Ancestors

Written by Dimitris Kontopoulos on 2025-01-06 at 12:00

Thrilled to share my first main #paper from my #EMBO #postdoc fellowship that is out today in #FunctionalEcology: https://besjournals.onlinelibrary.wiley.com/doi/full/10.1111/1365-2435.14739 🥳

Read on to learn about the #evolution of #torpor among #mammals and #birds!

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Written by Dimitris Kontopoulos on 2025-01-06 at 12:16

Numerous species of #mammals and #birds can respond to challenging periods (e.g., lack of food or water, extreme cold) through #torpor.

Photo: a torpid Eastern chipmunk. Taken by @dl_levesque / @daniellelevesque.bsky.social, the 2nd author of this paper.

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Written by Dimitris Kontopoulos on 2025-01-06 at 12:20

[#]Torpor involves programmed and reversible decreases in metabolic rate, along with a drop in body temperature. Based on its duration, torpor in endotherms can be classified as daily torpor (<24 hours) or #hibernation (from days or weeks up to several months).

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Written by Dimitris Kontopoulos on 2025-01-06 at 12:22

A wide range of #mammals can enter #torpor, including 🐻, 🦔, 🐭, 🦇, and 🐵.

Similarly, many clades of #birds include torpor-capable species. Yet, only a single bird species (the common poorwill; public domain picture by Louis Agassiz Fuertes) is known to hibernate.

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Written by Dimitris Kontopoulos on 2025-01-06 at 12:23

To address 3 key questions regarding #torpor #evolution, we compiled a #dataset of a) torpor capabilities and b) 21 ecophysiological variables for 1,338 species of #mammals and #birds.

We then analysed this dataset using a series of #phylogenetic comparative methods.

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Written by Dimitris Kontopoulos on 2025-01-06 at 12:23

Q1️⃣: Are daily torpor and #hibernation evolutionarily distinct #torpor types or parts of a continuum?

Our results strongly support the continuum hypothesis. That is, evolutionary transitions between no torpor and hibernation generally require an intermediate daily torpor step.

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Written by Dimitris Kontopoulos on 2025-01-06 at 12:48

Q2️⃣: Can we predict whether a given species is capable of torpor based on its physiological and ecological characteristics?

Features associated with torpor include low body mass, nocturnality, and a resource-poor environment. Nevertheless, such associations are quite weak.

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Written by Dimitris Kontopoulos on 2025-01-06 at 12:51

Furthermore, torpor-capable species cover a wide range of physiological and ecological parameter space. The distribution of daily heterotherms and hibernators in this space is primarily taxonomically structured rather than environmentally structured.

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Written by Dimitris Kontopoulos on 2025-01-06 at 12:53

Q3️⃣: Was #hibernation present in early mammalian ancestors or did it evolve multiple times independently?

The argument for a single origin of hibernation in #mammals stems from its high degree of complexity, which would make multiple gains of hibernation difficult to occur.

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Written by Dimitris Kontopoulos on 2025-01-06 at 13:00

Some have also suggested that #hibernation might have been instrumental to the survival of #mammals during the K-Pg boundary.

In contrast to these, we estimated a low probability for hibernation in ancestral mammals, with multiple gains of hibernation being more likely.

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Toot

Written by Dimitris Kontopoulos on 2025-01-06 at 13:01

A scenario of several independent gains of #hibernation is also consistent with:

a) the pattern of evolutionary transitions among #torpor states (post 6 above), and

b) the fact that variation among torpor-capable species is predominantly taxonomically structured (post 8 above).

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Descendants

Written by Dimitris Kontopoulos on 2025-01-06 at 13:04

I would like to thank #EMBO and my coauthors for this very cool collaboration which allowed us to shed light on the origins of the amazing diversity in #torpor patterns of endotherms!

Stay tuned for more related work soon! 😉

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Written by Dimitris Kontopoulos on 2025-01-17 at 11:29

Here's also a link to a Plain Language Summary of our study: https://fesummaries.wordpress.com/2024/12/20/repeated-evolution-of-torpor-throughout-the-evolutionary-history-of-mammals-and-birds/

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Written by Dimitris Kontopoulos on 2025-01-27 at 09:13

The Senckenberg Society for Nature Research @SenckenbergWorld / @sgn.one also made a press release for our paper: https://www.senckenberg.de/en/pressemeldungen/just-five-more-minutes-news-on-the-evolution-of-hibernation/

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