Data from: Patterns of trophic niche divergence between invasive and native fishes in wild communities are predictable from mesocosm studies

1. Ecological theory attempts to predict how impacts for native species
arise from biological invasions. A fundamental question centres on the
feeding interactions of invasive and native species: whether invasion will
result in increased interspecific competition, which would result in
negative consequences for the competing species, or trophic niche
divergence, which would facilitate the invader's integration into the
community and their coexistence with native species. 2. Here, the feeding
interactions of a highly invasive fish, topmouth gudgeon Pseudorasbora
parva, with three native and functionally similar fishes were studied to
determine whether patterns of either niche overlap or divergence detected
in mesocosm experiments were apparent between the species at larger
spatial scales. Using stable isotope analysis, their feeding relationships
were assessed initially in the mesocosms (1000 L) and then in small ponds
(<400 m2) and large ponds (>600 m2). 3. In the mesocosms, a
consistent pattern of trophic niche divergence was evident between the
sympatric fishes, with niches shifting further apart in isotopic space
than suggested in allopatry, revealing that sharing of food resources was
limited. Sympatric P. parva also had a smaller niche than their allopatric
populations. 4. In eight small ponds where P. parva had coexisted for
several years with at least one of the fish species used in the mesocosms,
strong patterns of niche differentiation were also apparent, with P. parva
always at a lower trophic position than the other fishes, as also occurred
in the mesocosms. Where these fishes were sympatric within more complex
fish communities in the large ponds, similar patterns were also apparent,
with strong evidence of trophic niche differentiation. 5. Aspects of the
ecological impacts of P. parva invasion for native communities in larger
ponds were consistent with those in the mesocosm experiments. Their
invasion resulted in divergence in trophic niches, partly due to their
reduced niche widths when in sympatry with other species, facilitating
their coexistence in invaded ecosystems. Our study highlights the utility
of controlled mesocosm studies for predicting the trophic relationships
that can develop from introductions of non-native species into more
complex ecosystems and at larger spatial scales.

Tran et al Journal of
Animal EcologyData for all aspects of
Tran et al. 2015, 'Patterns of trophic niche divergence between
invasive and native fishes in wild communities are predictable from
mesocosm studies'

Feb 02, 2016