Climate impacts on transocean dispersal and habitat in gray whales from the Pleistocene to 2100

Abstract

Arctic animals face dramatic habitat alteration due to ongoing climate change. Understanding how such species have responded to past glacial cycles can help us forecast their response to today's changing climate. Gray whales are among those marine species likely to be strongly affected by Arctic climate change, but a thorough analysis of past climate impacts on this species has been complicated by lack of information about an extinct population in the Atlantic. While little is known about the history of Atlantic gray whales or their relationship to the extant Pacific population, the extirpation of the Atlantic population during historical times has been attributed to whaling. We used a combination of ancient and modern DNA, radiocarbon dating and predictive habitat modelling to better understand the distribution of gray whales during the Pleistocene and Holocene. Our results reveal that dispersal between the Pacific and Atlantic was climate dependent and occurred both during the Pleistocene prior to the last glacial period and the early Holocene immediately following the opening of the Bering Strait. Genetic diversity in the Atlantic declined over an extended interval that predates the period of intensive commercial whaling, indicating this decline may have been precipitated by Holocene climate or other ecological causes. These first genetic data for Atlantic gray whales, particularly when combined with predictive habitat models for the year 2100, suggest that two recent sightings of gray whales in the Atlantic may represent the beginning of the expansion of this species' habitat beyond its currently realized range.

Geographic and temporal dynamics of a global radiation and diversification in the killer whale

“…Localized shifts in habitat suitability may also have driven population fragmentation and changes in ice coverage likely influenced interoceanic connectivity, as noted in other marine species (Alter et al . , ). There was, however, regional release of habitat after the LGM, most notably off the Antarctic continent.…”

Tropical ancient DNA reveals relationships of the extinct Bahamian giant tortoise Chelonoidis alburyorum

“…cave environments greatly improve the probability of DNA survival relative to the external landscape [2]. Marine environments in general are also known to provide promising potential for DNA preservation, as evidenced by studies of Late Pleistocene remains retrieved from temperate oceans [22,62]. Although the estimated endogenous DNA content and preservation of the C. alburyorum sample is poor, it is nevertheless sufficient for mitogenome sequencing using methods optimized for the retrieval of aDNA.…”

“…The fossils were retrieved from anoxic saltwater, and were found to contain substantial collagen [20], suggesting at least the potential for DNA preservation. Although samples from temperate saltwater deposits have yielded endogenous DNA [21,22], the validity of a recent report on aDNA from a Mexican underwater cave [23] has been questioned [24]. Thus, the preservation potential of DNA in tropical aquatic or water-logged environments is poorly understood.…”

Melting barriers to faunal exchange across ocean basins

“…The gray whale currently occupies coastal margins of the North Pacific. Historically, the range of the Pacific population extended from Japan to Mexico along the continental margin, and an extinct North Atlantic sister population is known from subfossil remains in both the western and eastern North Atlantic (Mead & Mitchell, 1984;Bryant, 1995;Alter et al, 2015). Gray whales occupy the edge of sea ice ( Fig.…”