Endozoochory: What the Heck is That?

Guest post by Sheila Mon and Becca Turnbow

This is a guest blog post done by Sheila Mon and Becca Turnbow. They are both graduating seniors at San Diego State University. Sheila will be graduating with a B.S. in biology with an emphasis in zoology and hopes to pursue a career working with animals. Becca will be graduating with a B.S. in biology and hopes to pursue a career as a physician’s assistant. The following was written in regards to ecology research they did this semester:

Think about the last time you were driving in your car eating an apple. You finished the apple and what did you do? You threw it out the window. Although you littered, you also aided in seed dispersal!

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Many plants depend on animals for seed dispersal. Humans disperse seeds by wearing clothing that seeds stick to or by throwing away fruit. Other animals also disperse seeds when the seeds stick to their fur or hair. Also, if a fruit is ingested by an animal, the seeds of the fruit have the chance of passing through the animal’s digestive track unharmed. When the animal passes the seeds, the seeds can potentially grow in the new location. This method of seed dispersal is called endozoochory. You can read more about animal mediated seed dispersal here.3osg4v5

Many plant-animal seed dispersal interactions are necessary for both the plant and the animal. The animal is able to gain energy and nutrients by eating the fruit. The plant would not be able to disperse its seeds without the help of the animal. Many plants have specific animals that are best to disperse their seeds. By eating a fruit an animal can help improve germination, but it can also have no effect on germination, or even sometimes prevent germination (depending on the species). If interested in dispersal by animals check this book out (starting on page 201).

For example, the video below depicts an important relationship between the Indian Rhinoceros and the Trewia Nudiflora plant in Nepal. The fruit of the Trewia Nudiflora has a problem because the seeds from the fruit it bears will not germinate in the shade of the forests they grow in. The fruit, nicknamed the “rhinoceros apple,” is a favorite food of the Indian Rhinoceros. During the heat of the day the rhinoceros goes into the forest to eat the fruit, and then it goes back out to the grasslands in the afternoon. The seeds have the ability to travel through the rhinoceros’s digestive system and germinate where it defecates in the grasslands.
The video is in Spanish, but you can read an English translation of the narration here.

Chimpanzees are frugivores (they eat fruit) that have been observed to be great seed dispersers. They are a larger animal, so they are able to ingest larger seeds. One study found that 98.5% of the chimpanzee feces had seeds in it! Read more about this study here. Chimps, and other primates, are important seed dispersers because of their size and ability to ingest and pass larger seeds.

chimp-eating-grapes

The Old World fruit bats (flying foxes) are also becoming more important as seed dispersers. As other seed dispersers, such as primates, are being hunted, flying foxes are taking on a larger role in dispersing seeds. This is taking place particularly in Asia, where wildlife habitats are being reduced. These bats have been found to even disperse more seeds than birds! Flying foxes are able to disperse seeds over a larger distance than most land animals and birds. They are also the largest bat in the world! (read more about this here)

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An interesting experiment that we came up with would be to study the possibility of seed dispersal by garden snails. Garden snails are an invasive species and well-known pest in the United States. We thought it would be interesting to determine whether snails aid in plant germination via seed dispersal. For the experiment, snails would be fed a fruit with seeds in it (for example: strawberries, blueberries, cucumbers, or tomatoes). Warning: make sure the fruits being used are not genetically modified to have sterile seeds…we learned that the hard way.

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“There is no such thing as a failed experiment, only experiments with unexpected outcomes.”-Richard Buckminster Fuller

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The snail feces (with seeds in it) would be collected and planted. Seeds from uneaten fruits would also be collected and planted separately as the control for the experiment. The plants would be observed daily for germination. If the germination rate of the eaten seeds differs from the control seeds, then seed condition (eaten or uneaten) impacts germination rate. We have not fully carried out this experiment. Although, we think it could provide important information on garden snails and their potential to aid in seed dispersal and germination.

Sources:
Djossa, B.A., J. Fahr, E.K.V. Kalko, and B.A. Sinsin. 2008. Fruit selection and effects of seed handling by flying foxes on germination rates of shea trees, a key resource in Northern Benin, West Africa. Ecotropica 14:37-48.

Iluz, D. 2011. Zoochory: The Dispersal of Plants by Animals. 201-204 in J. Seckbach and Z. Dubinsky, editors. All flesh is grass: plant-animal interrelationships. Springer, New York, New York, USA.

Wrangham, R.W., C.A. Chapman, and L.J. Chapman. 1994. Seed dispersal by forest chimpanzees in Uganda. Journal of Tropical Ecology 10:355-368.

Celebrate the American Hookworm!

hookworm-07022012-04Recently, the genome of the American hookworm, Necator americanus was completed (read more here). In celebration of this achievement, the American hookworm is our cool animal of the week. Also,  parasitic nematodes just really don’t get enough love and attention, so it is time to honor them.

The American hookworm is picked up by humans and other mammals from the soil and then feeds on blood before making a home in the small intestine. An estimated 700 million people are affected by this parasite worldwide and unfortunately none are investment bankers or other financial district employees (because that would be amazing–parasites living within the parasites of society….soo meta and karmic).

You can protect yourself from hookworm, by simply wearing shoes which means that poor people from developing nations are overwhelmingly the afflicted majority.

Hookworm FootCheck out the sensational (in a ridiculous way) video on hookworms by Animal Planet.

If you want to help–donate money to a world health organization, which can build proper latrines and put down cement, instead of buying a pair of TOMS shoes.

Babies in bubbles: foam nests in túngara frogs

Physalaemus petersi communal foam nest in Ecuador  (Photo Credit: Mónica Guerra)

Physalaemus petersi communal foam nest in Ecuador
(Photo Credit: Mónica Guerra)

Reproductive modes in frogs vary greatly, as do the ways in which they deposit their eggs.  The túngara frog, Physalaemus pustulosus (=Engystomops), which is the main focus in my lab  constructs a “foam” nest–an adaptive character which I’ve become interested in exploring. Foamy substances are produced by some insects, tunicates, fish and, perhaps most famously, frogs.

Foam nests  may be constructed by frogs in trees, underground burrows, on top of water, or nearby water sources. This phenomenon has evolved independently several times in both old and new world frogs, living in tropical and subtropical areas.

(Pleurodema diplolister  foam nesting – Video Credit: Amphibiaweb.org)
(Watch the video above to learn more about foam nest construction)

To form the nest, a gooey gelatinous substance comes out alongside the eggs, and it’s usually the male who whips the substance into a bubbly foam using his back legs. Biologically, these nests are incredibly resilient and able to withstand mechanical forces and environmental hazards.

Depending on the frog species, as well as individual differences within species, embryos and then tadpoles vary in the amount of time they spend in nests before emerging. The nest is thought to protect tadpoles from predators, and also maintains a moist environment to prevent desiccation.  The foam nest may additionally provide the eggs with more exposure to oxygen (a hypothesis I’m currently testing experimentally in the túngara frog).

Fig 2: a) foam nest from above b) illuminated from below 2) cross-section d) natural foam nest placed on a petri dish (from Dalgetty and Kennedy 2010)

Fig 2: a) foam nest from above b) illuminated from below c) cross-section d) natural foam nest placed on a petri dish (from Dalgetty and Kennedy 2010)

A member of  the family Leptodactylidae, the túngara frog is found in Central and South America, The male constructs the nests on or near temporary pools of water. The structure of the foam nest is shown in figure 2 (note the “cortex” of foam surrounding the eggs, evident in 2c).

(túngara frog nest construction – Video Credit: Amphbiaweb.org)

Nests may be singletons or many nests may be connected to one another. Community building is discussed in detail in a  paper from Dalgetty and Kennedy in 2010 where three distinct stages of nest building in the túngara frog are explained: 1) creating a bubble raft 2) main building and 3) termination. By exploiting the community nest, pairs spend less time on phase one. While it is unclear if community building is advantageous for all frogs within a given community, it is likely to be so for late joiners, who can skip the first stage of raft building, leaving the early birds to do more of the work–a classic example of the tragedy of the commons.

Stay tuned to this post in the future, where I’ll provide updates of my experimental findings. In the meantime, check out the papers below to learn more.

Dalgetty, L., and M.W. Kennedy 2010. Building a home from foam–túngara frog foam nest architecture and three-phase construction process. Biol. Letters. vol. 6 no. 3 293-296

Flemming, R.I., Mackenzie, C.D., Cooper, A., and M.W. Kennedy (2009). Foam nest components of the túngara frog: a cocktail of proteins conferring physical and biological resilience. Proc. R. Soc. B. vol. 276 no. 16631787-1795

This has been a RAmBlN blog post: part of a series on herpetological adaptations, in celebration of Darwin Day 2014. Check out the other posts here! Like us on Facebook! Or follow us on twitter!

Beetles figure out how to get a drink in the desert

Fig 1 A: O. unguicularis, B: O. laeviceps, C: S. gracilipes, and D: P. cribripes (from Norgaard and Dacke 2010)

Fig 1 A: Onymacris unguicularis, B: O. laeviceps, C: Stenocara gracilipes, and D: Physterna cribripes (from Norgaard and Dacke 2010)

The Namib desert is inhabited by a number of fantastic organisms that have adaptations for desert life. In particular, there are a few tenebrionids or Darkling beetles which call this locale their home. Beetles in the desert need to collect water and while some dig trenches others bask in the fog.

Elytra Structures Fig 2 A: O. unguicularis, B: O. laeviceps, C: S. gracilipes, and D: P. cribripes (from Norgaard and Dacke 2010)

Elytra Structures Fig 2 A: O. unguicularis, B: O. laeviceps, C: S. gracilipes, and D: P. cribripes (from Norgaard and Dacke 2010)

Most beetles have smooth elytra (wing cases), but ones that bask in fog are covered in raised bumps and are also hydrophobic. Fog basking is akin to basking in the sun to increase body temperature, but in this case the beetle uses the elytra to collect water. The increased surface area and hydrophobicity of the elytra increase the amount of water that can be extracted from the fog. This water is then funneled to the head of the beetle as a result of the adopted head-down stance.

Fig 4 Fog basking posture of Onymacris unguicularis (from Norgaard and Dacke 2010)

Fig 4 Fog basking posture of Onymacris unguicularis (from Norgaard and Dacke 2010)

Watch this behavior in action below:

This adaptation is so cool that humans are trying to exploit the technology to make a self-filling water bottle!

Read more in the paper below:

Norgaard, T., and M. Dacke 2010. Fog-basking behaviour and water collection efficiency in Namib Desert Darkling beetles. Front. Zool. 7:23.

 

“You’ve got something on your butt –my eyes!”

© 2014 Danté Fenolio / www.anotheca.com

Pleurodema thaul © 2014 Danté Fenolio / www.anotheca.com

WORST PICK UP LINE EVER, but amazing group of frogs.

The genus Pleurodema contains 15 species and is within the family Leptodactylidae and subfamily Leiuperinae. These so-called four-eyed frogs live in South America and possess a pair of inguinal poison glands that resemble eyes.

What is the purpose of having poison “eyes” on your bum? First of all, why not? I would do it if I could. Seriously…..

© 2014 Danté Fenolio / www.anotheca.com

Pleurodema thaul © 2014 Danté Fenolio / www.anotheca.com

More importantly, we look to the behavior to answer this question. When the animal is threatened it raises its rear (which then appears like the head with eyes and whatnot!) and if the predator attacks it will get a taste of some poison. The damage from the attack will be mitigated and as we all know it is easier to deal with a bite to your hindquarters than the face.
Check out these frogs calling below:

Finnish Forest Magic

The following narrative was written by my very good friend and colleague, Stephen Heap (University of Jyväskylä in Finland). He is a soft-spoken and incredible storyteller and this is a story about a forest survey, but really so much more.

story of forest 3

 Story of the Forest by Stephen Heap, PhD

The pale sun of an autumn dawn shines through the trees to illuminate a shallow valley. Brown ferns, fading into death with the chill of the coming winter, are speckled across a mat of green moss. Trees placidly stand on either side of the valley, comfortably watching the scene below. Their shadows leave dark bars across the floor. The subdued shade accentuates the brighter patches, which shine with a golden luster like the skin of a sensuous lover in a sunlit bedroom.

Standing at the foot of this short valley one can see a change of scenery up ahead. A hillside, dominated by the white bark of birch; their leaves having already fallen to freckle the land below with yellow leaves that gleam against the dark soil beneath. Senses rise in anticipation of what lies ahead, and curiosity takes a hold of the mind. Adventure beckons.

This is what the forests feel to me: a constant adventure waiting to happen. It is in the forest that I cultivate and refresh my capacity for curiosity, personal narrative, and reflection that serve as a source of strength in my daily life. My journey as a scientist, and the challenges that it requires, can only be made with this strength. Hence, my contribution to society depends upon the forest and other natural places. Perhaps this is why I was drawn to join a group of young conservationists on an initial survey of a threatened forest in eastern Finland.

The conservation group was responding to some recent aerial photos of potential areas in a forest that could potentially achieve protection status. The forest is at threat from logging interests and plans to develop lakeside cottages. To the idea of nature conservancy, however, these plans are unacceptable. This forest is one of the few remaining areas in all of southern Finland to be relatively healthy. Despite some cutting, much of the forest remains in an untouched state. Furthermore, little infrastructure exists beyond a road network. It is also a special forest. A recent documentary, set in the area and capturing the lives of plants and animals across the seasons, had touched the hearts of the Finnish people. As such, protecting this area as much as possible, to keep it as a source of natural woodland rather than a material resource, was a major goal for conservation.

The mission for the group that I joined was to briefly survey unexplored areas of forest and get an initial assessment for future areas to focus on. Basically, we would perform a short hike through different areas, noting the diversity of vegetation – a strong indicator for ecosystem health. We would also be on the lookout for the presence of any threatened species. This was a short term tactic, as evidence for threatened species could immediately establish areas protected by law within the forest, and thus serve as strongholds for conservation efforts to establish a large protected area. Species we were hoping to find included an EU-protected flying squirrel, Siberian jays (Perisoreus infaustus), and a variety of mosses and fungis.

            People, university students mostly, that possessed skills for species identification and ecosystem assessment were attracted to volunteer for the expedition. Of course, the lure of spending the weekend in a rustic cabin, complete with fireplace and sauna, had a lot to do with the decision as well. There weren’t only students, though. There was also a woman who grew up near the area, a hiker who wanted to preserve his source of recreation, his young son, and the professional conservationist that led the group. We were ten in all. Each of us shared a sense of personal value associated with the forests and the motivation to act on these values. But this weekend was not only about performing a civil duty for conservation efforts, it was about taking the opportunity to reconnect with a source of strength, and spending time with others that felt the same.

What we found was a great deal of variation in the quality of sites, even amongst those patches that looked healthy from the air. This discrepancy in the appearance of quality between aerial photos and from the ground exists because the health of a forest is not only determined by the density of trees, as people often assume. It is actually the diversity of trees, in age and species, that have more influence on ecosystem health. Vegetation is the source of energy, homes, growth and other resources for an entire community of species. More variety in vegetation allows greater variety in other species and the potential for the forest to persist in the environment. If there isn’t enough variation in the forest community, it is likely to disappear if the environment changes.

We found that some areas had been cut and cultivated in such a way as to only allow one tree species of the same age. No young trees to serve as homes and breeding resources for insects, no tall old trees to serve as pillars of the community. The lack of dead trees was especially concerning because they feed the renewal of the ecosystem. Removing dead trees is like forcing the forest to hold its breath. Unfortunately, most people are unaware that such monotonous forests are unhealthy. The lack of swarming insects, fungus infested trees and rotting wood, and the sense of neatness and order are commonly taken as signs of health rather than distress. People can thus be under the impression that exploiting the forest is being done sustainably. But such areas are not the forest, only the basest impression of one. They provide no homes for the woodland species, they are brittle in the face of change, and they do not serve as a personal source of enrichment. Whatever value these areas of forest had, in terms of economically valuable services performed, the potential to exist as a sustainable resource, and the emotional value to individuals, is lost.

But it wasn’t all so bleak. We also found areas that were much more diverse. Different habitats coiled around each other in patterns only guessed at, each filled with a range of denizens. We found glow-in-the-dark moss, tea-producing mushrooms, centuries-old junipers, and crantastic cranberries. Our major success was finding evidence for the endangered flying squirrel. This means that a small area will soon be protected by EU law and untouchable to loggers. Such small victories are critical for conservation efforts, because every bit helps when it comes to fighting the need to exploit our environment. Conservationists must adopt the strategy of killing with a thousand pinpricks because they lack the economic clout and basis in tradition behind the motivation to exploit the natural environment.

We also encountered two pairs of the threatened Siberian jay, fast disappearing from southern Finland due to habitat loss. These birds curiously approached us, investigating the new visitors to their neck of the woods. They flitted about the trees, taking a look from every angle. They followed us as we walked, watching our every move. They also proved to be quite friendly, and would even perch on an outstretched hand for an instant or two. These birds were an utter delight to interact with, and at one point our entire group marveled in glee as we played with the birds in a snowy gully. It is easy to see why the old folklore saw these birds as the returned souls of good people lost to the forest. To those suffering from loss, the friendly antics of these jays would serve as a warm comfort and reassurance that their lost one’s spirit is content. But such birds can only live in well-developed ecosystems, and widespread habitat loss has forced the few remaining families to disperse across the region and seek whatever small patches they can find. However, the distance between these disparate colonies is too great, the population too widespread, and they slowly fade away. Finding them in this forest is a good sign, but the rarity of these birds carries with it the reminder that we’re losing the ecosystems that can support them.

story of forest 1

 

But how can we act to ensure that such vibrant ecosystems remain? This is the crux of the conservation issue at stake. Standing on a steep hillside that had been blasted by storm and fire, we look down onto a cultivated section of forest at the base of the hill. We stood on scorched earth, piled with fallen trees burnt black. White snow lay in patches over the scene, standing in stark contrast to the ashen trees.

Fire is rare in such forests. People are typically quick to react and extinguish fires, but here they arrived a bit later than usual. Furthermore, people also tend to clean up after storm and fire damage, taking the dead trees for fuel, which they didn’t do in this case. Certain species of insects, adapted to exploit fire-damaged woods, are often taken to be a sign of poor forest health, encouraging speedy management of burnt areas. In truth, such insects reflect the natural breakdown of the burnt area. The ecosystem, of which these small beetles are a component, allow the matter and energy contained within the damaged area to return to the forest. Although we appeared to stand on scorched earth, amidst blackened trees covered in ash and snow, we actually stood on a vibrant source of life.

At the foot of the hill stood a patch of spruce. Nothing but spruce. Dotting the landscape at regular, metric intervals. All standing at the same height. The trees are a deep dark green, and the impression is one of military men performing drill at a front line base. Despite striking an impressive pose in the thin sheet of snow that rests along the branches, this orderly patch of trees is doomed, useless as anything other than a (diminishing) fuel source for humans, and completely uninspiring.

The typical considerations of what constitutes as healthy or damaged is skewed when it comes to the common assessment of forests. People also act on the belief that the forest needs their management for it to be healthy. But forests in a healthy state can take care of themselves. If we are wondering how to act in order to preserve diversity in our natural environment, this conservation group believes that it’s better to just leave things be when it comes to healthy forests.

It is the final hours before our mission ends and we go our separate ways. I lie comfortably on the stone floor of a cave. The contours of the ground are smooth and supportive; my head rests on my arm. The air is warm and refreshing and the light is dim. Outside, it is cold and it snows. A companion had found this small cave, a natural alcove beneath a cracked monolith, a short time ago. Inside, we found evidence for the comings and goings of many creatures. A dried scat pile told us that the cave had been used by badgers and wolves at some point. There was also a makeshift fireplace, a roll of birch leaves and the remains of a woven container, which got us thinking about the person that had left them there.

story of forest 2

Lying in the cave, I had an idea of what the cave was. It was a place of temporary refuge. A place that provides the opportunity to seek warmth, comfort and refreshment away from the harsh world outside. It is a source of respite, giving the inhabitant the strength to return to that harsh world and continue the struggle of life. I imagine the stories of the creatures that use this cave. A portly badger, using it as shelter when it ranges far from its sett to find food. A lone wolf, passing through the area in search of a new home after being expelled from its old range and tracked by hunters. It takes a day of rest to build strength for tomorrow, when it will continue its long search for a pack. A traveler from our grandfather’s age treks through a primeval forest on some quest that we will never know. In the blinding chaos of a storm that threatens his life, he finds shelter and a place to survive.

Perhaps all a bit dramatic, but it does get me thinking that the forest is like the cave. It is a place for people to find support in confronting the challenges that they face. Sometimes the journey through the forest can be long and confusing. We need places where we can take shelter and find strength. If such places are nowhere to be found, then we will be lost.

It was in that cave that I got a piece of understanding for why the forest needs to be protected. Undeveloped areas represent an important resource. They serve as our connection with the natural world, a connection that we must cultivate as a society if we are to persist in the face of an uncertain future. Scientists are increasingly finding evidence that our current economy is unsustainable and catastrophically damaging to the environment that nurtures us. We need a firm understanding of biological systems, and our connection with them, if we are to find our way. We need people who respect these connections when making individual and social decisions. But for people to make decisions that positively shape our future, we need to have pristine wilderness that allows people to reflect, find support, gather inspiration and define themselves. The forests nourish a person’s emotional well-being, and we need people with this emotional intelligence to help guide humanity. Conservationists are acting to keep this connection a strong one, but they fight a battle against centuries-old institutions that favor exploitation of natural areas for resources alone. If we are to overcome the old ways of doing things, and forge a brighter future for ourselves, we need to see the forests as the shelter and source of strength that they can be.

 

 Further Reading

Halme et al. 2013. Challenges of ecological restoration: lessons from forests in northern Europe. Biological Conservation 167. 248-256.

Metsän tarina (documentary set in the forest) IMDB: http://www.imdb.com/title/tt2066922/

Trailer: http://www.youtube.com/watch?v=mFamx2km5nQ

Klein 2013. How Science is Telling us All to Revolt. New Statesman. http://www.newstatesman.com/2013/10/science-says-revolt

Behold: the giant oarfish!!!

Picture credit: kalambo  http://kalambo.deviantart.com/art/Giant-Oarfish-365262027

Picture credit: kalambo
http://kalambo.deviantart.com/art/Giant-Oarfish-365262027

Warning: you might want to quit your job immediately to go out and find a giant oarfish (Regalecus glesne).

This fish is beyond huge and crazy looking. Also, these guys are thought to predict earthquakes. Please sit down in case you faint from this dose of amazing.

Video Credit: Mark C. Benfield

If you’d like to make this fish into a four course meal, click here.