Scale dependent niche evolution
Ecological niche is an important concept for investigating core
ecological problems such as species coexistence, community assembly
rules. Understanding how niche divergence (evolving) will be beneficial
for theoretical study to species coexistence mechanism and make
predications for species distribution and community structure, give
hints for future conservation. Previous studies have provided evidences
supporting niche conservatism. For
example, based on field experiments with 32 plant species, Burns &
Strauss (2011) proposed that more closely related species are more
ecologically similar. Culumber & Tobler (2016) found that closely
related species in the two swordtail clades exhibited higher levels of
niche overlap than expected given environmental background similarity
indicative of niche conservatism. Hadly et al. (2009) suggested niche
conservatism above species level (genera and families) of North American
mammals.
However, counter evidences were also provided by some authors. After
comparing geographical parameters with molecular phylogenetic distances,
Knouft et al. (2006) found that
no general relationship exists between phylogenetic similarity and niche
similarity, with some examples in which closely related species display
niche conservatism and some in which they exhibit highly divergent
niches. Losos et al. (2003) also suggested niche lability in the
evolution of a Caribbean lizard community. Pearman et al. (2014)
proposed no evidence for past phylogenetic niche conservatism of a
European avian assemblage in climatic, habitat and trophic niches.
For these controversial results, Crisp & Cook (2012) stressed that
phylogenetic niche conservatism is a pattern, not a process, and is
found only in some traits and some lineages. Wang et al. (2015) also
mentioned that different dimensions of ecological niche may display
different evolutionary patterns.
According to our present results, we propose that niche evolution could
be dependent not only on niche dimensions, but also on scales. On a
large scale, niche may exhibit conservatism; while on a small scale,
especially when the species co-exist in one local area, competitive
exclusion principle may work, and the very closely related species may
exhibit larger niche divergence. It is interesting to note that some
very distantly related species showed trophic niche convergence in the
present study. We guess that these distantly related species could have
evolved differences in different niche dimensions, so they could share
similar trophic niche. In overall, we believe that our findings will
contribute to future theoretical and empirical niche explorations.
ACKNOWLEDGMENTS. We sincerely thank Qiaoling Deng, Xianglong Jiang,
Huaming Hu for collection of samples. Thanks are also given to Shufan
yang, Qiang Qin for their laboratory
assistance. This study was supported
by the Strategic Priority Research Program of the Chinese Academy of
Sciences (XDB31000000), National Key R and D Program of China
(2018YFD0900806) and National Natural Science Foundation of China
(31872234).