iiinova — where your digital self keeps evolving

Javier Abalos @abalosaurus.bsky.social · 24/08/2026

New reptile welfare paper by @bartolomealicia.bsky.social Captive lizards provided with three different enrichments (structural, nutritional, chemosensory) reduced their abnormal behaviours and their "stress hormone" levels in their poop! 🦎 #animalwelfare www.sciencedirect.com/science/arti...

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Javier Abalos @abalosaurus.bsky.social · 18/10/2025

Today I found out that the sex pheromones of Aplysia (a genus of extremely large sea slugs) are called: • Enticin 🌶️ • Attractin 👁️🫦👁️ • Temptin 🌺 • Seductin 🔥 And I find that wonderful. Please vote for your favorite. Credits to Trystam Wyatt's book on Pheromones and Animal Behavior. #ethology

An Aplysia sea slug, also called sea hares

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Javier Abalos @abalosaurus.bsky.social · 06/10/2025

Many wall lizards briefly sport bright blue tails as predator decoys after hatching. Our new study shows their throats and bellies also change color, yet at wavelengths invisible to humans! Could other species, too, undergo such cryptic shifts? @uv.es @ucciuv.bsky.social tinyurl.com/4rjfmde9 🧪🦎

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Javier Abalos @abalosaurus.bsky.social · 29/09/2025

Our discovery reveals a hidden stage in lacertid colour development that reshapes how we understand animal coloration as a signal, reminding us how central development is in communication and sexual selection across nature.

A young Podarcis muralis lizard doubts before crossing a crevice using a grass blade as a bridge. The first of many challenges he will face growing up!

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Javier Abalos @abalosaurus.bsky.social · 29/09/2025

These colour changes may let juveniles avoid costly aggression or courting from adult males, while sparing adults wasted effort on non-competitors/immature mates. As lizards grow, greater colour differentiation may aid recognition and help stabilize social networks.

Adult Podarcis muralis lizards rest on top a log during a mesocosm experiment.

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Javier Abalos @abalosaurus.bsky.social · 29/09/2025

Could these changes be adaptive? Predation avoidance often explains juvenile colour shifts, but in P. muralis that’s unlikely. Instead, a social role seems more plausible: ventral colour is usually hidden, yet adults display throats & flanks in social encounters

Adult males of Lilford's wall lizard (Podarcis lilfordi) from the island of Aire, close to Menorca. Two males are facing each other on yop if a log while adopting a raised-body posture that exposes the UV-reflecting spots and acts as a threat behavioral display.

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Javier Abalos @abalosaurus.bsky.social · 29/09/2025

By the end of their first year, most juveniles show adult-like ventral colours. But only some, mostly males, develop UV-blue spots on their flanks, and these look still very different from adult ones to conspecifics.

Ontogenetic changes in Podarcis muralis throat coloration. (A) Pie charts represent the proportions of juveniles showing different throat colors (UV+w = UV+white, UV−w = UV−white, oo = orange, yy = yellow, ow = orange–white, yo = yellow–orange) in September (t1; 3–4 weeks after hatching), and June–July (t2; 1 year after hatching). The three pie charts correspond to the full data set of 417 hatchlings measured at t1 (purple), the subset of 66 surviving juveniles measured as hatchlings at t1 (green), and these same juveniles measured as yearlings in t2 (yellow). (B) Reflectance spectra from the 62 surviving yearlings showing pure color morphs (solid lines and shaded area represent means ± SEM). The dashed purple line represents the average throat spectra of 417 hatchling lizards (similar to that of the 62 surviving yearlings when first measured, see central pie chart). Spectra have been normalized by subtracting the minimum reflectance of each spectrum at all wavelengths. (C) Mean and CI95 of the chromatic and achromatic distances (dS and dL respectively) between paired measurements of throat reflectance (i.e., within-individual hatchling-yearling contrasts), separated by yearling throat color. JND stands for “Just Noticeable Differences”. Two dashed lines at 1 and 3 JNDs represent two theoretical discriminability thresholds. If the confidence interval of a point includes a discriminability threshold, the two colors are not distinguishable at this threshold according to receiver cone sensitivities and relative abundance.

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Javier Abalos @abalosaurus.bsky.social · 29/09/2025

We found: 🦎 Hatchlings look white to us, but reflect far more UV than adults. 🦎 This “UV+white” is distinct and visible to lizards. 🦎 Ventral colours and UV flank spots develop out of sync. 🦎 Males and females diverge in timing and pattern.

Ontogeny of ventral coloration in Podarcis muralis. (A) Representative photographs of ventral coloration in a hatchling lizard 2–3 weeks after hatching (left), and in four yearlings re-captured in March 2019 (7 months after hatching). SVL stands for snout to vent length in mm. (B) Young male of P. muralis showing incipient UV-blue and melanin-based black patches in the outer ventral scales (OVS). (C) UV photograph of a hatchling P. muralis lizard showing UV+white color in its ventral surface. (D) Paired UV and visible photographs of the same subadult female (< 1 year) showing UV−white in the throat and UV+white in the belly. The difference is only apparent in the UV image. Photographs in C and D were obtained with a full-spectrum camera and two filters, each transmitting light either in the visible (400–700 nm) or the near-UV (320–380 nm) range. Brighter areas in the UV image have higher UV reflectance (i.e., hatchling ventral surface and female belly).

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Javier Abalos @abalosaurus.bsky.social · 29/09/2025

In our “new” study (it’s from 2018, research goes slowly…), we tracked wall lizards from hatching to one year of age. We reared them in semi-natural conditions, measured their colours using spectrophotometry, and modeled how other lizards perceive them.

Juvenile common wall lizard hatching from the egg.

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Javier Abalos @abalosaurus.bsky.social · 29/09/2025

Wall lizards (Podarcis if you're feeling fancy) are famed for dazzling color diversity matched by a UV-sensitive vision system. The widespread P. muralis shows ventral & lateral colors—including UV-reflecting spots and alternative throat colors— which likely play a role in social communication

Coloration in common wall lizard (Podarcis muralis). a) Alternative throat colours in males and females. b) Detail of UV-reflecting spots in the outer ventral scales. Extracted from Abalos et al., 2020 (https://doi.org/10.1002/ece3.6659)

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Javier Abalos @abalosaurus.bsky.social · 29/09/2025

Spectrophotometry shows that UV colours are widespread in nature, and visual models can help to reveal its meaning. UV often acts as a private communication channel invisible to many animals. Flowers may seem flamboyant to us, but their colours are tuned to dazzle bees.

Left, conventional photography of a flower. Right, photography of the same flower obtained with a full spectrum camera equipped with a filter that only transmits light in the UV waveband. Brighter (yellow) areas show higher UV reflectance. Animals with UV vision see a difference in coloration between the center of the flower and the petals that we can't see.

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Javier Abalos @abalosaurus.bsky.social · 29/09/2025

Understanding the function and mechanisms of ontogenetic colour changes (OCC) is a central goal in ethology. A bit of a challenge, though. Researchers must follow individuals as they grow, and some changes may slip by entirely if they occur in wavelengths beyond human vision.

Contrast of a tiger against a green vegetation background when viewed by their typical prey (a; deers and other cervids) and to a human viewer (b). Extracted from Fennell et al., 2019 (https://doi.org/10.1098/rsif.2019.0183)

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Javier Abalos @abalosaurus.bsky.social · 29/09/2025

Growing up is tough. The world juveniles face often looks very different from the one awaiting adults. Many animal species deal with these shifting challenges by changing colour. Think of wild boar piglets losing their striped pyjamas, or bright-fluffed chicks maturing into duller adult plumage.

Wild boar mother, showing a much duller coloration than her piglets, which show a striped brown and yellow pattern.

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Javier Abalos @abalosaurus.bsky.social · 17/05/2025

La osadía de llamar cobarde a un toro (un animal social y doméstico) por rehuir el maltrato en la plaza. Pobre Antonio, quiere que los toros pongan de su parte en su sangriento espectáculo amañado. La tauromaquia, como los gladiadores: mejor en el cine y los cuadros, donde nadie sufre @elpais.com

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Javier Abalos @abalosaurus.bsky.social · 16/04/2025

Free-roaming cats threaten island biodiversity, yet countries like Spain and Italy only permit trap-neuter-release. While the authors offer valuable tools to improve management, persistent myths like “neutered cats don’t hunt” remain. No wonder Maltese lizards are vanishing—kudos to the authors!

Maltese wall lizard (Podarcis filfolensis) in the island of Filfla

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Javier Abalos @abalosaurus.bsky.social · 13/04/2025

🧪 Is lizard iridescence really about predators or conspecifics seeing them from different angles? Unlikely. Just look at this female—curled up so her front looks brown and her back green. It’s probably a nice byproduct… or maybe the trick is the ever-shifting appearance itself? shorturl.at/jfjIw

Female Podarcis liolepis female showing off her iridescent dorsal coloration

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Javier Abalos @abalosaurus.bsky.social · 12/04/2025

Well, these are the images that you should have seen in the first post...

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Javier Abalos @abalosaurus.bsky.social · 12/04/2025

We are far from having all the answers yet. But we do have a lot of spectra, a pile of skittish lizards, and a theory or two. And one thing’s for sure: Same lizard. Different angle. Unexpected shimmer.

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Javier Abalos @abalosaurus.bsky.social · 12/04/2025

At the very least, it’s a funny hypothesis to speculate about. And honestly? Probably worth testing. Stop us if you dare

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Javier Abalos @abalosaurus.bsky.social · 12/04/2025

And there is another twist: because of a slight shift toward longer wavelengths in the spectral sensitivities of birds, these changes may be more apparent to avian predators than to lizards themselves! Is this a bug? A feature? A cosmic joke? We don’t really know. It could be a total byproduct

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Javier Abalos @abalosaurus.bsky.social · 12/04/2025

And here’s the kicker: how this iridescence is perceived depends on the lizard’s base colour. More greenish or olive lizards show spectral shifts that better match the cone sensitivities of birds, humans, and other lizards. So their shimmer stands out more across viewers!

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Javier Abalos @abalosaurus.bsky.social · 12/04/2025

You know how those birds’ colours shift when you tilt your head or they move in the sun? That’s iridescence—the colour changes with the angle between light and observer. Turns out, lizards do it too. Subtly, but spectacularly

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Javier Abalos @abalosaurus.bsky.social · 12/04/2025

We already knew wall lizards vary in colour depending on sex and locality—lets just leave why that happens for future rants. But this time, we found something new: they’re iridescent. Yes, like the fancy necks of mallard ducks or city pigeons

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Javier Abalos @abalosaurus.bsky.social · 12/04/2025

But we weren’t deterred. We measured their colours with spectrophotometers, modeled their vision (lizards don’t see like us!), and ran enough stats to make our computers sweat

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Javier Abalos @abalosaurus.bsky.social · 12/04/2025

You see, wall lizards aren’t just colourful. They’re 𝑐ℎ𝑎𝑜𝑡𝑖𝑐𝑎𝑙𝑙𝑦 colourful.Their hues change with light, season (in some species), viewing angle, and possibly the whims of ancient lizard gods. Which makes studying their coloration a bit like measuring the taste of a rainbow with a fork

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Javier Abalos @abalosaurus.bsky.social · 04/02/2025

Good luck innovating without researchers

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Javier Abalos @abalosaurus.bsky.social · 26/01/2025

The offspring's sex is determined by a genetic system akin to ours—but with a twist: males have 5 X chromosomes and 4 Y, while females have 5 pairs of X. I could go on forever, but we know surprisingly little about echidnas. Nature really outdid herself with these delightful oddballs!

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Javier Abalos @abalosaurus.bsky.social · 26/01/2025

Echidnas face a logistical challenge: their spiky backs make the usual "on top" business impossible. So the female digs a trench, lies on her side, and waits, probably feeling a bit embarrassed. Meanwhile, males fight for the honor of digging a parallel trench, positioning themselves for...well, yk.

A short beaked echidna in the bushy vegetation of Tasmania

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Javier Abalos @abalosaurus.bsky.social · 26/01/2025

Echidnas boast a four-lobed dingalong, which must meet with the equally complicated four-lobed juju. How? Through echidna conga lines. Up to ten males compete by queuing and following the female for two weeks. That’s how long it takes for her to feel “in the mood” for a little echidna romance.

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Javier Abalos @abalosaurus.bsky.social · 26/01/2025

Monotremes are known for laying eggs, but echidnas take it up a notch: they lay A SINGLE EGG into a seasonally-developed pouch. (Fun fact: the pouch was only confirmed as real in 2023. Yes, 2023. Wtf) But before that egg can exist, there’s the matter of reproduction, which is...complicated.

A short beaked echidna among bushy vegetation in Tasmania

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Javier Abalos @abalosaurus.bsky.social · 26/01/2025

Platypuses may have "outweirded" echidnas in the public eye, but that's likely due to echidnas being broadly "hedgehog-shaped," which feels deceptively familiar. Nonetheless, these guys are top-tier bizarre in ways that are so absurd it’s funny. #nature #tasmania #echidna #monotreme #wildlife

A short beaked echidna among the bushy vegetation in Tasmania

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Javier Abalos @abalosaurus.bsky.social · 15/01/2025

The absolute legend Lennart Edsman sent his thesis after I cited it in paper last year. When I started the PhD, my supervisor told me about this Swedish ethologist that finished his thesis on wall lizards social behaviour the year I was born. Feels like a nice torch-passing. tinyurl.com/yywm39vy

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Javier Abalos @abalosaurus.bsky.social · 15/11/2024

Lastly, I'm thrilled to describe an appeasement signal in lizards, often seen as ruthless and simple. I hope this study helps change misconceptions about the complex social lives of these misunderstood creatures. It may only take one foot shakes to call off the dance of dragons!

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Javier Abalos @abalosaurus.bsky.social · 15/11/2024

As territory owners switch between resident and intruder roles, motivational signals indicating contextual changes in subjective resource value become more informative to receivers than intrinsic quality signals, which convey information on developmentally fixed traits

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Javier Abalos @abalosaurus.bsky.social · 15/11/2024

In contrast, melanin comes out in our results as a non-signaling correlate of aggression; with darker males showing higher levels of aggression regardless of their mismatch with the opponent. Why pass on a potentially informative cue??

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Javier Abalos @abalosaurus.bsky.social · 15/11/2024

Both melanin and displays correlate with outcome, but only the latter seem to affect receiver behavior. Raised-body displays elicit bites from the receiver, while foot shakes significantly decrease the likelihood of being bitten during contests or chased after running away

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Javier Abalos @abalosaurus.bsky.social · 15/11/2024

Signals should correlate with contest outcomes and affect receiver behavior. Opponents with matching signals are expected to fight longer and escalate aggression, while winner advantage should attenuate contest intensity by making rival assessment easier

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Javier Abalos @abalosaurus.bsky.social · 15/11/2024

To illustrate the effect sizes, the odds for a darker male to win doubled with each standard deviation of rival asymmetry and tripled if he won the last fight. Raised-body displays made winning 7 times more likely, while foot shakes made it 17 times less likely!

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Javier Abalos @abalosaurus.bsky.social · 15/11/2024

Unlike melanin, we found little evidence supporting a role for UV-blue patches in contests, despite their strategic body location and spectral tuning to lizard vision. I wonder if these patches “simply” convey categorical information on the bearer’s signal maturity…

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Javier Abalos @abalosaurus.bsky.social · 15/11/2024

What’s the mark of the perfect lizard bully? Black coloration was the only individual-level correlate of winning contests, but the association was small when compared to that of behavioral displays and, to a lesser extent, whether the male's last contest was a win or a loss

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Javier Abalos @abalosaurus.bsky.social · 15/11/2024

We created sites of differing appeal: 80% of females settled in high-quality sites, while only 20% of (dominant) males did the same. These males won more fights, mingled with more ladies, and fathered more babies than their peers in LQ sites.

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Javier Abalos @abalosaurus.bsky.social · 15/11/2024

We then recorded behavioral data on the lizards' social interactions, focusing on male-male contests (N = 544), for roughly 30 days. Check this clip where a roaming male approaches a couple and gets bullied away by the resident male. Notice the foot shakes?

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Javier Abalos @abalosaurus.bsky.social · 15/11/2024

We infested 10 independent cells at the Metatron (SETE at @cnrs.bsky.social in Moulis) with lizards, creating 3 high- and 3 low-quality sites in each by varying rocks, logs, and bricks piled on top. Papers should have a "campfire stories" section to share how we moved 1.5 tonnes of crap!

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Javier Abalos @abalosaurus.bsky.social · 15/11/2024

Males approaching peers often adopt a raised-body posture, extending the throat, arching the back, and laterally flattening the body. It took us a while to notice that the social language of lizards also includes foot shake displays—rapid forelimb movements into the air. Meaning?

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Javier Abalos @abalosaurus.bsky.social · 15/11/2024

Adult male wallies (and some females) have a conspicuous pattern of UV-blue spots often surrounded by black melanin in their outer ventral scales (OVS). These colours are absent in newborn lizards and are thought to remain largely static after sexual maturity

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Javier Abalos @abalosaurus.bsky.social · 15/11/2024

During contests, adult male wallies show a suite of visual signals, comprising exposure of normally hidden static color patches and behavioral displays. This presents a unique opportunity to study the interplay between developmentally-fixed signals and behavioral displays

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Javier Abalos @abalosaurus.bsky.social · 15/11/2024

Springtime means fence-line feuds for Pyrenean male wallies. Males compete for resources that attract females, like sun-basking spots, sheltering crevices, and bug-rich vegetation. Female mate choice seems largely absent—they're more into prime real estate than flashy males

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Javier Abalos @abalosaurus.bsky.social · 15/11/2024

We tried to shed some light on understudied aspects of agonistic signaling by studying male-male competition in 10 enclosures with 90 male and 90 female common wall lizards (Podarcis muralis). Last chance to run before I tell you why these lizards (i.e. wallies) are awesome

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