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The Beauty of Butterflies

July 11th, 2014 by San-Pei Lee

Butterflies in Cockrell Butterfly Center (Greta oto , Dryas iulia, Morpho peleides, Caligo memnon, Parides iphidamas, Attacus atlas). Photos by San-Pei Lee.

Have you ever found yourself entranced by the beauty of a fluttering butterfly? The Cockrell Butterfly Center (Houston Museum of Natural Sciences) is a marvelous place to stay for a long duration to observe butterflies’ behaviors or to just enjoy the beauty of butterflies. The simulated environment is as close to a tropical rainforest as one can get to in an urban area. The temperature and humidity of the rainforest conservatory was rather high (temperature around 85 degrees Fahrenheit) to accommodate the butterflies and tropical plants. Sunlight penetrated through the glass walls, and a waterfall filled the air with nature’s sounds. There were even smoothie-looking juices, dried fruit mixes, and nectar-filled sponges provided vitamins and minerals for the butterflies.

There were several species of butterflies fluttering all around and stopping for nourishments or rest. The ones I found most intriguing, all of which were in the family Nymphalidae, were the Blue Morpho (Morpho peleides), Giant Owl (Caligo memnon), Julia Longwing (Dryas iulia), and Glasswing (Greta oto). The Glasswing was truly amazing in that it really had transparent wings, and its small size and quick movements made it even harder to find. These physical traits are most likely adaptive for hiding and escaping from predators, such as birds and spiders (Binetti et. al, 2009). On the other hand, the Julia Longwing was bright orange, most likely demonstrating mimicry, where its bright color warns predators of its toxicity. Also, there was a passion flower potted plant on a bench that attracted countless Longwings, in particular the Julia Longwings. The longwings most likely found the passion flower plant, perhaps with pheromones (Maida and Zeisman, 2001), or secreted hormones, that the butterflies probably recognized from when they were caterpillars, and deposited an egg as many times as possible to ensure high reproductive success. I noticed that butterflies preferred to hang upside-down when laying eggs on the undersides of leaves, probably as protection for the eggs against predators like ants. An example of an even more clever physical adaptation is the Owl’s “owl eyes”. I sighted one owl-eyed spot on each wing so that when the Owl rests and closes it wings together, it looked like an owl. This appearance fools and scares away predators (Frederiksen, 2008). The Owl is crepuscular, signifying that it is mostly awake around dawn and dusk (Frederiksen, 2008). This butterfly’s brown owl-like appearance seems very fitting for it to be crepuscular and almost nocturnal or active at night, like the owl bird it imitates. I found a few resting on the rock walls, and when they did fly, it was an awkward, bat-like flight. My favorite was the Blue Morpho because its wings reflected a beautiful, glittering blue, another foil for predators. This large butterfly flew fast but smoothly, and I observed a lot of them playing and chasing each other. Something interesting about the Blue Morpho is that the undersides of its wings are similar to the Owl’s with dull colors and small eye-looking spots, which is most likely an added protection. Read the rest of this entry »

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Ornaments and Weapons

July 9th, 2014 by nyn1

 

In this post, I will discuss two tactics that animals use in order to gain access to mates as well as an example in each. You can also find both articles on Wikipedia. Find the weapons article at: https://en.wikipedia.org/wiki/Weapons and the ornaments article at https://en.wikipedia.org/wiki/Ornaments.

Weapons are traits that are used by males to fight one another off for access to mates. A mate is won in battle either by a male chasing off a fellow competitor or killing it off, usually leaving the victor as the only option for the female to reproduce with[1]. However, because stronger organisms, whether mentally or physically, are usually favored in combat, this also leads to the evolution of stronger organisms in species that use combat as a way to secure mates[2]. Examples of weapons include the antlers bucks use to fight one another off when competing for females.

Ornaments are traits that are used to attract mates based on physical attractiveness. These traits may help show good genes that potential mates may find desirable[1]. Although these ornaments are usually the main strategy in order to procure a mate, they come with the large cost of making the individuals more susceptible to being tracked by predators as well[2]. The most notable form of ornaments comes in the ornate plumage that the peacock has in order to attract peahens; the brighter and bigger the feathers, the better chance of finding a mate.

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An Analysis of a Media Portrayal of Goat Pheromones

July 7th, 2014 by cer7

 

Scientists have long searched for a tangible molecule that produces an effect on females called the “male effect” (Murata et. al. 2014). The male effect is a physiological process that causes the reproductive cycle of females to change in the presence of the scent of males. Researchers at the University of Tokyo were looking for a primer pheromone that would cause this change in the ovulation cycle of female goats, and they may have finally found one (Murata et. al. 2014). The researchers collected the smell released from a male goat’s head (known to be a place that secretes the most smell on a goat) and analyzed the chemical components of the mixture. Then, they isolated components and looked at which components elicited the biggest response in the female goat brain. They analyzed the female goat brain by looking at how many times her “GnRH pulse generator” was firing. GnRH is the gonadotropin-releasing hormone that activates LH (luteinizing hormone), which in turn causes female mammals to ovulate by stimulating their eggs to grow. When the GnRH pulse generator fires, GnRH is stimulated, and the researchers reasoned that this process caused ovulation in the female goats. This research could lead to some exciting new knowledge about the reproductive system of female mammals (especially other ruminants) and how it is affected by male pheromones.

The press release from this study was published in Science Daily very soon after the study was published. I found it interesting that the writing in Science Daily puts a heavier emphasis on human implications than does the original paper about the experiment. Science Daily publishes the quote “there is reason to think the findings will apply to other livestock, and perhaps even to humans, too” (Science Daily, 2014).  After reading the original paper from the researchers, I only noticed one mention of human implications, and the authors were discussing how the research would help humans to better breed livestock. The press release also uses words that seem to dumb down the scientific terms that the original study uses. For example, the press release uses the phrase “central reproductive axis” instead of using the actual terms for the neurotransmitters and the parts of the brain. These changes are logical considering that press releases are for a broad audience, and the emphasis of the press release might make the information more accessible to other scientists or the general public. Read the rest of this entry »

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Move that Head: The Behavior of Head-Bobbing in Rock Pigeons

July 4th, 2014 by svn2

 

As I strolled through Hermann Park on a sunny but chilly afternoon, I noticed a huge flock of birds flying down to the edge of the park’s lake from a tall, bare tree that they were resting in. I sat at a bench to watch these birds that seemed to stick together as they flew or pecked on the ground. Although I was watching these birds at the park, I knew that I had seen them around the city, especially at the MetroRail station, gathering at areas where they knew they could get food.  These birds had plump bodies covered in light grey feathers with two black bands on their sometimes speckled wings. However, their small, round heads and necks were covered in dark grey feathers with traces of iridescent purple and green.  With red eyes, they stared at their surroundings while walking on their red legs. These birds were none other than Columba livia, also known as the rock pigeon.

Rock pigeon. Photo by Razvan Socol.

Rock pigeon. Photo by Razvan Socol (CC BY-SA 3.0).

As I observed the rock pigeons, these birds behaved as they usually did whenever I saw them. They flew or walked, pecking the ground for food; however, I saw a behavior that I had never noticed before and that intrigued me: the bobbing of their heads. As the rock pigeons walked, their heads seemed to slowly move back and forth. As I chased after them, the pigeons would walk quickly with their head rapidly bobbing back and forth, most likely feeling threatened.  This made me wonder, “Why do the pigeons bob their heads while walking?” Read the rest of this entry »

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Seychelles Warbler Cooperative Breeding

July 2nd, 2014 by Alyson

This is my added edit to the Seychelles Warbler wikipedia page. I added the section for Cooperative Breeding that can be found here: https://en.wikipedia.org/wiki/Seychelles_Warbler#Cooperative_Breeding_Habits

Cooperative Breeding

Seychelles Warblers demonstrate cooperative breeding, a reproductive system in which adult male and female helpers assist the parents in providing care and feeding the young. The helpers may also aid in territory defense, predator mobbing, nest building, and incubation (females only).[1] Breeding pairs with helpers have increased reproductive success and produced more offspring that survived per year than breeding pairs with the helpers removed.[2] Helpers only feed the young of their parents or close relatives and do not feed unrelated young. This is evidence for the kin-selected adaptation of providing food for the young. The indirect fitness benefits gained by helping close kin are greater than the direct fitness benefits gained as a breeder. This could be evidence for the kin-selected adaptation of providing food for the young.

On high-quality territories where there is more insect prey available, young birds were more likely to stay as helpers rather than moving to low-quality territories as breeders.[3] On low quality territories, having a helper is unfavorable because of increased resource competition. Females are more likely to become helpers[4], which may explain the adaptive sex ratio bias seen in the Seychelles warblers. On high quality territories, females produce 90% daughters; on low quality territories, they produce 80% sons. Clutch sex ratio is skewed towards daughters overall.[5] When females are moved to higher quality territories, they produce two eggs in a clutch instead of a single egg, with both eggs skewed towards the production of females. This change suggests that Seychelles Warblers may have pre-ovulation control of offspring sex ratio, although the exact mechanism is unknown. Read the rest of this entry »

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How to Steal a Mate: Frog Edition

June 30th, 2014 by nyn1

 

When it comes to finding mates, that privilege is usually saved for the biggest, strongest, smartest, and whatever other positive adjective you might think of to describe the “perfect mate.” But that leaves you to wonder, what about those who aren’t necessarily the best at what they do, but still find a way to mate? The answer is simple: they’re the cheaters! The saying goes that “cheaters never win,” but in the case of this species of frog, that isn’t always necessarily the case.

A study was done on the European tree frog, Hyla arborea, to figure out why the males in this species choose to either seek out mates “traditionally” or “parasitically.” The traditional way would include actually going out and finding attracting or procuring a mate on their own, while parasitically involves using another competitors skills in order to procure a mate. They wanted to know if this behavior is caused by the size of the frog, or if it is caused by the energy cost that it would take to attract a mate. In order to test these two hypotheses, Brepson and his team set up an experiment in which they randomly caught 100 male frogs from a pond in France and emptied said frogs’ stomachs. The frogs were then split into two groups, one group was fed crickets and flies for seven days consecutively while the other group was starved for the same period of time. Then each frog was put into a container with two speakers, one in the center that played the “chorus” noise (mating calls at the average frequency of the male H. arborea’s croak), and one at the end of the container that played either “attractive” or “unattractive” mating calls for that species. A call was determined to be “attractive” or “unattractive” depending on how low or high the frequency of the call was as well as how often the call was played, with lower and more often was considered more “attractive.” The “satellite” zone was set at any point that was 10 cm or less from the speaker playing the mating calls as a standard for measuring levels of parasitism in this species. Males found in the satellite zone were identified to be acting more “parasitically” than “traditionally”. Read the rest of this entry »

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Manduca sexta

June 18th, 2014 by svn2

 

The Wikipedia article for Manduca sexta, or the tobacco hornworm, contained information about its lifecycle. However, no information was provided about its behavior even though there has been recent research about its behavior. I added a Behavior section in the Wikipedia article found here: https://en.wikipedia.org/wiki/Manduca_sexta.

Manduca sexta (Tobacco hornworm). Photo by Daniel Schwen (CC BY-SA 4.0).

Behavior

 Feeding

 Tobacco hornworms are facultative specialists; the larvae can grow and develop on any host-plants. However, the larvae prefer solanaceous plants, such as tobacco and tomato plants. On these types of plants, larvae grow and develop faster. The lateral and medial sensilla styloconia, which are sensory receptors, on their mouthparts help them to identify solanaceous plants by recognizing indioside D, a steroidal glycoside found in those particular plants (del Campo et al., 2001). [1] Tobacco hornworms are considered pests because they feed on the upper leaves of tobacco plants and leave green or black droppings on the plants. As adults, they do not damage the plants since they feed on nectar. [2]

Tobacco hornworm larvae prefer humid environments. When dehydrated, tobacco hornworm larvae will move towards a source of water or to an area with a high relative level of humidity. They use their antennae to locate water to drink (Rowley and Hanson, 2007). [3]

Defense

Nicotine is poisonous to most animals that use muscles to move because nicotine targets the acetylcholine receptor, an important neuromuscular junction. However, the tobacco hornworm is capable of metabolizing nicotine from the tobacco plant and using nicotine as a defense against predators. It possesses a gene called cytochrome P450 6B46 (CYP6B46) that converts nicotine into a metabolite. About 0.65% of nicotine metabolites are transported from the gut to the hemolymph, where they are reconverted to nicotine and released into the air from the tobacco hornworm’s spiracles. The emitted nicotine is used as a way to deter spiders, a practice known as “toxic halitosis.”  In one study, tobacco hornworms that fed from nicotine-deficient plants or expressed low levels of CYP6B46 were more susceptible to wolf spiders predation (Kumar et al., 2013). [4] Read the rest of this entry »

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It’s Important to Be a Social Lizard

June 16th, 2014 by akm6

 

Image of a veiled chameleon by Geoff (CC BY-SA 3.0).

It is a well-known fact that people need constant interaction with others in order to grow up to become normal, healthy adults. But do all types of animals require group contact with other members of their species as we do? Ballen and colleagues were interested in the behavioral differences caused by raising a particular type of lizard, the veiled chameleon, in a group or in isolation. The findings of their paper were further brought to public attention by the science writer, Mary Bates, in her news article titled “Lizards Need Social Lives, Too.” Although the main message from these two pieces of literature is the same, Ballen and colleagues wrote for the scientific community and Bates wrote for a more general and wider audience.

Ballen and colleagues knew from previous studies that birds and mammals raised in isolation had problems with “social behavior, mental performance, and foraging behavior” (Ballen 2014). However, they were curious if reptiles were also negatively affected by being raised alone. Ballen found a type of lizard known to grow up with its siblings in its early life: the veiled chameleon. Ballen decided to test if isolation early in life affected the chameleon’s ability to forage for food and interact with members of its species later in life. To do this, Ballen incubated chameleon eggs until they hatched and then raised some of these hatchlings in groups and others in isolated enclosures. The chameleons’ foraging ability was then tested by measuring the amount of time an individual took to catch a cricket. The scientists tested social behavior by placing two chameleons of the same size and sex together and observing aggressiveness and submissiveness in social interactions. Read the rest of this entry »

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Feather Ruffling in Black-bellied Whistling Ducks

June 11th, 2014 by cer7

 

Birds do a variety of behaviors to keep warm, avoid predators, mate, and find food. In my observations, I watched the Black-bellied Whistling Duck, or Dendrocygna autumnalis. This bird is a type of waterfowl native to parts of Mexico and South America, although they can be seen in the southern United States during the summer (“Black-bellied Whistling-Duck”). The Black-bellied Whistling Duck is brown with a grey head and a black underbelly. Its feet and beak are pink. The Whistling Duck gets its name from the whistling noise it makes. I observed flock of these birds at around 4:30 pm on a rainy cold day in Herman Park. The temperature outside was about 40°F, and the rain was very light.

The flock of ducks I observed numbered about ten, and they were walking along the path by the large pond in Herman Park. The behavior I thought was interesting happened a few times during my time observing these ducks. First, a duck would get a little taller in stance, and hold its wings out to the side. Then it would flap its wings, put them down, and ruffle its feathers a little as its wings shifted back into place. I took the picture below while observing the initial states of this behavior. You can see the raised wings of the Whistling Duck right before it folds them in and ruffles its feathers.

Black-bellied whistling ducks. Photo by Clare Randolph.

This behavior could have a lot of explanations. Read the rest of this entry »

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Geophagy

June 9th, 2014 by asa4

 

Geophagy is the behavior of consuming earth, clay, or soil-like materials. This behavior has been noted in many species including humans. My contribution to the Wikipedia page on Geophagy (http://en.wikipedia.org/wiki/Geophagy) included specific behaviors of geophagy in primates and bats.

Many hypotheses exist to explain the importance of geophagy in bats and primates2,3. Some documented benefits of geophagy include nutrition, detoxification, and benefit as an antimicrobial and anti-parasitic agent; however, the reasons for geophagy are largely species specific1, 3.

PRIMATES:

Krishnamani and Mahaney evaluated various hypotheses that could lead to maintained geophagy in different species of primates including Japanese macaques and chimpanzees2. Reasons for geophagy are largely dependent on the species as well as the habitat. For instance, mountain gorillas demonstrate geophagy as a result of an increased need for iron.  Iron supplementation from the soil helps to meet the demands of decreased oxygen partial pressure at high altitudes2.

BATS:

There has been great debate over whether geophagy in bats is primarily motivated by nutritional supplementation or by detoxification. It is known that some species of bats regularly visit mineral or salt licks to increase mineral consumption. However, Voigt et al. 2008 demonstrated that both mineral- deficient and healthy bats visit salt licks at the same rate3. Therefore, it would seem that mineral supplementation is not the primary reason for geophagy in bats. Additionally, it was found that bat occurrence at salt licks increased during periods of high energy demand. Voigt et al. 2008 concluded that the primary purpose for bat presence at salt licks is for detoxification purposes, compensating for the increased consumption of toxic fruit and seeds3. This was shown to be especially evident in lactating and pregnant bats as their food intake increases to meet higher energy demands3. Read the rest of this entry »

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