Experimental removals reveal dietary niche partitioning facilitates coexistence between native and introduced species

mmerrick — Fri, 12 Jun 2020 18:49:10 +0000

Authors

Jonathan J. Derbridge

John L. Koprowski

1. Niche overlap between native species and ecologically similar invaders can lead to
competitive exclusion of threatened native species, but if two such species also
co‐occur naturally elsewhere, interactions between native and introduced populations
may mirror coevolved niche partitioning that reduces competition and promotes
coexistence.
2. A single, insular population of Fremont’s squirrel (Tamiasciurus fremonti) the Mount
Graham red squirrel (MGRS; T. f. grahamensis) in the Pinaleño Mountains, Arizona,
USA, is critically endangered and resource competition with introduced Abert’s
squirrels (Sciurus aberti) may threaten its long‐term persistence. The species are
naturally synoptic in other mountain sites, and both consume diets comprised primarily
of conifer seeds and fungi.
3. We conducted experimental removals of introduced Abert’s squirrels and used
stable isotope analysis of diets before and after removals, and of diets in naturally
syntopic populations to test the hypothesis that dietary niche partitioning can
facilitate coexistence between native and introduced species. We also developed
a novel approach to determine the influence of fluctuating food availability on
carbon enrichment in consumers.
4. Mount Graham red squirrels and introduced Abert’s squirrels partitioned the dietary
niche similarly to naturally syntopic populations. Removals had no apparent
effect. Diet of MGRS was more closely linked to availability of resources than to
presence of Abert’s squirrels.
5. Flexible dietary niche of introduced Abert’s squirrels may have allowed them to
exploit a resource opportunity in syntopy with MGRS. Variable food production of
MGRS habitat may intensify competition in poor years, and territorial defense
against non‐native Abert’s squirrels likely imposes fitness costs on individual
MGRS. Similarity in our model species’ diets may make MGRS more vulnerable to
competition if climate change eliminates the advantages of larder‐hoarding.
Where introduced populations of ecologically similar species are better adapted

Additional Information

Ecology and Evolution

Date of publication:

2019

Topics

coexistence

diet

introduced species

niche

wildlife ecology

Research Categories

Behavioral Ecology Invasive Species Sky Islands Threatened and Endangered Species

Should we consider individual behavior differences in applied wildlife conservation studies?

thackerk1 — Tue, 23 Jul 2019 23:14:47 +0000

Authors

Melissa J. Merrick

John L. Koprowski

Individually distinctive behavioral traits, or personalities, contribute to population-level processes and ecological interactions important in applied wildlife conservation research. Inter-individual variation in behavioral traits (personality) and correlation among behavioral traits (behavioral syndromes), can influence empirical estimates of population size and structure, models of resource selection and population dynamics, harvest and control in wildlife and fisheries populations, population response to disturbance and novel environments, and the success of reintroductions. Despite the important role that personality and behavioral syndromes play in the ecology and dynamics of wildlife populations, a disconnect between basic and applied research realms continues. While the concept of animal personalities and their role in ecology and evolution is increasingly embraced in the animal behavior, ecology, and evolutionary biology literature, it is less represented in applied wildlife management and conservation literature. We identify 10 research foci, often considered the domain of applied wildlife management and conservation, summarize examples of how these research domains may be influenced by personality and behavioral syndromes, and outline potential implications. We suggest that a focus on individuals in wildlife conservation study can bridge the gap between basic and applied research and incorporate knowledge from both realms towards more effective management, conservation, and recovery of populations.