High vagility facilitates population persistence and expansion prior to the Last Glacial Maximum in an antarctic top predator: The Snow petrel (Pagodroma nivea)

Abstract

Aims: Pleistocene glacial cycles have had profound effects on the distribution and genetic diversity of high latitude species, which can vary with species-specific traits, such as vagility. Demographic responses of antarctic flying seabirds to the same events remain unassessed. We addressed this knowledge gap by studying the genetic population connectivity and demographic history of a flying seabird endemic to Antarctica, the Snow petrel. We hypothesize that their high vagility due to flight may represent an advantage over non-flying seabirds in enduring past climate variation.Location: Approximately 3,000 km of coastline in East Antarctica, covering three areas in Mac. Robertson Land, Princess Elizabeth Land and Wilkes Land. An inland location was also sampled at the Prince Charles Mountains, Mac. Robertson Land.Taxon: Snow petrel (Pagodroma nivea). Methods:We sampled 93 individuals and sequenced a total of 5,412 base pairs, including two mitochondrial genes, four anonymous nuclear loci and a nuclear intron. We used frequentist and Bayesian approaches to examine population genetic structuring and an Extended Bayesian Skyline Plot method to infer the demographic history of the species in the study area. In addition, evidence of exposed bedrock during glacial periods was summarized in maps of the studied area representing potential refugia for the species.Results: Differentiation indexes, genetic clustering and haplotype networks suggest long-term population connectivity for Snow petrels across the study area, with no evidence for reliction into refugia that were genetically isolated. Significantly, population expansions pre-dated the Last Glacial Maximum (LGM), but only where there was evidence of ice-free areas during this period. Main conclusions:The high vagility of Snow petrels may have been advantageous for access to foraging areas and supported large populations despite the harsh conditions during the LGM. Our results highlight that species-specific traits can exert a strong influence on demographic responses to the same environmental events.

Receding ice drove parallel expansions in Southern Ocean penguins

“…Recent demographic studies of penguins (Adélie, emperor, and king) (15,16,32) and the southern elephant seal (37), for example, inferred rapid postglacial recolonization events. By contrast, recent snow petrel analyses provide only limited evidence for such postglacial shifts (10). The choice of mutation rate, and possibly time dependency issues, might play some part in these apparently conflicting patterns among taxa.…”

“…Understanding past shifts in species distributions is crucial for forecasting responses to contemporary and future climate change. Currently, there is considerable uncertainty surrounding the extent to which high-latitude wildlife populations might have persisted in the Southern Ocean throughout the LGM versus the extent of post-LGM expansion (6,9,10). Recent genetic data, however, hint at major ecosystem-wide change following reductions in southern winter sea ice (9,11,12).…”

Selection against immigrants in wild seabird populations

“…However, this is unlikely to promote genetic differentiation between populations of the studied species since the proportion of immigrant recruits was high compared to the level of gene flow necessary to maintain panmictic populations (one effective immigrant per generation). Indeed, populations of wandering albatrosses exhibit little genetic differentiation across the species’ range (Milot et al ., 2008) as do populations of snow petrels in East Antarctica (Carrea et al ., 2019). Nevertheless, our results imply a lower contribution of immigrant recruits in population dynamics as compared with resident recruits.…”

Complete mitochondrial genome of the snow petrel, Pagodroma nivea

“…The species is a member of the family Procellariidae, order Procellariiformes, and is the only species representing the genus Pagodroma. It is divided into two subspecies (P. nivea and P. major) but taxonomic status remains controversial (Carrea et al 2019). Snow petrels exhibit broad geographic distribution and a large, relatively stable global population (Birdlife International 2020).…”

“…It is divided into two subspecies ( P. nivea and P. major ) but taxonomic status remains controversial (Carrea et al. 2019 ). Snow petrels exhibit broad geographic distribution and a large, relatively stable global population (Birdlife International 2020 ).…”