 When nests are laid below the high tide line or in areas of high predation risk, they are relocated to the hatchery. Simulated nests are dug by hand at the appropriate depth, depending on the species of sea turtle, in order to re-create the egg chamber environment. Doing so allows for researchers to insert temperature probes into each nest monitor temperature during embryonic development and estimate sex ratios. Also, natural predation and egg poaching are eliminated when the nests are in an enclosed and monitored area. In some hatcheries, shade-cloth coverings are used to reduce the amount of direct sunlight on nests and have been shown to improve hatching success along with cooling nesting temperatures in favor of males.6

There is a possibility that turtles will be able to respond naturally to climate change by altering nesting behaviors. Females opting to lay their eggs in cooler/shaded areas of the beach or shifting their nesting season to cooler/wetter periods are several ways turtles would be able to compensate for the rise in global temperatures. Likewise, differences in PT and TRT across populations may provide enough variation for turtles to adjust to a new climate. However, due to their long generation times it seems unlikely that turtles will be able to adapt rapidly to these changes.7 Feminization of entire populations is likely to occur in the near future.1 The use of turtle hatcheries as a management tool is vital for the conservation of sea turtle populations. The protection afforded to sea turtle eggs in a hatchery during crucial developmental periods not only produces a higher number of hatchlings entering the population but also helps to alleviate the gender bias between males and females.

Olive Ridley Hatchling (Lepidochelys olivacea)

Conservación de tortugas marinas y determinación del sexo dependiente de la temperature

En 2018, un grupo de biólogos marinos informaron sobre una tendencia alarmante que descubrieron en una de las poblaciones más grandes de tortugas marinas en el mundo. Encontraron que la población del norte de la gran barrera de coral de las tortugas marinas verdes (Chelonia mydas) ha producido principalmente hembras (99%) durante las últimas dos décadas. Mientras que la población del sur de la gran barrera de coral está experimentando un sesgo femenino moderado (67%) en su población. Cuando se superponen con los datos de temperatura de sus respectivas playas de anidación, las temperaturas más cálidas debido al cambio climático global se atribuía como la principal causa de esta feminización extrema en la población del norte.1

¿Por qué la temperatura es importante para determinar el sexo de las tortugas marinas? El sexo de la mayoría de los vertebrados está determinado por la información genética de los gametos que se unen a la fertilización. Esta estrategia se conoce como determinación genética del sexo (GSD), sin embargo, las tortugas marinas y varios otros grupos de reptiles utilizan una estrategia alternativa conocida como determinación del sexo dependiente de la temperatura (TSD).2 en este caso, la diferenciación de las gónadas en partes masculinas o femeninas se produce durante el período termosensible que es el tercio medio de desarrollo embrionario. El rango de temperatura de transición (TRT) es un rango estrecho de temperaturas que produce la descendencia masculina y femenina y la temperatura pivotante (PT) es la temperatura a la que la proporción de sexo es de 50/50.3 Por lo tanto, si las temperaturas medias de anidación durante el período termosensible está por encima del PT, entonces habrá un sesgo hacia el desarrollo de más hembras. También es de esperar que las temperaturas medias por encima de la TRT producirá 100% hembras (ver figura 1).

En todo el mundo, los proyectos de conservación de tortugas marinas han estado utilizando criaderos como una herramienta de gestión para proteger los huevos contra la depredación y producir un mayor número de crías.4, 5, 6 Cuando los nidos se colocan por debajo de la línea de marea alta o en áreas de alto riesgo de depredación, se trasladan al criadero. Los nidos simulados se cavan a mano a la profundidad apropiada, dependiendo de las especies de tortugas marinas, con el fin de recrear el ambiente de la cámara de huevo. Esto permite a los investigadores insertar sondas de temperatura en cada nido temperatura del monitor durante el desarrollo embrionario y estimar relaciones sexuales. Además, la depredación natural y la caza furtiva de huevo se eliminan cuando los nidos están en una zona cerrada y vigiladas. En algunos criaderos, los revestimientos de telas de sombra se utilizan para reducir la cantidad de luz solar directa en los nidos y se ha demostrado que mejoran el éxito de la eclosión junto con la refrigeración de las temperaturas de anidación en favor de los machos.6

Existe la posibilidad de que las tortugas puedan responder de forma natural al cambio climático alterando los comportamientos de anidación. Las hembras optan por poner sus huevos en las zonas más frías/sombreadas de la playa o cambiar su temporada de anidación a períodos más fríos/húmedos son varias formas en que las tortugas podrían compensar el aumento de las temperaturas globales. Del mismo modo, las diferencias en PT y TRT a través de las poblaciones pueden proporcionar suficiente variación para que las tortugas se adapten a un nuevo clima. Sin embargo, debido a sus largos tiempos de generación, parece improbable que las tortugas puedan adaptarse rápidamente a estos cambios.7 es probable que la feminización de poblaciones enteras ocurra en un futuro próximo.1 El uso de criaderos de tortugas como herramienta de gestión es vital para el conservación de las poblaciones de tortugas marinas. La protección otorgada a los huevos de tortuga de mar en una incubadora durante periodos cruciales de desarrollo no sólo produce un mayor número de crías que entran en la población, sino que también ayuda a aliviar el sesgo de género entre machos y hembras.

Leatherback Hatchlings (Dermochelys coriacea)


  1. Jensen MP, Allen CD, Eguchi T, Bell IP, LaCasella EL, Hilton WA, Hof CAM, Dutton PH (2018) Environmental Warming and Feminization of One of the Largest Sea Turtle Populations in the World. Current Biology 28: 154-159.
  2. Janzen FJ (1994) Climate change and temperature-dependent sex determination in reptiles. Natl. Acad. Sci. 91: 7487-7490.
  3. Mrosovsky N, Pieau C (1991) Transitional range of temperature, pivotal temperatures and thermosensitive stages for sex determination in reptiles. Amphibia-Reptilia 12: 169-179.
  4. Vannini F, Sánchez AR, Martínez GE, López CS, Cruz E, Franco P, García HP (2011) Sea turtle protection by communities in the Coast of Oaxaca, Mexico. Cuadernos de Investigación UNED 3(2): 187-194.
  5. Mutalib AHA, Fadzly N (2015) Assessing hatchery management as a conservation tool for sea turtles: A case study in Setiu, Terengganu. Ocean & Coastal Management 113: 47-53.
  6. García–Grajales J, Hernando JFM, García JLA, Fuentes ER (2019) Incubation temperatures, sex ratio and hatching success of leatherback turtles (Dermochelys coriacea) in two protected hatcheries on the central Mexican coast of the Eastern Tropical Pacific Ocean. Animal Biodiversity and Conservation 42(1): 143-152.
  7. Binckley CA, Spotila JR (2015) Sex Determination and Hatchling Sex Ratios of the Leatherback Turtle. In: Spotila JR, Santidrian Tomillo P, eds. The Leatherback Turtle: Biology and Conservation. Johns Hopkins University Press, Baltimore, pp 84-93.

*All images and figures are the property of J. Evans

Frozen Alive

When temperatures plummet below zero, animals have a few options. They can avoid the cold temperatures all together by finding a nice burrow or staying underwater where it hasn’t frozen, they can be lucky enough to be an endotherm (be able to produce their own body heat), they can die, or some can just let themselves freeze. This remarkable adaptation has been studied over the past 35 years using wood frogs (Rana sylvatica). Wood frogs are found all the way from the Arctic circle into the Appalachian Mountains. Throughout its range, wood frogs overwinter on the forest floor under a thin layer of forest debris (Costanzo, 2019).

Photos: Bethany Williams

Here you can compare what an unfrozen wood frog looks like compared to a frozen frog. Despite this frozen frog having no heartbeat whatsoever, it is alive and will emerge in the spring to mate.

So how do wood frogs do this? They must survive not only freezing, but a long period of not eating, dehydration, and long-term exposure to severe cold. For wood frogs in Alaska, hibernation can last up to 8 months. Therefore, wood frogs have an arsenal of adaptions that they use to survive overwinter (Costanzo, 2019).

To prepare for winter, wood frogs accumulate a large store of glycogen (the storage form of glucose). This stored glucose is an important source of energy during the long period of dormancy when wood frogs are not eating. For the freeze-tolerant wood frog, glucose is especially important as a cryoprotectant, a molecule that protects against freezing—more on those later. Unlike other amphibians which depend on their fat stores during dormancy, wood frogs convert all their fat to glycogen in preparation for winter. Additionally, wood frogs accrue urea as they prepare for winter, which would normally be excreted in urine. Urea helps by depressing the metabolism of the frog and is another important cryoprotectant (Costanzo, 2019).

Freezing injury occurs because as ice forms, water is lost to the ice crystals. This can lead to cell dehydration, membrane failure, and oxidative damage to the cell. Freezing for a long period of time can also deplete energy stores, lead to an accumulation of metabolic wastes that becomes toxic, and cause damage to structures when crystals form. This is where cryoprotectants come in. Once freezing begins, wood frogs mobilize their glucose stores and rapidly distribute them throughout their tissues. Urea, another important cryoprotectant, is already accumulated and distributed to the tissues prior to freezing. Another protective response to freezing is to redistribute tissue water from sensitive organs to places where damage from ice would be minimal like the body cavity. This also means that the concentration of urea and glucose in the cells is higher because there is less water. Both glucose and urea limit ice formation, minimize how much cells actually shrink, and can have other benefits such as regulating metabolism and protecting cell membranes (Costanzo, 2019).

Watch the video below to check out how all of this happens.

Video from PBS Nova ScienceNow


Costanzo JP (2019) Overwintering adaptations and extreme freeze tolerance in a subarctic population of the wood frog, Rana sylvatica. J Comp Physiol B 189: 1-15

Ritsko A (2005). Frozen frogs, PBS  Nova Science Now

Latent effects in conservation physiology: The need to examine long-term consequences of early life environments on populations

Latent effects are responses to conditions or events in an early developmental period that appear later in that individual’s life. Latent effects can set individuals on lifelong trajectories (e.g., high quality food in early life allows for more resilience throughout life, Adler et al., 2013), can allow individuals to be better able to utilize resources later in life (e.g., exposure to stressors in early life causes individuals to have more adaptive responses to stressors as adults, Wang et al., 2016), and alter life history tradeoffs (e.g., individuals who grow and reach maturity quickly die young, Bronikowski and Arnold, 1999). They can be considered a type of carry-over effect (O’Connor et al., 2014), and, similarly, latent effects are likely important for conservation and management strategies (O’Connor and Cooke, 2015).

This early life experience of pretending to be a banana is unlikely to cause a latent effect for this kitten. However, if adorable young animals becoming bananas becomes an alternate life history, physiologists need to study how this can happen and conservation science needs to explore the potential consequences for populations.
Photo from: https://pics.me.me/

When examined individually, latent effects can be thought of as causing two different responses: 1) latent effects make individuals stronger and more adaptive, and 2) latent effects establish an individual’s fate. Latent effects that make individuals stronger and more adaptive can be observed in studies that demonstrate how individuals with poor beginnings can better take advantage of resources once they become available. For example, guppies fed reduced amounts of food during their juvenile stage were able to increase their growth rates once food availability increased, eventually reaching a similar size of individuals that were not fed a restricted diet as juveniles (Auer et al., 2010).


Guppies demonstrated latent effects as compensatory growth during recovery from food deprivation. Photo from: https://wikimedia.org/wikipedia/commons

And, adult zebra finches that were exposed to poor nutrition in early life were able to learn patterns of where food was located more quickly compared with zebra finches that were well-fed in early life (Brust et al., 2014).

Zebra finch with poor quality food in early life (LQT) demonstrated a latent effect with their ability to learn patterns more quickly than individuals with high quality food (HQT). Figure modified from Brust et al. (2014) Fig. 3 and https://farm8.staticflickr.com

Latent effects establishing an individual’s fate can be observed in species that demonstrate a “silver spoon” effect, where the conditions in early life provide some individuals with a jump start and others with baggage. For example, python growth rates throughout life were correlated with their growth rate during the first year of life (Madsen and Shine, 2000). This was explained because prey variability differed across years, and pythons born in years with high prey availability had faster than average growth rates. Ultimately, fast growers in early life were always fast growers.

Pythons that grew fast in their first year of life had higher growth rates throughout their life.
Figure adapted from Madsen and Shine (2000) Fig. 3 and https://encrypted-tbn0.gstatic.com

Alternatively, a bad start can perpetuate difficulties throughout life. Pikeperch that were deprived of essential fatty acids during their larval period had a lower tolerance of stress caused by salinity later in life (Lund et al., 2012). Individuals may experience both the beneficial and the detrimental consequences of their early life experience throughout their life. Cumulatively, the latent responses an individual has adds layers of variation that may cause two individuals of the same species that live in similar environments to have surprisingly different lives (e.g., Xie et al., 2015).

This fascinating aspect of natural variation between individuals is well documented across a range of vertebrate and invertebrate species (Lindström, 1999; Pechenik, 2006); however, latent effects are rarely considered in questions about population or community responses to large-scale environmental changes. A major reason for this is that it can be difficult to track individuals throughout their entire life and take complicated measurements like body condition and number of offspring that survive to reproduce. Studies that examine cohort-level effects can address aspects of latent effects if they incorporate environmental conditions in the early life environment into predictions about current responses (Beckerman et al., 2003).

Understanding the influence of latent effects on individual, cohort, and population responses is becoming more important to conservation physiology as management and conservation of rare species may rely on being able to predict variation in responses to environmental change. Large-scale environmental changes affect individuals directly in the short-term in numerous ways (e.g., see the topics discussed on the blog for this class such as how microplastics may cause endocrine disruption in sea birds, how the warming of global temperatures may disrupt sex determination and reptile populations, etc.). However, the long-term consequences of these environmental changes may have surprising effects on populations if we do not consider latent responses of environmental change on individuals in early life.



Adler MI, Cassidy EJ, Fricke C, Bonduriansky R (2013) The lifespan-reproduction trade-off under dietary restriction is sex-specific and context-dependent. Exp Gerontol 48: 539–548.

Auer SK, Arendt JD, Chandramouli R, Reznick DN (2010) Juvenile compensatory growth has negative consequences for reproduction in Trinidadian guppies (Poecilia reticulata). Ecol Lett 13: 998–1007.

Beckerman AP, Benton TG, Lapsley CT, Koesters N (2003) Talkin’ ’bout my generation: Environmental variability and cohort effects. Am Nat 162: 754–767.

Bronikowski AM, Arnold SJ (1999) The evolutionary ecology of life history variation in the garter snake Thamnophis elegans. Ecology 80: 2314–2325.

Brust V, Krüger O, Naguib M, Krause ET (2014) Lifelong consequences of early nutritional conditions on learning performance in zebra finches (Taeniopygia guttata). Behav Processes 103: 320–326.

Lindström J (1999) Early development and fitness in birds and mammals. Trends Ecol Evol 14: 343–348.

Lund I, Skov PV, Hansen BW (2012) Dietary supplementation of essential fatty acids in larval pikeperch (Sander lucioperca); short and long term effects on stress tolerance and metabolic physiology. Comp Biochem Physiol – A Mol Integr Physiol 162: 340–348.

Madsen T, Shine R (2000) Silver spoons and snake body sizes: Prey availability early in life influences long-term growth rates of free-ranging pythons. J Anim Ecol 69: 952–958.

O’Connor CM, Cooke SJ (2015) Ecological carryover effects complicate conservation. Ambio 44: 582–591.

O’Connor CM, Norris DR, Crossin GT, Cooke SJ (2014) Biological carryover effects: Linking common concepts and mechanisms in ecology and evolution. Ecosphere 5: 1–11.

Pechenik JA (2006) Larval experience and latent effects – Metamorphosis is not a new beginning. Integr Comp Biol 46: 323–333.

Wang Y, Campbell JB, Kaftanoglu O, Page RE, Amdam G V., Harrison JF (2016) Larval starvation improves metabolic response to adult starvation in honey bees (Apis mellifera L.). J Exp Biol 219: 960–968.

Xie J, De Clercq P, Pan C, Li H, Zhang Y, Pang H (2015) Larval nutrition-induced plasticity affects reproduction and gene expression of the ladybeetle, Cryptolaemus montrouzieri. BMC Evol Biol 15. doi:10.1186/s12862-015-0549-0

the Elephants and the Bees

Most of us have heard about the birds and the bees, but what about the elephants and the bees?

As human populations continue to expand, African elephant (Loxodonta africana) populations are experiencing substantial declines. Part of this decline is due to human-elephant conflict. Elephants eat a TON of food – roughly 110 tons per elephant per year. That breaks down to around 220 to 880 pounds of food per elephant per day (Shoshani and Foley 2000). With their habitats slowly dwindling and becoming more fragmented, elephants have been increasingly turning toward raiding farmers’ lands to obtain these resources. As a consequence, elephants have damaged crops, depleted food stores and water sources, and sometimes have even threatened human lives (Hoare 2001). Early attempts to manage this conflict involved shooting the ‘problem’ elephants. However, this disturbs other animals and the surviving elephants have been known to respond with hostility toward humans (Vollrath and Douglas-Hamilton 2002). This situation is clearly dangerous for both humans and elephants and calls for a creative solution to this human-elephant conflict.

Image: Roger Le Guen

Inspired by the work of Vollrath and Douglas-Hamilton (2002), this creative solution came from Dr. Lucy King’s idea to use one the elephant’s worst fears to steer them clear of these farmers’ lands. You might be wondering, what could the largest animal on land possibly be afraid of? The answer: bees.

It turns out that even just the sound of African honeybees (Apis mellifera) causes African elephants to immediately retreat (King et al. 2007). During this retreat, these elephants warn other nearby elephants by producing distinct rumble sounds that causes other elephants to flee while shaking their heads, perhaps to prevent bee stings (King et al. 2010). Research has shown that elephants actually have different alarm vocalizations for bees compared to other threats such as humans, which causes elephants to react in different ways (Solstis et al. 2014). This special alarm call and behavioral response to the sound of bees, such as headshaking, highlights the urgency of the threat elephants perceive from these bees. The African honeybee is notorious for being easily aroused and for having large groups involved in aggressive, swarming attacks. African elephants have thin skin with blood vessels near the surface in several locations such as on their belly, in their trunk, around their eyes, and behind their ears. This makes these areas more sensitive to the African honey bees that can and will sting these elephants, and sometimes entire herds are affected by these swarms (Villrath and Douglas-Hamilton). Elephants are known for living in social groups and for having long memories, so it makes sense that such a negative experience can have long-lasting effects.

Image: Chris Eason

A pilot study was conducted by King et al. (2009) that used these bees as a way to deter elephants from raiding farmer’s crops. They accomplished this by constructing beehive fences and placing them around the crops. This preliminary study was remarkably successful at reducing the number of elephant raids of these crops. Not only are the farmers able to significantly reduce the amount of damage to their crops from elephants, but many suspected these fences also deter people from stealing their cattle and later, they were able to collect honey, beeswax, and other products for these hives as an additional source of income (King et al. 2009). News of the success of these beehive fences spread and these fences can now be found throughout several countries in Africa and Asia.

Image of the construction of the beehive fence, included from the preliminary study by King et al. 2009 aiming to prevent elephants from raiding crop farms.

These studies have given rise to a huge conservation effort to mitigate human-elephant conflict and support elephant conservation through the Elephants and Bees Project. This is a collaborative project involving teams of researchers from Save the Elephants, Oxford University, Disney’s Animal Kingdom, and several other institutions. More information, photos, and scientific studies from these efforts can be found on their webpage: http://elephantsandbees.com/

Image: Mario Micklisch


Hoare RE. 2001. Determinants of human-elephant conflict in a land-use mosaic. Journal of Applied Ecology 36(5): 689-700.

King LE, I Douglas-Hamilton, and F Vollrath. 2007. African elephants run from the sound of disturbed bees. Current Biology 17(19): 832-833.

King LE, A Lawrence, and I Douglas-Hamilton. 2009. Beehive fence deters crop-raiding elephants. African Journal of Ecology 47: 131-137.

King LE, J Solstis, I Douglas-Hamilton, A Savage, and F Vollrath. 2010. Bee threat elicits alarm call in African elephants. PLoS One 5(4): 1-9.

Shoshani J and C Foley. 2000. Frequently asked questions about elephants. Elephant 2(4): 78-87.

Solstis J, LE King, I Douglas-Hamilton, F Vollrath, and A Savage. 2014. African elephant alarm calls distinguish between threats from humans and bees. PLoS One 9(2): 1-11.

Vollrath F and I Douglas-Hamilton. 2002. African bees to control African elephants. Naturwissenschaften 89: 508-511.



All images, except the one detailing the beehive fence, were obtained from CreativeCommons.

Beehive fence construction was obtained from King et al. (2009), referenced above.

Microplastics Impact on Northern Fulmar Birds

I have attached screenshots of my Twitter thread looking at how Northern Fulmar birds are negatively impacted by microplastics in the ocean. This thread discusses how these birds commonly ingest these small plastics, and how it impacts the birds physiologically, such as endocrine disruption. There are so many ways to reduce our use of single-use plastic, and I’m hoping that this thread will bring about more awareness to this issue!

All photos are from the references listed below or CreativeCommons.


Costa M,  Ivar do Sul J (2013) The Present and Future of Microplastic Pollution in the Marine Environment. El Sevier, Environmental Pollution, 185: 352-364.

Galloway T, Lewis C (2016) Marine Microplastics Spell Big Problems for Future Generations. PNAS, 113 (9): 2331-2333

Herzke D et al. (2016) Negligible Impact of Ingested Microplastics on Tissue Concentrations of Persistent Organic Pollutants in Northern Fulmars off Coastal Norway. Environmental Science & Technology, 50 (4): 1924-1933.

Law KL, Thompson RC (2014) Microplastics in the Seas. Science, 345 (6193): 144-145.

Obbard R et al. (2014) Global Warming Releases Microplastic Legacy Frozen in Arctic Sea Ice. Earth’s Future, 2 (6): 315-320.