Arctic systems in the Quaternary: ecological collision, faunal mosaics and the consequences of a wobbling climate

Abstract

Climate oscillations and episodic processes interact with evolution, ecology and biogeography to determine the structure and complex mosaic that is the biosphere. Parasites and parasite-host assemblages are key components in a general explanatory paradigm for global biodiversity. We explore faunal assembly in the context of Quaternary time frames of the past 2.6 million years, a period dominated by episodic shifts in climate. Climate drivers cross a continuum from geological to contemporary timescales and serve to determine the structure and distribution of complex biotas. Cycles within cycles are apparent, with drivers that are layered, multifactorial and complex. These cycles influence the dynamics and duration of shifts in environmental structure on varying temporal and spatial scales. An understanding of the dynamics of high-latitude systems, the history of the Beringian nexus (the intermittent land connection linking Eurasia and North America) and downstream patterns of diversity depend on teasing apart the complexity of biotic assembly and persistence. Although climate oscillations have dominated the Quaternary, contemporary dynamics are driven by tipping points and shifting balances emerging from anthropogenic forces that are disrupting ecological structure. Climate change driven by anthropogenic forcing has supplanted a history of episodic variation and is eliminating ecological barriers and constraints on development and distribution for pathogen transmission. A framework to explore interactions of episodic processes on faunal structure and assembly is the Stockholm Paradigm, which appropriately shifts the focus from cospeciation to complexity and contingency in explanations of diversity.

Climate change will drive novel cross-species viral transmission

“…These “first encounters” between mammal species will occur everywhere in the world, but are concentrated in tropical Africa and southeast Asia (ED Figure 4). This result was surprising, and counter to our expectation that species might aggregate at higher latitudes, given that most research has focused on poleward range shifts 33,34,35 , and previous work has anticipated a link between climate change, range shifts, and parasite host-switching in the Arctic 36,37 . However, our findings show that communities tend to shift along latitudinal gradients together, with species rarely encountering new conspecifics 38 .…”

The Beringian Coevolution Project: holistic collections of mammals and associated parasites reveal novel perspectives on evolutionary and environmental change in the North

“…BCP collections are helping us to understand the implications of climate change for species distributions and community diversity (e.g., Baltensperger and Huettmann 2015;Hope et al 2015) and to monitor fundamental biological attributes such as life histories, life cycles, and parasite transmission dynamics (e.g., Kutz et al 2005;Jenkins et al 2006;Laaksonen et al 2015). For example, a series of discoveries based on field collections radically altered our understanding of the ungulate lungworm fauna in the Beringian region and broadly across the Holarctic (e.g., Hoberg et al 1995Hoberg et al , 2017Kutz et al 2001bKutz et al , 2007Jenkins et al 2005). Links between lungworm demography and climate were elucidated through the development of DNA sequence-based diagnostic methods that probed extensive archival samples from across the North American Arctic (e.g., Kutz et al 2012;Verocai et al 2014).…”

Insights about Diversity of Tetrabothriidae (Eucestoda) among Holarctic Alcidae (Charadriiformes): What Is Tetrabothrius jagerskioeldi jagerskioeldi? ?

“…Further, a sympatric assemblage of avian species is not required for transmission, as the influence of advective processes downstream and across insular systems may influence the distribution and availability of suitable and infected intermediate hosts in the water column, either limiting or expanding opportunity (e.g., Hoberg, 1995). These are dynamic systems where oscillations in temperature, water masses, production cycles, and cascades emanating from incremental climate warming and extreme events are predicted to be reflected in faunal structure for parasites (Hoberg et al, 2013(Hoberg et al, , 2017.…”

“…In an increasingly variable regime, stratification by temperature/salinity in the water column, changing water mass structure, and new current patterns, and connectivity will modify the distribution and availability of primary zooplankton and piscine prey that serve as intermediate hosts. Secondarily, a shifting spectrum for prey diversity, spatially and temporally, will influence transmission dynamics, occurrence, and abundance for a range of helminth and other parasites in marine birds (Hoberg, 1996(Hoberg, , 2005Mouritsen and Poulin, 2002;Muzaffar et al, 2005;Muzaffar, 2009;Hoberg et al, 2013Hoberg et al, , 2017. Anthropogenic disturbance related to fisheries and other factors will also directly influence the structure and diversity of helminth communities, especially among larids (e.g., Galaktionov, 1995;Galaktionov et al, 1993).…”

“…Consequently, parasites serve as direct indicators and as proxies for conditions in marine foodwebs over evolutionary and ecological time (e.g., Hoberg and Brooks, 2008;Hoberg et al, 2013). Parasite distributions demonstrate the outcomes of often subtle oscillations in atmospheric and sea-surface temperature, including regime shifts such as those of the El Niño Southern Oscillation and the Pacific Decadal Oscillation that initiate cascades in marine foodwebs on varying spatial and temporal scales (Mouritsen and Poulin, 2002;Chavez et al, 2003;Hurrell et al, 2003;Sydeman et al, 2015;Hoberg et al, 2017).…”