Linking patterns of intraspecific morphology to changing climates

Abstract

Aim: This study examines how climate shaped Microtus californicus (Rodentia: Arvicolinae) ecomorphology throughout the Quaternary. It tests three hypotheses: (a) climate corresponds with consistent shape variation in M. californicus dentition; (b) Quaternary warming and drying trends caused M. californicus morphotypes to predictably shift in range through time and (c) Quaternary warming and drying led to predictable changes in tooth morphological variation. Finally, we discuss how shifts in climate-linked morphological variation may affect the potential of M. californicus to react to future climate change. Location: Western United States. Taxon: Microtus californicus (Peale, 1848). Methods: Geometric morphometrics and partial least squares analyses were used to discern how climate contributes to consistent variation in the shapes of the M. californicus lower first molar (m1), validated for the full toothrow. We further corroborate this relationship, reconstructing precipitation at fossil localities using m1 morphology and comparing those values to palaeoclimate-model-derived precipitations. Disparity analyses and a MANOVA were performed to examine changes in variation and whether a shift in tooth shape occurred through time. Results: Microtus californicus m1 and toothrow shapes are narrower and more curved in cooler, wetter climates. Morphology-based palaeoclimate reconstructions align with model-based palaeoclimate estimations. When time averaging is accounted for, M. californicus demonstrates a 12% reduction in variation from fossil to presentday specimens, and these changes in tooth shape correspond with climate-related morphotypes. Main conclusions: As California became drier and hotter since the late Pleistocene, M. californicus dental morphology generally tracked these changes by adapting to the consumption of rougher vegetation in drier environments. This resulted in the loss of some high-precipitation morphotypes, indicating that ecomorphology, often observed at the species and community levels, translates to intraspecific variation and dynamically changes in response to changing climates. The loss of climate-linked morphological variation since the late Pleistocene may limit the ability of M. californicus to respond to future changes in climate. These findings portend that other species may have experienced similar losses in adaptability.

Searching for Function: Reconstructing Adaptive Niche Changes Using Geochemical and Morphological Data in Planktonic Foraminifera

“…We define a trait as any morphological, physiological, phenological or behavioral feature measurable at the individual level (Violle et al, 2007). Traits are the avenue through which an organism interacts with its environment (biotic and abiotic) (Lacourse, 2009;Oksanen et al, 2019) and determine whether an organism survives or meets its demise in a changing environment (McGuire and Lauer, 2020). Thus, traits capture the most important aspects of the environment, and consequently it is the trait and not taxonomic identity that is crucial (Lacourse, 2009).…”

“…Taxon-free traits are a specific class of traits that transcend taxonomic classification and provide a commonality to allow comparisons across communities in different climatic and geographical settings (McGill et al, 2006). Often these traits are phenotypic such as dental morphology (e.g., Renaud et al, 2005;Žliobaitë et al, 2016;Oksanen et al, 2019;McGuire and Lauer, 2020), overall body geometry (Bregman et al, 2014;Pimiento et al, 2017;Macumber et al, 2020;Antczak-Orlewska et al, 2021;Di Martino and Liow, 2021) and, in our study system planktonic foraminifera, test morphology (Baumfalk et al, 1987;Huber et al, 1997;Renaud and Schmidt, 2003;Schmidt et al, 2004Schmidt et al, , 2006Payne et al, 2012;Rego et al, 2012;Weinkauf et al, 2014Weinkauf et al, , 2019Weiner et al, 2015;Brombacher et al, 2017;Kucera et al, 2017). Traits can also include ecological traits like habitat (Bregman et al, 2014;Pimiento et al, 2017) and feeding behavior (Bregman et al, 2014).…”

South Asian Monsoon Variability and Arctic Sea Ice Extent Linkages During the Late Pliocene

“…In Oscillayers, benthic δ 18 O records are first merged with Community Climate System Model Version 4 LGM-model simulations (Gent et al, 2011), and then extrapolated across the Plio-Pleistocene using the δ 18 O data. Oscillayers data shows a reasonably good match with independent time-slice GCM simulations (Gamisch, 2019) and has been used in several studies covering different time spans (Hölzchen et al, 2022;Lawing, 2021;McGuire & Lauer, 2020). ) is indicated by a closed blue circle.…”

Evolutionary Palaeoecological and Morphological Response of Globorotalia menardii to Environmental Stress Conditions Preceding the Tortonian–Messinian Boundary in the Mediterranean Basin

“…Such functional traits define the role of an organism in an ecosystem [45] at an individual level [46] and vary through time and space [47]. Given that the functional traits capture how an organism interacts with the environment, they dictate its fate during environmental perturbations [12,48]. For past environments, where we do not have the ability of direct observations for identifying them as for modern ecosystems, this can only be achieved with body-size-related measurements.…”