Wednesday, February 12, 2025

Nighthawks: Wild medaka actively court female fish in wee hours

Field observations in natural river environment hold clues to easing model organisms’ life in labs

Osaka Metropolitan University

Medaka’s natural behavior — image:
Medaka have been found to be active late at night, with high levels of courtship behavior between 2 a.m. and 3 a.m.
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Credit: Osaka Metropolitan University

Observing animal behavior in a laboratory offers a controlled environment, but these model organisms can behave differently in the wild. An Osaka Metropolitan University-led research team that uses medaka in the lab has now clarified certain aspects of how these fish live in their natural environment.

Led by Dr. Yuki Kondo and Professor Satoshi Awata of the Graduate School of Science, the team recorded video of wild medaka in their river habitat to observe what goes on overnight, from 9 p.m. to 5 a.m.

Using this footage taken over a three-day period, they estimated the time of day when medaka spawn, finding that they start to spawn around midnight. Laboratory experiments had previously indicated that medaka spawned around one hour before or after sunrise.

The team also conducted a detailed analysis of medaka activity patterns, observing a low level of activity from 9 p.m. to 11 p.m. when many fish seemed to be resting. After midnight, there was a rise in activity, especially between 1 a.m. and 3 a.m. Medaka males appeared to have two types of courtship behavior: chasing females and a courtship display of making quick circles in front of the opposite sex. These behaviors were particularly high between 2 a.m. and 3 a.m.

“Observing animals in the wild is a valuable source of information for understanding their natural way of life, information that not only deepens our understanding of living things, but also helps us to create more comfortable environments for our model organisms in the laboratory,” Dr. Kondo explained. “If animals can spend their lives in the lab in a natural environment with little stress, we may be able to better understand their true nature, and more accurate laboratory research results might be obtained.”

Professor Awata added, “This research is a good example of the importance of combining laboratory research with field observations. We hope that it will also provide insights into the importance of elucidating the ecology of other model organisms in their natural habitats.”

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Medaka, small fish used as model organisms in the lab, are naturally found in freshwater streams.

Credit

Osaka Metropolitan University

About OMU

Established in Osaka as one of the largest public universities in Japan, Osaka Metropolitan University is committed to shaping the future of society through “Convergence of Knowledge” and the promotion of world-class research. For more research news, visit https://www.omu.ac.jp/en/ and follow us on social media: X, Facebook, Instagram, LinkedIn.

Journal

PLOS One

DOI

10.1371/journal.pone.0318358

Method of Research

Observational study

Subject of Research

Animals

Article Title

Medaka (Oryzias latipes) initiate courtship and spawning late at night: Insights from field observations

Article Publication Date

12-Feb-2025

Hate speech on X found to have increased under Elon Musk’s leadership

New findings contrast with X’s claims of reduced exposure to hate speech and bot activity

PLOS

X under Musk’s leadership: Substantial hate and no reduction in inauthentic activity — image:
Increases in hate speech for different dimensions of hate. Black lines represent standard errors.
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Credit: Hickey et al., 2025, PLOS One, CC-BY 4.0 (https://creativecommons.org/licenses/by/4.0/)

A new analysis suggests that the rate of hate speech on X was about 50 percent higher for several months after Elon Musk purchased the social media platform than in prior months, and the amount of bot and bot-like accounts did not decline. Daniel Hickey of the University of California, Berkeley, U.S., and colleagues present these findings in the open-access journal PLOS One on February 12, 2025.

Prior research has linked online hate speech to offline hate crimes, and bots and bot-like accounts can promote misinformation and spam that could cause harm, such as by contributing to scams, interfering with real-world elections, or hindering public health campaigns. Earlier studies have shown that, immediately after Musk purchased X, then known as Twitter, and became its CEO on October 27, 2022, hate speech increased on the platform, and the amount of bot or other inauthentic accounts did not decrease—despite Musk’s pledge to reduce bot activity.

However, it has been unclear whether such trends endured throughout the rest of Musk’s tenure as CEO, until June 2023. To address this gap, Hickey and colleagues employed previously developed methods to measure English-language hate speech and inauthentic activity on X during that period.

The analysis showed that a spike in hate speech that occurred just before Musk purchased X continued through May 2023. The weekly rate of hate speech was about 50 percent higher than in months prior to the purchase, including increased use of specific homophobic, transphobic, and racist slurs. The average number of “likes” on hate posts increased by 70%, suggesting that more people were exposed to hate speech on X. Meanwhile, the presence of bot accounts and other inauthentic accounts did not decrease and may in fact have increased.

These findings do not support public claims from X that exposure to hate speech decreased after Musk’s purchase.

The researchers note that, because information on specific internal changes at X is limited, they cannot draw firm conclusions about a cause-effect relationship between Musk’s purchase of X and their findings. Nonetheless, they express concern about the safety of online platforms and call for increased moderation on X as well as further research to illuminate activity across social media platforms.

The authors add: “The policies to reduce exposure to harmful content appear not to be sufficiently effective.”

In your coverage, please use this URL to provide access to the freely available article in PLOS One: https://plos.io/40V3E41

Citation: Hickey D, Fessler DMT, Lerman K, Burghardt K (2025) X under Musk’s leadership: Substantial hate and no reduction in inauthentic activity. PLoS ONE 20(2): e0313293. https://doi.org/10.1371/journal.pone.0313293

Author countries: U.S.

Funding: The full name of each funder DH is funded through the National Science Foundation (award #2051101; https://www.nsf.gov/), who did not play any role in the study design, data collection and analysis, decision to publish, or preparation of the manuscript. KL and KB are funded through the Defense Advanced Research Projects Agency (awards #HR0011260595 and #HR001121C0169; https://www.darpa.mil/), who did not play any role in the study design, data collection and analysis, decision to publish, or preparation of the manuscript.