The roles of morphological traits, resource variation and resource partitioning associated with the dietary niche expansion in the fish‐eating batMyotis pilosus

Abstract

Niche expansion and shifts are involved in the response and adaptation to environmental changes. However, it is unclear how niche breadth evolves and changes toward higher‐quality resources. Myotis pilosus is both an insectivore and a piscivore. We examined the dietary composition and seasonality in M. pilosus and the closely related Myotis fimbriatus using next‐generation DNA sequencing. We tested whether resource variation or resource partitioning help explain the dietary expansion from insects to fish in M. pilosus. While diet composition and diversity varied significantly between summer and autumn, the proportion of fish‐eating individuals did not significantly change between seasons in M. pilosus. Dietary overlap between M. pilosus and M. fimbriatus during the same seasons was much higher than within individual species across seasons. We recorded a larger body size, hind foot length, and body mass in M. pilosus than in M. fimbriatus and other insectivorous trawling bats from China. Similar morphological differences were found between worldwide fishing bats and nonfishing trawling bats. Our results suggest that variation in insect availability or interspecific competition may not play important roles in the dietary expansion from insects to fish in M. pilosus. Myotis pilosus has morphological advantages that may help it use fish as a diet component. The morphological advantage promoting dietary niche evolution toward higher quality resources may be more important than variation in the original resource and the effects of interspecific competition.

Food for everyone: Differential feeding habits of cryptic bat species inferred from DNA metabarcoding

“…Two main measurements of the trophic niche are classically used to characterize feeding ecology of interacting species: the trophic niche breadth, which allows to distinguish generalist from specialist feeding strategies (Lopes et al, 2015 ; Salinas‐Ramos et al, 2015 ), and the dietary niche overlap, which measures the extent of shared food resources between species (Aldasoro et al, 2019 ; Chang et al, 2019 ; Kartzinel et al, 2015 ; Leray et al, 2015 ; Sato et al, 2018 ). However, such ecological indices consider each prey species as a simple resource type, and do not account for information derived from the ecology of the prey itself (Spitz et al, 2014 ).…”

“…However, such ecological indices consider each prey species as a simple resource type, and do not account for information derived from the ecology of the prey itself (Spitz et al, 2014 ). Some authors relied on informal considerations about major prey groups or singular prey species hunted by co‐occurring bats (Chang et al, 2019 ; Salinas‐Ramos et al, 2015 ; Vesterinen et al, 2018 ), while others used comparative tests to assess habitat preferences of pairs of predators based on prey species assigned to different ecological categories (Razgour et al, 2011 ; Roswag, Becker, Drangusch, et al, 2018 ; Vallejo et al, 2019 ). More sophisticated approaches aiming to relate characteristics of multiple consumers to habitat or functional traits of their prey with RLQ approaches (Quéméré et al, 2013 ; Spitz et al, 2014 ) offer a promising analytical development.…”

Food for everyone: differential feeding habits of cryptic bat species inferred from DNA metabarcoding

“…Two main measurements of the trophic niche are classically used to disentangle feeding ecology of interacting species: the trophic niche breadth allows to distinguish generalist from specialist feeding strategies (e.g., Lopes et al, 2015;Salinas-Ramos et al, 2015), while dietary niche overlap measures the level of competition for food between species (e.g., Aldasoro et al, 2019;Chang et al, 2019;Kartzinel et al, 2015;Lerayet al, 2015;Sato et al, 2018). However, such ecological indices consider each prey species as a simple resource type, and little or no information is usually derived from the ecology of the prey itself (Spitz et al, 2014).…”

“…However, such ecological indices consider each prey species as a simple resource type, and little or no information is usually derived from the ecology of the prey itself (Spitz et al, 2014). Some authors relied on informal considerations about major prey groups or singular prey species (e.g., Chang et al, 2019;Salinas-Ramos et al, 2015;Vesterinenet al, 2018), while others used simple tests to assess habitat preferences of pairs of predators once prey species were assigned to different ecological categories (Razgour et al, 2011;Roswaget al, 2018b). Yet, more sophisticated approaches relying on multivariate statistical analyses exist to relate characteristics of multiple consumers to habitat or functional traits of their prey (Quéméré et al, 2013;Spitz et al, 2014).…”

Correlation of skull morphology and bite force in a bird-eating bat (Ia io; Vespertilionidae)

“…Like piscivorous bats [42], bird-eating bats fill a rare dietary niche that has expanded from low-to highquality food resources. Among the 1300 bat species, Nyctalus lasiopterus, N. aviator, Vampyrum spectrum, and I. io are known to regularly consume birds in addition to insects [43][44][45][46][47].…”