The battle within the sexes: When females fight

It is 30 years since the meerkat Timon and the warthog Pumba first taught Simba to lighten up and have fewer worries – “Hakuna matata¹” in The Lion King. Invoking images of sentries that scan the savannah for threats on two feet, it isn’t surprising that the bipedal humans melt at the mere mention of meerkats, little furry African mammals that remind them of themselves. Meerkats live and breed cooperatively. Both male and female offspring helped take care of younger ones born to the group allowing multiple breeding events to take place and more meerkat babies created and thriving. Cuteness continues.

But as we know with anything in nature, there is more than meets the eye.

Might of the matriarch

The seemingly hunky-dory social setup is maintained by aggression and struggles for dominance. The meerkats Suricatta suricatta are led by a matriarch who apparently rules the roost when it comes to mating opportunities. She has sole access to males, ensuring that all babies born are hers. Any other female that attempts to usurp her position and mating opportunities is promptly evicted and her offspring killed ² . In a recent study by Campbell et al. ³, the authors investigated the blood of wild meerkats to test for any genetic signatures that are associated with their social rank. The dominant individuals showed elevated responses to pathogens. This indicates higher innate immunity; their ability to heal and fight off diseases. This is after accounting for their body mass, relatedness, and other confounds that may convolute the results. Surprisingly, these gene regulatory signatures were seen only in females and not in males. Probably because it is only the females that engage in such physically demanding fights. But are dominant females just those that had better immunity to begin with? Fortunately, the same study also contains samples from females who transitioned from subordinate to dominant rank in their group. As they transitioned, so did the expression of their immunity-related genes change to match what they predicted.

Battles underground

While meerkats tussle in the Kalahari, similar battles for dominance are taking place even in species where access to males is a moot point…because there are no males. Enter Platythyrea punctata, a South American species I had the honour of working with during my Ph.D. In some populations, all ants in the nest are born from unfertilised eggs. These all-female populations propagate by a form of clonal reproduction called thelytoky. But even amongst these clones, exists a hierarchy. Two individuals of the same age and from the same rearing conditions can be placed together and promptly divide their labour after a few bouts of ‘antennal boxing’. The dominant egg-layer is the clone which will lay eggs that produce the next set of offspring living up to an average of 800 days while the subordinate clone has inactive ovaries and a much shorter lifespan of about 250 days.⁴ In a 2018 paper, Abel Bernadou et al.⁵ manipulated various environmental factors during a clone-pair’s rearing to then determine their chances at gaining dominance. The ant larvae raised at higher temperatures, subjected to non-lethal injury, stress and malnutrition were those that went on to lose the war of dominance and become the subordinate clone. This indicates that the clone that becomes dominant is probably one that is somehow intrinsically fitter than her clone, the difference probably too subtle or as of yet unquantifiable by us non-clonal and unantennated unless we purposefully manipulate the battle.

Mother most strong

The above two examples come from two distant taxa from different parts of the little rock we call Earth. And they both are just two examples from the animal kingdom demonstrating how females struggle to ensure their fitness-by being the sole reproductive members. A strong contender is rendered stronger via upregulation in genes garnering her further strength to physically or chemically keep her potential competitors in line. Maintaining the status quo isn’t easy either. So the next time you join Timon in his chant of Hakuna matata (it means no worries he says) maybe you’ll think of his Mata (mother) with a few worries you didn’t think of before.

1. https://youtu.be/0enTq1fCE9A?si=LybLqXzWRavbWPFm ↩︎
2. https://youtu.be/Dnx9T_PUMno?si=fI-fr_6KzGdl21Lv ↩︎
3. C. Ryan Campbell, Marta Manser, Mari Shiratori, Kelly Williams, Luis Barreiro, Tim Clutton-Brock, Jenny Tung 2023, A female-biased gene expression signature of dominance in cooperatively breeding meerkats ↩︎
4. Hartmann, A. and Heinze, J. (2003), LAY EGGS, LIVE LONGER: DIVISION OF LABOR AND LIFE SPAN IN A CLONAL ANT SPECIES. Evolution, 57: 2424-2429. https://doi.org/10.1111/j.0014-3820.2003.tb00254.x ↩︎
5. Bernadou Abel, Schrader Lukas, Pable Julia, Hoffacker Elisabeth, Meusemann Karen and Heinze Jürgen 2018 Stress and early experience underlie dominance status and division of labour in a clonal insectProc. R. Soc. B.2852018146820181468http://doi.org/10.1098/rspb.2018.1468  ↩︎

Backyard observations: ant associations

I’ve been spending some downtime at my parents’ place nestled among the green hills of the Western Ghats in Kerala. But my biologist self also has to contend with my gardener self as I attempt to plant and sustain plants in my parents’ yard. The most well-planned indigenous plants and fruiting trees get overrun by ants, and my neighbours- experienced farmers say it’s the ants that kill plants. There IS perhaps a correlation but ants being plant killers isn’t entirely true. The ants are actually often running around on your favourite tomato plant or orange bush for a whole other reason. They are looking for a sugar rush from an unlikely source.

Image 1: Oecophylla smaragdina ants accessing juicy sweet honeydew from their trophobionts- the sapsucking aphids (Kudayathoor, Kerala)

Look closely at the plant, braving the ants and their bites and you realise they seem to be guarding smaller white/green or red specks seemingly stuck on your plant’s stem. These are hemipterans such as mealybugs or aphids, which are tiny little agents of chaos. They can pierce the plant stem and suck the sap out of the plant parts. But they are pretty easy to squeeze and squish or eaten by any animal casually grazing on the plant. Cue, scuttling vicious 6-legged machines- the ants. Many species of mealybugs and aphids form mutualistic relationships with ant species ¹. This is a somewhat ‘tit-for-tat’ situation. The aphids feed on plant sap and excrete sweet sugar-filled honeydew drawing ants that can further access more by ‘milking’ the aphids. Ants file to these trophobionts regularly. They can discriminate between mutualistic and non-mutualistic aphids, but even form new mutualisms with previously unencountered species^{2 3}. And the aphids in turn obtain bodyguards that are quick to attack anyone who dares to get between them and their honey-dew. WIN-WIN!

It isn’t only some hemipterans that have formed associations with ants though. Far away in Australia, the female Australian walking stick (Extatosoma tiaratum) takes some time off from resembling a twig to drop her eggs from up in the canopy. What may spell doom for unsupervised eggs, is but a highly developed system. The eggs are deceptively good at mimicking oily seeds, with a little edible cap that makes the ants bring it into their nest for storage. The ‘plant seed’ hatches in the safe warmth of the ant colony and the baby Phasmid smells and even looks and walks like an ant to allay any suspicion from the ants. The interloper succeeds, gets older and leaves…getting to drop eggs of its own one day for another unsuspecting ant to pick and take back to her nest.⁴

Ants don’t just form interesting associations with insects. Ant-Fungus associations are often dominated by the ominous Zombie ant fungus Ophiocordyceps unilateralis . This fungus starts out as a tiny spore on the forest floor in the tropics, easily picked up by a passing carpenter ant (Camponotus sp). As the spore anchors itself further into the ant’s body and starts to grow, the ant starts behaving ‘un-ant-like’. In its moments of climax, the fungus mushrooms out through the head of the ant releasing new spores far and wide ⁵. However, I’ve worked with species of ants that have much friendlier associations with certain fungi ⁶. There is a whole clade of ants out there that developed mutualistic relationships with specific fungi years ago.

So much so that they live in fungus gardens that they tend to and feed off of. The pinnacle of such association is represented by the leafcutting ants of the Neotropics- Central and South America. The tribe Attini contains leafcutting ants such as Atta colombica and Acromyrmex echinatior whose workers famously cut leaves and take them back to their nest in large quantities⁷. But the cut leaves aren’t to be used by the ants directly. In fact, the ants cannot feed on anything EXCEPT what their fungal partner can break down for them from those leaves. The fungal partners of species such as Leucoagaricus gonglyophorus too can no longer survive outside of the mutualistic relationship with the ant. So when a new ant-princess (called gyne) flies off to establish her own colony as a queen, she carries a piece of her fungal garden with her. This dowry, a piece of her old colony becomes the new home and fungus garden ^{8 9 10}. This mutualism has sustained for about 20 million years, whereas human agriculture probably began about 12,000 years ago.

Image 2: Atta colombica workers mill about on the surface of the fungus garden (lab set up in the University of Freiburg)

I’m smarter than using all of the above as an argument with my folks about our vegetable garden or with my neighbours about their chillis though.

References

1. Zhou A, Lu Y, Zeng L, Xu Y, Liang G. Solenopsis invicta (Hymenoptera: Formicidae), defend Phenacoccus solenopsis (Hemiptera: Pseudococcidae) against its natural enemies. Environ Entomol. 2013 Apr;42(2):247-52. doi: 10.1603/EN12168. PMID: 23575014. ↩︎
2. Hayashi M, Nakamuta K, Nomura M. Ants Learn Aphid Species as Mutualistic Partners: Is the Learning Behavior Species-Specific? J Chem Ecol. 2015 Dec;41(12):1148-54. doi: 10.1007/s10886-015-0651-1. Epub 2015 Nov 21. PMID: 26590597. ↩︎
3. Xu T, Chen L. Chemical communication in ant-hemipteran mutualism: potential implications for ant invasions. Curr Opin Insect Sci. 2021 Jun;45:121-129. doi: 10.1016/j.cois.2021.04.004. Epub 2021 Apr 24. PMID: 33901733. ↩︎
4. Video ant-stick insect association- Australia ↩︎
5. Zombie ants ↩︎
6. Majoe Megha, Libbrecht Romain, Foitzik Susanne and Nehring Volker 2021 Queen loss increases worker survival in leaf-cutting ants under paraquat-induced oxidative stressPhil. Trans. R. Soc. B3762019073520190735http://doi.org/10.1098/rstb.2019.0735 ↩︎
7. Leafcutting ants ↩︎
8. North, R. D., Jackson, C. W., & Howse, P. E. (1997). Evolutionary aspects of ant-fungus interactions in leaf-cutting ants. Trends in Ecology & Evolution, 12(10), 386–389. https://doi.org/10.1016/S0169-5347(97)87381-8 ↩︎
9. Bass, M., & Cherrett, J. M. (1996). Leaf-Cutting Ants (Formicidae, Attini) Prune Their Fungus to Increase and Direct Its Productivity. Functional Ecology, 10(1), 55–61. https://doi.org/10.2307/2390262 ↩︎
10. Green, P. W. C., & Kooij, P. W. (2018). The role of chemical signalling in maintenance of the fungus garden by leaf-cutting ants. Chemoecology, 28(3), 101–107. https://doi.org/10.1007/s00049-018-0260-x ↩︎

Voyage of the dawn-threader: a pictorial

I had just been back in India a few days and sleep escaped me earlier thanks to the heat uncharacteristic of November. The only indicator for it being ‘winter’ in Kerala, India was that 5 am was still shrouded in darkness. It’s that pregnant pause after the mosquitos have stopped their high-pitched singing and the roosters have yet to find their morning motivation. As I sat down to contemplate what to do in the stillness of the hour without waking the others in the house, I felt something stir. I instinctively straightened up and sat with my feet up on the couch as I saw something scurry from under this roost I had chosen for viewing the breaking dawn. My eyes scanned the floor and rested on the threshold of my parents’ bedroom door where I beheld another resident that was awake at this hour. A member- not of my family but of the Arachnid family Sparassidae–A huntsman spider!

Luckily for the both of us, neither it nor I were startled by each other for too long. I hadn’t seen a huntsman spider in quite a while and it took me straight back to my field station in Serendip Sanctuary, Australia ¹ where I was often in the company of huntsman spiders and possums early in the morning. Being night active, I had caught this huntsman at the end of its shift. As I unfroze from my initial shock, so did the spider. I snuck back into my room and retrieved my camera to capture the fag end of the huntsman’s hunt. Any opportunity to show how useful these spiders are in keeping the other insects and the occasional small gecko population in check.²

In a scene that would probably disturb my parents (and even myself were I not behind my zoom lens at a safe distance), the spider deftly scaled the door in an unhurried calculated set of moves. It gave me time to study its eyes- spanning two rows, the patterns on its back (dorsal side), and the white ‘mustache’ (aka the clypeus) that apparently attracts moths while the stalker waits patiently to immobilise them with venom.^{3 4}

As the huntsman got to the ceiling and unfurled itself, I reveled in the glory of its full size, also somehow relieved that it was now farther away from me. As I watched, this living fossil started twitching. Alternating somehow between its fore and hind legs as if it had cramps it was straightening out reminding me of Michael Jackson song Thriller and scenes from Harry Potter.

Aragog (yep, Potterheads) moved back and forth between the ceiling and the floor, scaling up slowly and pushing itself off the wall like a pro rock climber; rappelling down to land gently like a cat.

Flying down with all the elegance of a trapeze artist, the above photo shows the biodegradable harness aka dragline (corner right attached to the rear of the spider) that helps dear Aragog become the stuff of Halloween horror. This thread allows them to hang while carrying themselves and even prey, their egg sac,s etc. ⁵

Aragog repeated this movement, climbing down the line with a spring in its step as a puppet literally attached to a string. Huntsman spiders do NOT spin intricate webs into which prey can get stuck. Instead, they hunt more actively, covering large distances thanks to their speed and long appendages. ⁶ I believe the spider here was actually trying to pounce on the little insects and alates on the floor from yesterday evening…go back up again. Get some insects closer to the ceiling and come back down. Sadly I couldn’t distinguish the insects or verify whether that was indeed what the circus entailed.

Either way, the acrobat climbed right back up swiftly again. It was as quick on the floor as it was lithe when suspended in air or upside down on the ceiling. While I fought the vertigo of following these antics through my zoom lens without disturbing this performance I noticed the shimmering dragline and the rapid movements of the spider which finally flattened itself to easily squeeze under my parents’ door. My family dozed on in the darkness while my nocturnal friend probably climbed back up again into a corner of their room. This is where it will bide its time waiting to ambush the right prey. I for one hope to meet Aragog again.

1. https://youtu.be/V2jGK5niQEA?si=RyjmLSd_42rNMBc8 ↩︎
2. https://arachnidanswers.com/huntsman-spiders/ ↩︎
3. https://roundglasssustain.com/species/huntsman-spider ↩︎
4. https://www.projectnoah.org/spottings/22374005 ↩︎
5. https://r.search.yahoo.com/_ylt=AwrOuM_BZB1mZb8UtGlXNyoA;_ylu=Y29sbwNncTEEcG9zAzYEdnRpZAMEc2VjA3Ny/RV=2/RE=1714411970/RO=10/RU=https%3a%2f%2fwww.nature.com%2farticles%2fnatrevmats20188/RK=2/RS=E7K72Z_JsxHIgtr6YJK9axHU_Lg- ↩︎
6. https://www.whatsthatbug.com/do-huntsman-spiders-jump/ ↩︎

Another shot detailing the features of the huntsman christened Aragog for the purpose of this post.

The ‘Arana’ under the ‘Anjili’

The Jheel-yard¹ has entertained me with some cool critters since I’ve become a resident here starting this month. The last time I visited my parents was my first time in India in 4.5 years, the whole duration of my PhD in Germany. And it was MONSOON. So it was a cornucopia of creatures I hadn’t seen in a while. This time around, November, the rains are not as forceful and the sun is powerful, the heat is oppressive- WINTER is just a name. But there are always weeds to pull, plants to tend to, and work to be done- come rain or shine. After a breakfast of boiled quail eggs with a ginger-soy dip, I headed out in my field gear bracing myself for the heat, even at 9 am. I checked up on the recently sown and transplanted seeds and saplings and trimmed the crotons and ornamental Brazilian red-hots. The Bauhinia purpurea and Bauhinea variegeta which we had recently subjected to a little grafting experiment seem to be doing well. A trellis I fashioned for the passion-fruit plant survived the storm and rain we had on Friday.

The Bauhinia purpurea in all its glory feat. a coconut-palm

I get to the area we refer to as the ‘Mesa²‘. This is one of the few areas I now focus on for my ‘rewilding’. While I love the layout and the topography the Mesa presents, the soil here obviously is the most prone to erosion. It also looks like a bald spot³ next to the majesty of our Anjili tree. The Anjili (Artocarpus hirsutus) is not only native to Kerala, it was also one of the few trees that was on this land, before my family bought it. Which means, it is endemic, old and HUGE. My ‘Mesa-rewilding’ project entails getting locally found wild creepers and runners to form a carpet on the Mesa and merge into the undergrowth of the Anjili. This morning, I trimmed my mother’s overgrown Panikurka which serendipitously had aerial roots, perfect for the Mesa’s incline. “Their shallow roots can probably survive the erosion-prone bed but still hold enough soil to be able to reduce further soil displacement.” I think to myself as I squat down to dig enough soil to gingerly place the new addition to my project. I am about to get up when I hear a rustle next to me….dried leaves move, and so does the little wild colocasia that grows willy-nilly in the locality. “NOT A SNAKE” I tell myself- whether based on factual awareness or as a confidence-garnering delusion…I do not know. The sound is too big to be a field mouse. They are also a lot more careful than to move around when they sense the presence of a bigger animal. An injured bird would have responded to my presence even earlier. I’m exhausting my checklist quickly.

The Mesa at the Jheel-yard with some wild things that managed to clamber on their own and some I have tried to introduce.

I am a biologist by training and curious by nature. This combination is powerful but will probably also be my undoing. I move around, trying to not step on any dried leaves myself. i) I was too lazy to get into the warm stuffy gum-boots this morning. My German “Garten-schuhe” would not protect me from the sharp claws of a monitor lizard or the fangs of a snake for sure. ii) I am still on the paved bits, away from the grass. iii) Can I wrangle this beast with my gloved hands and the little stem-cutting clippers? iv) How about I skewer it with a stick like all those images of St. George slaying the dragon? Before more ridiculous scenarios of me wrangling this mysterious beast could crowd my mind, I saw something glistening in the sunlight filtering through the tall canopy of the Anjili and amongst the grass growing tall in its undergrowth. The glistening was fleeting but enough to gather data I needed: i) small size ii) has limbs and a tail iii)definitely reptilian iv)stocky v) ***MORE THAN ONE! I get closer, knowing it is not a snake or a monitor lizard. CRACK, I snap a twig and it breaks the stillness of this hot Sunday morning, echoing the sound of my own anticipation. The rustling in the grass stops and my view is obscured by a little wild colocasia I vow will be transplanted if I have my way. I pause, catching my breath and finding a position best allowing me to stay still without sore muscles later. As I settle for a vantage point close enough for my voyeuristic pursuit and far enough to get a head-start, the rustle startles me again.

There they are, two of them. “Skinks” I mutter, chiding my past self for her oh-so-silly fears and recalling their Malayalam name- Arana. I’ve been mostly working with social animals and social insects but the rule of thumb for most animals, especially if they are generally not ‘social’, is that when you encounter two of them interacting with each other- IT MEANS LOVE…OR WAR. The curious biologist strikes again. I decided to fight the heat and investigate. I have a clearer view of the two individuals now- their golden bands on their scaly dark skin and their red snouts and pits on the sides of their heads⁴. Not the thinner species of forest skink I have previously seen around the Jheel-yard. I had just last week spotted a little one doing its best to hide in the grass.

Now that my initial fears have been allayed, I yearn to get a better view to confirm the nature of this interaction. But my concerns and cautious tai-chi moves to optimise my viewing pleasure did not seem to interrupt these two. They circle each other and I see the head-bobbing. One starts and the other reciprocates with its own head-bob. Then the push-ups begin. One starts by showing off its strength and the other responds though I cannot ascertain whether it is a show of strength associated with territorial-display or courtship. They circle each other again- slowly cautiously…no biting…just the display. Cannot be the pursuit associated with courtship although I am not familiar with the specific behaviour of this particular species. But from what I know from the years of documentaries and books- THIS is a territorial dispute. One Arana is defending his territory between the massive roots of the Anjili from the competitor who wishes to claim it.

The best I could do- capture the drama unfolding between the roots of the massive Anjili in our yard.

I started filming the proceedings with my phone and cursed the wild colocasia blocking my view. But hey…that’s probably an important part of Defending Arana’s territory…I guess it can stay- or maybe it won’t matter to the Competitor Arana should it be the victor in this battle of the Anjili. I move around…seeking comfort in the fact that my subjects don’t care about my presence. Once I’ve taken enough videos, I figure this one…like many territorial disputes is a marathon and not a race. I figured I might be able to rush into the house and grab the camera for some better pictures. I also could get to a better place with less unstable soil for my photography, provided the skinks didn’t move. Well, 5 minutes later they were still there…still chasing each other’s tails. Though I know that phrase is used in the context of courtship and mating, this routine of head bobbing, pushups and slow cautious circular movements interspersed with sudden rustle-inducing lunges at each other, was lovely too. I wonder if the courtship and mating behaviour in the species is more short-lived than this tiff that has been going on for more than 20 minutes since I’ve observed it. The choreography and moves are reminiscent of many human displays of strength and virulence. I took as many photos as I could and there still seemed to be no obvious victor in this battle. I felt the heat more harshly on my back. The sweat was fogging my glasses and I couldn’t stand the tendril of an ivy tickling my leg. While the dance-off between the Arana continued in the undergrowth, I decided to graciously bow out of my own battle against the heat.

Circular movements and cautious steps, all the while keeping eye contact. Tango or Wrestling?

This photo of the two individuals was taken almost 20 minutes into the proceedings. I thought the battle was done but this was just a pause between bouts.

It’s been a few hours since my encounter with the Arana under the Anjili and all is as still as can be in that undergrowth adjacent to the Mesa. The result of this fateful Sunday morning tussle will remain a mystery. Should I encounter an Arana near that Anjili again, I will remember the resilience, persistence and “SICK” moves required to possess that PRIME territory of the Jheel-yard.

EPILOGUE:

The reptilian higher-powers decided to bless me for as I took a break from writing this post to get lunch, I saw what I wished to see but hoped not to see at the Mesa by the Anjili this morning. Imagine two of these giants in a fight- I’ve seen such a tussle in Malaysia when I worked with pig-tailed macaques. I ran to get my camera but the Udumbu or Ghorpad as I better know it in Marathi had had enough and showed extreme speed and dexterity in climbing down our wall and rushing across the road into the thicket ahead. 

The claws and size and strength I feared- those of the ‘udumbu’ or monitor lizard

See you soon

1. Jheel meaning Lake in Hindi is the name of my parents’ home in Parapinkara, Kerala. Its name was inspired by the water body that the front porch overlooks- a reservoir of the local dam. The “Jheel-yard” meanwhile, refers to all areas outside of the main house. A project close to all our hearts has been to repair the damage done by the years of rubber monoculture and erosion on this land prior to its purchase. Thanks to the efforts of my family and neighbours who understood our somewhat weird vision; the red-laterite soil representative of the state of Kerala, seems to have recovered. The Jheel-yard is now a haven for many trees and plants endemic to the Western ghats ↩︎
2. The area we call the Mesa was one I was first fascinated to see and my father pointed out that it was indeed an effect of weathering that such a formation was created…similar to what created the other famous Mesas such as the Tibetan plateau among others. I also like the fact that the Malayalam word for table is also “Mesha” sounds very similar to Mesa though I wouldn’t want to confirm the word’s etymology without further reading ↩︎
3. Our Mesa and the ‘bald spot’ ↩︎
4. My best guess as to the species -the stars of this show ↩︎

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