Mammal species occupy different climates following the expansion of human impacts

Abstract

Cities and agricultural fields encroach on the most fertile, habitable terrestrial landscapes, fundamentally altering global ecosystems. Today, 75% of terrestrial ecosystems are considerably altered by human activities, and landscape transformation continues to accelerate. Human impacts are one of the major drivers of the current biodiversity crisis, and they have had unprecedented consequences on ecosystem function and rates of species extinctions for thousands of years. Here we use the fossil record to investigate whether changes in geographic range that could result from human impacts have altered the climatic niches of 46 species covering six mammal orders within the contiguous United States. Sixty-seven percent of the studied mammals have significantly different climatic niches today than they did before the onset of the Industrial Revolution. Niches changed the most in the portions of the range that overlap with human-impacted landscapes. Whether by forcible elimination/introduction or more indirect means, large-bodied dietary specialists have been extirpated from climatic envelopes that characterize human-impacted areas, whereas smaller, generalist mammals have been facilitated, colonizing these same areas of the climatic space. Importantly, the climates where we find mammals today do not necessarily represent their past habitats. Without mitigation, as we move further into the Anthropocene, we can anticipate a low standing biodiversity dominated by small, generalist mammals.

Disturbance type and species life history predict mammal responses to humans

“…These trade‐offs are particularly common for mammals, as greater resource availability and reduced competition or predation in human‐dominated landscapes (Bateman & Fleming, 2012; Moll et al, 2018) may offset the impacts of habitat loss and exposure to anthropogenic mortality (Hill et al, 2020; Sévêque et al, 2020). At the community level, the differential responses of species to human disturbance may have a filtering effect (Aronson et al, 2016; Santini et al, 2019), such that only species with “winning” combinations of ecological and life history traits (i.e., those suited to coexistence with humans) will persist in disturbed environments (Pineda‐Munoz et al, 2021). Human disturbance may, therefore, reshape mammal communities in ways that are predictable from suites of species traits, with implications for both single‐species conservation efforts and broader patterns of ecosystem functioning (Estes et al, 2011; Schmitz et al, 2018).…”

Scale‐dependent effects of niche specialisation: The disconnect between individual and species ranges

“…In comparison, ecological specialisation, that is, the range of resources or habitats a species can use, has received relatively little attention, but is also crucial for understanding species persistence in changing environments (Fernández & Vrba, 2005; Harcourt et al, 2002; Pyron, 1999; Schleuning et al, 2020; Sol et al, 2002). The loss of preferred resources and habitats might intensify climatic impacts (Peters et al, 2019; Pineda‐Munoz et al, 2021), or pose bigger threats to biodiversity than climate change per se, especially to endotherms like mammals (Khaliq et al, 2017). Therefore, we intend to fill this gap by directly focusing on ecological specialisation of terrestrial mammals along two niche axes related to the use of resources and habitats: the diet and habitat niche breadth.…”

Fire on the mountain—run, boys, run!

“…Since then, shifting environmental conditions have yielded a change in the realized niche of many species (Pineda-Munoz et al 2021), animal distributions have been altered (Thomas 2010), and conservation priorities have evolved (Parks et al 2020). Fire regimes are anticipated to change even further (Parks et al 2018 for review), and mitigation in the form of proactive measures-even in 'protected areas'-has been identified as desirable, or even necessary, to maintain biodiversity and facilitate population connectivity (Hannah 2008;Thomas and Gillingham 2015;Parks et al 2020;Pineda-Munoz et al 2021).…”