Biology subjects

Paijmans, J.

Publications and source records attributed to Paijmans, J..

5 recordsLinked to original sources

bioRxiv2025

Climate Shaped the Global Population Structure of Leopards and their Extinction in Europe

Environmental change is often invoked as a key force shaping species evolution and demography, but quantifying its role is challenging. Leopards (Panthera pardus), a widely distributed generalist species, provide an ideal case for studying the role of the environment. The population dynamics of African and Asian leopards differ dramatically, with near panmixia in Africa versus a strong structure and eight subspecies in Asia. Fossil records show that a population in Europe disappeared after the Last Glacial Maximum (LGM), further pointing to complex range dynamics in Eurasia. In this study, we explicitly test the role of climate in shaping leopards population dynamics across the continents, by quantitatively combining paleoclimatic, demographic, and genetic simulations over the last 450 thousand years. Using an Approximate Bayesian Computational framework, we show that the genetic structure differences between Africa and Asia can be explained by distinct historical climatic conditions in these two continents: most of sub-Saharan Africa and parts of Southeast Asia exhibited a stable range without geographical barriers, while other areas such as Morocco, Afghanistan and Northeast Asia showed expansion and extinction cycles during glacial and interglacials. We further model population dynamics in Europe and validate it against fossil and radiocarbon dates records. We find that European populations were likely fragile, with extinctions repeatedly predicted over multiple glacial cycles, indicating that climate change possibly led to the extinction of the European subspecies following the LGM. Notably, we found that climate during the Holocene should have allowed a more recent recolonisation that did not happen, indicating other factors such as human presence might have blocked it.

zoology↗

bioRxiv2024

Postglacial recolonization of the Southern Ocean by elephant seals occurred from multiple glacial refugia

The Southern Ocean is warming more rapidly than other parts of our planet. How this regions endemic biodiversity will respond to such changes can be illuminated by studying past events, through genetic analyses of time-series data sets including historic and fossil remains. Archaeological and subfossil remains show that the southern elephant seal (Mirounga leonina) was common along the coasts of Australia and New Zealand in the recent past. This species is now mostly confined to sub-Antarctic islands and the southern tip of South America. We analysed ancient seal samples from Australia (Tasmania), New Zealand, and the Antarctic mainland to examine how southern elephant seals have responded to a changing climate and anthropogenic pressures during the Holocene. Our analyses show that these seals formed part of a broader Australasian lineage, comprising seals from all sampled locations from the south Pacific sector of the Southern Ocean. Our study demonstrates that southern elephant seal populations have dynamically altered both range and population sizes under climatic and human pressures, over surprisingly short evolutionary timeframes for such a large, long-lived mammal. Significance StatementGenetic data, alongside historic, archaeological, and subfossil remains show that Australasian populations of the southern elephant seal have been shaped by range expansions and contractions following the Last Glacial Maximum, with subsequent contractions during the late Holocene. These expansion and contraction events are likely to have been a direct result of climate change-induced habitat expansion and contraction, along with Indigenous and European sealing. Prehistoric climate change and more recent human pressures have substantially altered the geographic distribution and population size of southern elephant seals over short evolutionary timescales.

ecology↗

bioRxiv2024

SNP panel for non-invasive genotyping of leopard (Panthera pardus)

Genetic resources for species monitoring should ideally be relevant for the species full distribution range, feasible economically and logistically, and validated for the range of sample types collected from the field. This is particularly important for large carnivores that are elusive and wide-ranging, where individual and population processes often traverse administrative borders, and where obtaining high-quality samples can be challenging. Here we present a small species-specific SNP panel for leopards. We used whole genome data from across the global range and RAD sequence data from Zambian leopards to select markers for assay development. These were ascertained for 590 individual leopards from eight African countries and final selection was based on marker variation and performance on non-invasive samples. The final 96 marker panel holds 5 mitochondrial markers for species recognition, 3 Y-markers for determination of individual sex, 3 X-markers and 85 somatic markers, with an associated genetic baseline holding nearly 900 individuals. The selected autosomal markers hold variation across the global range with high power to identify individuals (PID=2,45x10-35) and in most cases their provenance with high assignment probability (>95%). Markers were also selected based on their performance on samples with low target DNA content, with distinct genotype separation in the output marker plots. The genotypes from this panel are thus straightforward to analyze and do not require computationally challenging bioinformatic resources, making this a low cost and accessible resource for leopard monitoring and research.

genetics↗

bioRxiv2023

The everting Drosophila wing disc is a shape-programmed material

How complex 3D tissue shape emerges during animal development remains an important open question in biology and biophysics. In this work, we study eversion of the Drosophila wing disc pouch, a 3D morphogenesis step when the epithelium transforms from a radially symmetric dome into a curved fold shape via an unknown mechanism. To explain this morphogenesis, we take inspiration from inanimate "shape-programmable" materials, which are capable of undergoing blueprinted 3D shape transformations arising from in-plane gradients of spontaneous strains. Here, we show that active, in-plane cellular behaviors can similarly create spontaneous strains that drive 3D tissue shape change and that the wing disc pouch is shaped in this way. We map cellular behaviors in the wing disc pouch by developing a method for quantifying spatial patterns of cell behaviors on arbitrary 3D tissue surfaces using cellular topology. We use a physical shape-programmability model to show that spontaneous strains arising from measured active cell behaviors create the tissue shape changes observed during eversion. We validate our findings using a knockdown of the mechanosensitive molecular motor MyoVI, which we find to reduce active cell rearrangements and disrupt wing pouch eversion. This work shows that shape programming is a mechanism for animal tissue morphogenesis and suggests that there exist intricate patterns in nature that could present novel designs for shape-programmable materials.

biophysics↗

bioRxiv2016

Inactivation of thermogenic UCP1 as a historical contingency in multiple placental mammal clades

Mitochondrial uncoupling protein 1 (UCP1) is essential for non-shivering thermogenesis in brown adipose tissue and is widely accepted to have played a key thermoregulatory role in small-bodied and neonatal placental mammals that enabled the exploitation of cold environments. Here we map ucp1 sequences from 133 mammals onto a species tree constructed from a [~]51-kb sequence alignment and show that inactivating mutations have occurred in at least eight of the 18 traditional placental orders, thereby challenging the physiological importance of UCP1 across Placentalia. Selection and timetree analyses further reveal that ucp1 inactivations temporally correspond with strong secondary reductions in metabolic intensity in xenarthrans and pangolins, or in six other lineages coincided with a [~]30 million year episode of global cooling in the Paleogene that promoted sharp increases in body mass and cladogenesis evident in the fossil record. Our findings also demonstrate that members of various lineages (e.g., cetaceans, horses, woolly mammoths, Stellers sea cows) evolved extreme cold hardiness in the absence of UCP1-mediated thermogenesis. Finally, we identify ucp1 inactivation as a historical contingency that is linked to the current low species diversity of clades lacking functional UCP1, thus providing the first evidence for species selection related to the presence or absence of a single gene product.

evolutionary biology↗