The Eastern Kunlun Tectonic Event and How It Intruded in the First Place

Silurian-Devonian Granites and Associated Intermediate-Mafic Rocks along the Eastern Kunlun Orogen, Western China: Evidence for a Prolonged Post-Collisional Lithospheric Extension

Jinyang Zhang Huanling Lei Changqian Ma Jianwei Li Yuanming Pan 

Summarized by Makayla Palm 

What data were used? The goal of this study was to gain insight into how the Kunlun mountain formation and surrounding area were initially formed. The Kunlun Mountain range primarily has an intermediate and mafic composition, with felsic granite intrusions, or dikes. Dikes are intrusions of magma that cut across previously formed layers and are an indicator of a secondary formation process. Depending on the mineral composition, or silica content, of these dikes (or intrusions) they will be either felsic, intermediate, or mafic, with felsic rocks containing the most silica. There are several kinds of secondary igneous rock formations found in the Kunlun called dikes. If the composition of the dike is different from the surrounding rock, this will provide insight into how the dikes formed in the Kunlun and how it can be explained using plate tectonic theory. 

Granite is a commonly found felsic rock in the Kunlun and is formed intrusively (or underground). The mineral contents of the granite can tell the researchers how fast or slow the magma cooled, which will ultimately help answer the question of how the dikes formed. Within the granite, there were zircon crystals present with radioactive uranium decaying into lead. These ratios were recorded in order to estimate ages within the mountain range to determine when the different magma-cooling events took place. To summarize, this paper uses physical samples of the igneous rocks in the area to study mineral composition and isotope data from these rocks, too. 

Methods: The samples that were collected from different rock types in this area were studied under a microscope in order to observe the composition and individual mineral grains. In plate tectonics, there are two kinds of plates: continental plates and oceanic plates. Granite (felsic) comprises less dense continental plates, while basalt (mafic) comprises a denser oceanic plate. In the Kunlun, the researchers observed several granite inclusions surrounded by mafic rock. The isotope ratios of uranium to lead were recorded and radiometrically dated. These data determine if the different intrusions formed at the same time, or if they formed during several events. This would help support or reject the hypothesis they posed that when the continental and oceanic plates collided, creating the Kunlun Mountains, the edge of the oceanic plate broke while bending under the continental plate (the oceanic plate always goes underneath a continental plate, due to higher density).

Results: The radiometric dating of the granite inside the intrusions (the magma formations added after the formation of the surrounding rock) indicated four different formation events, with the earliest taking place 427-414 million years ago (mya) and the latest from 373-357mya. (For more about how radiometric dating works visit Geologic Time.) The variation in the composition of the rocks (felsic, mafic, etc) indicates a complicated tectonic history; along with the multiple events of granitic intrusions, scientists also found ophiolites (oceanic crust that was pushed onto land during an oceanic- continental plate collision), which indicates that a piece of the oceanic plate was pushed up and broken off during the collision. 

A volcano sits on top of igneous rock layers. The volcano is not erupting, but has a magma plume underneath it. There are also intrusive igneous rock formations in the figure. There is a pluton (depending on its size, it is either a stock or batholith) and there are dikes cutting through the rock layers. The rock layers are labeled on the left side, in order of fastest cooling, smaller crystals on the top, to slower cooling, larger crystal sizes on the bottom. The pluton lies at the very bottom of this image with yellow magma.
This figure demonstrates the relationship of cooling rates to crystal sizes. Since the granite of the Kunlun has large crystals, it would be represented by a dike that was set deeper into the rock layers because of longer cooling periods. The lower horizontal layers represent the mafic layers of the Kunlun, which also had large crystals. Figure Citation: Beckett, Megan. Flickr, Siyavula Education , 23 Apr. 2014, https://www.flickr.com/photos/121935927@N06/13598553484/. Accessed 30 June 2022.

Why is this study important? This study looked to test the hypothesis of a broken oceanic plate’s impact on the formation of the Kunlun mountain range and gain more specific knowledge of its origin. By taking inventory of its intrusive rock formations, getting radiometric dating for these intrusions, and noting the differences in mineral compositions, they were able to confirm their hypothesized four magma events. These events represent different periods of magma formation, which confirms the researcher’s hypothesis about oceanic plate breakage during a collision. 

The big picture: Clues from igneous geology, such as large crystal size, rock type, and mineral composition can give researchers details on how large formation events took place. Isotopes within radiometric dating were used to separate events from one another and place them in chronological order. This particular study answered questions about the origin of the Kunlun Orogen, or mountainous landscapes.

Citation: Zhang, Jinyang, Huanling Lei, Changqian Ma,  Jianwei Li,  Yuanming Pan. “Silurian-Devonian Granites and Associated Intermediate-Mafic Rocks along the Eastern Kunlun Orogen, Western China: Evidence for a Prolonged Post-Collisional Lithospheric Extension.” Gondwana Research, vol. 89, Oct. 2021, pp. 131–146., https://doi.org/10.1016/j.gr.2020.08.019.

The Scars of a Mastodon’s Tusk and the Story it Reveals About the Mastodon’s Bachelor Experience

Male Mastodon Landscape Use Changed with Maturation (late Pleistocene, North America)

Joshua H. Miller, Daniel C. Fisher, Brooke E. Crowley, Ross Secord, and Bledar A. Konomi

Summarized by Makayla Palm 

What data were used? The tusks from a single male mastodon specimen (the “Buesching” mastodon, housed in the Indiana State Museum) that died in its early thirties were analyzed in two stages of its life (teenage and adult) in order to understand how, as a bachelor, it moved away from its herd and interacted with other adult mastodons in what was likely a breeding ground. The skull and tusks of this particular specimen have scratches, dents and markings likely caused from fighting with other males over potential female mates. These marks inspired researchers to focus on mating behavior; they hypothesized that the place where the mastodon fossils were found was the same location as its summer breeding ground. Scientists also examined modern-day relatives like elephants, which added insight into the following data: isotope changes in both oxygen and strontium and the growth “rings” of the tusks during teenage and adult years, which shed light on how the mastodon might have moved seasonally. 

Methods: In order to test the hypothesis of the mastodon’s seasonal moving in his later years, scientists examined and compared changes in tusk growth throughout its life. The exterior damage on the tusks was observed and recorded to factor into results. The mastodon tusks grew each year by depositing a ring of dentin, which is dense tissue that is bony, similar to what makes up teeth. By looking at the differences in the rings, scientists can determine changes in lifestyle. In particular, to learn about where the mastodon traveled, two different isotopes were measured: one to determine seasonal temperature changes (an oxygen isotope) and the other for change in environment and age (a strontium isotope).

Results: The visible damage observed on the mastodon’s skull is consistent with a hypothesis scientists proposed of males fighting for territory and mates. This happened in seasonal periods of musth, an annual event where male mastodons experienced extra fighting based on increased aggression while on the search for a mate, leading to increased clashing tusks in the height of mating season. The dentin growth deposits show evidence of low nutrition value in the same growth years the male would be expected to separate from the herd. There was also a noticed abundance of nutrients a couple of years later, inferring it had become successful on its own as an adult. Oxygen and strontium isotopic changes in the tusk show that the mastodon traveled to a warmer location around the same time each year; the two isotope ratios indicate a pattern of more frequent visits to its summer ‘bachelor pad’ (or breeding ground) and as the mastodon got older, it was able to travel further from its typical location. 

Two graphs represent the frequency in which the mastodon visited his breeding grounds. The first graph (on the left) represents his teenage years, and the second graph (on the right) represents his adult years. The adolescent years show no interaction at the fossil location site (where the mastodon bred and was later excavated), but consistent travel far away from the breeding ground. The adult graph shows consistent interaction at the breeding site, indicated with a red horizontal bar above the “near fossil location” label. The adult graph indicates the same consistent travel away from the breeding grounds as the adolescent graph, implying the addition of the breeding ground travel was an addition he found as he sexually matured.
The figure represents the changes in the oxygen isotope that indicate warmer temperatures. The warmer temperatures are inferred to be the mating grounds for this particular mastodon. This figure shows no interaction at this site in its adolescent years, but consistent interaction there as an adult. There is a consistent pattern where it left the breeding grounds in both teenage and adult years. The fossil location is where the mastodon was excavated.

Why is this study important? A male mastodon perished after fighting to the death for a mate. Its tusks were analyzed for growth patterns and changes in trace isotopes to better understand where the mastodon went, its pattern of seasonal travel, and its behavior throughout its lifetime.

The big picture: This story sheds light on the behavior of mastodons as they matured over time, as well as male behavior displayed during mating season. The quality of the preserved tusks allowed researchers to learn about this mastodon’s teenage and adult life and compare the differences over time. 

Citation: Miller, Joshua H.,  Fisher, Daniel C., Crowley, Brooke E., Secord, Ross and Konomi, Bledar A.  “Male Mastodon Landscape Use Changed with Maturation (Late Pleistocene, North America).” Proceedings of the National Academy of Sciences, vol. 119, no. 25, 2022, https://doi.org/10.1073/pnas.2118329119.

Learning About the Leopards in the Cederburg Mountains

Population size, density, and ranging behaviour in a key leopard population in the Western Cape, South Africa

Lana Müller, Willem Daniel Briers-Louw, Barbara Catharine Seele, Christiaan Stefanus Lochner, Rajan Amin

Summarized by Habiba Rabiu, a student of environmental geosciences at Fort Hays State University. Habiba is interested in all aspects of environmental science and conservation & sustainability. She would like to work in educating others about those topics. In her free time, she likes to read, write, and bake.

What data were used? The researchers chose an area in the Cederburg Mountains in Western Cape, South Africa, about 200 km north of Cape Town. In the Western Cape Province, there is about 50,000 km² of potential leopard habitat, but only 30% of it is in conservation areas or mountain catchment zones. The density of the leopard population in the province is among the lowest in the country with only 0.25–2.3 individuals per 100 km2, however their home ranges are relatively large (35–910 km²). The aim was to determine the number of individual leopards in the region and the amount of land they occupy.

Methods: The area of study chosen was 2,823 km² in size and 73 camera traps were set up with a mean distance of 2.78 km between each trap. The cameras were placed along any trails or natural features that the leopards were likely to come across or had shown evidence of having already been there. The cameras operated 24 hours a day and took three images each time they were motion-triggered. From the pictures taken, the leopards were manually identified and digitally differentiated using a software that could distinguish each leopard’s unique spotted pattern. 

In addition to the pictures, the researchers also used various software and databases to track the population size and density, site use, and ranging habits of the leopard population, as well as any livestock depredation (or attacks) that occurred. This information contributed to creating a more complete picture of the leopards in the area and their movements. One topic that required special attention was the difference between the leopard movements in winter versus the summer, as the changing seasons had a significant effect on how far the leopards had to move for food and other resources.

Results: From the photographs taken, 63 adult leopards were identified (31 females, 26 males, and 6 of unknown sex.) In the summer, the leopard density was estimated to be 1.62 leopards per 100 km² and more concentrated towards the center of the study area, while in the winter the leopards were more spread out, causing the density to decrease to 1.53 leopards per 100 km². In both seasons, leopard density was higher in females with a female to male ratio of 2.42:1 in the summer and 2.45:1 in the winter.

The leopards were found to be present in nearly the entire area studied, with a total of 2,638 pictures being taken of them at 95% of the camera traps. The habitat type and altitude of the different parts of the study area did not seem to make a difference in the leopards’ movement. As could be inferred from the density measurements, the female leopards tended to keep their activity within a smaller radius around the center of the study area, occupying an average space of 117 km² in the summer and 182 km² in the winter, while the male leopards had an average range of 456 km² in the summer and 856 km² in the winter. The average number of instances of livestock attacks did not appear to differ in number from previous research. The mean number of livestock killed was 7.7 during the summer and 14.9 during the winter.

Images are the same size and shape depicting an oval-shaped region. In the left image, the black dots, yellow circles, and red crosses are all situated towards the center of the oval, with little to no activity shown in the outermost ⅓ part all around. Both the black dots and yellow circles appear mostly in clusters, with a few outliers. In the right image, the black dots are shown mostly on the periphery of the oval, with a few clusters in the center. The yellow dots are slightly more spread out but are all situated towards the center of the oval, as are the red crosses.
The image on the left depicts movement of the adult female leopards in the winter, and the image on the right shows movement of adult male leopards. Activity centers are shown as black dots, capture locations as yellow circles, and trap locations as red crosses.

Why is this study important? This research is a thorough study of the leopard population in the Cederburg Mountain region that employed several methodologies and programs. It supports previous research regarding the average low density (less than 2 leopards per 100 km2) of the leopard population in the Eastern and Western Cape Provinces of South Africa. 

The big picture: Since 2016, leopards have been listed as Vulnerable on the International Union for Conservation of Nature’s Red List. This status is due to a variety of factors, many of which are anthropogenic, or human caused, including habitat loss, loss of food sources, poaching for sale or body parts, and killing by farmers attempting to protect their livestock. Tackling issues of conserving threatened animals requires precise data about the animals’ population and activity.

Citation: Müller L, Briers-Louw WD, Seele BC, Stefanus Lochner C, Amin R (2022) Population size, density, and ranging behaviour in a key leopard population in the Western Cape, South Africa. PLOS ONE 17(5): e0254507. https://doi.org/10.1371/journal.pone.0254507

New Species of Sea Anemone Found with Symbiotic Relationship to a Hermit Crab

Carcinoecium-Forming Sea Anemone Stylobates calcifer sp. nov. (Cnidaria, Actiniaria, Actiniidae) from the Japanese Deep-Sea Floor: A Taxonomical Description with Its Ecological Observations

Akihiro Yoshikawa, Takato Izumi, Taekya Moritaki, Taeko Kimura, Kensuke Yanagi 

Summarized by Michael Hallinan 

What data were used? 16 specimens of a new species of sea anemone (Stylobatus calcifer) were collected by beam trawl from Japan’s Sea of Kumano. All specimens were collected at a depth of 100 to 400m, with 6 of them being treated with ethanol immediately for DNA extraction. Most of the others were anesthetized and treated with a variety of chemicals for structural analysis, only one was further studied through behavioral observation prior to being treated with ethanol. In addition to the sea anemones, the shells used by the sea anemones and the symbiotic host hermit crabs were identified. 

Methods: S. calcifer is a symbiotic species, it lives on the mollusc shells used by hermit crabs of the species Pagurodofleinia doederleini. The collected specimens were removed from the shells they were sitting on and dissected allowing for further analysis using different mixes of chemicals to help preserve and support the dissected parts during this series of observations. Following the visual observation, DNA was extracted from four of the specimens and compared to other species, with further comparisons to the most closely related species to analyze if the specimens found can be attributed to a new species. In addition to this qualitative data, a series of observations between one of the specimens and hermit crab were made in a seawater aquarium. These observations focused on recording the anemone’s interactions with the hermit crab, centered around the hermit crab’s shell, as well as what happened when a new shell was introduced. These observations were recorded and provided as supplementary material.

Results: S. calcifer was identified to be unique in its DNA, the shape of one of the muscles that manages openings in the anemone, direction of its mouth system, as well as the size distribution of its prey-capturing parts. However what sets it apart from previously known species even more is its symbiotic relationship and interactions with the hermit crab P. doederlein. Once the hermit crab discovered and moved into a new shell, it began to detach the sea anemone and encourage the sea anemone to transfer to the new shell through a series of pinches. There was no initial reaction from the sea anemone, but after about 43 hours from the hermit crab getting its new shell, the sea anemone has completed the transfer with it, mounting and covering the new shell. This allows the anemone to move across the seafloor by their hermit crab and collect food, while avoiding injury by being mounted on top of the shell. While symbiotic relationships between hermit crabs and sea anemones are known for over 30 other species, a hermit crab induced transfer to a new mollusc shell has never been observed until now.

A series of graphics labeled A through F that depict the various stages of the transition for the old hermit crab shell to the new hermit crab shell. (A) The hermit crab which has left its old shell and already moved into the new one begins to tap the central body of the sea anemone. (B) It uses its front claws to pinch the top of the anemone and remove the sea anemone from the old shell. (C) There is a lack of shell-mounting action from the anemone after removal. (D) The sea anemone is then flipped upside down by the crab and its center is aligned with the shell. (E) Finally it settles in on the host hermit crab’s new shell.
Behavioral sequence of the hermit crab transferring the sea anemone from the original shell to the new one. (A) The hermit crab which has left its old shell and already moved into the new one begins to tap the sea anemone. (B) It uses its front claws to pinch and remove the sea anemone from the old shell. (C) There is a lack of shell-mounting action from the anemone after removal. (D) The sea anemone is then flipped upside down by the crab and aligned with the shell . (E) Finally it settles in on the host hermit crab’s new shell.

Why is this study important? This study has expanded our understanding of taxonomy regarding sea anemones, but also provided a great observation of symbiosis between the hermit crab and anemone which not only allows us to better understand how both function but also opens the door for future research about the association between the two. All of this knowledge can better improve our ability to conserve as well as better understand relative biodiversity.

The big picture: A new species of sea anemone was discovered to have unique structural properties regarding its mouth and prey-capturing parts as well as a very unique symbiotic relationship with a hermit crab. The anemone is encouraged to transfer from shell to shell by the hermit crab. It mounts the shell inhabited by the crab as a means of transportation so it can acquire food easier. This new discovery allows us to better understand both respective organisms and their patterns but also conservation regarding both.

Citation: Yanagi, Kensuke (2022/04/01). Carcinoecium-Forming Sea Anemone Stylobates calcifer sp. nov. (Cnidaria, Actiniaria, Actiniidae) from the Japanese Deep-Sea Floor: A Taxonomical Description with Its Ecological Observations. The Biological Bulletin, 242, 127-152. doi: 10.1086/719160

 

Invasive Mice Pose Risk of Extinction to Albatross Species

Cryptic population decrease due to invasive species predation in a long-lived seabird supports need for eradication

Steffen Oppel, Bethany L. Clark, Michelle M. Risi, Catharine Horswill, Sarah J. Converse, Christopher W. Jones, Alexis M. Osborne, Kim Stevens, Vonica Perold, Alexander L. Bond, Ross M. Wanless, Richard Cuthbert, John Cooper, Peter G. Ryan

Summarized by Michael Hallinan

What data were used? This study uses data collected on the breeding population of Tristan Albatross (Diomedea dabbenena) from 2004 to 2021 on Gough Island, in the southern Atlantic Ocean, where they almost exclusively live. All adult birds were marked and identified using metal rings for identification across annual visits during breeding season. This resulted in 4,014 albatross having encounter histories, and a very high probability that any breeding individual will have been detected if the nest had not failed early as they are faithful to their breeding sites. In addition to population metrics the number of nests per study area was recorded.

Methods: From the population size and demographic data an estimation of population trajectory, annual survival probability, and probability of returning to breeding grounds were calculated. These models were used to create population projections under three different scenarios. One scenario where mouse predation of the hatchlings did not change average breeding success and survival, one where mouse eradication lead to an increase in annual breeding success, and one where gradual increase of mouse predation decreases adult survival by 10%

Results: Generally, between 2004 and 2021 albatross breeding pairs didn’t seem to decrease statistically significantly. However, when also considering immature and non-breeding birds there was a detectable decrease in the global population of ~1% per year. Since albatross survival was quite high, this long-term decrease seems to be explained by low breeding success which is later investigated in the three scenario projections. Within these projections, under scenario A (where mouse predation stayed the same) the population steadily declined up through the model. Under scenario B (where successful mouse eradication occurred) the albatross population experienced an increase to 1.8-7.6 times its current size by 2050. Lastly, under scenario C (where no mouse eradication occurred and impacts worsened) the population declined significantly by 2050 with less than 2000 birds remaining.  

A shaded range line graph which presents observed breeding population and estimated total population from 2005 to 2021, as well as modeled total populations from 2021 to 2050. Breeding populations were consistently between 2000 individuals and 4000 individuals for this period with little variation outside of this range. The estimated total population however, begins at about 10000 individuals in 2005 and steadily decreases with some plateaus and peaks till about 8000 individuals in 2021. In addition, this graph then presents modeled data from 2021 to 2050 of each of the three scenarios. In scenario A (where no change occurs) the median population declines steadily from about 8000 to a little under 7000 individuals by 2050. In scenario B (where mice are successfully eradicated) the population experiences a median population increase up to just under 10000 individuals by 2050 but estimation errors result in a very wide credible interval which ranges from as high as approximately 17000 to a little under 8000 individuals in 2050. Lastly, in scenario C (where mice population increases and no eradication occurs) the median estimated population falls under 2000 individuals plus or minus 1000 by 2050.
This diagram shows observed population size on Gough Island between 2004 and 2021 (all data left of the dashed vertical line) where the black data points and regression represent the breeding population and the green line represents total estimated population size including unobservable immature and non-breeding birds.The three lines and intervals shown to the right side of the dashed line present the three scenarios through 2050. The lines represent the median values and the shading represents the 95% credible interval.

Why is this study important? The Tristan Albatross is classified as critically endangered based on a previous demographic analysis, finding that the species might go extinct within 30 years. This study creates a better projection for albatross population health under the three scenarios, which allows for significantly improved conservation efforts and a data-based sense of urgency regarding their conservation. 

The big picture: A series of Albatross population health and nest quantity data from 2004 to 2021 was recorded. It was used to model future population health development among three different scenarios regarding invasive mice predation on the albatross chicks. One where mice predation stayed the same, one where it got worse, and one where the mice were successfully being eradicated leading to increased albatross breeding successes.  If the mice were to be eradicated, albatross populations could experience a significant increase by 2050 with a population of up to 7.6 times today’s size. 

Citation: Ryan, Peter G. (2022/06/18). Cryptic population decrease due to invasive species predation in a long-lived seabird supports need for eradication. Journal of Applied Ecology, n/a, -. https://doi.org/10.1111/1365-2664.14218

Which trees are better suited for drought resistance and why?

Small and slow is safe: On the drought tolerance of tropical tree species

Joannès Guillemot, Nicolas K. Martin-StPaul, Leticia Bulascoschi, Lourens Poorter, Xavier Morin, Bruno X. Pinho, Guerric le Maire, Paulo R. L. Bittencourt, Rafael S. Oliveira, Frans Bongers, Rens Brouwer, Luciano Pereira, German Andrés Gonzalez Melo, Coline C. F. Boonman, Kerry A. Brown, Bruno E. L. Cerabolini, Ülo Niinemets, Yusuke Onoda, Julio V. Schneider, Serge Sheremetie, Pedro H. S. Brancalion

Summarized by Habiba Rabiu, a student of environmental geosciences at Fort Hays State University. Habiba is interested in all aspects of environmental science and conservation & sustainability. She would like to work in educating others about those topics. In her free time, she likes to read, write, and bake. 

What data were used? In this study, data concerning 601 tree species were examined. To determine what characteristics of a tree would make it more drought resistant, three qualities were assessed: resistance of xylem to embolism, which is the blocking of water from moving through the plant (designated as P50 by the authors), leaf turgor loss point or the ability of a plant to maintain turgor pressure and operate under water stress (TLP), and the hydraulic safety margin (HSM) which is the risk that a plant will experience hydraulic failure in the driest conditions it could normally face. HSM can also be defined as the difference between turgor loss point and resistance to embolism (HSM=TLP-P50).

The researchers compiled data from previous meta-analyses on the TLP and P50 values of the chosen tree species. The species were further divided based on leaf habit, meaning whether they were evergreen or deciduous. Additionally, seven traits of the species were considered: leaf mass per area (LMA), leaf size, leaf nitrogen concentration (leaf N), leaf phosphorus concentration (leaf P), wood density, maximum height, and seed mass. The type of forest the species lived in, whether dry or moist, was also a factor that was considered.

Methods: To organize these data in a way that would allow classification of the tree species based on drought resistance, the researchers found two major axes (traits) that contributed to drought resistance. The most important factor (labeled the “fast-slow” axes) showed the difference in rate of resource attainment and processing between the tree species. The second most important factor was the “stature-recruitment” axes, which compared the relationship between preference for (that is more energy and resources are allotted to) growth and survival of individual plants, to preference for new seedling propagation.

LMA, wood density, and leaf N and leaf P concentrations are features that determine where the species falls on the fast-slow axes, while maximum height, seed mass, and leaf size indicate their position on the stature-recruitment axes. TLP and P50 values (plus the calculated HSM values) demonstrate how well the species respond to lack of water and the accompanying stress. Lower values of HSM, TLP, and P50 (which are expressed as negative numbers) indicate more drought resistance.

Results:  The research determined that TLP and P50 (blocking of hydraulic action and the ability of the plant to maintain water pressure) were more negative in dry forests, and evergreen species tended to exhibit more negative TLP and smaller TLP- based HSM (risk that a plant will experience hydraulic failure) in dry forests than deciduous forests. The species that had the more negative TLP/P50 values and smaller HSM values tended to be smaller (leaned more to the recruitment side of the “stature-recruitment” axes) and slower to get and use resources (leaning towards “slow” rather than “fast” on those axes). In other words, smaller and slower evergreen trees were more drought resistant, and dry forests were naturally better suited to survive water stress than moist ones. 

Both graphs have an x-axis showing the properties P50, TLP, HSM, and leaf habit. The y-axis shows a range of R² in percentages from 0 to 60. Graph (b) shows P50 at around 30%, TLP around 60%, HSM around 10%, and leaf habit around 2%. Graph (c) shows P50 at around 37%, TLP around 1%, HSM around 20% and leaf habit around 1%.
The R² value shows the strength of the relationship between the qualities shown on the x-axis and the subject of the graph. Graph (b) shows that TLP is strongly related to the fast-slow axes, while (b) and (c) show that P50 has a similar relationship with the fast-slow axes and the stature-recruitment axes.

Why is this study important? One significant takeaway from this study is that it shows that drought resistance is not an independent quality that can be assessed on its own, it’s a complex mix of many traits. Isolating which traits are possessed by the most drought-resistant trees is valuable information when contending with ecosystems that are becoming hotter and drier as global warming becomes a bigger threat.

The big picture: Planting trees to restore tropical forests could be a great tool to combat the ill effects of climate change. However, care has to be taken to ensure that the trees planted are equipped to deal with the increased temperature of the atmosphere and presence of greenhouse gasses that come with global warming. 

Citation: Guillemot, J., Martin- StPaul, N. K., Bulascoschi, L., Poorter, L., Morin, X., Pinho, B. X., le Maire, G., Bittencourt, P. R. L., Oliveira, R. S., Bongers, F., Brouwer, R., Pereira, L., Gonzalez Melo, G. A., Boonman, C. C. F., Brown, K. A., Cerabolini, B. E. L., Niinemets, Ü., Onoda, Y. Schneider, J. V., … Brancalion, P. H. S. (2022). Small and slow is safe: On the drought tolerance of tropical tree species. Global Change Biology, 28, 2622– 2638. https://doi.org/10.1111/gcb.16082

Using Dinosaur Models to Learn More About Their Behavior

Digital 3D Models of Theropod Dinosaurs for Approaching Body Mass Distribution and Volume

by: Matías Reolid, Francisco J. Cardenal , Jesús Reolid

Summarized by: Makayla Palm 

What data were used? This study picked physical dinosaur models from eight different genera, or groups of dinosaur species, to scan and create 3D computer models. These models were used, alongside measurements collected from previous studies on each genus, in order to infer how these dinosaurs may have hunted, moved, and lived. The eight genera in the study were: Coelophysis, Dilophosaurus, Ceratosaurus, Allosaurus, Carnotautus, Baryonyx, Tyrannosaurus, and Giganotosaurus

Methods: Each model was scanned by a 3D printer in order to make a digital image. After the eight models were scanned, data on body length, collected in other studies, was added to the models. information was used in order to calculate body mass, volume, and skull length. These calculations were then used to make three ratios: skull length/body length, surface area/volume, and length/mass. 

Results: The three ratios calculated, skull length/body length, length/mass, and surface area/volume reveal information about these genera that wouldn’t be easily found by just observing the fossils, such as metabolism, eating habits, and overall roles in the ecosystem. The study first looks at the skull length/body length ratio. The larger a skull the dinosaur had, the larger and more expansive their jaws were. This is directly correlated to a higher demand for energy and higher body mass; a large skull was required to take down enough prey to fulfill energy demands. . If a dinosaur had a smaller skull, it was less equipped to take down larger prey, so this limits the kind of prey it had access to. In the case of Coelophysis, the oldest and smallest genus in the study, its skull/body length ratio infers that its small jaws were suited to smaller prey on land, but also small fish. In contrast, the larger theropods, Tyrannosaurus and Giganotosaurus, had the ability to hunt larger prey because of their large skull/body ratio. 

The next ratio observed was the length/mass ratio. This ratio considers differences in body plan that the skull/body length ratio does not. For example, Carnotaurus had a short skull in comparison to the other genera in the study, so it is the outlier in the group. However, the length/mass ratio accounts for its build, which recognizes its ability to hunt larger prey. Similarly, Baryonyx has one of the largest skull/body length ratios, but its long snout shape, similar to modern crocodiles, suggests it fed exclusively on fish and other swimming organisms, rather than large land-living prey. This ratio also sheds light on locomotion possibilities for these theropods. Allosaurus, a mid-size theropod, had longer arms than most other large dinosaurs like Tyrannosaurus. This suggests it may have used its arms when taking down large prey unlike its larger theropod comparisons, which are famous for their seemingly useless arms. 

The final ratio observed in this study is the surface area/volume ratio. This was used to study the efficiency of the dinosaurs to release excess heat, which has strong implications for metabolism. If an organism can release heat efficiently, it can have a higher metabolism, because high-metabolism organisms need that heat release. Researchers found that the smaller the dinosaur, the higher heat release, therefore a high metabolism and vice versa. This is consistent with the study’s findings on feeding habits. Coelophysis preyed on smaller organisms, but was probably able to do so more frequently. Tyrannosaurus hunted larger prey, but most likely needed to rest in between for significant periods of time because of its slower metabolism. 

A scatter-plot graph represents the different body mass and skull/body ratios of each theropod dinosaur genus . The overall trend is a positive exponential growth, which represents a consistent increase in these ratios over time, with Carnotaurus as the outlier because of its shorter skull shape. Coelophysis, the smallest of the studied genera, has the smallest body mass and skull-to-body length ratio and plots on the x-axis. Dilophosaurus, Ceratosaurus, Baryonyx, Allosaurus, Giganotosaurus and Tyrannosaurus all follow the curve of the graph and are listed here in order from smallest to largest skull to body length ratios. Carnotaurus, the outlier on the graph, has a point on the graph that lies close to the origin despite its slightly larger body mass.
This scatter plot displays each dinosaur’s body weight by skull-to-body ratio. As body weight increases, so does the skull/body length ratio. The outlier in the group is Carnotaurus, as its shorter skull gives it a smaller skull/body length ratio.

Why is this study important? This study allows observations of theropod dinosaurs to be made that would not be possible from studying just the bones. This data strengthens previous ideas about theropod behavior, such as larger dinosaurs need more energy and need to hunt larger prey. Therefore, their body structure is reflective of a creature able to take down the kind of prey it needs. This study also provides new information previously not available because of new data about metabolism and body surface area, such as a surface area/volume ratio, which indicates what dinosaur metabolism may have been. 

The big picture: This study of 3D scans of theropod dinosaurs infer information from new data by scanning to scale models. These data allow researchers to compare new measurements like surface area and volume to better understand what dinosaur metabolisms and body plans may have been like, which may confirm or reform what we already know about their roles in their respective environments. 

Citation: Reolid, Matías, et al. “Digital 3D Models of Theropods for Approaching Body-Mass Distribution and Volume.” Journal of Iberian Geology, vol. 47, no. 4, 2021, pp. 599–624., https://doi.org/10.1007/s41513-021-00172-1. 

How climate change and other factors have affected Caribbean reefs for 150 years

A century of warming on Caribbean reefs

Colleen B. Bove, Laura Mudge, and John F. Bruno

Summarized by Habiba Rabiu, a student of environmental geosciences at Fort Hays State University. Habiba is interested in all aspects of environmental science and conservation & sustainability. She would like to work in educating others about those topics. In her free time, she likes to read, write, and bake. 

What data were used? The researchers compiled data from three ocean temperature databases (HadISST, Pathfinder, and OISST) to assess changes in sea surface temperature (SST) and marine heatwave (MHW) occurrences in coral reefs situated in the Caribbean from 1871 to 2020. These data consisted of both in situ readings (those that were taken directly at the surface of the water from boats or buoys) and remote satellite readings. 

Methods: Using data from multiple sources, the researchers determined the locations of 5,326 coral reefs in the Caribbean. Referring to the World Wildlife Fund marine ecoregion classifications, these reefs were sorted into 8 ecoregions. From these data, they assessed the SST for the Caribbean basin as a whole, each ecoregion, and the individual reefs. They also assessed the frequency and duration of MHV events (periods of time, lasting at least five days, when the temperature of a marine area is abnormally high for that location and time) in the basin and the reefs. 

Results: Over the past 150 years, Caribbean coral reefs have warmed by 0.5-1˚C. As a whole, the Caribbean basin has experienced an increase of temperature at a rate of 0.04˚C per decade since 1871 and 0.17˚C per decade since 1981. The rate of increase in each ecoregion differed slightly, with the most recent measurements describing a range from an increase of 0.17˚C per decade in the Bahamian ecoregion to 0.26˚C per decade in the Southern and Eastern Caribbean ecoregions. 

 The frequency and duration of MHW have also increased, particularly since 2010. In the 1980s, MHW occurred once a year on average, which increased to an average of five times a year in the 2010s. This has drastically decreased the return time of the MHW events (the number of days between each event.) In the 1980s an average of 377 days elapsed between each MHW, while in the 2010s, an average of 111 days of return time was recorded. Additionally, recent MHW events have lasted for an average of 14 days compared to the 1980s when they typically lasted less than 10.

The figure shows a series of colored stripes, each of which represents one year from 1870 (on the left) to 2020. The higher temperatures are shown in dark red, which lighten to lighter red and pink as the temperature decreases. The coldest temperatures are shown in dark blue, lightening to paler blues as they get warmer. The left side of the figure (about 2/5 of it) shows mostly blue stripes, while the remainder is mostly pink and red, with the darkest red stripes on the rightmost side showing the late 2010s and 2020.
Stripe diagram showing the increase in mean annual temperature of Caribbean coral reefs, with warmer temperatures (max annual SST of 28.0) depicted in shades of red and cooler temperatures (min annual SST of 26.6) depicted in blue.

Why is this study important? Oceans make up the majority of the Earth’s surface, and the organisms that live there are being greatly affected by global warming and other degradational occurrences in the environment such as sewage pollution and pesticide runoff. Coral reefs are especially rich in biodiversity and contribute greatly to the overall health of the oceans. Given that most marine animals species are ectothermic (they have little to no internal/physiological control of heat and rely on their environment to regulate their temperature), drastic changes in temperature can affect their metabolism, alter their growth rates and caloric needs, cause disease outbreaks, and in some cases lead to the loss of a species entirely which further disrupts the food webs and other delicate systems of the ecosystem. 

The big picture: There are several factors that are causing the destruction of coral reefs, including overfishing (and other human activities), pollution, and overabundance of macroalgae (which thrives in warmer waters), but marine temperature increase has proven to be a primary factor, mainly due to how it causes coral bleaching (when algae is forcibly expelled from the coral, leaving it vulnerable). This is important because it shows that coral reefs are not only affected by regional and local activity, but also by global warming that is largely caused by the activity of first world countries, even if they are not necessarily close to the areas being affected. Halting the ruin of the reefs and other complex ecosystems will require global attention and effort, particularly from more populous, technologically advanced regions that use the greenhouse gasses that are increasing the temperature of the Earth’s surface.

Citation: Bove CB, Mudge L, Bruno JF (2022) A century of warming on Caribbean reefs. PLOS Climate 1(3): e0000002. https://doi.org/10.1371/journal.pclm.0000002

Ecologically diverse clades dominate the oceans via extinction resistance

Ecologically diverse clades dominate the oceans via extinction resistance

Matthew L. Knope, Andrew M. Bush, Luke O. Frishkoff, Noel A. Heim, and Jonathan L. Payne

Summarized by Anna Geldert

What data were used? Researchers examined taxonomic data of marine organisms across 444 million years of geologic time. Taxonomic data relates to the level of biodiversity of organisms, and classifies them under different evolutionary categories (domain, kingdom, phylum, class, order, family, genus, and species). On the whole, this study examined 19,992 genera (species groups) from the fossil record and 30,074 genera of living marine species..

Methods: This study examined speciation (origination) and extinction rates of marine species over the past 444 million years. Speciation refers to the evolution of new species, while extinction occurs when a species dies out; both factors impact the overall level of biodiversity. Net diversification rates (i.e., the difference between speciation and extinction rates) were calculated for each period  of geologic time. Additionally, researchers graphed a relationship between the species richness and ecological diversity at different points in geological time. Species richness refers simply to the number of species in a group, while ecological diversity indicates the number of “modes of life” present, such as varying habitats, levels of mobility, and feeding methods.

Results: An examination of the fossil record found that a high biodiversity among species groups could be reached in two primary ways: firstly, by a relatively short period of high speciation, and secondly, by a gradual increase over time due to average speciation and low extinction. While the first category tended to reach high biodiversity faster, they were more vulnerable to mass extinctions than the second group. Most species groups alive today, therefore, evolved via the second route. With respect to the relationship between species richness and ecological diversity, this study found a positive correlation between the two factors, meaning that a variety of life modes can be tied to having more species. 

The figure compares ecological diversity and species richness over the past 444 million years of geologic time. Species richness is graphed as the log10 of the number of genera on the x-axis, while ecological diversity (in log10 of the number of modes of life) is on the x-axis. The x-axis spans from 0 to 4 in increments of 1, while the y-axis spans from 0.0 to 1.5 in increments of 0.5. Several slopes in different colors are shown, with a legend indicating the geologic time to which the slope corresponds. The geologic stages of time included are: Silurian to Devonian (443.4 to 358.9 million years ago), Carboniferous to Permian (358.9 to 252.2 mya), Triassic (252.2 to 201.3 mya), Jurassic to Cretaceous (201.3 to 66.0 mya), and Paleogene to Neogene (66.0 to 0.0117 mya). The slope of the modern relationship between species richness and ecological diversity is also shown. Slope values range from approximately 0.20 to 0.32 and appear generally to increase steadily over time, with some overlap between geologic stages. The modern slope is approximately 0.30, and lies in the middle of the range of slope values for the Paleogene to Neogene category.
Fig 1. Relationship between species richness and ecological diversity of marine species from 444 million years ago to present.

Why is this study important? The results from this study reveal that, in the long run, rapid diversification within a species group is not sustainable because the majority of this species group is likely to be wiped out during a mass extinction event. On the other hand, gradual diversification in species groups that are able to survive mass extinctions is a more probable explanation for modern levels of marine biodiversity. These species were most likely able to survive mass extinctions due to higher levels of ecological diversity, a theory which would also explain why ecological diversity has been increasing compared to species richness over more recent eras. This study is important because it calls into question an accepted theory that directly links ecological diversity to speciation rates. While the results from this study likewise recognizes a correlation between these factors, it also implies that the relationship between the two factors may be more complex. It is only because species groups with high ecological diversity were able to survive mass extinction events that this correlation is seen so clearly today.

The big picture: This study is important in the larger field of evolutionary ecology because it impacts our understanding of how species evolve and respond to extinction pressures over time. Researchers should not assume that the tight correlation between species richness and ecological biodiversity implies a direct causational relationship, because as this study reveals, in many cases the relationship is more complicated than that. Further research is needed to fully analyze the role that ecological diversity plays in survival of mass extinctions.

Citation: Knope, M. L., Bush, A. M., Frishkoff, L. O., Heim, N. A., & Payne, J. L. (2020). Ecologically diverse clades dominate the oceans via extinction resistance. Science, 367(6481), 1035–1038. https://doi.org/10.1126/science.aax6398

 

44% of Earth’s land surface must receive conservation attention to stop the biodiversity crisis

The minimum land area requiring conservation attention to safeguard biodiversity

James R. Allan, Hugh P. Possingham, Scott C. Atkinson, Anthony Waldron, Moreno Di Marco, Stuart H.M. Butchart, Vanessa M. Adams, W. Daniel Kissling, Thomas Worsdell, Chris Sandbrook, Gwill Gibbon, Kundan Kumar, Piyush Mehta, Martine Maron, Brooke A. Williams, Kendall R. Jones, Brendan A. Wintle, April E. Reside, James E. M. Watson. 

Summarized by Michael Hallinan

What data were used? No new data was generated for this study, instead already existing data from different sources was combined in a new way. Spatial data about existing protected areas, key biodiversity areas, and ecologically intact areas was taken from the World Database on Protected Areas from February 2020 and 2017. In addition, data from the September 2019 version of the World Database of Key Biodiversity Areas was used, as well as animal distribution data from IUCN Red List and the BirdLife International Handbook. All this data was then merged to create an existing guide to important conservation areas as well as biodiversity. This is necessary to determine the existing species health and eventually predict future species health.

Methods: Using the animal distribution data, targets were set for what percentage needs to be conserved based on the range and quantity of each of the groups such as freshwater crabs, terrestrial mammals, and birds. Following this, an analysis on each species range and the determined important conservation areas was performed to identify what additional range may be needed as well as a potential lack of species in those areas. Then, a series of optimization analyses was performed on 30 x 30 km land units to determine which land would need to be conserved to reach those targets. Factors like cost, historical inquiry, human development, and the inability to perform agriculture as a result of conservation were also estimated. Finally, after all these considerations, potential areas for future conservation efforts were identified and outlined as different components. There are four components: Protected areas, which are areas outlined for general conservation; Key Biodiverse areas, which is land labeled for conservation of specific biodiversity; Ecologically Intact communities are ecological land which contain all the expected species within the ecosystem; and Conservation Priorities, which is land that requires conservation attention.

Results: Ultimately, the study estimates that the minimum land area that needs conservation attention to safeguard biodiversity is 64.7 million square kilometers (~24.9 million square miles), or roughly 44% of Earth’s terrestrial area. This 64.7 million comprises 35.1 million km of ecologically intact areas, 20.5 million of already existing protected areas, 11.6 million of key biodiversity areas, and 12.4 million km of additional land needed to promote species wellness in the smallest range possible. As for specific regions, this means 64% of the land in North America, and at least 33.1% of Europe’s land needs to be protected.

In addition to these spatial statistics, it’s also found that currently 1.87 billion people live on land that needs conservation attention, or approximately 24% of the world’s population with Africa, Asia, and Central America being the most affected due to high population density.  Approximately 55% of this land is located in developed economies such as Canada or Germany. As for the animal targets themselves, amphibians, reptiles, and freshwater animals were found to be below even half the target population . On the other hand, birds and mammals were found to be between 50 and 75% of the target population.

A map of the world, where terrestrial land is marked with protected areas, key biodiversity areas, ecologically intact areas, and additional conservation priorities identified. North America features many areas of key biodiversity with much of the United States being labeled as additional conservation priorities, specifically along the coast and the south-east. Canada is overwhelmingly labeled as ecologically intact with some already protected areas and some key biodiversity areas. Central America is heavily labeled as in need of conservation priorities with a relatively-high quantity of key biodiversity areas. South America consists of heavily protected areas in the Amazonas with many areas of additional conservation priorities along the coasts, and some key biodiversity areas. Large parts of identified areas in Europe are already protected, with some new conservation priorities near coastal regions and eastern Europe such as Belarus. Africa is mainly ecologically intact with the Sahara desert in the north, anda diverse mixture of protected areas, additional conservation priority areas, and key biodiversity areas across the whole continent. Next, Oceania has a large quantity comprising mostly protected areas and ecologically intact areas in central Australia with additional conservation priorities identified around the coast and neighboring island nations. Lastly, Asia is heavily ecologically intact towards the northern part of Russia, and becomes a mixture of protected areas, ecologically intact, and a heavy quantity of conservation priority areas as you go from the southern part of Russia through the rest of the continent. It’s also notable that China contains a large amount of the protected areas in the Himalayas.
This graph shows the protected areas (light blue), Key Biodiversity Areas (purple), and ecologically intact areas (dark blue), as well as new conservation priorities (green). The Venn Diagram to the left shows proportional overlap between features, showing that the majority of both the ecologically intact areas as well as the key biodiversity areas are currently not yet protected.

Why is this study important?: Land loss and conversion is one of the biggest threats to biodiversity. As climate change increases and human development expands, plants and animals become increasingly threatened and infringed upon leading to potential permanent damage, loss of life, and possibly even extinction. By performing studies like these, we can identify what areas are especially valuable, create action plans to remediate damage and support existing animal biodiversity.

This study identifies not only the amount of land needed, but also suggests where specific conservation attention needs to be focussed, as well as economic and social considerations that should be taken into account. In addition it needs to be kept in mind that historically, some conservation actions have adversely affected Indigienous people, Afro-descendants, and other local communities such as forcible removal of native populations off land in the name of conservation. By considering all of the social, economic, scientific, and historical factors that affect this issue, we can support the world around us better. 

The Big Picture: To safeguard biodiversity throughout future years, conservation attention needs to be given to an estimated minimum of 64.7 million square kilometers or roughly 44% of the Earth’s terrestrial land. This was estimated through mapping and data analysis of existing protected areas and existing species distribution data, which was then viewed on a global scale. Amphibians, reptiles, and freshwater animals are the furthest from the targets they need to meet to survive in the long run.The majority of the land which needs the most conservation efforts appears in developed nations. 

Citation: Allan, J.R., Possingham, H.P., Atkinson, S.C., Waldron, A., Di Marco, M., Butchart, S.H., Adams, V.M., Kissling, W.D., Worsdell, T., Sandbrook, C. and Gibbon, G., 2022. The minimum land area requiring conservation attention to safeguard biodiversity. Science376(6597), pp.1094-1101.