Tag: Reproduction

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New Beginning by John Hawkhead

protostar flare
a new beginning
in the sonogram

by John Hawkhead

A protostar is a young star still gathering mass from its parent molecular cloud. The protostellar phase is the earliest the process of stellar evolution.

A sonogram is a picture made by ultrasound waves to show the inside of the human body, including in pregnancy assessment.

Further reading:

‘Protostar’, Wikipedia article – https://en.wikipedia.org/wiki/Protostar

‘Ultrasound’, Wikipedia article – https://en.wikipedia.org/wiki/Ultrasound

Author bio:

John Hawkhead (@HawkheadJohn) has been writing haiku and illustrating for over 25 years. His work has been published all over the world and he has won a number of haiku competitions. John’s books of haiku and senryu, ‘Small Shadows’ and ‘Bone Moon’, are now available from Alba Publishing (http://www.albapublishing.com/).

Enjoyed John’s sciku? Check out more of his sciku here: ‘Dark matter’, ‘Chirality’, ‘Spooky Interaction’, ‘Dancing’, ‘Planetarium’, ‘Empty Space’, ‘Averages’, ‘Interactions’, and ‘Surface Tension’.

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Ant-y-insulin

Long live queens! But why?
Ovaries might change growth cues
to extend lifespan!

By Dr Nathan Woodling

A queen takes the throne.
Insulin surges, eggs grow.
A switch extends life.

By Dr Andrew Holmes

Reproduction is linked to reduced lifespan in many animals, yet ant queens have a far greater longevity compared to workers in their colony – black garden ant queens can live up to 30 times longer than the 1-year lifespan of their workers. Ant queens have the same genome as their workers, and in some species of ant they aren’t reared differently but switch caste following the death of the current queen.

The Indian jumping ant (Harpegnathos saltator) exhibits this switching behaviour. When a queen dies, workers duel each other, with the winners transitioning into pseudo-queens known as gamergates. These gamergates begin laying fertile eggs and their lifespan is substantially increased – from 7 months to 4 years. Gamergates can even transition back into the worker caste if replaced by another queen, their lifespan reverting back to 7 months.

How is ant lifespan so mutable?

New research by Yan et al. (2022) points to an insulin-suppressing protein as a possible answer.

The researchers compared gene expression during caste switching and found that ants that switch from worker to gamergate produce more insulin. The increased insulin results in a change in the balance of activity between the two main insulin signalling pathways, MAPK (which controls metabolism and egg formation) and AKT (which controls ageing).

On transitioning to a gamergate, the MAPK insulin signalling pathway’s activity increases, inducing ovary development and the production of eggs. But this also results in the production of an insulin-suppressing protein (Imp-L2) which blocks the AKT insulin signalling pathway, increasing longevity.

IMP-L2 essentially acts as a switch between a worker being short-lived and sterile compared to a queen being long-lived and fertile.

Original research:

http://dx.doi.org/10.1126/science.abm8767

A note about the sciku:

Nathan and Andrew independently wrote their sciku about this research and discovered the coincidence when Nathen posted his poem on Twitter. The two different approaches to writing about the same subject demonstrate why sciku are such a consistently interesting medium for exploring and sharing research.

Author bios:

Dr Nathan Woodling is a lecturer in molecular biosciences at the University of Glasgow. You can follow him on Twitter here: @NathanWoodling.

Dr Andrew Holmes is a former researcher in animal welfare and the founder and editor of The Sciku Project. You can follow him on Twitter here: @AndrewMHolmes.

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Lost Matters

Birthweight advantage
of Black immigrants: lost in
a generation.

Birthweight can be a predictor of a range of health and socioeconomic outcomes, and in the United States Black women are known to have the highest prevalence of low birthweight babies of all racial groups. Evidence also suggests that immigrant women who give birth in the US have babies with higher weights than women born in the US.

Yet new research suggests that this birthweight advantage of immigrants extends beyond a single generation… for some races.

Andrasfay & Goldman (2020) looked at 1971-2015 Florida birth records to assess intergenerational changes in birthweight. They found that Black immigrants typically have larger babies than US-born Black women but that, in contrast to Hispanic immigrants, this ‘healthy immigrant’ effect is lost within a generation.

Whilst the study did not specifically investigate reasons for this difference, the authors suggest that a “lifetime exposure to discrimination and socioeconomic inequality is associated with adverse health outcomes for Black women.”

Original research: Andrasfay & Goldman (2020) Intergenerational change in birthweight: effects of foreign-born status and race/ethnicity, Epidemiology, https://doi.org/10.1097/EDE.0000000000001217

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Signs of Spring by Dr. Jon Hare

silvery white
shadbush blossoms
swim upstream

By Jon Hare

Shadbush (Amelanchier arborea) blooms in the spring. Clusters of small white flowers appear in March through May before leaves grow. The bloom time coincides with the upstream migration of American shad (Alosa sapidissima). Millions of shad used to return to east coast rivers, but these runs are now greatly reduced because of historical overfishing, dams, and loss of habitat.

Much like salmon, shad return to rivers to reproduce after several years at sea. Unlike salmon that reproduce and die, shad go back to sea after reproducing to return to rivers in following years to reproduce again. Thus salmon are termed semelparous from the Latin semel – once, a single time. Shad are termed iteroparous from the Latin itero – to repeat.

Photo credit: NOAA Fisheries Northeast Fisheries Center.

Shadbush is also iteroparous – blooming year after year in the spring to mark the return of the shad. Recent research by Nack et al. (2019) indicates shad migration will be earlier in the season; whether shadbush will bloom earlier remains to be seen.

Original research: https://doi.org/10.1002/mcf2.10076

Dr. Jon Hare is a scientist who works Woods Hole, Massachusetts. His research background is in fisheries oceanography and climate change impacts on marine fisheries. Check out Jon’s other sciku ‘Owls of the Eastern Ice’, ‘Varves’, ‘Cobwebs to Foodwebs’ and ‘Glacier Mice‘.

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Climate Masting

Seed production up,
surely that’s a good thing, no?
Benefits declined.

Whilst the world stirs slowly into action to limit climate change, general consensus is that there will be some winners amongst the losers as temperatures rise. All organisms have their niches and changing environments will benefit some just as much they cost others.

Or at least that’s the simplistic take on the matter…

New research into plant masting – synchronous seed production – suggests that all isn’t as clear cut as that. The phenomenon of masting is beneficial to plants as the synchronicity “increases the efficiency of pollination and satiates predators” – sure predators will eat lots of seeds but the overwhelming numbers of seeds mean that large numbers aren’t eaten. It’s a bit like the synchronous emergence of some cicada species, which only emerge on mass every 13 or 17 years, with the gaps between emergence ensuring that predators aren’t reliant on the cicadas as a stable food source.

Bogdziewicz et al. (2020) looked at a 39 year-long masting dataset for the European beech and found that whilst climate warming increased seed production, the trees are actually losing out for three reasons:

1) Increased temperatures result in more consistent numbers of seed produced year-on-year – preventing the traditional boom and bust nature of seed production that helps to limit predator numbers.

2) Increased temperatures reduce synchronicity, resulting in less effective pollination.

3) Reduced seed production synchronicity means that predators aren’t overwhelmed by the sheer numbers of seeds available and are able to eat more seeds over a longer period of time.

All of this means that whilst the simple story suggests climate warning leads to increased seed production, the truth is more complex and instead those that actually benefit are those that eat the seeds.

Original research: https://doi.org/10.1038/s41477-020-0592-8

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Spreading

Tiger mosquito,
spreading northwards, adapting.
Deadly time capsules.

Many mosquito species struggle to survive at low temperatures, preventing their spread into cooler climates and thus limiting the spread of diseases carried by the mosquitoes. Yet new research by Medley et al (2019) suggests that some mosquito species may be able to adapt part of their reproductive cycle to survive cold winters.

The Asian tiger mosquito is a vector for a number of pathogens, including Zika and dengue viruses. The species first arrived in the USA in Texas in 1985 and today the current range extends as far north New Jersey.

How has this tropical and sub-tropical species managed to survive the temperate conditions?

The secret lies with a process called diapause – a type of animal dormancy where development is delayed in response to unsuitable environmental conditions such as cold winters.

In the Asian tiger mosquito, the length of day or night (photoperiodism) can induce egg diapause – as the days get shorter with the approach of winter eggs become dormant and only start developing again once the days start to lengthen and temperatures are likely to be more suitable for the species.

In the new study the researchers found that northern diapause eggs survive northern winters a lot better than southern diapause eggs, but both northern and southern diapause eggs survive southern winters the same as each other. The research demonstrates the species adapting to colder conditions as it expands northwards over a period of around 30 years. Not only have northern populations adapted to northern climes by producing more eggs but those eggs are adapted to survive the northern winters better too.

Original research: https://doi.org/10.1111/1365-2664.13480

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Adaptation by Prof Fred W. Allendorf

Survive, reproduce
Mendel rules, pass on your genes
That’s adaptation

by Prof Fred W. Allendorf

Natural selection is one of the primary mechanisms of evolution. Those individuals with higher survival and greater reproductive success are more successful at passing on their genes to future generations. This brings about adaptation which increases the fitness of individuals in future generations.

Further reading: A brief history of the genetic theory of adaptation by H. Allen Orr (2005): http://dx.doi.org/10.1038/nrg1523

Prof Fred W. Allendorf is Regents Professor of Biology Emeritus at the University of Montana. His primary scientific interest is the application of population genetics to conservation biology. He is senior author of the book Conservation and the Genetics of Populations. Check out Fred’s other sciku on Genetic Drift, Inbreeding Depression and Gene Flow.

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Supine Risks

Supine position,
dreaming towards tragedy.
The risk of stillbirth.

New research has found that the risks of stillbirth are higher when the mother falls asleep lying on her back. Cronin et al (2019) analysed sleeping position and resulting birth success. Whilst no difference was found between going-to-sleep on the left or right side, the researchers found evidence that the supine going-to-sleep position is a contributing factor for late stillbirth. In fact, they suggest that if every pregnant woman of 28 weeks gestation and beyond settled to sleep on her side the number of late stillbirths could be reduced by 5.8%.

Original research: http://dx.doi.org/10.1016/j.eclinm.2019.03.014

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Gene flow by Prof Fred W. Allendorf

Move away from home

Find a mate and reproduce

That is called gene flow

by Prof Fred W. Allendorf

Gene flow is the movement of alleles or genes from one population to another (Slatkin, 1987). Gene flow is crucial in reducing the harmful effects of genetic drift and inbreeding depression in populations. As global change, habitat destruction, and fragmentation rapidly progress, many natural populations are becoming smaller, more isolated, and more affected by inbreeding depression. However, Sewall Wright (1951) demonstrated that even very small amounts of gene flow are sufficient to avoid the harmful effects of genetic drift and inbreeding within local populations.

Original research:

Slatkin, M. 1987. Gene flow and the geographic structure of natural populations. Science 236: 787-792.

Wright, S. 1951. The genetical structure of natural populations. Annals of Eugenics 15: 323-354.

Prof Fred W. Allendorf is Regents Professor of Biology Emeritus at the University of Montana. His primary scientific interest is the application of population genetics to conservation biology. He is senior author of the book Conservation and the Genetics of Populations. Check out Fred’s other sciku on Genetic Drift, Inbreeding Depression and Adaptation.

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Couple affection

Art class and board games –

oxytocin released for

couple affection.

Oxytocin is often known as the ’hugging hormone’ and is important for attachment forming in relationships. Shared activities between two individuals in a relationship can help with bonding and release oxytocin. But what sort of activities can promote this?

Melton et al (2019) investigated the impact of two activities on couple’s oxytocin levels: playing board games and attending art classes. Both activities resulted in an increase in oxytocin in both men and women but there were interesting differences between the activity, sex and location of the activities.

The greatest increase in oxytocin was in men during the art class. Interestingly, greater levels of eye contact were observed between couples playing board games but greater physical contact observed during art class, whilst couples in a novel setting and doing a novel activity also released more oxytocin than couples in a familiar environment. These results show that whilst joint leisure activities do result in increased oxytocin, the type of activity and the novelty can affect the amounts.

Original research: http://dx.doi.org/10.1111/jomf.12556

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Spider milk

Unexpected milk –

not a mammalian trait?

Lactating spider.

Caring mothers aren’t the first thing that spring to mind when you think about spiders. Yet plenty of evidence exists of female spiders providing food for their young and protecting their offspring. A recent and very surprising example of arachnid maternal care comes from a species of ant-mimicking jumping spider.

Chen et al (2018) observed female spiders secreting a nutritious milk-like substance, which the offspring first consume from the floor of the nest and once they are a bit older directly from the mother herself. Through a careful set of experiments the researchers found that the spiderlings are entirely dependent on this ‘milk’ for survival, and that there are still huge survival benefits to it even once they are old enough to forage independently.

Milk provision was once seen as an exclusively mammalian trait but this research adds to growing evidence that the practice is more widespread across animal taxa than previously thought.

Original research: http://dx.doi.org/10.1126/science.aat3692

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Ensnared

Poor social spider.

Ensnared, building its own tomb.

Parasitoid wasp.

 

Parasitoid wasps are known to lay eggs on their victims which are then consumed by the hatching larvae. Some species will even paralyse their victim and place them in a nest to be eaten alive by their offspring. Yet behaviour observed by Fernandez-Fournier et al (2018) has revealed a wasp species that behaves even more disturbingly.

Adult Zatypota sp. wasps were found to target a species of social spider that lives in a colony web and rarely leaves it. The wasps lay their eggs on the abdomen of the spider and when the larvae hatches it attaches to the spider. The larvae influences the spider to then leave its colony and spin a cocoon web in which the spider then waits until the larvae finally kills it. Its meal consumed, the larvae then spins a pupal cocoon within the protection of the outer cocoon web and a few days later emerges as an adult.

The results reveal that the spider is manipulated into performing unusual behaviours, since such social spiders rarely leave their colony and the cocoon web is a complete different form of web. The infected spider makes its own tomb before being eaten alive within it.

Original research: http://dx.doi.org/10.1111/een.12698

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Domino effect

Domino effect.

Ocean-behaviour-hookworms

lead to seal pup deaths.

 

The web of life, food chains, ecological balance – there are a lot of terms that indicate how interlinked ecosystems are. A recent, tragic example of this is how a rise in ocean temperatures can indirectly result in increased seal pup death from hookworm infection.

Seguel et al (2018) found that sea temperatures influenced the survival of South American fur seal pups. Sea temperatures effect wind patterns and ocean currents, changing the abundance of nutrients and as a result fishes. Higher sea temperatures resulted in lower fish abundance, meaning that fur seal mothers needed to spend more time at sea feeding, consequentially spending less time with their pups. The reduced maternal care led to lower pup growth rates and a less effective immune system, making the fur seal pups more susceptible and less likely to successfully fight off hookworm infection.

Original research: http://dx.doi.org/10.7554/eLife.38432

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Small and spherical

Small and spherical,

the eggs of forest blue tits.

Urban differences.

 

Populations of many species live in different environments that provide varied resources and have differing selection pressures. Research by Bańbura et al (2018) investigated the eggs of blue tits living in a forest environment compared to a nearby urban park.

The researchers found that urban-dwelling blue tits produced eggs that were on average 5% larger than their forest-dwelling counterparts, and the urban eggs were less spherical as well. These differences are potentially the result of blue tit diets in each environment – the forest is caterpillar-rich but calcium-poor whilst the urban park is the opposite, with 5-6 times the density of snails which have calcium-rich shells. The smaller, rounder forest egg shape requires less calcium compared to the less spherical urban egg shape.

Original research: http://dx.doi.org/10.1186/s12983-018-0279-4

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Absentee parents

Absentee parents.

Selection pressure leads to

self-sufficiency.

 

Parents invest in the survival of their offspring to differing amounts across the animal kingdom. Some parents provide for their young until they reach independence, whilst in other species the parents are absent from birth onwards.

The burying beetle shows a mix of these tendencies. The parents use small dead mammals and other vertebrates as edible nests for their young. The larvae hatch and enter the carcass, while the parents may help the larvae enter the nest by biting small incisions in the carcass and may even feed them. Yet the larvae can also survive without parental care, using their mandibles to enter the edible nest and feed themselves.

By experimentally manipulating the levels of parental care across 13 generations, Jarrett et al (2018) found that both parental behaviour and offspring anatomy changed. Parents removed before larval hatching began to make the incisions earlier to provide support for the offspring before they hatched. The larvae of such absent parents also evolved larger mandibles to help enter the carcass and feed themselves.

In contrast, when parents were present the larvae had smaller mandibles, as the production of large mandibles is costly and unnecessary when parental support is provided. The research is nice evidence of evolutionary changes to different partners in the parent-offspring dynamic.

Original research: http://dx.doi.org/10.1038/s41467-018-06513-6

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Eggy difference

The Baltic flounder:

Native to namesake region.

Eggy difference.

 

A new species of flounder has been identified as separate from the European flounder by Momigliano et al (2018). The Baltic flounder (Platichthys solemdali sp.) is native only to the Baltic Sea – the first fish species to be identified as endemic to the area.

Its reproductive behaviour differs from the European flounder, spawning eggs that sink in coastal areas as opposed to buoyant eggs in open water. There are also differences between the species in egg morphology, egg and sperm physiology. Unfortunately, the small morphological differences mean that it is difficult to unambiguously distinguish the species and genetic methods or egg/sperm analyses are required.

Original research: http://dx.doi.org/10.3389/fmars.2018.00225

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Cuckoo bee

No longer extinct,

cuckoo bee, nest parasite,

found further afield.

 

The Macropis Cuckoo Bee was thought to be extinct until the early 2000s when a specimen was found in Nova Scotia. The bee is one of the rarest bees in North America, with only a handful found during the past decades. A new specimen found in Alberta and reported by Sheffield and Heron (2018) has now pushed the known geographical range of the Macropis Cuckoo Bee further west and gives hope to the continued survival of this species.

The Macropis Cuckoo Bee lays its eggs in the nests of Macropis bees and therefore requires the presence of its hosts in order to reproduce, yet cuckoo bees are not always found where their hosts are. In turn Macropis bees are entirely dependent on plants of the primrose genus meaning that the there is a chain of co-dependence between the plants, bees and cuckoo bees.

Original research: http://dx.doi.org/10.3897/BDJ.6.e22837

 

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Egg quality

Low egg quality –

the impact of age. Blocking

proteins slows decline.

 

As women age their reproductive ability decreases due to declining egg quality. However, research by Templeman et al (2018) suggests that blocking a particular group of proteins may help to slow this decline, potentially extending the reproductive period.

The proteins, known as cathepsin B proteases, are more common in age-degraded oocytes (unfertilised eggs) and appear to be part of the problem of decreasing quality. By blocking the proteins in C. elegans worms oocyte quality was maintained for much longer, regardless of whether the drug was administered at the beginning or part way through the worms’ reproductive period. Whilst it’s not ready for testing with humans, it points the way towards an interesting new approach.

Original research: http://dx.doi.org/10.1016/j.cub.2018.01.052

 

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Secretive flatworms

Secretive flatworms

divide coyly in darkness

by three-stage fission.

 

Freshwater flatworms are able to reproduce asexually by dividing in half – the head and tail pieces then each become a new worm. This process of binary fission was previously difficult to study as it occurred in darkness, halts with any disturbance and occurs infrequently (about once a month) but researchers now have more of an understanding of how the process occurs.

Malinowski et al (2017) found that fission occurs in three steps: 1) a local constriction along the body of the flatworm as if a waist is forming, 2) pulsations that apply stress to the ‘waist’ ultimately leading to 3) a rupture at the waist and the creation of two pieces which then re-grow their missing halves. The researchers also developed a linear mechanical model of the fission enabling a better understanding of the division process and accurate predictions of where on the body of a flatworm it will occur.

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The kids help out

Staying at home, the

kids help out. Breeding becomes

cooperative.

 

In cooperatively breeding species individuals help to raise offspring that are not their own, but how did this costly behaviour evolve? By comparing 3,005 species using phylogenetic analyses Griesser et al (2017) suggest that cooperative breeding in birds occurred in two stages.

First, families formed by the prolonging of parent-offspring associations, with chicks not leaving the nest when nutritionally independent. This appears to have occurred in productive environments where the cost of the offspring remaining at home for longer is less.

Second, the offspring remaining at the home nest then start to help out. In contrast to the formation of family units, the researchers suggest that this happened in more variable environments where the retained helpers can buffer in harsh years.

This theory helps to explain the geographic distribution of cooperatively breeding bird species too – areas where these species are found have often experienced historical declines in productivity. The pre-decline environment may have fostered family formation whilst the decline may have then resulted in the step to cooperative breeding.

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Hijacked ant

Little hijacked ant,

blade held in jagged pincers,

awaits her demise.

 

The lancet liver fluke is a parasite of devious means. As an adult it lives in the livers of ruminant animals, often cattle, but it has an ingenious method of getting from one liver to another. First, its eggs are excreted in its host’s faeces, which is then consumed by a snail. The larvae develop into juveniles in the snail’s digestive tract and are eventually themselves excreted.

This is where the ants come in. Ants use snail slime for moisture and so consume the juveniles. Once inside an ant the parasites cause it to climb a blade of grass and clamp its mandibles to the top. The ant will remain attached all night and then return to its normal behaviour during the day. The aim of the parasite is for the ant (and attached blade of grass) to be eaten by a grazing animal – the parasite is then back in its main host and the cycle starts again. Summarised in Tarry, 1969.

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Twisted naval string

Twisted naval string:

Forty turns of jelly and

contrary vessels.

 

Break benefits both before

severing the thread of life.

 

The umbilical cord has traditionally been cut (or at least clamped) 15-20 seconds after birth but increasingly research suggests that a longer delay before cutting is beneficial for both term and pre-term infants.

For term infants a delay of 30-60 seconds can increase haemoglobin levels at birth and iron stores in the first months of life. In preterm infants a delay can improve transitional circulation, result in the better establishment of red blood cell volume and decrease the need for blood transfusions.

A delay before clamping and cutting is therefore recommended by both the World Health Organisation and the American College of Obstetricians and Gynaecologists.

This sciku is actually an example of a tanka – the first two verses of a traditional renga, where haiku originate from. Learn more about haiku, renga and tanka here.

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Plenty of fish

Plenty of fish yet

male voles choose monogamy

… but do their partners?

 

Monogamy is relatively rare in the animal kingdom, with extra-pairs matings happening a lot more than you might think. Males in particular are thought to gain the most from polygamy by being able to sire multiple offspring, whilst females may gain from monogamy through defence or paternal care of their young.

Yet despite having access to multiple females, male prairie voles choose to form exclusive pair bonds with individual females (Blocker & Ophir, 2016). In contrast,  female prairie voles readily engage in promiscuous mating (Wolff et al, 2002).

So why (under laboratory settings) are male prairie voles monogamous whilst females are promiscuous?

Blocker & Ophir, 2016 argue that one explanation could be that the costs to males of trying to hang on to multiple females at once are too great, and that male prairie voles gain the most by aggressively monopolising just one female. Females on the other hand have nothing to lose from polygamy so will mate with other males if the opportunity presents itself.

In prairie voles it seems that monogamous behaviour may be male-driven.

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Paternal spider

Paternal spider

to die at the ‘little death’,

worthy sacrifice.

 

Mating is a dangerous game for males of many species of spider, with females often winding up with a nutritional meal to help fuel egg production. Taking their paternal responsibilities to an extreme, male dark fishing spiders spontaneously die during copulation. Females that are allowed to eat their dead mates produce a greater number of offspring, of a greater size and with an increased survivorship compared to females prevented from eating their mate or females provided with an equivalently sized cricket. It seems cannibalism isn’t all bad. Schwartz et al, 2016.