Biology subjects

Szpak, P.

Publications and source records attributed to Szpak, P..

4 recordsLinked to original sources

bioRxiv2022

Impact of Holocene environmental change on the evolutionary ecology of an Arctic top predator

The Arctic is among the most climatically sensitive environments on Earth, and the disappearance of multiyear sea-ice in the Arctic Ocean is predicted within decades. As apex predators, polar bears are sentinel species for addressing the impact of environmental variability on Arctic marine ecosystems. By integrating genomics, isotopic analysis, morphometrics, and ecological modelling, we investigate how Holocene environmental changes affected the evolutionary ecology of polar bears around Greenland. We show that throughout the last [~]11,000 years, Greenlandic polar bears have been heavily influenced by changes in sea-surface temperature (SST) and sea-ice cover. Most notable are major reductions in effective population size at the beginning of the Holocene and during the Holocene Thermal Maximum [~]6 kya, which coincide with increases in annual mean SST, reduction in sea-ice covers, declines in suitable habitat, and shifts in suitable habitat northwards. Furthermore, we show how individuals sampled from west and east Greenland are genetically, morphologically, and ecologically distinct. We find bears sampled in west Greenland to be larger, more genetically diverse and have diets dominated by ringed seals, whereas bears from east Greenland are smaller and less diverse with more varied diets, putatively driven by regional biotic differences. Taken together, we provide novel insights into the vulnerability of polar bears to environmental change, and how the Arctic marine ecosystem plays a vital role in shaping the evolutionary and ecological trajectories of its inhabitants. TeaserMultivariate investigations of the environments role in the evolutionary ecology of Greenlandic polar bears.

evolutionary biology↗

bioRxiv2022

Sex and size matter: foraging ecology of offshore harbour porpoises in waters around Greenland

Individuals of different sex or age can vary in their resource use due to differences in behaviour, life history, energetic need, or size. Harbour porpoises are small cetaceans that rely on a constant prey supply to survive. Here, we use bone collagen carbon ({delta}13C) and nitrogen ({delta}15N) isotope compositions to elucidate sex and size differences in the foraging ecology of harbour porpoises from West Greenland. In this region, populations have a unique offshore, deep-water ecology. Female harbour porpoises are larger than males and we find that females have a higher trophic level than males, and {delta}15N positively correlates with size for females only. This indicates that size may matter in the ability of females to handle larger prey and/or dive deeper to catch higher trophic level prey. These results suggest that females, which also feed their calves, may be under different ecological constraints than males. We also analysed the harbour porpoise data with comparable stable isotope data from Greenland populations of belugas and narwhals. Consistent with their small body size, and a diet consisting primarily of capelin, we find that harbour porpoises have a lower trophic level than belugas and narwhals. Furthermore, harbour porpoises have the largest ecological niche of the three species, which is in accordance with tagging studies indicating they have a wide range in shelf and deep offshore waters of the sub-arctic and North Atlantic.

ecology↗

bioRxiv2021

Combining δ13C and δ15N from bone and dentine in marine mammal palaeoecological research: insights from toothed whales

Stable carbon ({delta}13C) and nitrogen ({delta}15N) isotope compositions of bone and dentine collagen extracted from museum specimens have been widely used to study the paleoecology of past populations. Due to possible systematic differences in stable isotope values between bone and dentine, dentine values need to be transformed into bone-collagen equivalent using a correction factor to allow comparisons between the two collagen sources. Here, we provide correction factors to transform dentine{delta} 13C and{delta} 15N values into bone-collagen equivalent for two toothed whales: narwhal and beluga. We sampled bone and tooth dentine from the skulls of 11 narwhals and 26 belugas. In narwhals, dentine was sampled from tusk and embedded tooth; in beluga, dentine was sampled from tooth.{delta} 13C and{delta} 15N were measured and intraindividual bone and dentine isotopic compositions were used to calculate correction factors for each species. We detected differences in{delta} 13C and{delta} 15N. In narwhals, we found (i) lower average{delta} 13C and{delta} 15N in bone compared with dentine; (ii) no difference in dentine{delta} 13C between tusk and embedded tooth. For belugas, we also detected lower{delta} 13C and{delta} 15N in bone compared with tooth dentine. The correction factors provided by the study enable the combined analysis of stable isotope data from bone and dentine in these species.

ecology↗

bioRxiv2021

Late Pleistocene palaeoecology and phylogeography of woolly rhinoceroses

The woolly rhinoceros (Coelodonta antiquitatis) was a cold-adapted herbivore, widely distributed from western Europe to north-east Siberia during the Late Pleistocene. Previous studies associate the extinction of the species ~14,000 years before present to climatic and vegetational changes, and suggest that later survival of populations in north-east Siberia may relate to the later persistence of open vegetation in that region. Here, we analyzed carbon ({delta}13C) and nitrogen ({delta}15N) stable isotopes and mitochondrial DNA sequences to elucidate the evolutionary ecology of the species. Our dataset comprised 286 woolly rhinoceros isotopic records, including 192 unpublished records, from across the species range, dating from >58,600 14C years to ~14,000 years before present. Crucially, we present the first 71 isotopic records available to date of the 15,000 years preceding woolly rhinoceros extinction. The data reveal ecological flexibility and geographical variation in woolly rhinoceros stable isotope compositions through time. In north-east Siberia, we detected{delta} 15N stability through time. This could reflect long-term environmental stability, and might have enabled the later survival of the species in the region. To further investigate the palaeoecology of woolly rhinoceroses, we compared their isotopic compositions with that of other contemporary herbivores. This analysis suggests possible niche partitioning between woolly rhinoceros and both horse (Equus spp.) and woolly mammoth (Mammuthus primigenius), and isotopic similarities between woolly rhinoceros and both musk ox (Ovibos moschatus) and saiga (Saiga tatarica) at different points in time. To provide phylogeographical context to the isotopic data, we analyzed 61 published mitochondrial control region sequences. The data show a lack of geographic structuring; we found three haplogroups with overlapping distributions, all of which show a signal of expansion during the Last Glacial Maximum. Furthermore, our genetic findings support the notion that environmental stability in Siberia had an impact on the paleoecology of woolly rhinoceroses in the region. Our study highlights the utility of combining stable isotopic records with ancient DNA to advance our knowledge of the evolutionary ecology of past populations and extinct species.

evolutionary biology↗