Exposure to different colors of light impacts circadian rhythm and speed of embryonic development in bird eggs

What if eggs are just greenhouses for embryos – their colors, markings, and thicknesses all working together to create the optimal light environment for growth inside the shell?

A leading German oologist, Max Schönwetter, first came up with this hypothesis in the 1960’s. Since then, we’ve been finding a growing body of evidence for his idea. Commercial poultry breeders shine colored LEDs on chicken eggs to make them hatch faster, and the eggs of some species fluoresce under UV light.

In their 2015 paper, First Light for Avian Embryos: Eggshell Thickness and Pigmentation Mediate Variation in Development and UV Exposure in Wild Bird Eggs," ornithologist Golo Maurer and his team explored Schönwetter’s hypothesis. Using reflectance spectroscopy, they measured the percent light transmission, thickness, permeability, water vapor conductance, and pigment concentration in the eggshells of 74 different British breeding species! Here’s a link to their paper for a closer look!

https://besjournals.onlinelibrary.wiley.com/doi/epdf/10.1111/1365-2435.12314

Air Pollution Destroying Developing Immune Systems?

Last week we discussed how impressive our immune systems are, so I decided to look more into the innate immune system. I wanted to research the importance of white blood cells, and I came across a paper that analyzed the effects air pollution has on developing immune systems. This study specifically focused on school children in China since children have weaker immune systems and air quality there is horrendous!

In this study, the researchers took a group of students that were chronically exposed to air pollution, and then another group that was from a controlled area without as much exposure to air contaminants. They compared the levels of immune cells, immunoglobulins classes, and complements between schoolchildren living in areas with different air pollution levels in eastern China.  They also determined 2 systemic inflammatory biomarkers as they might help us to understand the biological processes related to the alterations of immune biomarkers.The results concluded that the total lymphocyte, T lymphocyte, CD4+ T lymphocyte, CD8+ T lymphocyte, and NK cell counts of schoolchildren in the polluted area were not significantly different from those in the control area. In contrast, the B lymphocyte count and CD4+/CD8+ ratio of schoolchildren in the polluted area were borderline significantly lower than those of children in the control area.

Overall, exposure to a higher level of air pollution was associated with a decreased B lymphocyte count and C3 and C4 levels, as well as an increased monocyte count and CD8+ T lymphocyte proportion. Out of all the other types of white blood cells, only monocytes showed a significant difference between groups of children, with a higher monocyte count in schoolchildren in the polluted area. These results suggested that air pollution may affect the immune function of children, but not in a very concerning way. Surprisingly, we did not observe differences in the IgG, IgA, or IgM levels between schoolchildren from the different areas. It might be due to that B lymphocytes were more activated in the circumstance of higher air pollution level. This suggests that there were some adaptive responses that boosted immune function to compensate for the immunotoxic effects of air pollution.

Although these results didn’t present alarming results, that doesn’t mean that the effects of air pollution on the immune system of children should be ignored. Air pollution is still a rising issue today, and as the next generation, we need to make sure we can discover ways to not just protect our own health, but also the health of our planet!

Li, X. (2019) Air pollution exposure and immunological and systemic inflammatory alterations among schoolchildren in China. The Science of The Total Environment, 657, 1304-1310

T.gondii: General Microbe Profile

T. gondii, otherwise known as toxoplasmosis gondii, is an apicomplexan that causes the disease toxoplasmosis; apicomplexans are endoparasitic protozoans that have apicoplasts (a photosynthetic plasmid) and an apical structure. T. gondii was first discovered in 1908 at Tunis by Charles Nicolle and Louis Manceaux in the tissues of a gundi.[1] Nicolle and Manceaux noticed that the gundis only were infected when in captivity and found the parasites only in the blood of the rodents, leading them to believe arthropods had transmitted T. gondii. It was not until 1938 that additional research was conducted on the parasite, as T.gondii was found in an infant girl’s body, then infected into mice and rabbits. Despite T. gondii’s ability to infect multiple species, its main vectors tend to be felids, the only organisms that can shed oocytes through feces.

            T.gondii can infect a host in one of two primary ways: through oocyte ingestion, or in tissue cysts—which are primarily found in the meat of infected animals; however, it can be transmitted via blood transfusion or organ transplants.[2]Once in the host, it has the potential to alter the behavior of its host to favor transmission. For example, when mice are infected, the parasite rewires its mind to favor the scent of cat urine, leading to these mice to be eaten by cats—the end goal of T. gondi. The reversal of prey’s aversion to their predators is not exclusive only to mice; other studies with different animals have yielded the same result: in 2004, infected sea otters were found to be 3.7 times as likely to be attacked by sharks, and in 2016, chimpanzees with toxoplasmosis were found to have an exclusive attraction to leopard urine—their only feline predators. Humans are not exempt from T.gondii’s effects—while they do not rewire our brains to be attracted to predator waste, people infected with it tend to exhibit higher aggression, suspicion, mental illness, and have a penchant for careers related to entrepreneurship or business. In 1992, an ongoing study by Jaroslav Flegr of Charles University in Prague revealed that not only did the parasite affect personality traits in humans, but also had separate effects on men and women. Men were more likely to be more “expedient, suspicious, and dogmatic,” and women tended to be “warmer and had higher superego strength.” [3] Separate research has concluded people infected with toxoplasmosis tend to have slowed development, lower IQ scores for the first seven years of life, and slower reaction time.

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[1] Dubey, “History of the Discovery of the Lifecycle of Toxoplasma gondii.”

[2] Hill, Dubey, “Toxoplasmosis gondii: transmission, diagnosis, and prevention.”

[3] The Stanley Research Institute, “Effects of T. gondii on Behavior and Psychiatric Symptoms.”

Facts about Bird Feather Colors!

·     Birds= most colorful land vertebrates ( not sure how validated this claim is ) 

·     Bird Feathers have two basic sources of color: 

o  1.) Pigment= chemical compounds located in the feather or skin itself

§ Absorb every wavelength of light except for one; that is the color that is reflected instead and seen by the human eye

o  2.)Structural colors= produces blue or iridescent colors

§ Produced by minute particles within the feather that are smaller in diameter than the wavelength of the color red

§ These colors appear the same when transmitted in different angles of light, however, if the feather is put in between the sight of vision and the light the colors appear clear, ( as if you are seeing straight through the feather ) 

·     Most colors in bird feathers evolved as a form of attraction to a gender of the same species, ( males trying to attract a mate ) 

o  Ex: peacock feathers 

·     Non-demonstrative colors typically help a bird avoid predation

·     Many birds experience “Counter-shading”    

o  Counter-Shading= darkest along the back and gradually become lighter while ending up as white on the belly

o  This tactic tends to eliminate a sharply defined shadow for any predator bird watching from above, ready to swoop down for some dinner

·     Many birds experience “Disruptive coloration”

o  Disruptive Coloration= use of striking patterns to break up the outline of the bird

o  Technique used to avoid detection by predators

o  Another word for this= CAMOFLAUGE ( duh ) 

·     Other reasons for coloration on birds: 

o  Birds often use certain colors to identify within a flock thus helping them keep all of their flock members together

o  Some colors within the inside of the mouths of hungry chicks may also function to stimulate the adults brains into wanting to feed their children

o  Other colors may be a way to keep track of the young

§ Ex: Red spot of the bill of the herring gull? 

·     Some colors don’t hold a purpose but are a product of another purpose: 

o  Some colors are produced accidentally by pigments deposited within the bird for a different reason

§ Ex: Feathers on the wingtips of birds are more subjected to wear and tear

§ Feathers with a lot of pigment are tougher feathers for things such as wear and tear

§ Thus, it is hypothesized that the this is the reason most birds have darker colored wingtips

Fun-Facts about Sharks!

·     Shark embryos attack each other: 

o  The largest embryo in a shark litter is known to eat it’s fellow embryos= intrauterine cannibalism

o  This strategy proves helpful especially to Sand Tiger sharksàit allows them to have larger children at birth which allows the offspring to be less vulnerable to predators

·     Sharks have a “sixth sense”

o  While dolphins have echolocation, sharks are able to identify prey by tapping into the small electrical around them that other animals generate= ampullae of Lorenzini

o  Small pores located near their nostrils are connected to long “jelly-filled tubes” that in return are connected to the sharks nervous systemàsignals when a fish is near

o  Hammerheads are the best at this with 3,000 pores

·     Sharks have a long gestation period

o  Some sharks can be pregnant for up to 2 years!

o  This is the longest gestation period to any known vertebrate

·     You can ride a shark! 

o  Largest shark species= whale shark ( also the largest fish in general )= also the easiest going

o  You can “hitch a ride” on a whale shark as they generally cause no harm to humans

o  Marine life experts disapprove of this as people holding onto the shark chips away at their slime covering and ultimately can cause harm to the fish

·     You can have shark half-siblings 

o  Female sharks can be impregnated by multiple sharks at once meaning the same litter of shark can have the exact same mother but different fathers- creating half siblings within the same bunch of shark eggs 

·     Female Sharks can reproduce without Male sharks! ( Talk about girl power) 

o  Two cases, ( Zebra shark from Australia and a Hammerhead shark from Nebraska), displayed female sharks that had been isolated from males and yet still ended up giving birth to multiple baby sharksàpossible asexual reproduction? 

o  Another theory is the sharks had been storing male sperm, however during DNA testing, the baby sharks were found to have only had DNA from their mother

·     Sharks don’t sleep like people

o  In order to breath numerous sharks must keep swimming to allow the water to pass through their gills and provide oxygenàthus when sharks “sleep” they are still semi-conscious as they swim

·     Sharks have teeth for days! 

o  Sharks have an average of over 50,000 teeth in its lifetime! 

o  The ocean floor is riddled with shark teethàpeople collect this and turn it into jewelry ! 

·     Sharks have scales?

o  “Dermal denticles” or shark scales are on their exterior! As the shark grows larger however the scales do not grow with it, instead the shark grows extra scales to fill in the gaps

·     Shark eggs are smart!

o  Shark embryos can sense danger and have been found to deploy a similar electrical receptor as adult sharks do when finding a predator

·     Shark age? 

o  A shark’s vertebrae tell you it’s age

·     Sharks have got the senses down!

o  Sharks have incredibly acute hearing, eyesight, and smell! 

o  They can hear their prey up to 3,000 feet away!

o  For better eyesight, sharks apart of the Laminid group have a special retina that warms up their eyes and brain in order to detect movement easier

·     Sharks are loyal to their first home

o  Some shark’s ( Lemon sharks ) will return to their birth place in order to reproduce

·     Sharks have no vocal chords and do not express anything audibly

o  Instead sharks use their own version of “sign language” and express things physically through flips, swimming maneuvers, etc.

·     Surprise, surprise!

o  A sharks biggest threat/predator is humans

Link to Article About Deep-sea Vision

   
I loved this article from the New York Times about new discoveries of how fish perceive color from light and bioluminescence at great depths. While many deep-sea fish no longer have the cones necessary to perceive different shades of red and ultraviolet, they have many more rods than other vertebrates. These rods allow them to wield vision "more sensitive to blue than any other vertebrate." It's crazy to imagine what else we haven't discovered yet in the deepest parts of the world, and its implications for life here on land!

Here's the link:
Klein, J. (2019, May 10). How Fish May See Color in the Deep Ocean's Darkness. Retrieved from https://www.nytimes.com/2019/05/10/science/fish-deep-ocean-eyes.html

Passion Flowers Perhaps Harmful to Pregnancies?

A few weeks back, we talked about biodiversity and how there are so many exotic species out there that haven’t been looked into enough. One of those species was the Passiflora long filamentosa, which is this very rad flower found in Brazil! I tried researching this species but since it has been new discovered, I couldn’t find any papers discussing the angiosperm. So, I decided to look up the Passifloraceae family in general and came across the Passiflora incarnata.

I found this species very interesting because I learned that it has been used as an anxiolytic herbal substance to treat anxiety and depression for many years. I came across this paper that analyzed case studies of pregnant women with psychiatric challenges that were treated with Passiflora incarnata during their pregnancies. Out of five case studies, two of the newborns faced similar respiratory complications at their birth, but were able to recover under treatment within a few weeks. The other babies didn’t face any developmental abnormalities, so this paper raised the question if taking the Passiflora supplements affect prenatal development in the womb.

Definitely an interesting topic that still needs more research to be conducted on it, if you want to check out more info, here’s the link!

https://www.sciencedirect.com/science/article/pii/S0965229917304831

Courtship & Parenting Tips from the Male Superb Fairy-Wren (Malurus cyaneus)

Native to the scrubland fringes of Australia’s eucalypt woodlands, superb fairy-wrens spend most of their days hunting grasshoppers or snuggling on low-hanging branches in bundles of 2… 3… sometimes 5. Lavishly-feathered, “rampantly promiscuous,” and a common visitor of children’s parks, they’ve been ballyhooed by The Guardian as Australia’s favorite bird. Despite their cotton-ball size, these flamboyant daredevil passerines pack a suit of evolutionary aces up their tail feathers, especially when it comes to courtship!

1. Keep in mind that your vibrant plumage attracts predators

3 seasons of the year, fairy-wrens don the drab, downy coloration of a miniature koala, but come the next molt, all bets and feathers are off. With dazzling sapphire cheek plumes and a midnight-blue jabbot, the breeding plumage of the male superb fairy-wren is a spectacle of sexual selection. But while gleaming like a crown jewel captivates females, it’s also a flashy candy wrapper to predators. Being sexy is dangerous.

Male fairy-wrens are cognizant and even cautious of this (McQueen, Naimo, Teunissen et. al. 2017). In their 2017 paper, “Bright Birds are Cautious: Seasonally Conspicuous Plumage Prompts Risk Avoidance By Male Superb Fairy-Wrens,” an Australian research team details differences in antipredator responses between superb fairy-wrens of different plumage types. Broadcasting the species’s alarm calls to a population in Lysterfield Park, Australia, they found that blue males were 50% less likely to forage on open ground, took over twice as long to reemerge from cover, and showed a stronger immediate response to predator alarm calls (2017). They propose that breeding fairy-wren males are well aware of their conspicuous plumage and make behavioral adjustments accordingly to avoid predation, and that flock members can benefit from the heightened vigilance of these blue males, either as an early warning system or as a bright decoy (2017).

2. When in doubt, bring her flowers

Because being fabulous ain’t enough to turn up the charm, the superb fairy-wren suitor will bequeath females with a single yellow flower petal, perhaps to accentuate his scintillating blue-black plumage. However, despite the temptingly-anthropomorphic similarities, petal-bearing is no diamond-ring proposal – more like a booty call!

Superb fairy-wrens have the highest rate of “extra-pair fertilization” (AKA cheating) out of any bird species (Double, Cockburn 2000). Though superb fairy-wren flocks are headed by an older, territorial “primary” male that is socially bonded to a single female, cheating is rampant, and a whopping 95% of their broods contain offspring sired by a different father (Mulder, 1997; Mulder, Dunn, Cockburn et. al.  1994). An observation-based study by Raoul A. Mulder, “Extra-group Courtship Displays and Other Reproductive Tactics of Superb Fairy-wrens,” determined that in its 375 observations of fairy-wren courtship displays, petal bearing was performed “exclusively (97%) for extra-group females during excursions into neighbouring territories by lone males, and appears to have evolved specifically for the purpose of soliciting future extra-pair fertilizations” (1997).

3. Evolve Extra-Fancy Sperm

Polygamy’s rough – to maximize reproductive success, individuals of promiscuous species not only have to tirelessly woo as many partners as possible, but also have to deal with sexual selection post-copulation – rife with chemical manipulation, copulatory inhibitors, competitive sperm morphology, hostile pH fluctuations, and intersexual conflict, fertilization is a gametic war zone. Mating multiple times is great, but how does an organism ensure that each of its efforts successfully produced offspring?

Sometimes, it’s a numbers game. Fairy-wrens are known for their copious sperm loads – Malurus splendens, a close cousin to the superb fairy-wren, produces over 8.3 billion sperm per ejaculate (In comparison, a dose of human ejaculate only contains around 280 million) (Tuttle, Pruett-Jones, Webster 1996)!

Alongside gamete quantity, sperm variation and competition becomes especially intense amongst superb fairy-wrens, where the reproductive success of different paternal strategies vary with sperm morphology (Calhim, Double, Margraf et. al. 2011).

In quantifying the relationship between head : flagellum ratio and reproductive success in this species, Calhim, Double, Margraf et. al. mist-netted, banded, and non-invasively sampled sperm from M. cyaneus males from different reproductive stages in their life history. After observing and determining parentage of the offspring, the team calculated intrapair success, measured as the number of offspring the male sired for his social mate, as well as extrapair or “cuckolding” success, “measured as the lifetime number of illegitimate offspring that survived to four weeks after fledgling” (2011). Their study, “Maintenance of Sperm Variation in a Highly Promiscuous Wild Bird,” details that intrapair success was strongly associated with a longer flagellum and relatively shorter head, while a short flagellum and a relatively large head was associated with better extrapair success (2011).

4. Help your mate teach your chicks a song to distinguish them from brood parasites.

Even after their eggs are laid and their brilliant feathers dust over, fairy-wren parents must still be on high alert: both for predators, and for the insidious Horsfield’s bronze cuckoo, who lurks around poorly-guarded nests. Given the opportunity, the female cuckoo will descend, roll one of the wrens’ eggs out of the nest, and replace it with one that looks deceptively similar – pink, with a ring of dark speckles at its base. Securely tucked within the lofty grass walls of the nest, superb fairy-wren parents would hardly be able to tell the difference, so what they do instead is sing a secret passcode to their eggs (Colombelli-Ne´grel, Hauber, Robertson et. al. 2012).

9-10 days before the brood hatches, superb fairy-wren mothers titter a fast, high-frequency trill ranging from 5782.8-11,011,2 ± 250.0 Hz, which her chicks embryonically learn as they develop within their eggs (2012). Within every incubation call is a signature sequence that is unique to each female – the hatchlings who can sing their mother’s fingerprint best are the ones who get fed, and the hatchlings that can’t imitate her calls are abandoned or discarded (2012). The females communicate this to their mates, too, so that they could aid in distinguishing their chicks (2012). The eggs hatch after 15 days, and as the cuckoos start laying 13 days into the fairy-wrens’ incubation period, their foreign chicks get less time to memorize their foster mother’s calls, and thus are most likely to be pushed or starved out of the nest (2012). The joint team of psychology and zoology researchers who reported these findings in their paper, “Embryonic Learning of Vocal Passwords in Superb Fairy-Wrens Reveals Intruder Cuckoo Nestlings,” speculate that this co-evolutionary arms race between superb fairy-wrens and their brood parasites could intensify selective pressures for finer-tuned acoustic learning in both species’s offspring (2012).

All in all, superb fairy-wrens are frickin’ awesome! Ever flitting, singing, and glittering in the Aussie sun, these avian divas are a star 3.4 billion years in the making. Their richly-textured social lives have established new extremes in our study of coevolution, intersexual conflict, postcopulatory selection, and avian social psychology, and that’s barely the beginning of the profound body of research that needs to be done on this species. It just goes to show that even the tiniest species have eons to reveal about the diversity of life on Earth, and our study of evolution will never be complete without them!

SOURCES:

Colombelli-Ne´grel, D. Hauber, M. E. Robertson, J. et. al. (2012).

Embryonic Learning of Vocal Passwords in Superb Fairy-Wrens Reveals Intruder Cuckoo Nestlings. Current Biology, 22: 2155–2160.

Mulder, R. A. Dunn, P. O. Cockburn, A. et. al. (1994). Helpers liberate female fairy-wrens from constraints on extra-pair mate choice. Proceedings of The Royal Society B, 255(1344): 223-229.

Tuttle, E. M. Pruett-Jones, S. Webster, M. S. (1996). Cloacal protuberances and extreme sperm production in Australian fairy-wrens. Proceedings of The Royal Society B, 263(1375): 1359-1364.

Calhim S, Double MC, Margraf N, Birkhead TR, Cockburn A (2011) Maintenance of Sperm Variation in a Highly Promiscuous Wild Bird. PLoS ONE 6(12): e28809. https://doi.org/10.1371/journal.pone.0028809

Mulder, R. A. (1997). Extra-group Courtship Displays and Other Reproductive Tactics of Superb Fairy-wrens. Australian Journal of Zoology, 45(2) 131 - 143.

McQueen, A. Naimo, A. C. Teunissen, N. et. al. (2017). Bright Birds are Cautious: Seasonally Conspicuous Plumage Prompts Risk Avoidance By Male Superb Fairy-Wrens. Proceedings of The Royal Society B, 284(1857).

Double, M. Cockburn, A. (2000). Pre–Dawn Infidelity: Females Control Extra-Pair Mating in Superb Fairy–Wrens. Proceedings of The Royal Society B, 267(1442): 465-470.