Falcidens aequabilis

A recent study published in the journal <a href="http://dx.doi.org/10.1111/brv.12931">Biological Reviews</a> has found that over one in six bird eggs fail to <a href="https://www.earth.com/news/neon-gobies-decide-when-to-hatch-their-embryos/">hatch</a>, and hatching failure increases as bird species decline. Moreover, the experts discovered that hatching failure is a much bigger problem in the case of captive threatened species, with nearly half of their eggs failing to hatch. These findings provide evidence that conservation managers could use in their decision making for creating the best possible outcomes for endangered bird species recovery.



By assessing 241 bird species across 231 previous studies to examine hatching failure, the researchers discovered that almost 17 percent of bird eggs fail to hatch, which is nearly double than the number reported four decades ago. These values are even more worrisome in the case of endangered species, with 43 percent of eggs from threatened species bred in captivity being unsuccessful in hatching.



“Around 13 percent of bird species globally are currently threatened with extinction, and things are getting worse instead of better. Species on the verge of extinction have much higher levels of hatching failure compared to non-threatened species, and breeding birds in captivity appears to be having a negative impact,” said study co-author Nicola Hemmings, an expert in Biosciences at the <a href="https://www.sheffield.ac.uk/">University of Sheffield</a>.



“There are important considerations that we need to make - does the benefit of captivity and other interventions outweigh the reduced reproduction of these species? For many species, these practices are absolutely vital for species survival, so we need to carefully weigh up the pros and cons of different approaches to ensure that we are doing everything that we can to protect birds from extinction.”



The scientists outlined four different conservation practices associated with lower hatching rates, including keeping birds in captivity, hatching eggs in artificial incubators, feeding the birds supplementary foods, and providing them with artificial nest boxes or sites. However, despite their potentially negative impact of hatching, some of these measures may still prove important to birds’ survival and reproduction. For instance, the eggs of some ground-nesting birds are at such a high risk of predation that leaving them in the wild would most likely result in their destruction.



“With this work we hope to provide vital evidence needed to understand how effective different management practices are at improving hatching success and aid population recovery,” said study senior author Patricia Brekke, a researcher at the <a href="https://www.zsl.org/science/users/patricia-brekke">Zoological Society of London</a> (ZSL).&nbsp;



“Conservation managers are doing an amazing job of preventing species decline, but they have an incredibly difficult job of making decisions when species are at the brink of extinction, on what tools to implement, and when. This kind of work provides the evidence necessary to improve decision making and hopefully improve recovery,” she concluded.



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By <a href="mailto:andrei.ionescu5891@gmail.com">Andrei Ionescu</a>, <a href="https://www.earth.com/staff/">Earth.com</a> Staff Writer



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Hatching failure rates increase as bird species decline

A recent study published in the journal Biological Reviews has...

A team of researchers led by the <a href="https://www.uc.edu/">University of Cincinnati</a> (UC) has recently discovered a new species of frog in Tanzania’s Ukaguru Mountains. The Ukaguru spiny-throated reed frog (Hyperolius ukaguruensis) has a distinct feature: it is among the few species of <a href="https://www.earth.com/news/why-do-frogs-have-fused-forearms/">frogs</a> in the world that do not vocalize at all. Belonging to a group of “spiny throated” reed frogs, it is characterized by the presence of tiny spines on the male’s throat, which the frogs use to recognize other members of their species.



“It’s a very odd group of frogs,” said study lead author Lucinda Lawson, a conservation biologist at UC. “The male frogs don’t call like most other frogs do. We think they may use the spine as something like Braille for species recognition. “Without a call, they need some other way to recognize each other.”



H. ukaguruensis belongs to a family of nearly 200 species in the genus Hyperolius. According to the experts though, it may be significantly different from other species from this genus. “With any Hyperolius, I can probably tell by looking at it whether it’s new or potentially new,” Lawson explained. “Immediately it was clear that it was a spiny-throated reed frog. But this one was a golden, greenish brown instead of the green color found in the other species. Sometimes color variation doesn’t mean anything, but it might here.”



A combination of genetic and genomic analyses confirmed that this frog was distinct from other members of Hyperolius, while measurements shown that it had unique body proportions, with smaller eyes in relation to its head than other spiny-throated reed frogs.



As many of its relatives, H. ukaguruensis is a critically endangered species and should thus be considered of high conservation concern, particularly since amphibians are highly susceptible to human impacts, such as deforestation. “If a bird’s habitat is destroyed, they sometimes can fly to a new forest. But that’s hard for amphibians,” Lawson said.&nbsp;



Conservation measures are highly important because having a diversity of species is crucial to maintain healthy ecosystems. “We think about this question a lot: why does one species matter?” Lawson said.&nbsp;“If this one species goes extinct, nothing much happens. We just lose one more strand in the fabric of the ecosystem. But if you keep pulling out strands, the ecosystem becomes destabilized and the fabric unravels,” she concluded.



The study is published in the journal <a href="http://dx.doi.org/10.1371/journal.pone.0277535">PLoS ONE</a>.&nbsp;&nbsp;



Image Credit: Christoph Liedtke



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By <a href="mailto:andrei.ionescu5891@gmail.com">Andrei Ionescu</a>, <a href="https://www.earth.com/staff/">Earth.com</a> Staff Writer



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Voiceless frog recently discovered in Africa

A team of researchers led by the University of Cincinnati...

Scientists have long argued that play is an indicator and promotor of animal health and welfare. Now, by applying in-depth empirical methods to analyze data gathered from around the world, a team of researchers led by the <a href="https://www.adelaide.edu.au/">University of Adelaide</a> in Australia has found that playing with your <a href="https://www.earth.com/news/can-you-tell-if-your-cat-is-playing-or-fighting/">cat</a> can also nurture closer human-cat bonds.



To investigate play-related factors associated with welfare in cats, the scientists devised an online survey in consultation with veterinarians, animal behaviorists, and cat owners, aiming to measure factors such as cat quality of life, cat-owner relationship quality, behavioral changes, and problem behavior prevalence.



“Our survey results, based on responses from 591 cat guardians from 55 countries, indicated greater cat playfulness and more types of games played were significantly associated with better cat quality of life,”&nbsp;said study lead author Julia Henning, a PhD student in Feline Behavior at Adelaide.



“Also, longer amounts of daily play, greater number of games, both cat and guardian initiating play, and heightened guardian playfulness were also associated with better quality cat-guardian relationships.”



Moreover, exclusive indoor housing for the cats was significantly linked with both increased cat quality of life and better cat-owner relationship in comparison to cats with outdoor access. “Behavioral changes that indicated stress, frustration, or unease were reported when play was absent. Therefore, we can conclude play may be a very important factor in assessing and maintaining cat welfare,” Henning explained.&nbsp;



However, as senior author Susan Hazel (an expert in Animal Behavior and Welfare at the same university) admitted, self-reporting surveys such as this often have significant limitations. “Cat lovers’ answers may be prone to respondent and recall bias and limited in their ability to assess behavior. Participants who dedicated their time and effort on a voluntary basis are more invested in their cat’s care than the average cat guardian. Therefore, responses may not be an accurate representation of the general population.”



Further research is needed to clarify how much and what kind of play is most efficient for improving cat welfare.



The study is published in the journal <a href="http://dx.doi.org/10.1017/awf.2023.2">Animal Welfare</a>.



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By <a href="mailto:andrei.ionescu5891@gmail.com">Andrei Ionescu</a>, <a href="https://www.earth.com/staff/">Earth.com</a> Staff Writer



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Cats have a better quality of life if you play with them

Scientists have long argued that play is an indicator and...

Symbiotic relationships are everywhere in nature. Fungi enhance water and <a href="https://www.earth.com/news/water-quality-threatened-by-nutrient-pollution-in-40-u-s-states/">nutrient</a> absorption for plants by feeding on their roots. Ants find food and shelter in tree structures, while insects defend the trees from being eaten. However, not all symbiotic relationships are created equal.&nbsp;



Some interactions are specific, where one host pairs off with only one other species. Others are general and flexible. Specific relationships have advantages, allowing the two species to reap mutual benefits and co-evolve. But this type of partnership can also come with a cost, where one partner exploits the other and takes more than it offers in return.



To investigate the evolutionary dynamics of specialization, researchers at the <a href="https://www.upenn.edu/">University of Pennsylvania</a> developed a model framework using game theory.



“Each interaction has very different dynamics,” said study senior author Erol Akçay. “Generalists may evolve to work better with more partners, specialists may be specializing to be more cooperative, and other specialists may be specializing to exploit better. Ours is the first study that gets at that dialectical nature of specialization, not just looking at specialization versus generalization.”



As an undergraduate student, Chris Carlson became interested in understanding why variations in generalism and specialism might persist.&nbsp;



Working with Akçay and Bryce Morsky, a model was developed that imagines the interactions of designated “hosts” with either general or specialized preferences and “symbionts” that provide and receive different benefits and costs from their interactions with various hosts.



The experts found that a cooperative partnering strategy, where both parties benefit, could persist in populations with one specialized host and a corresponding specialized symbiont. Depending on the benefits or payoffs, a generalist partnering strategy could also persist.



On the other hand, in partnerships where the host increased benefits while the symbiont reaped less, a more dynamic outcome arose. Different hosts and symbionts rise and fall in the population over time. Generalists were driven to extinction if the payoff was lower than that of being a specialist.&nbsp;



The researchers applied a spatial layer to their models to reflect that symbiotic relationships require that the two species involved encounter one another in space.



“Neighbors are going to be more likely to interact with neighbors, so who your neighbor is and how they interact can affect the outcome,” said Morsky



The team found that cooperative specialists could develop “patches” of dominance if they could move over short distances. If the payoff was high enough, generalists could persist around the periphery of these patches. If, however, hosts and symbionts could move over greater distances, just one host-symbiont pair could completely dominate a space.



“Let’s say you have a coral reef with different types of coral and different types of algae,” said Akçay. “If a host is a cooperative specialist, and the symbiont it specializes on gets fixed, the host does better, and therefore those hosts may expand. That creates specific spatial patterns that we were able to track.”



An overall takeaway is that cooperative specialization appears to be a valuable strategy, but it comes with risks. A host’s cooperating partner could go extinct, leaving the host without a symbiont.



The researchers hope their work lends insight into the variety of patterns of mutualisms that exist in nature and contribute to biodiversity.



“When people discuss specialization, this dualism is always in the background,” said Akçay. “This work helps bring it out and clarifies the tensions that exist between mutualisms.”



The research is published in the journal <a href="http://dx.doi.org/10.1093/evolut/qpac056">Evolution</a>.



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By <a href="mailto:katherinebucko@gmail.com">Katherine Bucko</a>, <a href="https://www.earth.com/staff/">Earth.com</a> Staff Writer



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How do symbiotic relationships evolve between species?

Symbiotic relationships are everywhere in nature. Fungi enhance water and...

Mammals exhibit a wide variety of social structures, including solitary, pair-bonded and group-living species. They also show an extreme 100-fold range in longevity, from around two years in shrews and mice, to 200 years in bowhead <a href="https://www.earth.com/news/can-whales-help-mitigate-climate-change/">whales</a>. This led Professor ZHOU Xuming from the Institute of Zoology at the <a href="https://english.cas.cn/">Chinese Academy of Sciences</a> (CAS) to wonder whether these two variables were linked.&nbsp;



Along with other researchers from the Institute of Zoology at the CAS, Professor ZHOU undertook an analysis of various traits found in 1,000 mammalian species, such as their maximum lifespan, body mass, sociality, lifestyle, ecological factors, life history traits, and phylogenetic relationships. The scientists searched published literature for information on these traits, and used the data to determine whether there is a link between sociality and longevity, while taking into account the possible influence of the other factors.



Previous research has usually focused on the effect of sociality on longevity within a single species. For example, chacma baboon females with strong and stable social bonds within a troop live longer than those with weaker bonds, due to better health, reduced levels of stress and increased vigilance against predators. Similar results have also been found for rhesus macaques.&nbsp;



The researchers used only three categories of sociality, dividing the 974 mammalian species into three types of social organization: solitary, pair-living, and group-living. They then compared models with different evolutionary conjectures between social organization and longevity across the mammalian species, using a Bayesian framework.&nbsp;



The results of the analysis, published in the journal <a href="http://dx.doi.org/10.1038/s41467-023-35869-7">Nature Communications</a>, showed that group-living species live longer than solitary species. These results suggest a correlated evolution between social organization and longevity. Even species that live in pairs had greater life expectancies than the solitary species. And this relationship held, even when the researchers controlled for phylogeny, body mass and factors related to external mortality, such as activity (diurnal, nocturnal or others), lifestyle (terrestrial, aerial, arboreal, semi-arboreal, freshwater, marine, or terrestrial-marine), and fossoriality (living underground or above ground).&nbsp;



The researchers then conducted a comparative brain transcriptomic analysis of 94 of the mammal species to identify genes that could underpin the correlated evolution of social organization and longevity. They hoped to detect candidate genes and pathways associated with both social organization and longevity, in order to elucidate the molecular mechanisms involved in this relationship.&nbsp;



The experts found that hundreds of genes were significantly associated with solitary living, pair-living, or group-living, and a total of 262 genes were significantly correlated with longevity. However, they crucially identified 31 genes whose expression levels were significantly associated with both social organizations and longevity. Some of these genes were involved with hormone regulation, but many were associated with immunity pathways. The researchers propose that “hormonal regulation and immunity constitute the mechanistic foundation for the association between social organization and longevity.”



The findings indicate that mammals living in groups have better innate immune responses, perhaps precisely because diseases and parasites can be spread so easily between group members. Indeed, previous research has shown that in captive group-living macaques, individuals with more social connections have enhanced immune responses when compared to those living in isolation or with few social ties.



"Our study provides insights into the correlated evolution of social organization and longevity and serves as a basis for experimental validation and follow-up studies on the mechanistic drivers of this correlated evolution," concluded the researchers.



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By <a href="mailto:bosman@truewan.co.za">Alison Bosman</a>, <a href="https://www.earth.com/staff/">Earth.com</a> Staff Writer



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Solitary mammals live shorter lives than social species

Mammals exhibit a wide variety of social structures, including solitary,...

The kākāpō <a href="https://www.earth.com/news/new-zealand-worlds-largest-parrot/">parrot</a> (Strigops habroptilus) is the only flightless parrot in the world and possibly one of the world’s longest-living birds, with a reported lifespan of up to a century. It is a nocturnal, herbivorous, sexually dimorphic bird, with a low basal metabolic rate and no male parental care.



Currently, this species is critically endangered, consisting of a total known population of only 249 individuals which are confined to four small islands off the coast of New Zealand that have been cleared of predators. Factors such as infrequent breeding, high infertility, and low hatching success significantly hamper conservation efforts and, while habitat restoration and predator control are useful strategies for enhancing survival, the problems related to reproductive output are those that limit recovery the most.



Now, a new study published in the journal <a href="https://doi.org/10.7717/peerj.14675">PeerJ Life &amp; Environment</a> has provided critical insights into the factors that affect the fertility of the kākāpō in order to improve conservation management efforts. These findings highlight the need for a balanced approach to conservation management that takes into account both the short-term benefits and the potential long-term negative impacts of hand-rearing and other management strategies.



According to the experts, hand-rearing – in which animals are raised in captivity by humans – should be limited as much as possible for males, since although it undoubtedly increases chick survival, it reduces clutch fertility. Thus, hand-rearing appears to affect copulation behavior in males more than females, in accordance with imprinting behaviors found in hand-reared male but not female parrots.



In addition, population densities should be maximized so there is a sufficiently high number of males at leks to ensure adequate mate choice for females, but the male:female sex ratio is kept only as high as the habitat can efficiently support. Finally, artificial insemination should be continued in order to ensure sufficient sperm competition, while increasing founder representation.



These findings emphasize the critical importance of collecting comprehensive longitudinal data and assessing similar effects of hand-rearing and sex ratios in other endangered bird species.



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By <a href="mailto:andrei.ionescu5891@gmail.com">Andrei Ionescu</a>, <a href="https://www.earth.com/staff/">Earth.com</a> Staff Writer



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New insights will help protect the kākāpō parrot

The kākāpō parrot (Strigops habroptilus) is the only flightless parrot...

A new analysis of finds from the Neumark-Nord archaeological site complex near Halle in Germany has provided the first indisputable proof of active hunting of elephants by <a href="https://www.earth.com/news/neanderthals-first-home/">Neanderthals</a>, changing our perception of these early hominins’ lifestyle and social organization.



The now extinct straight-tusk elephant (Palaeoloxodon antiquus) – a gigantic creature with a height of up to four meters and a weight of nearly 13 tons – roamed the landscapes of Europe and Western Asia between 800,000 and 100,000 years ago. The remains of over 70 such elephants were unearthed in the 1980s and 1990s during archaeological excavations in a massive lignite pit in the vicinity of Halle.



By closely examining these fossils, the scientists were surprised to find that they were almost exclusively body parts of adult male individuals. Further detection of clear and unusual lesions in the bones helped the experts infer that they were most likely hunted by Neanderthals during a period of over 2,000 years, for dozens of generations. “This constitutes the first clear-cut evidence of elephant hunting in human evolution,” said study senior author Wil Roebroeks, an archeologist at <a href="https://www.universiteitleiden.nl/en">Leiden University</a>.



According to the experts, since male adult elephants most likely kept to themselves, they were easier to approach closely without the protection of the herd, and were thus an easier catch for the early hominins. Moreover, since they were also larger, hunting them would have yielded more meat for significantly less risk.



Hunting and afterwards processing these massive beasts demanded close cooperation between the participating group members, suggesting that Neanderthals congregated in groups much larger than the approximately 25 individuals that scientists previously considered to be the maximum size of a local group. Moreover, the complexity of prey processing – entailing extensive butchering and drying products for long-term storage – provides evidence that Neanderthals may have had social and cultural means for large-scale food processing and storage.



“The intensity and nutritional yields of these well-documented butchering activities, combined with previously reported data from this Neumark-Nord site complex, suggest that Neanderthals were less mobile and operated within social units substantially larger than commonly envisaged,” the authors concluded.



The study is published in the journal <a href="https://doi.org/10.1126/sciadv.add8186">Science Advances</a>.



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By <a href="mailto:andrei.ionescu5891@gmail.com">Andrei Ionescu</a>, <a href="https://www.earth.com/staff/">Earth.com</a> Staff Writer



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Neanderthals hunted gigantic elephants for food

A new analysis of finds from the Neumark-Nord archaeological site...

Falcidens aequabilis

Taxonomic tree: