The family Soricidae, encompassing shrews, represents a diverse group of small (head-body length 30-178 mm) omnivorous or carnivorous mammals distinguished by unique morphological and physiological traits. Ecologically, shrews are dominant small predators, significantly impacting invertebrate populations. Their foraging strategies are diverse, with species adapted to fossorial, psammophilic, scansorial, semiaquatic, semifossorial, and terrestrial guilds. High metabolic rates necessitate nearly constant food intake, influencing their prey selection and feeding behaviors. Physiologically, shrews exhibit adaptations for thermoregulation, with Soricinae generally having higher mass-specific metabolic rates compared to Crocidurinae, who can enter torpor to conserve energy. These metabolic differences are crucial for their ecological distribution and competition dynamics, particularly in regions where the ranges of subfamilies overlap. Size plays a crucial role in shaping the biology of species, influencing aspects such as behavior, energy balance, thermoregulation, locomotion, and reproductive strategies. This study explores the ecological drivers of size variation with the family Soricidae. Using extensive skull and body measurements from a comprehensive literature review and detailed ecological data, this research examines the relationship between size and ecological factors such as foraging guild, biome, elevation, and venom presence. Larger sizes are observed in semiaquatic guilds and those with venom, while terrestrial species are generally smaller. Biome-related size variations align with metabolic and thermoregulatory adaptations. Additionally, range latitude and elevation significantly correlated with minimum and maximum size measures. These findings underscore the importance of ecological and evolutionary factors in shaping size within Soricidae, providing insights into niche partitioning and species coexistence in insectivorous mammal communities. Competition is a critical driver of speciation and adaptation, significantly shaping ecological communities. This study investigates the predictors of potential competition among shrew species using morphological character displacement as a proxy. I collected skull length (SL) and head-body length (HBL) data for 456 and 457 shrew species, respectively, from an extensive literature review. Using spatial analyses and linear modeling, I examined the relationship between character displacement and factors such as species richness, elevation, and distance from the equator across 1,000 shrew assemblages worldwide. The findings indicate that character displacement, and thus potential competition, increases with the number of shrew species, elevation, and distance from the equator. Conversely, the number of shrew genera negatively correlates with character displacement. Interestingly, the number of non-shrew insectivorous mammal species did not consistently predict competition levels. This study underscores the importance of morphological, ecological, and abiotic factors in shaping competition and adaptation in shrews. The complex interplay of these factors allows for the coexistence of numerous morphologically similar species, highlighting shrews as an ideal taxon for studying morphological diversification and niche differentiation.
| Identifer | oai:union.ndltd.org:siu.edu/oai:opensiuc.lib.siu.edu:theses-4291 |
| Date | 01 August 2024 |
| Creators | Holland, Wesley B |
| Publisher | OpenSIUC |
| Source Sets | Southern Illinois University Carbondale |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | Theses |
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