Contrasting forms of competition set elevational range limits of species

Abstract

How abiotic and biotic factors constrain distribution limits at the harsh and benign edges of species ranges is hotly debated, partly because macroecological experiments testing the proximate causes of distribution limits are scarce. It has long been recognized – at least since Darwin’s On the Origin of Species – that a harsh climate strengthens competition and thus sets species range limits. Using thorough field manipulations along a large elevation gradient, we show the mechanisms by which temperature determines competition type, resulting in a transition from interference to exploitative competition from the lower to the upper elevation limits in burying beetles (Nicrophorus nepalensis). This transition is an example of Darwin’s classic hypothesis that benign climates favor direct competition for highly accessible resources while harsh climates result in competition through resources of high rivalry. We propose that identifying the properties of these key resources will provide a more predictive framework to understand the interplay between biotic and abiotic factors in determining geographic range limits.

A chemically triggered transition from conflict to cooperation in burying beetles

“…Since blowfly species are diurnal and N. nepalensis is nocturnal, it is more likely that the presence of maggots influences N. nepalensis behaviour than the presence of adults. The blowfly treatment was conducted by exposing a 75 ± 5 g rat thawed carcass (a previous study showed that 75 g is optimal for offspring production of a pair of N. nepalensis ; Chan et al ) to oriental latrine flies ( Chrysomya megacephala ) in 32 × 32 × 32 cm fly cages for 50 h before the start of each experiment. We chose oriental latrine flies because this species is one of the most abundant species of blowflies in the study region.…”

Specialization of plant–pollinator interactions increases with temperature at Mt. Kilimanjaro

“…Interspecific species interactions are known to limit the diversity and distribution of species (Bairey, Kelsic, & Kishony, 2016;Bascompte, 2006;Bastolla et al, 2009;Chan, Shih, Chang, Shen, & Chen, 2019;Wisz et al, 2013), to promote species evolution (Ramos & Schiestl, 2019), and to determine ecosystem functions (Brosi & Briggs, 2013;Garibaldi et al, 2013). Much progress was made in understanding the structure and dynamics of species interaction networks (Bastolla et al, 2009;Blüthgen, Menzel, & Blüthgen, 2006;Olesen, Bascompte, Dupont, & Jordano, 2007;Petanidou, Kallimanis, Tzanopoulos, Sgardelis, & Pantis, 2008).…”

Locally-adapted reproductive photoperiodism determines population vulnerability to climate change in burying beetles

“…6, sensu ref. 32 ). During summer, we found a significant interaction between mountain range and the source population being transplanted.…”

“…To estimate beetle densities and determine breeding phenology at each site, we averaged the number of beetles by month because we replicated the experiments for~3 years. Adult burying beetles were collected using hanging pitfall traps baited with rotting pork 32,60 Fig. 1).…”

“…Since carcass preparation and burial, which occur above ground, are critical to the successful breeding of burying beetles, we believe that air temperature is an appropriate measure of environmental temperature (see also refs. 32,60,61 ). Although we acknowledge that soil temperature could be important for the larva development, those data are not available.…”