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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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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. (more…)

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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] (more…)

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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. (more…)

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Whooper Swan Signaling Behavior

May 30th, 2014 by vld3

 

Originally, the wikipedia page for Whooper Swans focused on their feeding habits and distribution, but focused very little on the behavior of these swans. I added this information about Whooper Swan behavior to the page: http://en.wikipedia.org/wiki/Whooper_Swan#Distribution_and_behaviour.

When Whooper Swans prepare to go on a flight as a flock, they use a variety of signaling movements to communicate with each other. These movements include head bobs, head shakes, and wing flaps and influence whether the flock will take flight and if so, which individual will take the lead. Whooper Swans that signaled with these movements in large groups were found to be able to convince their flock to follow them 61% of the time.  In comparison, swans that did not signal were only able to create a following 35% of the time.  In most cases, the Whooper Swan in the flock that makes the most movements (head bobs) is also the swan that initiates the flight of the flock – this initiator swan can be either male or female, but is more likely to be a parent than a cygnet. Additionally, this signaling method may be a way for paired mates to stay together in flight. Observational evidence indicates that a swan whose mate is paying attention to and participates in its partner’s signals will be more likely to follow through with the flight. Thus, if a Whooper Swan begins initiating flight signals, it will be less likely to actually carry through with the flight if its mate is not paying attention and is therefore less likely to join it.

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Vampire Bat

May 14th, 2014 by amm18

 

The following includes an excerpt which was attached to the Wikipedia page “Vampire Bat” (http://en.wikipedia.org/wiki/Vampire_bat). The first and last sentence in this excerpt come directly from previous Wikipedia information and are used solely as a reference to identify what was added.

…This has been noted by many naturalists as an example of reciprocal altruism in nature.

It was previously thought that food sharing depended equally on relatedness and reciprocation.[i] However, it has recently been discovered that the predictive capacity of reciprocity surpasses that of relatedness.[ii] This finding suggests that vampire bats are capable of preferentially aiding their relatives, but that they may benefit more from forming reciprocal, cooperative relationships with relatives and non-relatives alike.[ii] Furthermore, a recent study demonstrated that donor bats were more likely to approach starving bats and initiate the food sharing. These findings contradict the harassment hypothesis—which claims that individuals share food in order to limit harassment by begging individuals.[ii] All considered, vampire bat research should be interpreted cautiously as much of the evidence is correlational and still requires further testing.[iii] For example, researchers question vampire bats’ ability to identify kin when past association, or interaction, is controlled.[iii] Similarly, scientists question if bats modify investments based on how other bats cooperate.[iii]

Another ability that some vampire bats possess is identifying and monitoring the positions of conspecifics (individuals of the same species) simply by antiphonal calling.[iv] Antiphonal calling is simply a song or verse sung in response.

Vampire bats also engage in social grooming…

[i] Wilkinson, G. S. (1984). “Reciprocal food sharing in the vampire bat”. Nature 308: 181-184. doi: 10.1038/308181a0

[ii] Carter, G. G., & Wilkinson, G. S. (2013). “Food sharing in vampire bats: reciprocal help predicts donations more than relatedness or harassment”. Proc R Soc B 280: 20122573. doi: 10.1098/rspb.2012.2573

[iii] Carter, G., & Wilkinson, G. (2013). “Does food sharing in vampire bats demonstrate reciprocity?”. Communicative and Integrative Biology  6(6): e25783. doi: 10.4161/cib.25783

[iv] Carter, G. G., Fenton, M. B., & Faure, P. A. (2009). “White-winged vampire bats (Diaemus youngi) exchange contact calls”. NRC Research Press 87: 604–608. doi: 10.1139/Z09-051

 

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Group Living

May 10th, 2014 by ss55

 

This post is an edit that I wrote to expand on the “Living In Groups” section on Wikipedia’s “Ethology” page. You can visit the page here.

Benefits and costs of group living

One advantage of group living can be decreased predation. If the number of predator attacks stays the same despite increasing prey group size, each prey may have a reduced risk of predator attacks through the dilution effect1. Additionally, a predator that is confused by a mass of individuals can find it more difficult to single out one target. For this reason, the zebra’s stripes offer not only camouflage in a habitat of tall grasses, but also the advantage of blending into a herd of other zebras2. In groups, prey can also actively reduce their predation risk through more effective defense tactics, or through earlier detection of predators through increased vigilance1.

Another advantage of group living can be an increased ability to forage for food. Group members may exchange information about food sources between one another, facilitating the process of resource location1.  Honeybees are a notable example of this, using the waggle dance to communicate the location of flowers to the rest of their hive3. Predators also receive benefits from hunting in groups, through using better strategies and being able to take down larger prey1. (more…)

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