A study published in Science on January 11 seems to be the first to lay empirical evidence that concur with Charles Darwin’s hypothesis: … that mate selection might have contributed to the evolution of intelligence or cognitive abilities. Scientists from China and the Netherlands collaborated in a study on budgerigars, Melopsittacus undulatus. Based on what they observed, problem-solving skills apparently increased the attractiveness of male birds. Accordingly, female birds chose to spend more time with male birds that appear to be smarter.
Darwin on mate selection
In animal kingdom, mate selection is a real deal. One of the generalized traits that distinguish the animal from the plant is the former’s tendency to select a mate. Animals, including humans, have their set of preferences when it comes to choosing a mate. While plants chiefly let nature do the “selection” for them, animals tend to seek a potential mate by themselves. And when they find a suitable mate of their choice, they often make a conscientious effort to succeed at coupling. In particular, males engage first in a courtship ritual, for example, by wooing a female with a song, a dance, or by a display of beauty or prowess.
Sexual selection evolved as one of the means of natural selection. A male, for instance, chooses a female to mate with, and, if need be, may tenaciously compete against other males to stack the odds in his favor. Charles Darwin’s long-standing theories on sexual selection are still relevant to this day. Darwin believed that sexual selection had a key role in how humans evolved and diverged into distinct human populations. In view of that, sexual selection could have contributed as to how intelligence evolved.
Intelligent males, more attractive
Many studies on birds revolved around the notion that female birds favor male birds with vibrant feathers or stylish songs. A recent study claims that intelligence is preferred over such fancy features and skills.
In the first experiment conducted by Chen and colleagues, small budgerigars (Australian parrots) were observed inside their cages to test the hypothesis that intelligence might affect mate selection. To do that, they allowed each female budgerigars to choose among a pair of similarly-looking male budgerigars to interact with. The chosen males were called preferred whereas those that were not were referred to as the less-preferred. Next, they trained the less-preferred males into learning a skill that opens closed lids or boxes. They, then, allowed the female budgerigar to observe the less-preferred male demonstrate the skill. Consequently, almost all of the females changed their preference. They chose the less-preferred males over the initially preferred males.
To test if this preference was social rather than sexual, they conducted a second experiment with a similar experimental design but this time a female budgerigar was exposed to two females (instead of males). The results showed that none of the female budgerigars changed their preferences. [1, 3] Based on these experiments, the researchers concluded that the demonstration of cognitive skills altered mate preference but not necessarily social preference.
Video of the animal model, male budgerigar that learned a problem-solving skill that seemingly increased its attractiveness to females. [Credit: Hedwig Pöllöläinen].
Why did mate selection evolved? The answer could be associated with the species survival or longevity. Individuals must be able to stay in the mate selection pool, if not on top of it. In general, males deemed as superior or “preferred” will gain higher chances at mating, and thereby will have better opportunities at transmitting their genes as they dominate the access to fertile females. Females, on the other hand, gain an upper hand from the mate selection by being able to choose the seemingly finest among the rest. Females must choose. That is because they have a generally limited reproductive opportunity to give life to. Moreover, the energy that a female invests in producing an offspring is so great that it has to be worth it.
— written by Maria Victoria Gonzaga
1 Chen, J., Zou, Y., Sun, Y.-H., & ten Cate, C. (2019). Problem-solving males become more attractive to female budgerigars. Science, 363(6423), 166–167. https://doi.org/10.1126/science.aau8181
2 Jones, A. G., & Ratterman, N. L. (2009). Mate choice and sexual selection: What have we learned since Darwin? Proceedings of the National Academy of Sciences, 106(Supplement_1), 10001–10008. https://doi.org/10.1073/pnas.0901129106
3 GrrlScientist. (2019, January 11). Problem-Solving Budgies Make More Attractive Mates. Forbes. Retrieved from https://www.forbes.com/sites/grrlscientist/2019/01/10/problem-solving-budgies-make-more-attractive-mates/#515f24d66407
Blacked-legged Kittiwakes are pelagic gulls that often feed on fish and macro-zooplankton at the ocean surface. They breed in colonies ranging from few to thousands of pairs which prominently observed in their open, sea-cliff nesting habitats. Blacked-legged Kittiwakes are the most popular models for research because they can be easily monitored and captured. They also considered as prime indicators of fluctuating conditions in marine ecosystem. The purpose of this research is to collect live sperm of blacked-legged Kittiwakes using a non-invasive method. Also, be able to provide information on suitable extenders and timing in relations to the breeding phenology. Additionally, it will offer informations to different disciplines including veterinary science, conservation biology, ecotoxicology and evolutionary biology.
Sperm collection of Blacked-legged Kittiwakes
Sperm of blacked-legged Kittiwakes were obtained by firmly massaging the lower back and the tail base of the male bird. Since, the researchers observed that during mating the male tend to wag their tails thus, releasing the sperm naturally. After massaging the handler lift the tail, clear the feathers around cloaca and gently squeeze the cloacal area. While doing this a capillary tube placed on the top of the cloaca to collect directly the translucent liquid. Then, verified directly to the laboratory under the microscope.
The result demonstrates a successful collection of live sperm under field condition of blacked-legged Kittiwakes for the first time. In which the researchers discovered two extenders suitable for maintaining the sperm however, undiluted sperm also performed well in terms of survival. Since, seminal fluids alone are sufficient enough to maintain the sperm alive. Though, the researchers still recommend using sperm extenders since it is necessary to dilute highly concentrated ejaculates. Also, extenders are necessary on sperm quality examination when comparing experimental groups and sperm production.
Blacked-legged Kittiwakes are strictly monogamous and stores semen inside their body unlike passerine birds that stores semen in seminal glomera. Interestingly, one has to keep in mind that sperm quality may vary seasonally. So, the researchers suggest that one should statistically account for this effects using date relative to laying eggs. Also the researchers recommends to target specific time window when the birds are about to copulate but not after copulation within a day.
Source: Prepared by Joan Tura from BMC Avian Research
Volume 9:24, 14 July 2018
Dolphins performing acrobatic tricks have, time and again, fascinated and mesmerized people. As early as 1860s, capturers took dolphins and other cetaceans (e.g. whales and porpoises) out of their aquatic habitats and held them in captivity in various parts of Europe and North America. At first, they kept them in a dolphinarium mainly as an amusement for a paying audience. Later on, they discovered that these aquatic marvels could be taught to perform tricks. Since then, people have gravitated to various dolphin shows as one of their “must-dos” off their bucket list.
Dolphins learning tricks
The tricks that dolphins can do seem limitless. Apart from their fantastic leaps and bounds, they can do complex tricks like tail-walking, playing ball, synchronized swimming, and rhythmic gymnastics. How do they learn these tricks? Trainers use positive reinforcement method to teach dolphins the jaw-dropping tricks. Accordingly, they reward them with food whenever they do a trick correctly. Watching them do these tricks, though, seems that they perform not only for the food reward but also for their own enjoyment based on their playful nature.
Wild dolphins’ ballistic jumps
Frequently, wild dolphins leap above the water surface. They do so by swimming fast near the surface, and then execute a ballistic jump. This behavior, called porpoising, seems a demonstration of their playful behavior. Nevertheless, another hypothetical reason surfaced. Accordingly, this porpoising behavior points to the benefit it furnishes. The friction up in the air is less; therefore, porpoising would help save dolphin energy.1
Seeing dolphins doing leaps and bounds in the wild is something that is truly remarkable yet not unusual. However, a pod of playful aquatic creatures in the wild were observed doing a trick rarely seen in the wild. Furthermore, the trick was something that they learned from a formerly captive dolphin.
Wild dolphins’ tail-walking trick
Recently, a study2 reported what they observed in wild dolphins. They saw a pod (particularly, a group consisting of nine dolphins) off the Australian coast that learned from a previously captive dolphin how to “walk” on water using their tail.
Tail walking is one of the fundamental tricks taught to captive dolphins. It involves rising vertically out of the water. Then, the dolphin moves forward or backward on top of the water. This skill is rarely seen in wild dolphins.2
Whale and Dolphin Conservation, together with the universities of St Andrews and Exeter, conducted a thirty-year study where they revealed that dolphins in the wild were able to learn a human-coached tail-walking trick from Billie. Billie is a rescued dolphin from a creek near Adelaide’s Patawalonga River in 1988. The dolphin was in captivity temporarily. During its captivity, it learned how to tail-walk. When it was released into the wild, it taught its companions by continuing to demonstrate the skill. Soon after, its peers copied it. In 2011, nine dolphins began tail walking. However, this spectacular display of “walking” by fins turned out to be just a fad. The number of wild dolphins that tail walk declined over time. As of 2014, only two of them remained to demonstrate the skill. 2
Dolphins, just as all the other living beings, deserve an inhabitable space in order to thrive and keep surviving. The ability of the dolphins to imitate skills could be used in spreading learnt behaviours that could be beneficial to their survival. The lengthy study that tracked the tail-walking behavior of Billie and the local dolphin community for years revealed an important insight. Accordingly, dolphins learning a behavior from each other can persist from one generation to the next. However, there is a tendency that certain learnt behaviors will fade, and, inopportunely, vanish through time.
— written by Maria Victoria Gonzaga
1 Weihs, D. (2002). “Dynamics of Dolphin Porpoising Revisited”. Integrative and Comparative Biology. 42 (5): 1071–1078. doi:10.1093/icb/42.5.1071
2 Whale and Dolphin Conservation. (2018 Aug. 29). WILD DOLPHINS LEARN FROM EACH OTHER TO ‘WALK ON WATER’…BUT IT’S JUST A FAD. Retrieved from https://uk.whales.org/news/2018/08/wild-dolphins-learn-from-each-other-to-walk-on-waterbut-its-just-fad
3 Whale and Dolphin Conservation (WDC). (2014 Nov. 5). Dolphins tailwalking – Port River, Adelaide | Whale and Dolphin Conservation. Retrieved from https://www.youtube.com/watch?v=6tn5TJfR3k4
Whale shark is a slow moving carpet shark and known as the largest extant fish species. It has a very huge mouth yet it feeds almost exclusively on plankton and small fishes. In marine biodiversity records whale shark showed the longest migratory path. Migratory behavior of marine species has been subject for research studies since it is important for optimizing growth and foraging opportunities. It also caters the breeding ground at discrete geographical locations and identification of different habitats across several jurisdictions. Also, it serves as the key for spatial planning and international policy management for ecosystem resources. Furthermore, gene flow, connectivity and population status are essentials for the marine conservation especially for migratory species.
Whale shark Migratory Route
On September 16, 2011 three female whale shark were tag using satellite transmitter model SPOT 253C. The tag specifies battery life wherein transmission occurs only when the animal is swimming near surface to maximize battery life. One female whale shark named Anne remained in Panamanian waters for 116 days then to eastern Pacific for 226 days. Then transmission began again at Hawaii after 235 days of silence then continued to Marshall Islands for about 268 days. But then transmission were interrupted again when the Anne reach the Mariana Trench.
So, the whale shark Anne travelled a long distance of 20,142 km approximately from Panama to Mariana Trench. Throughout this period Anne spent the entire time above thermocline with a temperature ranging from 15.1–35 °C. The route taken by Anne followed primarily westward North Equatorial Current similar to other whale that has been tracked previously. These results show that long periods without transmission do not necessarily entails tag shedding. Thus, this unusual long distance travelled of Anne and the intervals between detection offers evidence both tracking and genetic studies. It also suggests that whale shark is capable of long-distance travel.
Whale shark can migrate from Eastern Pacific to Western Indo-Pacific connecting two ocean basin using North Equatorial Current. It also imply that a potential passageway to reach Philippine Sea into South China Sea to get to Indian Ocean. Moreover, the results of this record are consistent to the genetic studies showing potential dispersal of whale shark. Overall, these two tracks showed by Anne expose the complexity of management of endangered species crossing multiple jurisdictions. Yet, the protection and conservation programs focused only at the local level rather than across Pacific.
Source: Prepared by Joan Tura from BMC Marine Biodiversity Records
Volume 11:8, April 19, 2018
Butterflies are flying colored wing insects that vary in color and pattern from individual to another individual. It has wings covered with overlapping rows of scales. Most of butterflies have developed mechanisms to avoid predators making disguise coloration blending like leaf or bark of the tree. Some releases chemicals as a defense mechanism wherein butterfly evolved to have toxic chemicals. But recent finding due to extreme weather events and trend linked to ongoing anthropogenic climate change species shifts its dynamics. Droughts occur more often in larger spatial scale which has an effect on insects. Generally, drier and warmer climatic conditions have an impact either positive or negative to insect populations. The aim of this research is to address the knowledge gap using multi-decadal dataset of 163 butterfly species. All of this butterflies experienced millennium-scale drought.
Impacts of droughts on Butterflies
To know the faunal dynamics, investigation of phenology, species richness and diversity with its elevation gradient has been conducted. In which linear model used to understand differential sensitivity of butterflies to climate change at low and high elevation. A decade of dataset of 163 butterfly species across elevational gradient in Northern California has been considered. Results showed that a prolonged shift towards spring flight during drought years and change in phenology is evident across elevations. It also happened that the total flight window expanded at lower elevations while at higher elevation shifted and compressed. This leads the notion that fewer overall flight days at higher sites.
The millennium drought in California created across site with elevation-specific changes in flight windows and species richness. This resiliency reveals that lowest elevations are less detrimental than biotic-abiotic association at higher elevations. Most of the researchers hypothesized a mismatch between trophic levels as a result of climate change. But, results of butterflies from low elevation would suggest that at consumer trophic level need not always have negative impacts. Additionally, species at lowest elevations have access to agricultural lands though irrigation does not correlate the population dynamics during drought. Thus, there is a possibility that low elevation population buffered by irrigated crops or agricultural margin during drought.
Indeed, that at high elevation butterflies declined in number and become sensitive to dry years with warmer temperatures. Contrary to the theory that mountains offer microclimatic refugia and adapt species for climatic changes. It has been known that high latitude environments are warming faster with negative consequences to several species. But positive or have a neutral effect for other species. Consequently, this research suggests more thorough investigation about organismal responses to extreme weather. As well as on the extent wherein different habitat type may or may not buffer species populations against climate change.
Source: Prepared by Joan Tura from Springer BMC Climate Changes Responses
Volume 5:3 26 January 2018
Eastern whip-poor-will (Antrostomus vociferous) is continuously declining due to habitat loss and unavailability of insects for food. Little is known about whip-poor-will migration because of their nocturnal quite habit during non-breeding season. At high latitude 80% avian species are migratory wherein factors affecting migration includes predators, anthropogenic threats and pathogens. Migratory strategies allows individual to track seasonal changes mostly for temperate breeding aerial insectivores. However, population declines among temperate insectivore birds due to extreme weather condition, cost of migration and reliance on sensitive prey. In addition it is important to determine the migratory routes, year round habitat requirement and temporal constraints of threatened species.
Geolocator deployment of Whip-poor will
There were 20 males and 2 females of whip-poor-will have been tracked using geolocators in four regions of Canada. The study shows that this species breed more in northern part than southern breeding population and experienced different wintering conditions. Also a high migratory cost happens such as novel threats, energy expenditure and the ability to adjust time in tracking breeding ground condition. In contrast, both eastern and western breeding individuals wintered together wherein mostly concentrated in Guatemala and some provinces of Mexico. However, male often have higher benefits of early arrival on the breeding grounds thus accept higher cost of wintering further. Additionally, early arrival on breeding grounds is more advantageous on whip-poor-will males allowing occupation on higher quality territories.
On the other hand female whip-poor-will forced to migrate further on lower latitude with less competition and more abundant resources. Most of this species travel overland through Mexico and Central America. However, only two individuals flights across portion of the Gulf of Mexico during autumn and spring. It just shows that this pattern is the response to prevailing winds and availability of resources along different route. Also more species migrating along Eastern North America, South and Central America over ocean flights during autumn. While in spring more species taking longer over land route around western side of the Gulf of Mexico.
Therefore, geolocators is helpful in identifying wintering areas, stopovers and migratory route of whip-poor-will. These migratory stopovers in the southeastern and central United States as well as in southern Mexico and Central America are both important for the whip-poor-will species. Finally, habitat protection and insect population might increase the number of these species despite pressures of long migrations and climate changes.
Source: Prepared by Joan Tura from Springer BMC Zoology
Volume 2:5, 2017
Thanatosis — pretending to be dead — is one of the best strategies that certain wild animals came up with in order to survive. Since the prey is usually inferior to its predator, it must use wit to its advantage. When all else seems futile, thanatosis seems the only way to go.
Thanatosis – what is it?
Thanatosis, colloquially speaking, is playing dead. It is a behavior manifested by certain animals to deceive their predators. Running away could have been the best option but when cornered the animal has to make a hasty decision between fighting back and feigning death. In certain situations, thanatosis works; it proves to be more useful than battling it out in the rubble. Not only does it make the animal save up precious energy but it also buys time to figure out a route with higher chances of escape. Instead of forcing a way out, thanatosis applies trickery, i.e. by deceptively submitting to the opponent only to seize the right opportunity to escape when it comes.
Thanatosis and predation
Several animals use thanatosis to facilitate escape. For instance, a threatened Eastern hognose snake (Heterodon platirhinos) initially displays an intimidating pose. It raises its head off the ground, hiss, and strike. When the threat display fails, the snake engages its opponent to a dramatic performance of thanatosis. As if poisoned and about to die, the snake rolls onto its back, shudders, and hangs out its tongue. Not only will it look dead… it will also smell dead when it releases a foul-smelling fluid from its cloaca.1
The phrase “playing possum” stems from the thanatosis behavior of Virginia opossum (Didelphis virginiana). When it senses extreme danger, it appears dead similar to a comatose state. Out of great fear, it lies on its side with eyes and mouth open and tongue hanging out. It releases a greenish fluid that smells rotten through its anus. This thanatosis display causes the deterrence of predators. A prey that died suddenly seemed like something went wrong and eating it might lead to trouble.
Unfortunately, there are also predators that utilize thanatosis to deceive preys. Cichlids (Nimbochromis sp.), for instance, act dead by not moving so that an unsuspecting prey will be lured closer, and therefore get a better chance of capturing it.
Thanatosis to evade sexual cannibalism
Apart from evading a predator, certain animals use thanatosis to deceive an aggressive female to mate with. Mating in some spiders can be a dangerous activity. The female spiders attack the male spiders to feed on them after sex. This devouring of another individual of the same species before, during, or after copulation is called sexual cannibalism. While there are spiders that welcome it (read: The Amazing Spider Dads), other spiders attempt to circumvent it. For instance, the male wolf spiders perform thanatosis to avoid ending up as a meal after copulating.2 The male nursery web spiders (Pisaura mirabilis) also resort to thanatosis but apart from it they also do nuptial gift-giving during courtship rituals. In a study by Hansen et al.3, the male spiders that played dead had more success in mating with hostile females and stayed alive right after.
In the wild, resorting to thanatosis to survive is not uncommon. At the edge of demise, these animals enact the greatest performance of their lives. They appear to have died a disturbing death to mislead predators. Who prefers a spoiled meat? Most predators want their meal fresh; hence, they may no longer find a prey looking repulsive and smelling putrid appetizing. Thanatosis proves its invaluable use as an anti-predation strategy. Besides that, animals playing dead for sex and evading cannibalism demonstrate that thanatosis is tantamount to surviving — die to live!
— written by Maria Victoria Gonzaga
1 FrankSnakes. (2012). Eastern Hognose (Heterodon platirhinos) Playing Dead. Retrieved from https://www.youtube.com/watch?v=UxbT2acTsrM
2 Seriously Science. (2016). Male spiders play dead to avoid “sexual cannibalism.” Retrieved from http://blogs.discovermagazine.com/seriouslyscience/2016/05/26/5406/
3 Hansen, L.S., Gonzales, S. F., Toft, S., & Bilde, T. (2008).Thanatosis as an adaptive male mating strategy in the nuptial gift–giving spider Pisaura mirabilis. Behavioral Ecology, Volume 19, Issue 3, 1 May 2008, Pages 546–551. Retrieved from https://academic.oup.com/beheco/article/19/3/546/185057